# 2002 VW Golf stealth SQ build (an engineering student's perspective)



## Justin Zazzi

I was first inspired by John Whitledge's sprinter van and his scientific approach. As an engineering student I knew the pursuit of sound quality in car audio was a matter of breaking down the process into smaller, more simple concepts. My goal was to learn as much as possible, re-use my existing gear, and change my installation a little at a time to hear the differences. I bought some books, found some excellent resources online, and signed up to be a judge for MECA events here on the west coast (best thing ever!).

This is the 2nd car I've built, the first was a 1995 Jeep Grand Cherokee and I built a transmission line subwoofer to experiment with low frequency extension (the in-car resonant frequency of that sub was 28 hertz and was an absolute joy, I miss it!). The same equipment is being used in both cars except for the subwoofer. Here is the list for the Golf:

Morel Hybrid Ovation 6.5" 2-way component speakers
Alpine PDX-5 5 channel amplifer
Eclipse CD7200 MkII head unit
Focal Polyglass 21 V2 8" subwoofer
sound treatments from Lowe's and sounddeadenershowdown

By experiencing many iterations of the installation in both cars, I am truly astounded by how awesome (and how terrible) the exact same gear can sound. It is so common to see people swapping out speakers and amplifiers because they don't like it, or their midbass driver is muddy, or their tweeter is harsh, or whatever. I am now a strong believer that good installation and good tuning are absolutely essential no matter what price range your speakers and amplifiers fall into.

The subwoofer, sound treatments, and passenger midbass are complete right now. I'll post some more this week, as I want to finish it for the meca competition this saturday in San Jose.









_the Jazzy-mobile_









_my 6 month old austrailian shepherd, she loves to "help" with whatever I'm doing, often borrowing tools and pieces of hardware_


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## Justin Zazzi

*Subwoofer: Cabin Gain and Getting Good Bass in Small Spaces*

This was pretty straight forward and similar to many other subwoofer builds in a small hatchback like my Golf. When I built the transmission line subwoofer for my Jeep, I knew I could change the geometry of the enclosure and drastically alter the frequency response. This was great because I could also measure the cabin gain, or transfer function, of the Jeep and adjust the geometry of the transmission line to match. This photo should help some:









_Matching subwoofer frequency response to measured cabin gain_









_Transmission line built for the Jeep_









_Installed resonant frequency was 28 hertz, like nothing I've ever experienced_

With the Golf however, I needed to keep all of my cargo space and had very limited options for a subwoofer. A sealed enclosure in the rear corner of the cargo area where the factory CD-changer is very common for this car, so I went with it. A sealed enclosure could not be tuned the same way a transmission line could be, so I didn't bother measuring the transfer function of the Golf. I did however pay close attention to the air volume of the enclosure I built.

The newly released Morel Ultimo SC 10" seemed like an excellent match for what I wanted with very low frequency extension and excellent sq reviews from countless sources. I only had about 0.6 cubic feet after the enclosure was built and decided a 10" would not be the best fit. After searching for a while, my local shop recommended the Focal Polyglass 21 V2 (8") and I was skeptical at first but it matched the power rating of my amplifier, matched the volume requirements of my enclosure, and was about what I wanted to spend on the Ultimo SC. It did have a low resonant frequency for an 8" woofer too.

Experimenting showed that having a subwoofer in the corner of a vehicle is better than placing it midway between the front and rear, or anywhere more than a foot or two away from each boundary of the interior (floor, side, and rear hatch). Reading both books I bought (linked in first post) confirmed placement has a huge effect on which frequencies are reinforced and which are cancelled. Ingvar Öhman has summarized it better than I can:



> A good starting point is to try to get as many reflections as possible in phase (preferably all three; floor, rear wall and side wall), to arrive in phase with the direct radiation for the entire working range of the subwoofer (typically 20- 80 Hz). This means that no path via a reflecting surface should be more than a quarter of a wavelength longer than the direct path.
> I practice, this means that no adjacent surface should be at a longer distance than 1/8 of a wavelength from the driver in the subwoofer. (Since the sound then will travel a quarter of a wavelength to go there and back). The wavelength at 80 Hz is 340/80 = 4,25 meters, and 1/8 of a wavelength becomes 53 cm. The subwoofer driver should be placed within this 1/8 wavelength sphere.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> _text and image borrowed from The placement of a subwoofer_


Now I knew what driver to use and where to put it and I just had to build it. This was the first time I've tried to fiberglass into a tight space and my first attempt at using a mold (the factory carpet lining of that cargo pocket). I started by removing that section of carpet, expanding the shape a little using carboard to get maximum air volume, then applied a layer of tape over everything, then a layer of aluminum foil so the resin would hopefully release after curing. The fiberglassing went well and conformed to the shape very well, but unfortunately it did not fit well back into the car because I made mistakes preparing the mold and didn't allow enough clearance on all sides (also the carpet mold was floppy and not the best idea). trim trim trim trim sand sand sand sand ....









_the cardboard expansions, tape, and foil all laid out on top of the carpet mold_









_first layer of fiberglass applied using lightweight chopped strand mat in case I make mistakes so it will be easier to modify_









_the factory cargo pocket where I want to install the sub, and the fiberglass shell I made after being sanded and trimmed in many places to clear sheet metal_

The materials used were from US Composites and I am very pleased (inexpensive, knowledgeable staff, good quality). I had some other fiberglass projects in mind and bought WAY too much stuff in hindsight haha. I picked up two gallons of their 435 resin, one yard of 1.5oz chopped mat for quick layout work and for complex compound curves, and five yards of their #1708 Biaxial because it was very heavy and would require just a few layers to be super strong. If you decide to fiberglass stuff, be sure to get lots of disposable mixing bowls and cheap paint brushes.

The baffle and carpet were very easy compared to wrestling with the fiberglass shell. The whole thing is mounted to the car using the same screws used to mount the factory CD changer and is very solid.









_the baffle is two layers of 1/2" mdf which sounds thin by some standards, but the small dimensions of this enclosure and modest power requirements justify it_









_mating the fiberglass shell to the baffle was a nightmare due to poor planning. I tried to fiberglass the gap seen here but wasn't able to create an air-tight seal. Eventually I went with a resin and bondo milkshake to fill in the holes and it worked great_









_covered in matching carpet and installed in the rear corner of the Golf. There is a factory cover that rests over the cargo area so when the car is parked, this area is completely blocked from view_

The subwoofer would start to look simple in both fabrication and research involved as I started other portions of the car like sound treatments and especially midbass installation in the doors. I'll post some more in the next day or two, thanks for reading.


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## Chaos

Cool. I always like to see OEM spaces modified for better aftermarket gear, while maintaining the "stock" look.


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## captainobvious

Great looking work thus far. Cute little helper you've got there.


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## papasin

Be interested to take a listen Saturday.

As an FYI, agree with your food recommendation personally as you probably saw what I was suggesting too, but doesn't look like we'll get consensus.


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## Justin Zazzi

captainobvious said:


> Great looking work thus far. Cute little helper you've got there.


Thanks for the compliment. She went to get spay'ed today and wow she is unhappy, but better than suddenly! puppies. At the very least, my tools will stay where I leave them for the next few days.




papasin said:


> Be interested to take a listen Saturday.
> 
> As an FYI, agree with your food recommendation personally as you probably saw what I was suggesting too, but doesn't look like we'll get consensus.


I look forward to hearing lots of cars Saturday! Looks like there will be many in the Modified class, should be fun.

As for food, I'm happy with most anything.


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## papasin

Jazzi said:


> I look forward to hearing lots of cars Saturday! Looks like there will be many in the Modified class, should be fun.
> 
> As for food, I'm happy with most anything.


I was at the meet couple months ago so heard some of the cars, but I think more folks heard mine. I'll be competing mainly because I'm curious and due to some of the urgings of the folks from the meet...never really thought of competing until then.

Being a native of the South Bay Area for nearly 30 years, have experienced lots of good places...problem is making everyone happy. You'd be surprised at some of the food discussions we had at the meet .


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## Justin Zazzi

I wanted to post some resources I found useful, and I will be referring to these later when this thread catches up to my installation.

Webpages:
The Car Audio System Nobody Would Build 6 part series

Roxul Safe'n'Sound is a mineral wool insulation similar to fiberglass in acoustic absorbtion, but does not absorb water and will not grow and fungus or mold. I installed a bunch in my car doors with great success. Lowe's was the only hardware store near me that carried it.

SoundIsolationStore.com has some detailed and easy to understand articles about sound isolation that is very relevant to cars even though their products are intended for residential homes.

Help my soundstage ate my windshield a thread here on how to tune using independent L/R eq, and my inspiration to aim my midrange drivers more on-axis but still symmetrical (I'll write about this later)

Viscoelastic Damping 101 by Palu Macioce, Roush Industries. A technical description of damping and a good read, though not very sensational

Cross Spectrum Labs sells inexpensive calibrated measurement microphones, and is run by a very knowledgeable guy who has answered many of my questions

Audioholics Online A/V Magazine has an outstanding free educational article section

Sound Deadener Showdown has excellent sound treatment products for a great price

Tricks to getting 500hz response a great thread on this forum regarding midbass holes in car doors


Books:
Master Handbook of Acoustics 5th Edition by Everest & Pohlmann
This book covers all the basics very well and goes into more depth than most people would care to read. I found it an excellent resource for understanding how sound waves move and what they are affected by, but there is little emphasis on how to use this technical information to make a system sound "good".

Sound Reproduction - The Acoustics and Psychoacoustics of Loudspeakers and Rooms by Floyd Toole
Toole goes into great depth citing study after study about what sound artifacts are audible and how much they effect our perception of sound. This book clearly helped me decide which artifacts I wanted to put the most effort into controlling (resonances, reflections, standing waves) and which ones I could reasonably ignore (high frequency comb filtering, diffraction). It is not an easy read nor would I call it a cookbook, and I re-read many chapters to understand some concepts. Overall though, exceptionally useful.


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## Justin Zazzi

Just returned from a trip to Tahoe to move some furniture around. The Golf towed a 5x8' trailer up and back fairly well, but after having to downshift into second(!) gear a couple times, I really started to miss the 5.2L engine of my old Jeep.

The midbass in both doors is complete, I have a ton of writing to catch up on. Tonight I was looking forward to sharing experiments with damping tiles vs asphalt-based roofing material (a commonly suggested alternative), but that will have to wait. Good night, and I look forward to meeting everyone this Saturday in San Jose at the competition.


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## t3sn4f2

Jazzi said:


> Just returned from a trip to Tahoe to move some furniture around. The Golf towed a 5x8' trailer up and back fairly well, but after having to downshift into second(!) gear a couple times, I really started to miss the 5.2L engine of my old Jeep.
> 
> The midbass in both doors is complete, I have a ton of writing to catch up on. Tonight I was looking forward to sharing experiments with damping tiles vs asphalt-based roofing material (a commonly suggested alternative), but that will have to wait. Good night, and I look forward to meeting everyone this Saturday in San Jose at the competition.


Nice job on the sub enclosure, looks really clean.

Here's a good thread on the asphalt tile topic.

Why Not Asphalt?


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## Justin Zazzi

t3sn4f2 said:


> Nice job on the sub enclosure, looks really clean.
> 
> Here's a good thread on the asphalt tile topic.
> 
> Why Not Asphalt?


That is an excellent introduction to the topic, thank you very much for the link. I echo much of what was expressed there. I have also taken it a step further and done some experiments, gathered data, and made some cool charts to really show the difference between the materials I gathered. After reading that one though, I'm tempted to expand my collection of materials and tests


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## Justin Zazzi

*Damping Materials: name-brand product vs asphalt-based alternative*

When I started learning about damping resonances and sheet metal, I was (like many people) surprised by how expensive materials like Dynamat, Hushmat and other name-brand CLD tiles were. Many forum warriors were convinced it was a grand scam and we could easily substitute products from other industries with similar materials for much less money. But there was much controversy about asphalt vs butyl, and weather or not the presence of foil backing made a difference, or how thick it should be, and so on.

At the time, I was in the middle of a physics class dealing with light, optics, waves and whatnot. As an extra credit project I ran an experiment to see how effective a single layer of asphalt-based roofing sealer (Grace Ice and Water Seal as commonly suggested during my reading) would be compared to a single layer of Stinger Roadkill (the first name-brand product I found at a local shop). The results were astounding.

If you are interested in the specifics, this report from E-A-R Specialty Composites is a great primer on the difference between a free-layer damping system (FLD) and a constrained-layer damping system (CLD). One of their illustrations is below. From what I understand, it seems a single very thin constrained layer sandwiched between two metals that are similar to eachother will give the best results. So when shopping for a damping tile, find one with excellent adhesion, high temperature rating, a thin viscoelastic (usually butyl) layer, and a thick aluminum backing (ie. almost every name-brand product meets this).









_Image borrowed from E-A-R Specialty Composites
Understanding Damping, E-A-R Specialty Composites_

In this example, a single layer of asphalt-based roofing material material with adhesive on one side attached to sheet metal is a free-layer damping system. A layer of Stinger Roadkill is a constrained-layer damping system because it sandwiches the butyl between the aluminum backing and the sheet metal of the car. Hopefully the above diagram helps.

The experiment was simple: measure the damping factor of resonances of my car door as it came from the factory, after applying asphalt-based product, and again after removing the asphalt and treating it with Roadkill. In addition, I would test a single piece of sheet metal on the bench to see if there was a significant difference between trying to damp the resonances of my car door (a complicated system) vs a single sheet of steel (a simple system).

Damping factor is easy to visualize using an RTA and some division. No complicated maths here. Viscoelastic Damping 101, Roush Industries is an article describing how to calculate it, and here is an example from TrueRTA in my measurements.









_A sample calculation: damping factor of 95hz resonant peak: η = (106hz - 82hz) / 95hz = 0.25
(a higher number is better)_










_Above is test 1: this is what the outer door skin looked like from the factory. Notice the single free-layer damping material that has been applied in the top-left corner._










_Above is test 2: this is two layers of asphalt-based roofing applied over the top of the factory damping material._










_Above is test 3: all asphalt and factory damping materials have been removed, and about half of all accessible surface area has been treated with Stinger Roadkill, a constrained-layer damping material._

After each treatment the doors were fully assembled before taking measurements. Essentially I hammered the outside of the door using a soft mallet and recorded the sound from the inside, used TrueRTA to help calculate the damping factor, then made some graphs. First is the test using the car, the second graph is from a single piece of sheet metal suspended in air, and tested the same way.









_Above is damping factor of the car door untreated from the factory, after applying a single layer of asphalt-based roofing material (Grace), after a single layer of name-brand product (Stinger), and finally with additional Stinger Roadkill plus a layer of MLV for sound isolation.
(higher is better)_










_Above is the bench test of a single piece of sheet metal. (higher is better)_

In the bench test, the result is obvious. A single layer of asphalt-based roofing material provides some damping to the sheet metal, an increase of about 29% average damping factor. But a single layer of CLD is phenomenally more effective with an average increase of 770%! So, myth busted, Grace Ice & Water Shield may be a fine roofing material, but it is nearly worthless as a damping material.

In the car door test, the results are much less clear. Two layers of Grace yields an average decrease (!) in damping factor by 1%, but a single layer of Roadkill only has an increase of 13% on average. Confused by this, I tried to go crazy and added more Roadkill to the outer door skin, applied some to the inner door skin, and then added a mass-loaded-vinyl barrier to the inner door skin to further isolate noise and prevent it from entering the cabin. Even with these stronger measures I only saw an increase of 26% damping over the factory car door.

So what is going on? Clearly from the bench test a single layer of Roadkill (on 25% surface area) should have a drastic effect on damping factor for sheet metal. However the car door behaves differently. I believe the car door having (1) an outer wall of sheet metal and (2) an inner wall of sheet metal and (3) another inner wall of plastic and vinyl door card and (4) air chambers between all these layers are responsible. I believe the air chambers themselves have resonances that cannot be affected by damping the sheet metal and must be addressed other ways.

Conclusion? Buy a CLD tile from a common brand (or sounddeadenershowdown) and apply it in a single layer over about 25% to 50% surface area for excellent results (adding more doesn't increase benefits for the high additional cost). Also, further study needed to find sources of resonance in car doors. I'll have measurements for a new idea to address this soon.


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## What?

An additional problem with asphalt based products is that they will not remain bonded to vertical panels or when installed upside down (like on the roof). People should have been done using asphalt based deadeners 20 years ago but cheap people are cheap.


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## papasin

Great sounding car, and glad to meet you. Seems like we share common interests besides car audio . I think your car really does belong in street, and depending on number of eq bands on your HU, maybe can pass for stock if you have your spare??

It really doesn't pay to be in modified as you probably noticed. If you took a look at the full scores across classes, the top 3 in modified scored higher than top person in modex and this is with the same judge...so I think that's saying something. So flush your mids, but I guess it might be battle of the VWs .


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## Justin Zazzi

I may try flush mounting the woofers into the doors again for the purpose of competition in the future, but this car is more for me and for learning than for winning. I want to further explore the symmetrical on-axis mounting I built before going back to flush, if I do.


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## papasin

You're the judge . Not sure if it was me, but I was wondering if you noticed that your center image seems to wander at times. What was the other feedback you received from Fred?

EDIT: Also wondering...do you have room for kicks? That maybe another solution.


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## Justin Zazzi

papasin said:


> You're the judge . Not sure if it was me, but I was wondering if you noticed that your center image seems to wander at times. What was the other feedback you received from Fred?
> 
> EDIT: Also wondering...do you have room for kicks? That maybe another solution.


Yeah the center moves around a bunch, I know it, you know it, Fred knows it, but surprisingly many of the people that listened to the Golf said it was "rock solid" and the center was "right there" as they emphatically defined a tiny spot in the air with their hands.

I don't like kicks. The ones I have heard so far translate too much tactile feedback to my feet and are super distracting, plus I have long legs and enjoy having room to move around. I'm sure there are kicks done "right" that don't have either of these problems, but I haven't experienced one yet.

One day soon I'll continue the this build log, there is lots to catch up on.


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## Justin Zazzi

Sound Barrier Installation

Deadening vibrations is a great thing, but it will not prevent airborne noise from entering the cabin from the outside. The sound of my tires against the pavement and the sound of other cars on the road next to me were two of the loudest intrusions on an otherwise quiet interior. Engine noise is also up there, but not easy to hear over how loud the car rolling down the highway was.

I learned a lot from the great examples set here (2008 Yaris Sedan Deadening and Sound System by derickveliz) and here (sounddeadenershowdown). Essentially I wanted to create a massive, isolated layer of material between the outside of the car and the interior. I would do this with the front doors later, so I started with the floor and as much of the lower firewall as I could reach. I also added what I could to the rear wheel wells.

There is nothing special here other than lots of labor and fighting to re-install the factory carpet, seats, and interior trim panels with the extra material sandwiched between them. I purchased mass-loaded-vinyl from a company called Acoustiblok in Florida (mistake! shipping was expensive). It was a recommendation from a friend who builds broadcast trucks and they use it for sound isolation in their builds. I eventually ran out of that and purchased more MLV from SoundDeadenerShowdown, but if I need to get any more in the future I would try hard to find a local place to avoid paying for shipping.

The material is a thick vinyl sheet with a density of 1lb. per square foot. It is isolated from the factory sheet metal on the floor by the factory carpet pad as seen in the photos, so I did not have to use any additional closed cell foam as some installations require (yet another example of why the Golf is a great car to install in).









_All of the factory trim panels, seats, and carpet is removed first_









_Factory carpet removed and then re-installed in one piece, the most difficult step_









_A "before" shot showing the carpet pad that sits just below the carpet. I laid the MLV on top of this to mechanically isolate it from the floor of the car._









_MLV initially laid on top of the carpet pad, lots of detail work to seal it up nice later_


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## derickveliz

Got to LOVE the smell of MLV!

*Awesome!*

D.


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## papasin

Been there as well for 3 or 4 cars now . I got my MLV from soundproofing.org

Mass Loade Vinyl Mat

which is in CA, so shipping isn't as bad. I tried calling around locally, and even with shipping, I found soundproofing.org cheaper up to the Bay Area. I was talking to JT during the meet back in June and mentioned this to him, and he told me at the comp he just drove down to pick some up .


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## Justin Zazzi

derickveliz said:


> Got to LOVE the smell of MLV!
> 
> *Awesome!*
> 
> D.


Thanks Derick !




papasin said:


> Been there as well for 3 or 4 cars now . I got my MLV from soundproofing.org
> 
> Mass Loade Vinyl Mat
> 
> which is in CA, so shipping isn't as bad. I tried calling around locally, and even with shipping, I found soundproofing.org cheaper up to the Bay Area. I was talking to JT during the meet back in June and mentioned this to him, and he told me at the comp he just drove down to pick some up .


Good to know, they have lots of great products to choose from.


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## Justin Zazzi

*Sound Absorption*

With the results from my resonance tests above (damping sheet metal with cld tiles), I was really confused about the huge difference between the bench test and the in-car test. The door still had some huge resonances in it, but if damping the sheet metal wasn't the trick, what else could I do?

In a recording studio or very serious home theater build, sound absorption is a huge factor to consider. Essentially you want the decay time of each frequency to be the same from the lowest bass notes up to the highest treble. If some frequencies "bounce" around a room much longer than others and take a noticable time to decay, this can be heard as ringing, or in the case of low frequencies, "one note bass" because certain frequencies will dominate over time. The measurement is called RT60, the amount of time for a sound to decay to -60db (about one millionth) from when it stops. It requires an impulse (sound, gunfire, hammer, etc) and a 3-d plot of frequency vs amplitude vs time. Below is an example 2d plot, excluding the frequency domain:









_Image borrowed from RT60 calculator Sabine calculation reverb time reverberation time Sabin formula - sengpielaudio Sengpiel Berlin_

Realtraps.com has an excellent introduction of this concept and how to measure it using REW, a free software tool and rta.
RealTraps - Room Measuring Series

I love this 5 part series on practical sound treatments. It has a light touch of math for anyone interested in numbers, lots of very practical information, and isn't overly complex to be accessible by most anyone.
Practical Acoustic Treatment, Part 1

Frequencies in the kilohertz range are easy to attenuate and reduce their decay times. A simple dash pad 1/2" thick will absorb almost everything above a kilohertz. In a studio or theater, any padded furniture or drapes several inches thick will severely attenuate frequencies down to around 300hz.

But to attenuate bass frequencies is much more difficult because the wavelengths are so much longer. A common tool is a tuned bass trap placed at the high-pressure node of as many relevant frequencies as possible (a corner is great). Because these traps are enormous relative to the interior of a car, I had to try something different.

While reading The Master Handbook of Acoustics 5th by Everest and Pohlmann, I was intrigued by the section of absorption and this diagram in particular. It is comparing thickness of glass fiber material to the absorption coefficient when mounted flush against a wall.









_Image borrowed from The Master Handbook of Acoustics 5th by Everest and Pohlmann, page 191_

If I could somehow get 1-2" of glass fiber with a density of 3lbs./sqft into my doors as an acoustic absorber, it should attenuate the resonances I measured earlier when applying cld tiles. The effectiveness of the glass fiber material falls off as it approaches 125-200hz, but my resonances are worst in the 125-300hz range so I expected some improvement.

Glass fiber insulation materials notoriously absorb water and promote all kinds of fungal and mold growth. The inside of the door cavity is prone to moisture and I couldn't use this material. Luckily, there is a basalt rock-based alternative that shares fiberglass's excellent sound absorption properties (and r-value thermal insulation) that does not absorb water and inhibits all kinds of mold and rot.

Mineral Wool or Rockwool is perfect. Roxul Safe'n'Sound home insulation is perfect for this application. It is designed for sound insulation, fire retardant, and moisture resistance in residential environments. 









_This stuff is only sold in a large package of 12 batts, each 4 feet long. The whole package was about $40 and I only used 2 batts. Maybe it'll be useful for other projects._









_Mineral Wool is super easy to work with and cuts very well with a hack saw blade or razor. I used this simple jog to get a consistent 2" thickness._









_I used some wire fencing from a previous project to create a mold to hold the mineral wool into the door._









_The first mold and mineral wool is installed, the second mold above is seen without any material yet._









All mineral wool is installed. Some steel beams are used to hold it tight against the outer door skin so it will not bulge inwards and interfere with the window motor track.

This was the easiest part of the entire install on this car so far.

I'll have some measurements posted soon, good night for now.


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## Toslink

I didn't see how you're dealing with water retention in the Rock-wool.


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## hatemi

That wool will absorb water like a sponge. And stay wet even after the world ends.


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## Justin Zazzi

From Roxul's website: Water-Repellent



> Water-Repellent
> Roxul insulation does not absorb water or hold moisture. Its unique stone wool orientation is ideal for repelling and draining water away from the exterior walls, industrial pipe, interior walls, or whatever Roxul insulation is protecting. And, since Roxul insulation does not absorb water, it will not sag or lose its shape, and will retain its R-value. So the R-value installed today, will be the same for years to come. Being water-repellent also means Roxul insulation does not rot, corrode, or promote fungi or bacterial growth.


Perhaps you are thinking of rockwool hydroponics material, which does absorb water. Depending on the manufacturing process stone wool can be hydrophilic (water absorbing) or hydrophobic (water repelling). The former is great for hydroponics, the latter is great for in-home insulation.

I admit I have not tested it like this, and just to be sure I'll do this test tomorrow, but this is what I am expecting:
https://www.youtube.com/watch?v=gLDxhbKfVeo
start at 4:05 mark


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## stochastic

Totally subscribing to this thread. I'm glad to see another engineering student thinks the same way about car acoustics. I'm still on my first build.

Don't you want your rigid insulation (much better on absorptive coefficients than soft batting) in an area that can absorb the airborne pressure waves on a boundary effect rather than hidden behind your door card and inner door skin? Where you have it, the sound that has been transmitted through the first two layers is what you're absorbing further. From an internal cavity acoustic perspective, outwardly transmitted sound energy can be considered as already absorbed sound in most circumstances. You are however taming any resonant air spaces within your door. Just my understanding anyways.

Some great links in this thread too. Double thumbs up.


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## Justin Zazzi

Owens Corning ridgid fiberglass panels are about the most respected and highly rated absorption panels I could find. They have three problems with this particular installation though: 1) they made from fiberglass and have all the downfalls of water retention, 2) they are rigid and will not compress or conform to the compound shape of my door panel, and 3) relative to the mineral wool I purchased, the Corning materials are very expensive.
Owens Corning 703, Johns Manville fiberglass



> Don't you want your rigid insulation... in an area that can absorb the airborne pressure waves on a boundary effect rather than hidden behind your door card and inner door skin?


In general these products are used inside a room and are visible to the listener, you are correct. I plan on experimenting with using this material in key locations to eliminate early first reflections in both my home theater and in the car, though I don't know how practical it will be to install this stuff in the interior of the car. Maybe it will be a removable panel that I can tote with me for competition.



> Where you have it, the sound that has been transmitted through the first two layers is what you're absorbing further. From an internal cavity acoustic perspective, outwardly transmitted sound energy can be considered as already absorbed sound in most circumstances. You are however taming any resonant air spaces within your door. Just my understanding anyways.


Maybe this will help:

(outside of car)
outer door skin
*mineral wool*
inner door skin
mass loaded vinyl layer
door card
(interior of car)

I am using the mineral wool to tame the flutter echos (and reduce the RT60 times of all frequencies) in the sealed air chamber between the inner and outer door skins. This is where the back wave of the midbass drivers lives, and now hopefully dies.


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## Justin Zazzi

Also stochastic, your Hyundai build is very interesting. Much more ambitious than usual! Also, +1 for Roxul products hah. I look forward to seeing that project evolve.


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## stochastic

This chart might help you in deciding which panel materials you might use for acoustic treatments http://www.bobgolds.com/AbsorptionCoefficients.htm coplete with thickness measurments. Some of the products listed are old and no longer produced, but it's a great rescource.


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## Justin Zazzi

stochastic said:


> This chart might help you in deciding which panel materials you might use for acoustic treatments http://www.bobgolds.com/AbsorptionCoefficients.htm coplete with thickness measurments. Some of the products listed are old and no longer produced, but it's a great rescource.


Oh ... wow.
Great find, thank you.


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## req

Very cool build sir! I also have a mk4 gti with a fairly in depth build. I might follow up on some of your sound dampening techniques. I have done mlv/ccf/cld all over as well... I wonder if we can put some roxul above the headliner, there is a 2-3 inch gap up there... But the headliner is kind of a cardboard type deal. 

Cut a hole in the headliner, fill hole with metal mesh, re-wrap headliner, install roxul between roof/headliner and there you have a large low frequency absorber.


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## John Reid

Nice thread! 

Your use of Roxul, while ingenious, makes me a tad nervous; if I were you, I'd either do a water test, or check them periodically to make sure nothing's funky.

I say this since even their website does a little waffling:

"Ideally, these products do not promote fungi, mildew, or bacteria growth"

Their use of the word "ideally" is their law departments' way of getting off the hook for any issues in home installs-gone-wild.

Don't get me wrong, I think it's a great idea, even if it just reduces free-way noise... but I wouldn't "set it and forget it". 

Oh, and let us know how it fares in the hydrophobia department.

I went a more traditional route in my MKV by removing the door skins and usinga layer of B-Quiet Extreme mass loader and then a layer of V-comp; the doors soundlike concrete when you tap them, and freeway noise is down considerably.

VWVortex.com - John Reid's JSW audio system build


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## Justin Zazzi

req said:


> Very cool build sir! I also have a mk4 gti with a fairly in depth build. I might follow up on some of your sound dampening techniques. I have done mlv/ccf/cld all over as well... I wonder if we can put some roxul above the headliner, there is a 2-3 inch gap up there... But the headliner is kind of a cardboard type deal.
> 
> Cut a hole in the headliner, fill hole with metal mesh, re-wrap headliner, install roxul between roof/headliner and there you have a large low frequency absorber.



http://www.diymobileaudio.com/forum...25253-2010-hyundai-elantra-touring-build.html
Neat idea. stochastic's build uses a very similar idea and he reports great success. This might need more investigation, however I have a sunroof and that might limit the available space I have up there to work with.


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## Justin Zazzi

John Reid said:


> Nice thread!
> 
> Your use of Roxul, while ingenious, makes me a tad nervous; if I were you, I'd either do a water test, or check them periodically to make sure nothing's funky.
> 
> I say this since even their website does a little waffling:
> 
> "Ideally, these products do not promote fungi, mildew, or bacteria growth"
> 
> Their use of the word "ideally" is their law departments' way of getting off the hook for any issues in home installs-gone-wild.
> 
> Don't get me wrong, I think it's a great idea, even if it just reduces free-way noise... but I wouldn't "set it and forget it".
> 
> Oh, and let us know how it fares in the hydrophobia department.


I did submerge a piece in the pool yesterday and the water did not seep into the material like it would with the hydroponics version of mineral wool. Hydrophobic, yes. However if I squeeze the mineral wool it released all the trapped air, and inevitably the water soaked in. Since I don't plan to squeeze the material I installed in my doors, I think it's pretty safe, and I do plan to check on it once in a while (that was the plan from the start).





John Reid said:


> I went a more traditional route in my MKV by removing the door skins and usinga layer of B-Quiet Extreme mass loader and then a layer of V-comp; the doors soundlike concrete when you tap them, and freeway noise is down considerably.
> 
> VWVortex.com - John Reid's JSW audio system build


Ahh yes, I remember reading this build mostly because of your cleaver use of molding the plastic sheets and welding them together to form your subwoofer. Well done


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## req

Jazzi said:


> http://www.diymobileaudio.com/forum...25253-2010-hyundai-elantra-touring-build.html
> Neat idea. stochastic's build uses a very similar idea and he reports great success. This might need more investigation, however I have a sunroof and that might limit the available space I have up there to work with.


i have a sunroof too. but if you notice the part of the roof aft of the sunroof, there is a weird depression. the part between this depression and the sunroof is where the sunroof shield is stowed while open. the depression is just a void.

cut the void out, replace with mesh, install a tuned basstrap on the roof, and recover with suitable headliner cloth.

bingo bango bongo. 




///edit

after reading the thread you linked, similar to that but just cut a huge hole out. dont bother with speed holes or any of that. just my thoughts.


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## Justin Zazzi

There is certainly some room to play with up there, and I want to exploit the whole area behind the B-billiars for fun to see how much can be done. I am guessing a lot, but I'm also wondering why I have not seen bass traps in other competition cars before. Either I am onto something AMAZING, or it has been tried before and is not worth the time or the results are poor. Either way, I want to explore.


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## req

i think in our particular case it should be very effective... as far as that area goes.

i think that midrange\midbass tuned absorber would be more effective because usually cars have big problems in the 200hz area. a team mate of mine has a real weird null at 80hz in his car - no amount of EQ can touch it - it has to be a phase or enviornment related usse, but getting an absorber up front for that type of problem in the area it needs to be would be virtually impossible as his 8's are on the dash - unless he could put it above his head... but the only way to figure out where it will work is to make one and put it all over the place haha.

i think the thing that i have not looked into is the method of tuning a trap of this kind.


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## Justin Zazzi

To find the placement, I was thinking about this. All frequency pressure nodes will exist in a sharp corner. If I play broadband pink noise and "sniff" around my car using an RTA microphone, it should be really easy to spot the acoustic corners of the car when the frequencies of interest spike. Or, at least it will be easy to find where the nodes of the frequencies I want are very high, and choose a spot that is most convenient that way. The traps (as I understand it) do not have to be close to the listener or close to the speaker, they just have to be in a location where the specific frequencies are excited so the trap can absorb them.


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## Justin Zazzi

*On-axis vs off-axis mounting - frequency response and imaging*

Start by reading Andy's great response to the on-axis/off-axis question here:
http://www.diymobileaudio.com/forum/1709447-post9.html

There is no shortage of recommendations about where to mount speakers in a car. Ask around and you're likely to get as many ideas as the number of people you ask. They might say the midbass should be in the doors, or it should be in the kicks, in the floor, or in the dash with a complete rebuild. The midrange should be with the midbass, or it should be in the sail panel, on the dash, or in the a-pillar. The tweeter should be within a quarter wavelength of the midrange, no it should be in the a-pillar, no it should be in the sail panel, or even in the dash aiming straight up at the windshield. Speakers should be aimed at the driver's seat, no they should be aimed at the dome light, or exactly straight across from one another, or slightly off-axis to the driver, or exactly on-axis.

What does it all mean, and where is the common thread among so many great sounding systems that have speakers in such varied arrangements? I bought a book that turned out to be an _excellent_ resource on the subject: Sound Reproduction: The psychoacoustics of loudspeaks and rooms by Floyd E. Toole.

Imaging seems to come down to a few things:
-Interaural Intensity Difference (IID) is dominant above ~1khz
-Interaural Time Difference (ITD) is dominant below ~1khz
-The Precedence Effect determines direction
-Early strong reflections determine apparent source width (ASW)
-Late Reflections determine listener envelopment (LEV)
-Off-axis response is critical and affects most of the above

*Interaural Intensity Difference (IID) *is how we localize a sound at higher frequencies, above roughly 1khz. The Difference in Intensity between our two ears determines where the sound appears to come from in the horizontal plane. This means either have all speakers in the 1khz+ range with equal path lengths (for direct and reflected sound) so they have an equal intensity at the driver's seat, or adjust the level of each speaker individually to match their intensity. In addition, each frequency band (generally 1/3 octave) must be balanced between the left and right channels otherwise the image will smear itself horizontally for all frequencies above 1khz. Below is a measurement taken in my car with each tweeter measured separately, and without any EQ.









_The difference in intensity between my left and right tweeters contributes to a large, unfocused center image that is difficult to pinpoint. Below about 3khz and again above roughly 7khz the image shifts to the left, but between it will shift to the right slightly. Graph smoothed to 1/3 octave._

There are few physical ways to address this because of the severe path length difference between the two tweeters for both direct and reflected sound. Plus the geometry of the dashboard and the listening position are not symmetrical. I do not think it is impossible, though it is beyond my current skill to get identical frequency response from both tweeters from the driver's seat without using any equalization. It would involve heavy control of reflections using absorbent materials and careful placement of the drivers along with careful aiming to minimize strong early reflections.

Enter equalization. An EQ is not going to solve every problem including this one because _what happens in the time domain_ (third axis of a waterfall plot) is very important and will reveal resonances that will severely alter a frequency response curve. This page at Realtraps has lots more information about this and how to measure it. In addition, the RTA is only summing the intensity of all arriving wavefronts at a point in space _with no regard from which angle it arrives at_. The RTA is directionally blind and is adding all the reflections from every direction to the direct sound. So even though you can EQ a ruler flat response curve (and I did below), some of that energy is going to be arriving from other directions and can pull your image in other directions or make it harder to pinpoint the image.
But EQ can be a band aid in most situations.









_The same speakers and setup as before, but now with a very aggressive EQ. Both tweeters at the listening position measure +-2db, and the difference in intensity between the two tweeters is even closer. The result is a much more precise center image than before._

Another thread goes more in depth to equalizing the left and right channels: http://www.diymobileaudio.com/forum/technical-advanced-car-audio-discussion/13888-help-my-soundstage-ate-my-windshield.html

*Interaural Time Difference (ITD)* is very similar to IID above but is dominant in how we localize sounds below about 1khz. Essentially you want the two wavefronts from the left and right channels to arrive at your ears at exactly the same time. I've had great success using a tape measure from the center of each speaker to my left or right ear when sitting in the driver's seat. The subwoofer counts too! I find this calculator to be useful. I've tried Bikinpunk's method of using noise tracks but didn't have any luck with it. Time alignment is the feature used to address ITD, simple as that.

*The Precedence Effect* is pretty simple to understand. The first wavefront that arrives at our ear dominates the direction we perceive the sound to be coming from. The shortest distance between a source and our ears is a straight line, so echos and reflections naturally take longer to arrive. This is why it is easy to localize a performer in a very large and reflective hall, or a small bathroom with hard reflective walls, despite all the distracting reflections.

For my application, I need to leave a direct path between the speakers and my ears and that's about it. So kick panels are out because my legs get in the way, and the idea of mounting anything in the dash directed up into the windshield is no good either. To get the widest sound stage, I want to mount them as far to the left and right as I can because the angle of the direct sound will dominate the apparent location of hard left and hard right sounds. Thankfully the Golf has a sail panel perfect for this. I cut out the old tweeter, removed the center portion of the plastic trim panel, and covered it in grille cloth. I'll revisit the tweeters later to play with aiming and such.









_Morel Hybrid Ovation MT-22 tweeters mounted in stock location._


This is way more writing than I planned and it's still not done. There is so much stuff bouncing around in my head right now it's hard to keep it straight, but writing it down helps (and maybe helps you, I hope).

Time for a break, taking the puppy to the dog park.

Edit: Wow .... just wow. If I hold my head in the right place (duh) the center image is fantastic. It still suffers from the left stage being very narrow compared to the right, but wow the center is great now. Tonality is superb too. I'm very happy for now!


----------



## stochastic

Jazzi said:


> To find the placement, I was thinking about this. All frequency pressure nodes will exist in a sharp corner. If I play broadband pink noise and "sniff" around my car using an RTA microphone, it should be really easy to spot the acoustic corners of the car when the frequencies of interest spike. Or, at least it will be easy to find where the nodes of the frequencies I want are very high, and choose a spot that is most convenient that way. The traps (as I understand it) do not have to be close to the listener or close to the speaker, they just have to be in a location where the specific frequencies are excited so the trap can absorb them.


I wanted to quickly touch on a few things before reading that last monster of a post. First, sharp corners are not necessarily where pressure nodes occur. For a detailed engineer's model of modes inside a car take a quick watch of Finite Element Examples. Lecture 4. - YouTube
Yes, the traps only have to be in a positive or negative pressure zone for that mode.

You're wrong in the concept that nobody has ever done this in a car before. Some of the OEM acoustic materials in my Hyundai are obviously tuned bass traps (cheap ones, but still). Also, the Magic Bus proudly boasts about the 30+ or some silly figure of designed acoustic modifications including traps.

If you're wondering how to tune a bass trap look into Helmholtz resonators and quarter wave bass traps.

Please keep in mind that modes can be broken up not only by absorption, but also by diffusion. This is the reason why I put the diffuser pattern on my headliner. Too much absorption will make you not want to spend much time in the space - it will be unnaturally dead if you take it to the extremes.

OK, now to get some sleep and read your last post with a pot of coffee in hand tomorrow.


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## Justin Zazzi

stochastic said:


> You're wrong in the concept that nobody has ever done this in a car before. Some of the OEM acoustic materials in my Hyundai are obviously tuned bass traps (cheap ones, but still). Also, the Magic Bus proudly boasts about the 30+ or some silly figure of designed acoustic modifications including traps.
> 
> Please keep in mind that modes can be broken up not only by absorption, but also by diffusion. This is the reason why I put the diffuser pattern on my headliner. Too much absorption will make you not want to spend much time in the space - it will be unnaturally dead if you take it to the extremes.


The point I was trying to make was, very few people attempt to modify the acoustics of their interior and even less seem to write about it. The Magic Bus certainly has modifications, though I do not remember reading about the traps. Can you link that info?

Also I know what you mean about diffusion vs absorption. I worked in radio broadcasting for 6 years and the dead silence of the studios took some getting used to. It was always a bit too sterile, too perfect to be natural or friendly.

Enjoy your coffee.


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## Noobdelux

got anny photos of when you rebuilt the sail panels?


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## Justin Zazzi

Noobdelux said:


> got anny photos of when you rebuilt the sail panels?


Sadly, no. I will take some when I redo them though.


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## Noobdelux

thank you.


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## Justin Zazzi

To finish the earlier post... 

*Early strong reflections determine apparent source width (ASW)*
_an very simple and picture-book style explanation is here at av-info_

Toole's book does a good job defining apparent source width:

_ASW - A measure of perceived broadening of a sound image whose location is defined by the direct sound ... Strong reflections have the ability to shift the apparent position of a source in the direction of the reflection and/or to make the source appear larger._

"Early" reflections arrive roughly <80ms after the direct sound. ASW is how wide does the sound source appear to be? How large does the drum set appear to be? How large does the piano appear to be? A singer with a small ASW would be perceived as very focused and it would be easy to point to where the singer's mouth would be. A piano with a large ASW might sound like it is as wide as the entire listening room.









_Image borrowed from www.av-info.eu_

The part I'm paying attention to is how a reflection can affect where the direct sound from the speakers are telling me the image should be by pulling it towards the reflected sound. Reflections off the dashboard, instrument cluster, windows and windshield can pull the image in every direction. Early strong reflections can also make an image appear larger and more difficult to pinpoint.

So how can I use this information?
1) By adding a dash mat I can reduce reflections from the dashboard and instrument cluster.
2) By mounting the tweeters flush against the sail panel I can reduce reflections from the adjacent window.
3) If I reduce early reflections too much in the tweeter frequency range, then the reverberation time of the lower frequencies will be relatively much longer than the higher frequencies and possibly result in a mismatch of muddy bass or dry treble.


*Late Reflections determine listener envelopment (LEV)*

Again I'll let Toole define this:

_LEV is a sense of being in a large space, of being surrounded by a diffuse array of sounds not associate with any localizable sound images. This is regarded as perhaps the more important component of spaciousness, differentiating good concert halls from poor ones._

"Late" reflections arrive roughly >80ms after the direct sound. In a car, the tiny volume of the interior essentially eliminates the late reflections because for any sound wave to survive for 80 milliseconds, it would have to travel 90 feet within the car (speed of sound is 1,116 ft/sec ... so 1,116ft*(80/1000ms)=90ft). Considering the tiny interior dimensions of a car, the sound wave would have a dozen or more reflections to travel 90 feet and it would be easily absorbed by all the soft fuzzy upholstery. Conversely in a large room or especially a concert hall, a 90ft reflection is all but guaranteed.









_Early strong reflections contribute to ASW_









_Late reverberations contribute to listener envelopment
from Room Acoustic and Side Reflections_

*So how can I use this information?*
1) I cannot make my interior larger or significantly more reflective, so achieving >80ms reflections must be done another way.
2) Mark Whitledge's choice of using a Sprinter van was influenced when he was considering reverberation time (RT60) because it has one of the largest interiors of any car available.
3) In my car and in many other typical passenger cars, electronic delay must be used to artificially generate late reflections. This might explain why products like the JBL MS-8 and other processors encourage the use of rear fill channels.


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## Justin Zazzi

I just found the site below and it is full of very simple, very illustrated explanations of everything I'm talking about here. Highly recommended if you want to learn more about ... everything.

Precedence Effect

Room Acoustic and Side Reflections

Reverberation Time

Reverberation Time Measurement

Room Acoustics / Concert Hall Acoustics - an Overview


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## Justin Zazzi

Enough theory, now for some build photos 

The 6.5" Morel Hybrid Ovation midbass in the doors is responsible for playing up to 2khz where the crossover for the tweeter is. I had them mounted in the doors off-axis in the stock locations aimed at the center console, but the driver's midbass was so far off-axis compared to the passenger's midbass there was a huge mismatch in response from the two. I had to use trigonometry (useful afterall) to find the best point to aim both midbass at so that the off-axis angle to my ears would be equal. The aiming point turned out to be 55" away from the centerline between the two woofers, at an angle in line with my ears (it is a spot on the headliner about where the dome light would be in most cars, so +1 for aiming speakers at the dome light). This results in 14 degree off-axis for each woofer to my head, not bad!










The photos make it look easy, but this the most challenging fabrication so far, and I only settled for "ok" instead of fantastic in the end. This was about a month from start to finish with lots of head scratching and searching for ideas on how to finish the design, to make it presentable, but also be simple to build. Perhaps the only reason it is finished was an SQ competition two weeks out that I wanted to be part of.









A laser pointer is tied in the center of the mdf baffle for the midbass, then the contraption is placed in the door card with the door closed. Aim the laser at the point on the headliner calculated earlier, and hot glue the speaker baffle (with chopsticks) to the other baffle already mounted to the inner door skin.










Add a ring of sheet metal simulating the motor and basket of the woofer so when fiberglassing, I will leave adequate space for the entire speaker to fit inside.










Before the initial layer of cloth/resin dries I mounted a temporary circular mdf ring onto the speaker's baffle, sandwiching the cloth/resin so it would dry flat against the speaker baffle to ensure the woofer would lay flat against it.










Baffle structure and woofer mounted to the inner door skin before the MLV layer was applied.










And after the MLV is in place.










The source of all my frustration. The woofer was clearly not sealed against the door card and would allow bass into the cavity between the door card and the inner door skin causing all kinds of resonance and interference.










I made a series of crescent shapes out of 1/4" and 1/8" mdf and glued them together to create a stair-step shape. This along with some foam seals the gap directly in front of the woofer to the door card.










Lowe's carries Ideal product #31-601 Duct Seal in little one pound bricks. I saw someone using this on the forums in another build. I smeared about 1.5 pounds of Duct Seal on the back side of the fiberglass of each woofer and used it as a gasket to seal the rear of the fiberglass to the door card.










I went with a 1/8" ring bolted to the door card to create a lip, which I then sewed some cloth around it like an elastic shower cap. This way the cloth is removable, I can access the woofer without dissasembling anything, and the door card can come off without removing and hardware too.




















The material bunches up in the back despite being somewhat elastic. It's not visible with the door closed, so I don't really care.


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## metalball

Interesting build. Sub'd.


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## slade1274

Love the "engineering approach"- keep up the progress and posts


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## Justin Zazzi

Noobdelux said:


> got anny photos of when you rebuilt the sail panels?


Now I do.









The factory tweeter location has a cutout in this foam material. The Morel MT-22 fits right in.










Stock tweeter grille has the center portion cut out along with the tweeter. 










I wrapped some grille cloth over the outside to make it look clean.










This image is really brightened up, the cloth in daylight is pretty dark. You can see the slight shape in the lower half of the fabric, that's the MT-22.


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## Justin Zazzi

The Morel tweeters are fantastic and I really enjoy them. They have a Fs of around 900hz and therefore will not play very low. I have them crossed at 2khz. That is not really a problem, except the woofers in the doors have to play 2khz and down.

After a few months of listening to this setup, I'm convinced the stage has a rainbow effect and the right side is pulled down into the door. This was confirmed at the last competition by the judge, a well respected one at that.

Enter the Legatia L3SE widebander. I picked up a pair from the scratch & dent sale on this forum last week. They can play down to about 300hz and should solve my rainbow problem. In addition, I have seen nothing but raving reviews of these, and they can be used without a tweeter if mounted on-axis. So now I'll have the *top six octaves from a point source* without any crossovers to tune in the critial midrange frequencies.

This is great for both Interaural Intensity Difference (localization at frequencies roughly above 1khz) and Interaural Time Difference (localization below 1khz) because in the *transition between the two, I also have no crossovers.* Fantastic.

Another benefit is I can mount the midbass drivers flush with the door like they used to be. It will be much easier to look at, and I won't have to worry about the off-axis response of those woofers beyond 300hz, which they should be omnidirectional anyhow. I'll loose all the time and fabrication I put into mounting them on-axis, but oh well, that was fun.



















The L3SE will be vented into the door, IB style.










A rough and simple sealed enclosure for verifying location and aiming while in the car. 3" abs pipe, some mass-loaded-vinyl, and some tape.

The best part though, is with the temporary sealed enclosures and only level matching with time alignment, the L3SE sound nearly as good as the MT-22 even after I EQ'ed them. There is great promise here and I'm excited.


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## Justin Zazzi

Here's a neat trick I did a while back.

Take the factory radio, surgically remove the faceplace and retain all the push buttons. Glue or screw any extra bits in place so it looks complete from the front. Add a magnet to the back side, align it with your aftermarket radio, and violla.


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## sydmonster

Thats an old school trick that I haven't in quite a while!! Nice work here. Great choice of wideband driver too! Lorv those L3SE's.


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## req

the only problem with moving the speakers inboard and putting them on axis is that your width will suffer 

you would be better off making kick panels for the midbass in the floor and relocating the hood release mechenism.

just a thought. also try and find some black Lycra. its super duper stretchy.


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## bradknob

Reading this thread makes me feel like i have a mental retardation. LOL




Please dont take that negatively, I find your appraoch fascinating and something i could never carry out myself. Very interesting build, keep it up


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## Justin Zazzi

req said:


> the only problem with moving the speakers inboard and putting them on axis is that your width will suffer
> 
> you would be better off making kick panels for the midbass in the floor and relocating the hood release mechenism.
> 
> just a thought. also try and find some black Lycra. its super duper stretchy.


I have thought about kick panels but the ones in the cars I've judged have too much physical feedback for my liking. I find toes getting a nice massage while I'm trying to listen to be very distracting. Maybe a really solid kick build would not have this problem but I have not heard one yet.

As for width suffering, I'm not sure I follow. I know you've put a ton of work into your Golf and you have more experience with installing in that car than I do. But can you explain how the width will suffer in more detail?


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## derickveliz

Jazzi said:


> As for width suffering, I'm not sure I follow. I know you've put a ton of work into your Golf and you have more experience with installing in that car than I do. But can you explain how the width will suffer in more detail?


Not exactly but I'm trying to explain the loss of width when aiming on axis versus off-axis:



















.


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## GavGT

Or even better, do what i did


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## t3sn4f2

derickveliz said:


> Not exactly but I'm trying to explain the loss of width when aiming on axis versus off-axis:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> .



Seems like the opposite if you ask me. On axis will focus more of the off axis midrange to the further apart kick panels. Combining the two point sources to a summed effective wider spot. Where firing it straight across will reflect on the foot well and less on the kicks. IE dispersion characteristics.

Your reasoning is works well for dedicated mid bass apps but not for non omni-directional midrange frequencies.


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## jon w.

dear jazzi,

i've enjoyed reading your build log. well done, indeed! i'm delighted to know some of my work has been inspirational. 

i thought you might like to know that my website has been entirely rebuilt from scratch. it's taken me over three months and hundreds of hours of work to compile the information contained in my all-new website. now, my build log is entirely complete, from start to finish, documented with almost 800 photos. there, you'll find pictures detailing the fabrication of my acoustical treatments, including the Helmholtz absorbers and BAD ("binary amplitude diffusor") panels. in addition, you'll find a summary of my acoustical measurements. all of my 17 magazine articles are available for download (as a polymer scientist i'm particularly proud of part 5). there are video testimonials by ANT, Earl Zausmer, and Dan Brooks, all of whom enthusiastically describe the Magic Bus (not to mention the written testimonials by Robert Harley, and other great home audio professionals). additionally, there are a multitude of links to other websites of potential interest, and videos of incredibly famous and talented musicians playing live instruments through the Magic Bus' audio system. there are pre- and post-show reports for CES, Newport, and more. finally, there are hi-res images of all the autographs adorning the walls and subwoofer. 

my website is still in its "beta release". i'm pleased with the enormous content and its easy navigability. many will be pleased to know that it was also designed to work well with mobile devices. please remember, my goal for this website was to create an informative, no frills, easy-to-use, functional experience. 

i invite you to visit the ALL NEW www.whitledgedesigns.com

warmest regards,
jon


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## Justin Zazzi

jon w. said:


> dear jazzi,
> 
> i've enjoyed reading your build log. well done, indeed! i'm delighted to know some of my work has been inspirational.
> 
> ...
> 
> i invite you to visit the ALL NEW www.whitledgedesigns.com
> 
> warmest regards,
> jon


Hi Jon,

A welcome surprise! Of all the people who might notice and comment on my efforts ... thank you, so very much.

I am also excited about your new website. It has been difficult to locate a complete set of information about your build, and I'm happy to see it collected in one place. It is simple to navigate, and I really look forward to reading about your acoustic treatments in the Build section. And the other sections of the Build area when they are ready.

-Jazzi


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## Bluenote

Looking forward to hearing this soon Jazzi! Nice work throughout!


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## stochastic

Crazy, I didn't know John used BAD diffusion as well!


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## req

basically man, distance of voice coil to voice coil will give you a rough estimate on your width, physically speaking.

there are tons of other things that can change it - but moving them inboard by angling them will pull your outside boundary inboard. 

i put small midranges in the kicks, on axis, and left the midbass in the doors from 50~200hz, and things got way better. even matt roberts commented that i had good width.

i dunno what to tell you, it is my expierence that every time i have speakers inboard of the boundaries of the car my width suffers badly... patrick bateman has done some expierements that have tweeters in the center and all kinds of things - and there are solutions if you open your mind up, i am sure. but as of my expierementations with the gti, the further outboard you can push the speakers, the wider your stage will sound - BUT, the more off-axis other things suffer.

its just a game of trade-offs. 


btw, anyone else not getting any images to load on jon w.'s site?


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## GavGT

Images are fine for me on there, if a little slow to load.


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## jon w.

Jazzi: i hope you enjoy the content of my website. i describe my website as being in its "beta release" from the standpoint of aesthetics. the content is 100% complete, including the entire build log. 

GavGT: about the speed of the site ... there is over 120 MB of content in the site, and it was my decision to use higher quality images even though i knew it would slow things down a bit. nonetheless, i tested every aspect of the site on my iPhone4 to prove the site is manageable even at 3G speeds.


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## Justin Zazzi

jon w. said:


> Jazzi: i hope you enjoy the content of my website. i describe my website as being in its "beta release" from the standpoint of aesthetics. the content is 100% complete, including the entire build log.
> 
> GavGT: about the speed of the site ... there is over 120 MB of content in the site, and it was my decision to use higher quality images even though i knew it would slow things down a bit. nonetheless, i tested every aspect of the site on my iPhone4 to prove the site is manageable even at 3G speeds.


When using Chrome and Firefox and Internet Explorer on my desktop I see the following:
http://www.whitledgedesigns.com/magicbus_build_acoustical.php



> Magic Bus / Build / Acoustical Treatments
> 
> cache/wst.opf.2879884.xml
> 
> 
> 
> 
> 
> 
> 
> 
> Content copyright 2012. WHITLEDGEDESIGNS.COM . All rights reserved.



Internet Explorer gives an error on line 175, character 3, "Object Expected"

But on my *phone* the photos load.

It looks like you use javascript for the gallery. I'm not sure why my computer does not load it. From what I remember of javascript, either it completely works or it doesn't. But it works on other pages just fine, so I'm not sure what the problem is.


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## jon w.

dear jazzi,

i check the operation of my website today on a windows machine running 8 and internet explorer - it worked great! then i checked my website with firefox on the same machine and it ran great, too! i think the problem lies with your computer.

best,
jon


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## ErinH

I'm really late to the party regarding ASW, but I wanted to add $.02...

Don't forget driver's don't only beam. This seems like common sense but it seems it's sometimes just not really paid attention to. There's a wide polar pattern relative to the driver diameter and this is what creates the wide sound field we chase. I feel that most cars with off-axis mounting are the ones that seem to suffer "width" and easy localization of drivers moreso than when drivers are aimed on axis. The more you can make the car blend with the music, the less separation you have in the apparent stage. If you have holes in your sound field then you'll spot those, and one easy way to create a hole is by having a poor polar response. If you have drivers off axis, it's easy to have the stage stop there because the driver's energy is focused in front of the cone and less so to the side/behind, creating what I would (for a lack of better words) call a brick wall.

Yes, yes, there is certainly more to it than this. I just often see people discuss speaker aiming without realizing that the speaker isn't a constant beam and you should really be focused on the polar pattern of the system as a whole. If drivers are properly matched at crossover points, it's less of an issue but still an issue nonetheless.


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## bergend2

Jazzi said:


> Now I do.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> The factory tweeter location has a cutout in this foam material. The Morel MT-22 fits right in.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Stock tweeter grille has the center portion cut out along with the tweeter.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I wrapped some grille cloth over the outside to make it look clean.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> This image is really brightened up, the cloth in daylight is pretty dark. You can see the slight shape in the lower half of the fabric, that's the MT-22.


THANK YOU! I am just starting to get my setup together in my Jetta, and I just was trying to figure out who to mount my tweeters in the sail panel, I didn't even think of just leaving them in the foam cup. Just started cutting them, my NX30's are a veryyyyyy tight fit, hopefully it will work out. Loving the build so far!


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## Justin Zazzi

Some progress today. A big thank you to user Papasin for letting me borrow (and break) (and repair) his router and circle jig. I couldn't have made these mounting rings without it!









3/4" thick mdf turned into mounting rings using a combination of the included cutting template from Hybrid Audio and measuring with calipers. Lots and lots of trial and error to figure out how to use the router, plunger base, and circle jig. Overall though, not very difficult once you figure it out.










L3SE driver resting in the ring, a snug fit.










The trim ring painted black then wrapped in grille cloth and secured with Super77 spray adhesive. This will rest inside the ring using a friction fit.










A mockup of what the whole thing might look like.


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## Justin Zazzi

bergend2 said:


> THANK YOU! I am just starting to get my setup together in my Jetta, and I just was trying to figure out who to mount my tweeters in the sail panel, I didn't even think of just leaving them in the foam cup. Just started cutting them, my NX30's are a veryyyyyy tight fit, hopefully it will work out. Loving the build so far!


You're welcome! Good luck with your build too.


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## papasin

Jazzi said:


> Some progress today. A big thank you to user Papasin for letting me borrow (and break) (and repair) his router and circle jig. I couldn't have made these mounting rings without it!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 3/4" thick mdf turned into mounting rings using a combination of the included cutting template from Hybrid Audio and measuring with calipers. Lots and lots of trial and error to figure out how to use the router, plunger base, and circle jig. Overall though, not very difficult once you figure it out.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> L3SE driver resting in the ring, a snug fit.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> The trim ring painted black then wrapped in grille cloth and secured with Super77 spray adhesive. This will rest inside the ring using a friction fit.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> A mockup of what the whole thing might look like.


Like the progress and glad the router was put to good use. Couldn't have picked a cooler day? I mean, what's up with 102 degree weather in the Bay Area on the last day of September?!?


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## metalball

Router is definitely the way to go. My jigsaw skills suck...


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## Justin Zazzi

I want to aim the L3SE wideband drivers as on-axis as possible to my listening position in the driver's seat (hopefully to get excellent high frequency response), but also geometrically symmetrical relative to the car too (for aesthetics and hopefully to get a similar frequency response from the passenger seat).

Some measurements with the tape measure and a little trigonometry later ....










Hopefully this will help if you want to do something similar.

1) measure the three distances L, R, and W
2) plug them into the formula I derived and grind it out
3) draw an imaginary line from the midpoint of the two drivers to your head at the listening position. This will be the angle to the aiming position relative to the floor (lower left corner of drawing).
4) measure distance (A) from the midpoint of the two drivers, at an angle relative to the floor from step 3, to a point in space in the center of the interior. This is where you aim the speakers.

.........

I'm excited to be judging during MECA California State Finals this weekend and hope to see lots of you there!


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## req

looking cool man!

interested to see how you apply the math to fabrication!


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## Justin Zazzi

Hah yeah, me too!


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## TOOSTUBBORN2FAIL

Jazzi said:


> I want to aim the L3SE wideband drivers as on-axis as possible to my listening position in the driver's seat (hopefully to get excellent high frequency response), but also geometrically symmetrical relative to the car too (for aesthetics and hopefully to get a similar frequency response from the passenger seat).
> 
> Some measurements with the tape measure and a little trigonometry later ....
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Hopefully this will help if you want to do something similar.
> 
> 1) measure the three distances L, R, and W
> 2) plug them into the formula I derived and grind it out
> 3) draw an imaginary line from the midpoint of the two drivers to your head at the listening position. This will be the angle to the aiming position relative to the floor (lower left corner of drawing).
> 4) measure distance (A) from the midpoint of the two drivers, at an angle relative to the floor from step 3, to a point in space in the center of the interior. This is where you aim the speakers.
> 
> .........
> 
> I'm excited to be judging during MECA California State Finals this weekend and hope to see lots of you there!



This is excellent. I did exactly this recently in my car for a test, using L6SE's and L1 Pro R2's in baffles with the frames of the tweeter and midrange touching. Both speakers ended up at 17 degrees off axis. I had previously had problems with my stage being "compressed" on the right side, and evenly spaced on the left. I had a feeling that it was due to aiming, the speakers were in the kicks. So I moved them up to the dash, and tried this. When I set the time alignment before, it took hours to get it as good as I could. With the speakers equally off axis in the dash, it took 5 mins to dial in the time alignment. It fixed the staging problems I had, and also eliminated some early reflection problems I had (although the reflections problem was from getting them away from the plastic on the bottom of the dash. I think there is a pic in my build log of the passenger side speaker temporarily set up like this.


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## Justin Zazzi

This one? So much woofer on the dash!

I'm thinking about something experimental to make my L3SE mounting even smaller in diameter. The rings I made are 4" in diameter and are much larger than I thought they would be when mounted near the sail panels. With some _crazy_ machining, I estimate I can get the speakers and trim ring to no larger than 3 1/8" diameter. I have to draw it out to make sure it will work, more on that later.

Current inspiration for fabricating the sail panel baffle is from user krotzn and his build thread. Here are the photos of his super low profile L3SE mount:
http://www.diymobileaudio.com/forum/1611063-post13.html


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## GavGT

Interesting work Jazzi, i'm going to be keeping an eye on this build ready for when i rebuild my L3se's into whatever car i choose next. My builds at the minute are fairly slim but not taken to the limits of that Merc. I would be slightly worried about the restriction on the backwave of the driver and how this would effect the sound. I have about 1kg of lead shot mixed with resin lining the inside of my pods, usefull way to deaden them if you plan on getting them to play low.

Gav


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## TOOSTUBBORN2FAIL

Yep, that pic about sums it up. Took a lot of time to get them to sit on the sweatshirts at the right angle. In the end I planned on making the baffles much much smaller. I think I may be trying to BG Neo10's now though. With either midrange setup, I'll be running a dedicated midbass in the kicks, well, two per kick. Going to try an opposed firing manifold for midbass, to cancel out vibrations and get more cone area in a smaller space. I'll have pics of the test setup on my build this weekend. Probably wont have objective distortion measurements for a couple of months though.


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## Justin Zazzi

Working two jobs and attending school leaves little time for building! Time for some progress, finally. The goal is to have these things finished by year's end. There is a friendly rivalry with a local buddy competing in MECA modified class with me this year, and his build will be done very soon ...

-remove the rear seats (done)
-re-run all the electrical (done)
-mount the amp and 6to8 and leave room for a 3rd amp for later (done)
-build a hardwood floor to fill the entire rear of the car (in progress)
-install auxilliary lighting to the cargo area
-goto pick-n-pull and replace all kinds of factory trim I've torn up
-re-mount the midbass in the doors behind the factory door card instead of on-axis like they are now
-build curtains for the rear cargo
-experiment with turning the curtained-off cargo area into a bass trap
-experiment with rear fill using the 6to8 and some clever looping of output/input channels










_The beginning of the hardwood floor and new amp rack. The floor will mount upon the factory rear seat mounting posts and will be hinged just like the rear seats so it can fold up and down, allowing access to the spare tire. As a neat side effect, the hardwood floor acts like a false floor in that it creates a pocket of space below it. The amp rack will sit in this space on the driver's side, and the passenger side will turn into a concealed cargo pocket for keeping valuables out-of-sight, or hiding clutter and garbage._









_The lower half of the factory rear seats hook into these 1/4" holes and allow them to pivot out of the way when folding the seat-backs down. By installing a 1/4" steel rod and attaching some clamps, I'm able to use them as an anchor for the walls of the false floor and also for the amp rack without drilling or modifying anything, and retaining the ability to reinstall all factory rear seats, seatbelts, and other hardware within a reasonable time._









_Another view of the 1/4" rod and clamps._









_New amp rack mockup_









_New amp rack using threaded inserts for stability and serviceability. These are size #8-32 and are reusable as much as I want. Test fitting parts and installing/removing components is not a headache because I don't have to worry about stripping any wood using normal wood screws._









_The car as it sits tonight. Amp and processor installed on new amp rack, wiring re-run, new grounding point utilizes the factory seatbelt bolt, there will be a small fan for forced ventilation, and the hardwood floor is not in the picture but parts are in the garage and ready for work in the next few days._


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## Justin Zazzi

I've browsed a bit of the hardwood floor threads and still don't know exactly what I'm looking for. Below are some ideas and if you have thoughts on what would look clean but unique, I'd love to hear it!










_I thought at first a simple layout like this one would be nice. But after searching more and more, I'm starting to love the hardwood deck work found on boats (they have the coolest looking stuff ever)._










_This color of dark brown is really appealing._










_Here is a Range Rover concept car's cargo area. This would be absolutely fantastic, but damn it looks like a lot of work. I love how the simple lines are broken up into what looks like a piece of art, and the coloring is perfect._


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## [email protected]

Liking the build so far! I see a mix of new and old school and I certainly appreciate that! The Dummy head unit takes me back a few years for sure! I once did an install where we took a double din OEM headunit and allowed the dummy OEM faceplate to slide up and out of the way to reveal the Pioneer Premier P99 (old DEX model) underneath. 

I also like the use and consideration of absorption and diffusion in this thread. I have always dreamed of an insane install where the head liner is built down to allow a motorized absorption panel comes down to cover the windshield and similar panels come up out fo the door panels to cover the side windows. Crazy work I know but after spending the last few years building my theater room and working with OC 703 and other materials to build my absorption, bass trapping, and diffusion panels I can only think about how to apply them to car audio. 

I am also curious to see where you wind up with placement in the end and that leads me to a question... 

Any reason why you are using the sail panels instead of moving them further away to try and equalize PLD's, or are you hoping to use this with TA now that the single driver will be covering a much larger F range? 

Keep the updates coming!


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## Justin Zazzi

[email protected],

If you have any pictures of that install with the sliding faceplate I would really enjoy seeing it. Sounds like a fun project!

I have not posted it yet, but I'm happy with the temporary placement of the midrange drivers in the corners of the dashoboard rather than the sail panels. They have been sitting in their temporary enclosures wedged into the corners of the dashboard by a couple dish towels for the past two months while I haven't been able to make any progress, and I'm really happy with the placement and aiming. As for path length, I'm not fond of putting anything other than midbass in the kicks because the mid and upper frequencies can be attenuated by a huge margin depending on where you put your feet, or how large your body is. I also have not heard a full-kick install that images at horizon level from far left to far right. The corners of the dash are the next best placement for path length considerations, so that's a happy accident.

Happy holidays everyone!


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## Justin Zazzi

_-install auxilliary lighting to the cargo area_ (done)

I picked up a pair of these cold cathode ray tubes from Fry's Electronics for about $5 each. They are meant for the custom computer modders and are supposed to illuminate the inside of a computer case. But they run on 12vdc, use very little energy, are cheap and (supposedly) reliable, so we'll give it a try and see how long they last.

One foot-long tube on each side of the cargo area semi-hidden up under the factory trim panel. Below are the before and after photos. Both are taken using identical exposure and post processing to really show how weak the factory light was, especially if *anything* was in that cargo area because it is mounted so low and easily blocked.









_Before ...._










_... and after!_










_a little bit of detail, though not easy to see when they are turned on_










_30,000 candella output is a huge overestimate hahaha, but I hope some of the other claims are somewhat true. They cost about $5 each and are worth the gamble._


The current draw was spot-on at least. They draw 0.3A at 12v and put almost no load on the factory lighting system which makes installation a snap.

-J


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## sydmonster

certainly makes a difference though... but maybe thats just the exposure time on the photo!
Still looks good to me.

Keep going! were watching.


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## bbfoto

Awesome build log. Really appreciate all of the information and the supporting links.  Very interested in your progress...keep it up!


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## Justin Zazzi

sydmonster said:


> certainly makes a difference though... but maybe thats just the exposure time on the photo!
> Still looks good to me.
> 
> Keep going! were watching.


Believe it or not, the camera was set on manual and the exposure was identical for both shots. Yeah, that factory light was THAT terrible :mean:

Thanks all for the kind words.

-J


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## sydmonster

Jazzi said:


> Believe it or not, the camera was set on manual and the exposure was identical for both shots. Yeah, that factory light was THAT terrible :mean:
> 
> Thanks all for the kind words.
> 
> -J


 well... you have WIN here then!! nice one mang!


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## Justin Zazzi

_-build a hardwood floor to fill the entire rear of the car (in progress)_

I purchased 20 feet of 3/4" by 3/4" by 1/8" thick angle iron from a local welding yard and had them cut it to lengths. After some more cutting and drilling i took it to a buddy's house and did some mig welding. Both he and I were about the same level of inept, but in the end the welds held and I was able to grind off the ugly bits. Drilled some more holes and lined everything up nice, then painted it all black with a coat of primer.

The goal was to emulate the factory rear seats and the mechanism they use to slide into place and then lock in, making them very easy to install and remove with a simple screwdriver as a lever. Success! No new holes were drilled or any factory metal modified.

The next step is to measure, cut, and install a layer of plywood on top of the metal frame. I'll have to build a little bit more wood framework underneath it to support the weight of the new floor and the cargo I plan to lay on it, then the fun begins and I'll get to finally install the hardwood itself.









_An overall view from the driver's side showing the frame and amp rack._










_An overall rear view of the frame and the new (!) cargo area lights installed a couple days ago. You can also see the two long steel rails that extend to the rear of the car that will support the back half of the hardwood floor. More supports will be built._










_The factory seatbacks slide onto these posts near the center of the car, and my steel frame has matching holes that slide onto them as well. This allows my frame (and floor) to rotate up and down just like the factory seats could, giving me easy access to the audio gear underneath._










_The bolt and plastic shim that was threaded into the side of the factory rear seatback has been re-located onto my steel frame, and slides into the slot in the car frame perfectly. _

...

Audio projects are coming along too. I have completed a fleece sleeve that is now stuffed with rockwool mineral wool insulation that will occupy the rearmost two feet of the cargo area as an experiment in creating a bass trap. The amplifier and processor are mounted and operational. I have not had any luck finding my model year at the local pick-n-pull yards to salvage door cards and other interior trim pieces from, so that will progress when it does. And finally when the garage gets above 40 degrees in the evenings I might be tempted to fiberglass the front midranges into place.

Happy new year everyone!

-J


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## co_leonard

Very impressive! 

I applaud your efforts at scientific approach brought down to the nuts-and-bolts level as well as your drive to try new things.

I have no doubt that your car will sound excellent!


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## Justin Zazzi

Thanks Leonard!

I'm having trouble with fiberglassing in the recent cold weather and started a new thread for help. I think I have a solution but it will have to wait until after the holiday weekend.

The goal is to be presentable by Autorama in Sacramento in about a month. I also plan on judging for Meca during the event and hope to see lots of you there!


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## papasin

Jazzi said:


> Thanks Leonard!....I also plan on judging for Meca during the event and hope to see lots of you there!


Be hard for Leonard, given he's on the other side of the globe


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## co_leonard

papasin said:


> Be hard for Leonard, given he's on the other side of the globe


Yup, but I really do plan to visit one of these days. 

I'll bring along what we use here to judge SQ cars. I'd like to let you listen to the CD on your cars, and get your opinions on the CD. Specifically, how it compares with what you use. 

Click here for a picture of the CD: http://emmaeurope.hserver625.goller.cc/shop/images/product_images/popup_images/cd-regelwerk12en.jpg


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## papasin

co_leonard said:


> I'll bring along what we use here to judge SQ cars. I'd like to let you listen to the CD on your cars, and get your opinions on the CD. Specifically, how it compares with what you use.


Jazzi can tell you that all I listen to is SPL stuff .

Honestly, I've been enjoying about a dozen SQ CDs from this forum's BigRed. Also, this forum's bertholemy has a couple mix CDs I particularly enjoy for critical listening.


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## co_leonard

papasin said:


> Jazzi can tell you that all I listen to is SPL stuff .
> 
> Honestly, I've been enjoying about a dozen SQ CDs from this forum's BigRed. Also, this forum's bertholemy has a couple mix CDs I particularly enjoy for critical listening.


Then in that case, I'll bring along my old, scratched-up Bass 305 CDs! :laugh:


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## papasin

co_leonard said:


> Then in that case, I'll bring along my old, scratched-up Bass 305 CDs! :laugh:


Nah, no need. Only Jazzi thinks I have too much bass in my car . Then again, he hasn't listen to it yet since the new speakers, processor, and amps...so he might be surprised, or not :laugh: .


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## Justin Zazzi

Yeah that papasin guy is a real bass head haha. Or maybe I'm anti-bass? Something like that... also I need to borrow all your CDs.

No new photos yet because after 7 years and 45,000 shots my trusty Rebel XT has had exactly two problems: 1) I lost the rubber eye-piece only to find it later and 2) the batteries on my camera now hold a charge for about 2-4 shots at a time. I am absolutely amazed with how durable it is, and have new batteries on the way.

The sub-floor for the hardwood is complete and works great. The corners of the dash are taped off and the a-pillars are removed and everything is ready for fiberglass (whenever I decide to troubleshoot why it takes days to fully dry). The 2nd amplifier arrived and is ready for a surround-channel experiment using a hafler matrix, bandpass filtering, and time delay. I've completed making the curtain that will partition the rear cargo area from where the 2nd row of seats used to be, and it will nicely hide the large mineral wool bass trap that is also complete.

The other night I spent a marathon session using TrueRTA's free oscilliscope feature and my trusty M-Audio Fasttrack Pro to set all of my gains and Room EQ Wizard to get an initial tune on the setup (best software ever! seriously, and it's free!)

*Pro TIP:* To safely examine the output voltage of any piece of gear (amplifier) that is higher than the maximum input voltage of your tools (sound card), you can make a _voltage divider_. There is a tiny bit of easy math involved, but you only need two resistors to make one (make sure they are both high values though, something like 100k ohms or larger).

Lastly, I had a coolant leak that went for a couple weeks. After finally looking in to it, the o-ring on my coolant temperature sensor failed. I was absolutely amazed when the guy at NAPA auto parts had THE exact o-ring with a "made in germany" sticker on it. Unbelievable. So $0.75 later, fixed.

-J


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## SciPunk

I will be watching this as i too have 0 rear seats and a rear floor made of bamboo (soon to be tigerwood ) its more show than functional as in its static up to the lid for the spare which is covered in hardwood. 
Looking forward to progress


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## Justin Zazzi

SciPunk said:


> I will be watching this as i too have 0 rear seats and a rear floor made of bamboo (soon to be tigerwood ) its more show than functional as in its static up to the lid for the spare which is covered in hardwood.
> Looking forward to progress


Hey SciPunk,

I am curious why the switch from bamboo to tigerwood? I was looking at both and really liked the look and feel of the bamboo. As I understand it, the more unique hardwoods like bamboo and Hawaiian woods are much more durable than others. I'm told laminates are most durable, but they look fake and unpleasing. I'd love to have a distressed or hand-sanded look as well, but that might be too specific to find for cheap. Lastly, a local shop recommended I go with an un-finished wood and simply lay some teak oil on top so if ti does get scratched or banged up, I can sand it out and restain it really easy.

Anyone with experience have thoughts on any of this hardwood floor stuff? I'm trying to avoid reinventing the wheel on this one....

-J


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## SciPunk

I agree with you on the laminates. They just feel plastic but they do take a beating altho nearly impossible to repair. 

We decided on a switch from bamboo to tigerwood as we had bamboo for the last year and this season we wanted to switch things up some. My car is themed in a steampunk fashion and i think the darker tigerwood will bring a warmth to the back to counter the harsher industrial look found on the sides. 

This tigerwood is actually bamboo core with tigerwood on top, bamboo sits at about 1600-1800 hardness while tigerwood is around 3k...lol So cutting it is gonna be a nightmare but dammit all we are gonna try. 

You can find a scraped/sanded look for relatively cheap. the box we got (one box should be more than enough) was around 63 shipped. I know there were a few that were in the style you like around that price, ill have a look. 

Ours is the snaplock style, makes it a touch easier for making the main floor but the edging can be a pain. 
Heres a pic of how it looked last year:









This was our first time ever doing anything like this in a car, so we learned a lot and the judges loved it. We plan to make it better this time. 

As far as advice, plan your cuts which considering what you are im not worried..lol. Also remember to make side panels where the rear doors are to hide everything. Gorilla wood glue works very well and remember it will need a sub floor for strength. Also it will creak till it settles. For protection you could cut out fabric to cover the floors when your not showing it off/daily use. 

If i missed anything let me know!


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## co_leonard

Jazzi said:


> The other night I spent a marathon session using TrueRTA's free oscilliscope feature and my trusty M-Audio Fasttrack Pro to set all of my gains and Room EQ Wizard to get an initial tune on the setup (best software ever! seriously, and it's free!)


I agree 100%. I use TrueRTA as well.


----------



## Justin Zazzi

_-build curtains for the rear cargo (done!)_

Curtain is some on-sale fleece from the local fabric shop, sewn onto a curtain rod that was also on sale. About $10 total.




















_-experiment with turning the curtained-off cargo area into a bass trap (done!)_

The majority of the leftover Rockwool was cut into a rough block and then covered in some more fleece. I sewed a zipper into the size (twice because I'm a sewing rockstar) and it fits in the rearmost cargo area perfectly. The measurements taken below are using Room EQ Wizard and the RT60 function (the T20 option actually).











_When adding the bass trap the T20 time for my largest peak around 120hz is reduced from roughly 0.49 seconds to 0.37 seconds ... in improvement of nearly 25%. Is this audible? I'm not sure. The time required to remove it and listen again is too long to make a serious comparison. But I am happy to see it does make a measurable difference and works as intended._











_This graph is borrowed from Whitledge's Magic Bus for comparison. My car has a very lot RT20 time in the higher octaves similar to the other un-modified cars he has measured (much lower than his bus)._



I am a little confused about two things. 1) why do I have such a high T20 peak in the 120hz range whereas all of the other cars the RT does not rise until roughly one octave lower? and 2) why does my RT fall in the lowest octaves whereas the other cars rise sharply? I assume I am making different measurements or using my software differently but I'm not sure how exactly.










_And finally 2x 250w heat lamps to dry fiberglass over the next couple nights. This should fix my drying issues ...._


----------



## SciPunk

Floor is looking good, love the curtain idea! Your side cuts (near the doors) match the contours well  Looking forward to more!


----------



## speakerpimp

I have been working on reading all of the info for weeks in this thread! Awesome job and thread, thanks for sharing everything!!


----------



## Justin Zazzi

speakerpimp said:


> I have been working on reading all of the info for weeks in this thread! Awesome job and thread, thanks for sharing everything!!


I am thrilled this thread is useful! It was my goal all along to share what I've learned and hopefully others can learn from it, as I have learned from others before me.


----------



## SciPunk

Jazzi said:


> I am thrilled this thread is useful! It was my goal all along to share what I've learned and hopefully others can learn from it, as I have learned from others before me.


Thats what it's all about 

BTW jazzi i posted my car in the build logs finally...lol


----------



## Justin Zazzi

The weather is slightly warmer plus I'm loving these infrared heat lamps. So fiberglass'ing is going really well. Today's progress:










_Another build thread for a-pillars used closed cell foam as a spacer between the pod and the windshield so the final product will not be smashed against the glass and look stressed from the outside. I borrowed that idea and laid down a layer of blue tape, then foam against the glass, and a layer of foil on all sides._











_A half hour under the heat lamp and it was dry (winning!). Hot glued the baltic birch baffle in place then trimmed all the excess fiberglass using some tin snips. I was careful initially to make the mold as close to the metal a-pillar as possible so I can bolt to it later._











_Side view with L3SE test fit. After placing some cotton over the missing side from the this photo and fiberglassing from the inside, I used some body filler to seal up the gaps between the battle and the fiberglass. _











_The factory a-pillar had to be trimmed to fit the pod. The goal is to tuck the speaker so far into the corner that I can make a very low profile extension to the a-pillar and gently wrap around the speaker pod. With some ninja skills, I hope my work will be invisible and there will be no hints of a speaker to the untrained eye._











_The pod is held in place with a single bolt that screws into a rivet-nut. It is a female threaded insert that crushes in place just like a rivet. They are very secure, install cleanly, and inexpensive._











_This is what the installation tool looks like. Place the insert, the die, and the supplied bolt into a pre-drilled hole and then tighten the bolt against the die to crush the insert into place. It is not mentioned in the instructions, but you really want to use lubricating oil on all moving surfaces (threads and bolt head) to prevent the tool from destroying itself prematurely._


----------



## Justin Zazzi

The driver's side speaker pod and pillar are complete. I apologize about the photos, it is not easy to get good ones in a dark garage at night. The overall appearance is close to my mind's eye. I have a lot of appreciation for pro pillar builders like JT and others. Their work looks so effortless, whereas mine is exhausting!









_I was tired of fiberglass and wanted to try something new, faster, and easier to shape on-the-fly. So to create the flowing shape around the speaker pod I used some 1/4" wire mesh. I had to cut it and sew it back together using some thin wire to get the compound curves I wanted._











_Test fit with the a-pillar and a piece of foam in place of the midrange driver._











_If I wrapped the wire with grille cloth, it wouldn't strech and would bunch up so I chose Lycra instead. However it clearly showed the rib-like structure of the wire mesh underneath so I had to first wrap it with a nylon screen door material to smooth out the peaks and valleys. The nylon was stitched in place with some kite string, then I was able to finally wrap the entire piece in Lyrca._











_I'll post a new photo in daylight sometime soon, but this will have to do. The entire pillar is wrapped in black Lycra, as well as the door jamb air seal which was originally grey. The tiny airbag badge was painted black to match. I'm not happy the defrost vent for the driver's window is partially blocked, but I'm not sure how I could do better._


----------



## SciPunk

Looks great man, we all have to make sacrifices for our cars... sometimes that means a little less defrosting 

Love to get your opinion on my car sometime, link is in my sig.


----------



## Justin Zazzi

SciPunk said:


> Looks great man, we all have to make sacrifices for our cars... sometimes that means a little less defrosting
> 
> Love to get your opinion on my car sometime, link is in my sig.


I saw your car on the euro forum when you posted the link earlier. This might fall into the right timeline for your theme: the lost art of wire lacing. Pick up some heavy waxed thread off eBay if you want to try it. I found some used to stitch horse saddles for pretty cheap.


----------



## req

that actually looks really cool, and the fact that it is faster and cleaner than glass while being acoustically transparent is awesome as well. i have been contemplating doing something similar to this but more off-axis. the insturment cluster hump is quite large on our cars.


----------



## sydmonster

Top shot!! 

Keep going, I like the way and reasoning your going about your build with!


----------



## nervewrecker

Interesting build I must say.


----------



## bigbubba

Jazzi said:


> The driver's side speaker pod and pillar are complete. I apologize about the photos, it is not easy to get good ones in a dark garage at night. The overall appearance is close to my mind's eye. I have a lot of appreciation for pro pillar builders like JT and others. Their work looks so effortless, whereas mine is exhausting!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> _I was tired of fiberglass and wanted to try something new, faster, and easier to shape on-the-fly. So to create the flowing shape around the speaker pod I used some 1/4" wire mesh. I had to cut it and sew it back together using some thin wire to get the compound curves I wanted._
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> _Test fit with the a-pillar and a piece of foam in place of the midrange driver._
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> _If I wrapped the wire with grille cloth, it wouldn't strech and would bunch up so I chose Lycra instead. However it clearly showed the rib-like structure of the wire mesh underneath so I had to first wrap it with a nylon screen door material to smooth out the peaks and valleys. The nylon was stitched in place with some kite string, then I was able to finally wrap the entire piece in Lyrca._
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> _I'll post a new photo in daylight sometime soon, but this will have to do. The entire pillar is wrapped in black Lycra, as well as the door jamb air seal which was originally grey. The tiny airbag badge was painted black to match. I'm not happy the defrost vent for the driver's window is partially blocked, but I'm not sure how I could do better._


Awesome job on the install so far.

That wire mesh method is clever as HELL! I always seem to find the most backassward method to do the easiest tasks sometimes. Gonna have to file that away for the next project.


----------



## BigRed

Cool stuff Jazzi!!


----------



## MeioFomiga

I keep ending up back here, and seeing your work! Again, outstanding!


----------



## Justin Zazzi

Finally had some spare time this weekend to get more done. Finished the passenger side pillar and pod. Attempted to tune the system using three new techniques with mixed results.

The first was to experiment with Jon W's idea of rolling off the mid and high frequencies in the right channel slightly to compensate for hrtf effects (on his build page here). I guess he has great success with it based on his response measurements, but it didn't work at all for me. Perhaps it is car and install-specific, or I don't really understand what he was doing there.

The second thing was to experiment by using using time delay to match the PHASE between subwoofer and midbass drivers at the crossover point instead of matching DISTANCE like most people suggest. The results are _excellent_. After reading the thread below a few times and fully digesting what was discussed, I used TrueRTA with a running average of about 20 samples. While adjusting the relative time delay between the subwoofer and midbass, I carefully watched for interference in the crossover region on the RTA. When the area around 45-55hz looked the highest, I stopped. So simple, so effective.
http://www.diymobileaudio.com/forum...sion/92336-up-front-bass-just-illusion-5.html
(discussion picks up around post 100, and is sizzling by post 150, thank you Lycan and Andy!)

Third was to learn about "house curves" and how to use them. Essentially they a target to aim your frequency response for your system. Some people prefer more bass than others, some prefer different amounts of treble or midbass, and so forth. Most of us will have two curves: one for competition with relatively mild deviations from flat, and one for casual enjoyment usually with more bass and slightly rolled off treble. This photo show's Andy's preferred curve and I used it as a starting point. It is really entertaining and has a lot of energy down low without sounding boomy.

This particular curve has too much bass for me, so I might try to lower the shelf below 60hz to +6db instead of +9 tomorrow and see what happens. The neat trick is you can create a very simple .txt file with your house curve and use it in TrueRTA or RoomEqWizard or any other program. Then you only have to tune what you see on the screen to be "flat" instead of trying to tune a curve which can be more difficult.

A sample house curve text file might look like this: (frequency +-gain)
20 6
60 6
160 0
3000 0
15000 -3











_With the experience of building the driver's side a-pillar wire mesh, the passenger's side was easier and looks much better._











_Only two pieces of screen this time, with different geometry and overall shape. The screen goes up much further towards the pillar to make the shape more ... flowy._











_Test fit. Mostly I'm posting more photos because these turned out better than the driver's side ones._











_Last one of the dash pods and pillar._


----------



## Justin Zazzi

I will be bringing the Golf to Autorama this coming weekend in Sacramento and hope to see lots of you there!


----------



## sydmonster

Is it finished??


----------



## Justin Zazzi

Is it ever finished? Nope.
It is done for the moment though.

I still need to install the hardwood floor, experiment with delayed rear fill, and a few other tricks. By then ill surely have some new ideas too.


----------



## khaoticle

sub'd


----------



## papasin

Jazzi said:


> I will be bringing the Golf to Autorama this coming weekend in Sacramento and hope to see lots of you there!


Congrats on the podium finish, wow, what an exciting year lies ahead for the MECA Modified class in CA this season .


----------



## cyrusthevirus23

very sweet cant beat that idea hiding it


----------



## Justin Zazzi

Thank you! I'm thrilled that there is a lot of competition in our class, and that there are some very well built cars to measure against. 5th place to 3rd place were separated by less than five points, and 1st place was only 5 more above that!

Lots of fun to be had this year.


----------



## cyrusthevirus23

good luck with it


----------



## papasin

Jazzi said:


> Thank you! I'm thrilled that there is a lot of competition in our class, and that there are some very well built cars to measure against. 5th place to 3rd place were separated by less than five points, and 1st place was only 5 more above that!
> 
> Lots of fun to be had this year.


IIRC, 1st to 5th was about 5pts .


----------



## Darth SQ

Jeez Justin, I didn't know this thread existed until today.
Sorry for being late to the party.
I will be using the trig formulas to calculate my a-pillar positions so I thank you for doing the legwork on them.

I had the opportunity to audition this car a the Autorama show this last Saturday.
I was very impressed about it's ability to produce a very focused stage.
With my eyes closed, there was zero doubt in my mind that the singer or narrator (MECA Chesky CD) was smack dab in the center of the hood.
Well done buddy!
As for the way the rest of sounded, I was definitely impressed as well but since I'm not qualified to enumerate further without sounding silly, I'll stop right there. 
I noticed that you have not flush mounted the midbass yet.
Ran out of time, or did you just change your mind?

Lastly, my only complaint in this build thread has nothing to do with the build at all, but for the life in me, I just don't understand why Jon W. can't post a comment anywhere without always turning into a commercial about the bus. :shrug:

Oh well......it was great to spend some quality time with you and Papasin this weekend at the show and thanks again for the opportunity to audition your VW.
I imagine I'll see you in March right?

Bret
PPI-ART COLLECTOR


----------



## papasin

PPI-ART COLLECTOR said:


> Jeez Justin, I didn't know this thread existed until today.
> Sorry for being late to the party.
> I will be using the trig formulas to calculate my a-pillar positions so I thank you for doing the legwork on them.
> 
> I had the opportunity to audition this car a the Autorama show this last Saturday.
> I was very impressed about it's ability to produce a very focused stage.
> With my eyes closed, there was zero doubt in my mind that the singer or narrator (MECA Chesky CD) was smack dab in the center of the hood.
> Well done buddy!
> As for the way the rest of sounded, I was impressed but sinnce I'm not qualified to enumerate further without sounding silly, I'll stop right there.
> I noticed that you have not flush mounted the midbass yet.
> Ran out of time, or did you just change your mind?
> 
> Lastly, my only complaint in this build thread has nothing to do with the build at all but for the life in me, I just don't understand why Jon W. can't post a comment anywhere without always turning into a commercial about the bus. :shrug:
> 
> Oh well......it was great to spend some quality time with you and Papasin this weekend at the show and thanks again for the opportunity to audition your VW.
> I imagine I'll see you in March right?
> 
> Bret
> PPI-ART COLLECTOR


We're waiting for your Suburban to get Modified stacked even further .


----------



## Justin Zazzi

Bret,

I'm glad the diagrams and math can be helpful, it was rewarding to use school to solve a real world problem.

Thank you for the warm compliments, I very highly value everyone's feedback and it is a driving force to get my butt out to competitions and get-togethers. I did not flush-mount the midbass drivers because I ran out of time, but should likely have that done before the next event.

I too am becoming bitter against Jon's constant use of these forums as an advertising platform and he comes across as very non-genuine. I'm sure the thin representation of his personality here is unfair to judge him as a person, but yeah it's really annoying.

I too look forward to your Suburban and its build. I may not mention it always, but I'm happy to help everyone with anything I can. Do not hesitate to ask questions and if I don't know the answer, I'll try to refer you to someone who does.

-J


----------



## Justin Zazzi

So after the competition this weekend and getting tons of great feedback, I am even more strongly convinced that tuning is just as important (if not more) than installation. It's really hard to put numbers to it, but I feel that tuning and installation are tied for significance, and equipment selection is a definite third. I've been using the exact same gear for countless builds and rebuilds in the past two cars (except for replacing my tweeters with a 3" wideband) and the difference in results are staggering. The same car and gear can sound absolutely stellar or horrifyingly terrible. It is dumbfounding.

Here is a brief list of things that have worked, and have not worked:

*Worked well:*
point-source driver (3" wideband) on the dash
using time alignment to match phase between drivers _at their crossover points_
sound deadener showdown
closed cell foam under driver's footwell carpet to isolate bass during competitions
mounting 6" midrange driver on-axis _when playing up to 2khz_
transmission line subwoofer for extended low frequency response and huge efficiency
active processing, but more importantly, _understanding how to use it_
calibrated microphone from Cross·Spectrum Labs - Sound | Vibration | Engineering
TrueRTA and Room EQ Wizard
reading absolutely everything I can find about everything
becoming an SQ judge and becoming a part of the community - huge huge huge
3M Super 77 spray adhesive
router and circle jig ... omg what a game-changer
nut-serts and threaded wood inserts are fantastic
The Acoustics and Psychoacoustics of Loudspeakers and Rooms - by Floyd Toole
mineral wool as a bass trap, though it puts me into the highest competition classes so I do not use it
Ideal brand Duct Seal from Lowe's ... useful for everything
using my hiking headlamp to work in the garage in the evenings


*Didn't work well:*
6" midrange in the doors playing down to 2khz pulled the image down a ton
using time alignment as a compensation for physical distance _only_
cheapo "damping" materials from home improvement stores
fiberglass'ing without a clear plan from concept to finish ... soooo much wasted effort
tuning based on _someone else's_ house curve, rta response, or expectations
fiberglass'ing in cold weather without any accelerant or heating devices
t-nuts or hurricane nuts are dumb and not very resilient


----------



## sydmonster

Jazzi said:


> So after the competition this weekend and getting tons of great feedback, I am even more strongly convinced that tuning is just as important (if not more) than installation. It's really hard to put numbers to it, but I feel that tuning and installation are tied for significance, and equipment selection is a definite third. I've been using the exact same gear for countless builds and rebuilds in the past two cars (except for replacing my tweeters with a 3" wideband) and the difference in results are staggering. The same car and gear can sound absolutely stellar or horrifyingly terrible. It is dumbfounding.
> 
> Here is a brief list of things that have worked, and have not worked:
> 
> *Worked well:*
> point-source driver (3" wideband) on the dash
> using time alignment to match phase between drivers _at their crossover points_
> sound deadener showdown
> closed cell foam under driver's footwell carpet to isolate bass during competitions
> mounting 6" midrange driver on-axis _when playing up to 2khz_
> transmission line subwoofer for extended low frequency response and huge efficiency
> active processing, but more importantly, _understanding how to use it_
> calibrated microphone from Cross·Spectrum Labs - Sound | Vibration | Engineering
> TrueRTA and Room EQ Wizard
> reading absolutely everything I can find about everything
> becoming an SQ judge and becoming a part of the community - huge huge huge
> 3M Super 77 spray adhesive
> router and circle jig ... omg what a game-changer
> nut-serts and threaded wood inserts are fantastic
> The Acoustics and Psychoacoustics of Loudspeakers and Rooms - by Floyd Toole
> mineral wool as a bass trap, though it puts me into the highest competition classes so I do not use it
> Ideal brand Duct Seal from Lowe's ... useful for everything
> using my hiking headlamp to work in the garage in the evenings


Thanks for sharing mang,...
Do you mind expanding a little more on why these worked for you.
More so on the less seen/heard about things such as your tuning techniques and tips?


----------



## Justin Zazzi

sydmonster said:


> Thanks for sharing mang,...
> Do you mind expanding a little more on why these worked for you.
> More so on the less seen/heard about things such as your tuning techniques and tips?


I would love to, and have thought about it many times. Whenever I start though, I'm paralyzed by the overwhelming amount of information I've learned and cannot decide where to start.

So help me out. Pick a topic, something specific if you can, and I'll do my best to share what I know.


----------



## BigRed

Ahhh. Wise one. Tuning and placement. What a concept


----------



## SPLEclipse

Jazzi said:


> *Didn't work well:*
> 
> fiberglass'ing in cold weather without any accelerant or heating devices
> \


Ugg...tell me about it. 

Awesome build so far! It's a huge help to me to have people like you on the forum who's technical knowledge is beyond my reach (for now)!


----------



## sydmonster

Jazzi said:


> I would love to, and have thought about it many times. Whenever I start though, I'm paralyzed by the overwhelming amount of information I've learned and cannot decide where to start.
> 
> So help me out. Pick a topic, something specific if you can, and I'll do my best to share what I know.


Topic - Cabin/Environmental treatments.
-Pro's, con's.
-What would you have done differently.
-What gave you the most gain/acoustical benefit Vs what was best value for benefit (incase there's a difference). 

Thank you!!!


----------



## req

glad the duct seal worked for you


----------



## Justin Zazzi

sydmonster said:


> Topic - Cabin/Environmental treatments.
> -Pro's, con's.
> -What would you have done differently.
> -What gave you the most gain/acoustical benefit Vs what was best value for benefit (incase there's a difference).
> 
> Thank you!!!


*Cabin and Environmental treatments*

Pros: 
As fancy and well marketed as processors and other electronics are, there are some things they cannot compensate for such as standing waves, decay times (rt60), resonant door cavities or other surfaces, reflections, and a few others. The only way is to address these problems is by physical means, not by manipulating the electronic signals that are fed to the speakers. When the right physical treatments are applied to the right problems the results can be astounding and also cannot be achieved any other way. I have a few examples in this thread like using closed cell foam and duct seal to isolate vibrations, mass loaded vinyl to create sound barriers, constrained layer damping to reduce resonant panels, bass traps, and especially the physical location of the speakers themselves.

Cons:
Unfortunately every single car and every single listening room is unique in this respect. It is very difficult to create a rule of thumb for physical treatments because of the absurd number of variables involved in each system as a whole. So while a particular technique I used solved my particular problem, it may only slightly help if you have a problem _in your car_. In addition, each variable is related to other variables so while you may improve one aspect of a system, often times you must trade something undesirable. Bass traps are fantastic, but take up huge amounts of space. Damping and sound barriers are effective but can weigh a fair amount and are very labor intensive. Reflections are ridiculously hard to control without significantly altering the drivability of the car.

In addition and perhaps more significant, there is a certain amount of craftsmanship and a lot of time that is required to make physical treatments really effective. Sealing every seam of mass loaded vinyl takes a lot of patience, reinstalling all factory panels cleanly without evidence of a half inch of new material hiding behind them is tough, accessing and cleaning all the surfaces you want to damp with tiles is not easy, and so on.

What would I have done differently:
Not much. I am happy with my journey so far and glad I've approached it with an inquisitive mind. My goals from the start were to learn as much as possible, change one thing at a time, and share what I've learned with other people along the way. I feel successful.

What gave you the most gain/acoustical benefit Vs what was best value for benefit:
The number one thing is becoming an SQ judge, _critically_ listening to other people's cars, and being forced to _translate what I'm sensing into words_ on paper. I feel many people enjoy training their ears and this is a great skill to have. However I didn't realize until now how critical is to be able to describe to someone else what I am hearing so that _they_ can understand it. It is said the best way to learn and understand something is to teach it to others, and I completely subscribe to that belief. (This is very cheap by the way and doesn't cost much money at all!)

Similarly, learning how to use the common tools and _understanding what it all means_ was super important. Being able to understand something in my mind and have it confirmed by a measurement (TrueRTA, REW, etc) is very satisfying. This is only possible with lots of reading. Quality reading though like books I've mentioned on page one of this thread and the other authoritative sources I've quoted along the way. Sifting through the buzz and rabble of people quoting eachother on the internet to find the real contributors is a huge challenge. Names like Andy Wehmeyer, Patrick Bateman, Martin J King, Lycan, Linkwitz, Floyd Toole, Everest, Ethan Winer, and many others stand out for example.

So, knowledge is king.

-J

.... feel free to ask more!


----------



## Darth SQ

Jazzi said:


> *Cabin and Environmental treatments*
> 
> Pros:
> As fancy and well marketed as processors and other electronics are, there are some things they cannot compensate for such as standing waves, decay times (rt60), resonant door cavities or other surfaces, reflections, and a few others. The only way is to address these problems is by physical means, not by manipulating the electronic signals that are fed to the speakers. When the right physical treatments are applied to the right problems the results can be astounding and also cannot be achieved any other way. I have a few examples in this thread like using closed cell foam and duct seal to isolate vibrations, mass loaded vinyl to create sound barriers, constrained layer damping to reduce resonant panels, bass traps, and especially the physical location of the speakers themselves.
> 
> Cons:
> Unfortunately every single car and every single listening room is unique in this respect. It is very difficult to create a rule of thumb for physical treatments because of the absurd number of variables involved in each system as a whole. So while a particular technique I used solved my particular problem, it may only slightly help if you have a problem _in your car_. In addition, each variable is related to other variables so while you may improve one aspect of a system, often times you must trade something undesirable. Bass traps are fantastic, but take up huge amounts of space. Damping and sound barriers are effective but can weigh a fair amount and are very labor intensive. Reflections are ridiculously hard to control without significantly altering the drivability of the car.
> 
> In addition and perhaps more significant, there is a certain amount of craftsmanship and a lot of time that is required to make physical treatments really effective. Sealing every seam of mass loaded vinyl takes a lot of patience, reinstalling all factory panels cleanly without evidence of a half inch of new material hiding behind them is tough, accessing and cleaning all the surfaces you want to damp with tiles is not easy, and so on.
> 
> What would I have done differently:
> Not much. I am happy with my journey so far and glad I've approached it with an inquisitive mind. My goals from the start were to learn as much as possible, change one thing at a time, and share what I've learned with other people along the way. I feel successful.
> 
> What gave you the most gain/acoustical benefit Vs what was best value for benefit:
> The number one thing is becoming an SQ judge, _critically_ listening to other people's cars, and being forced to _translate what I'm sensing into words_ on paper. I feel many people enjoy training their ears and this is a great skill to have. However I didn't realize until now how critical is to be able to describe to someone else what I am hearing so that _they_ can understand it. It is said the best way to learn and understand something is to teach it to others, and I completely subscribe to that belief. (This is very cheap by the way and doesn't cost much money at all!)
> 
> Similarly, learning how to use the common tools and _understanding what it all means_ was super important. Being able to understand something in my mind and have it confirmed by a measurement (TrueRTA, REW, etc) is very satisfying. This is only possible with lots of reading. Quality reading though like books I've mentioned on page one of this thread and the other authoritative sources I've quoted along the way. Sifting through the buzz and rabble of people quoting eachother on the internet to find the real contributors is a huge challenge. *Names like Andy Wehmeyer, Patrick Bateman, Martin J King, Lycan, Linkwitz, Floyd Toole, Everest, Ethan Winer, and many others stand out for example.*
> 
> So, knowledge is king.
> 
> -J
> 
> .... feel free to ask more!


Did you see your name in that list Papasin?
I sure didn't see mine.
Maybe we haven't won enough trophies yet. 


Bret
PPI-ART COLLECTOR


----------



## papasin

PPI-ART COLLECTOR said:


> Did you see your name in that list Papasin?
> I sure didn't see mine.
> Maybe we haven't won enough trophies yet.
> 
> 
> Bret
> PPI-ART COLLECTOR


Jazzi knows he can ask me questions...like can I borrow your router lol...although even that no longer is the case because he didn't want to rely on mine.

But as far as trophies...Bret, you're the one with the two first place finishes, so you trump me for sure and I have no idea why Jazzi didn't put you on his top SQ people to go to given your vast knowledge of how to make a bone stock system win.


----------



## Justin Zazzi

True story!

I have to also thank PPI-Art (the winningest Stock competitor I know), Papasin (the guy with the most toys and gadgets), and so many others (I could not remember all their names) for all the great feedback on my car, discussions about judging and ear training, and general comradery over the past year or so. Without the community both here online and also in person at the competitions and get-togethers, this would be a much more lonely hobby.


----------



## captainobvious

Jazzi-
Great build! Can you please take a minute to comment on the Roxul and how it is holding up? I'm very curious about this material and want to make sure it's not retaining any water.


Thanks !!


----------



## Justin Zazzi

captainobvious said:


> Jazzi-
> Great build! Can you please take a minute to comment on the Roxul and how it is holding up? I'm very curious about this material and want to make sure it's not retaining any water.
> 
> 
> Thanks !!


It's raining this weekend, and I've developed some new rattles and buzzes that need to be hunted down. I'll see if I can tear into one of the doors and check up on the Roxul. I'm really curious too. It'll be a few days or a week before I have something to report, but I'll get there.

Thanks for asking.


----------



## Darth SQ

Up late tonight Jazzi? 
Rain's just starting up here in the Sierras.
Happy Easter!


Bret
PPI-ART COLLECTOR


----------



## Dmack

Have you by chance seen the build log on my MKIV Jetta? This is the third incarnation of the build, so I have certainly learned a great deal from experience with these cars. Here, check it out. http://www.diymobileaudio.com/forum...l-gallery/145907-2013-hybrid-jetta-build.html
The L3's need plenty room to breathe. The accomplish this, I build the pods where they vent into the a-pillars, and more importantly, into the defroster ducts. The pods are thin fiberglass, but then they were reinforced, internally with mat and resin, and three layers of Rammat--this things are solid. I also packed them fairly tightly with polyfill. After break-in, I get amazing high-end extension to 20Khz, even to the point of being too "bright." 
Also, I get no rainbowing, an amazing center image and a very high soundstage which extends well outside the boundaries of the car.


----------



## metalball

Keep up the good work! Can't wait to see what other innovations are "accidentally" discovered on this build!


----------



## sqgodz

About all I can say is wow... Another word that comes to mind is "huh"... 

But no in all reality, awesome build. I wish I had the requisite knowledge to understand what the hell you are talking about sometimes though. 

Really awesome build... I'm in...


----------



## Justin Zazzi

Dmack said:


> Have you by chance seen the build log on my MKIV Jetta? This is the third incarnation of the build, so I have certainly learned a great deal from experience with these cars. Here, check it out. http://www.diymobileaudio.com/forum...l-gallery/145907-2013-hybrid-jetta-build.html
> The L3's need plenty room to breathe. The accomplish this, I build the pods where they vent into the a-pillars, and more importantly, into the defroster ducts. The pods are thin fiberglass, but then they were reinforced, internally with mat and resin, and three layers of Rammat--this things are solid. I also packed them fairly tightly with polyfill. After break-in, I get amazing high-end extension to 20Khz, even to the point of being too "bright."
> Also, I get no rainbowing, an amazing center image and a very high soundstage which extends well outside the boundaries of the car.


I have not seen it before now, but I like your pods. They fit the lines of the trip panels nicely. I too love those L3SEs, they perform admirably in this particular installation. It is interesting how we are both very happy with our setups despite having very different details in the installation. Thank you for sharing!


----------



## Justin Zazzi

sqgodz said:


> About all I can say is wow... Another word that comes to mind is "huh"...
> 
> But no in all reality, awesome build. I wish I had the requisite knowledge to understand what the hell you are talking about sometimes though.
> 
> Really awesome build... I'm in...


Hi sqgodz,

Welcome to the forums!

Wow and Huh .... alright, I'll take that as a compliment 

My goal is to learn and to share, so _please_ ask if something is beyond your current understanding and I'll do my best to explain it, or my reasoning behind it. I enjoy sharing with other people just as much as I enjoy building and tuning.

-J


----------



## Justin Zazzi

Finally had enough free time to go shopping for wood to finish the hardwood floor in the rear. I wanted to emulate the lush hardwood decks on high-end boats with their uniformly long planks and decorative layouts. I love the combination of craftsmanship and art that makes a nice deck come together. It was impossible to find any sort of boxed or factory-made hardwood floor planks that were narrow, crazy durable, and looked natural. They were either finished in 10 coats of some kind of protective film or were laminate or printed or something else that looked like crap.









_(this is what I'm aiming for!)_

Teak wood is (or was) very commonly used for boat decks because it is so durable but for whatever reason it now costs hundreds of dollars for just a few square feet at my local lumber yard. IPE, Tigerwood, and Mangaris are the next best materials to choose from because they are the most dense and durable, and they are all fantastically gorgeous.

So I picked up a sample of Mangaris with the intent of using Teak Oil to stain/finish it. The beauty of this method is if I manage to scratch or damage it, all I have to do is lightly sand the damaged area and wipe some new teak oil onto it ... good as new.

Below is the sample and the right side is natural, untreated wood, and the left side is treated with teak oil. Damn it's pretty. Its a shame the photo does not do it justice. The color is much deeper in person, whereas on the monitor it looks really faded.










I just stumbled upon a company that makes phosphorescent caulk to go in between the planks. Now that would be neat ...










-J


----------



## captainobvious

Pretty neat looking stuff. I love the wood floor idea. That should look terrific.


----------



## Justin Zazzi

Jazzi said:


> I too am becoming bitter against Jon's constant use of these forums as an advertising platform and he comes across as very non-genuine. I'm sure the thin representation of his personality here is unfair to judge him as a person, but yeah it's really annoying.
> 
> -J


I wrote this awhile ago and, at the risk of starting a much wider debate, I wanted to share an experience I found very valuable. I do not intend to derail my own thread so please help me keep comments on this to a minimum.

In short, Jon Whitledge invited me to chat for many hours over a couple phone calls about various things audio related. I also spoke with a few members of this forum who are critical of his work and his intents, both personal and business related.

After getting a much more clear picture of why Jon's name and his work are such magnets for controversy and also after speaking with and learning more about him and his experiences, I wanted to apologize for jumping on the bandwagon and attacking him along with everyone else. At the end of the day, he's just another guy who loves acoustics and music just like the rest of us, or maybe more than the rest of us!

So if you ever catch yourself doing or saying something but not knowing why, take a moment to investigate and understand. This is one of my favorite things to do, because this is when true learning happens.


----------



## Darth SQ

He will always be P.T. Barnum and that rubs me the wrong way.
So what changed you mind?
And what prompted you to post this now?


Bret
PPI-ART COLLECTOR


----------



## Justin Zazzi

What changed my mind was taking the time to talk to him, to the others I mentioned, and forming my own opinion. I hate nothing more than being ignorant on purpose.

I'm posting this now because I've also sent someone else a private message about something similar from a few months ago.

It just feels, good.

-J


----------



## 3fish

Jazzi said:


> So if you ever catch yourself doing or saying something but not knowing why, take a moment to investigate and understand. This is one of my favorite things to do, because this is when true learning happens.


"There is a principle which is a bar against all information, which is proof against all arguments and which cannot fail to keep a man in everlasting ignorance---that principle is contempt prior to investigation."

----Herbert Spencer


----------



## sqgodz

Jazz - "wow" and "huh" are meant purely as compliments as you are speaking over my head. I can understand the math but not the acoustics of it as I just haven't had much exposure to it. You did fill out my summer reading list though as I will have about 3 months to dig into the books that you mentioned. I unfortunately do not posses the skills or the knowledge (read balls) to cut into my car like that. No kicks or a-pillars for me... Stock locations with the addition of a sub... Thank you for the idea of a wood floor. I might try that in my trunk somewhat like Bowdown and his wood false floor. Have a good one...


----------



## Justin Zazzi

It's been a while. But I'm glad I took a break from car audio because I posted my best grades ever, which allows me to continue my education at a university this fall. I have a few weeks break until moving to a new home, so it's time to make some progress again.

Bought a bunch of Mangaris hardwood today and had the wood shop shape it up with their mill. 2.5" wide strips, 1" thick, cut to 4ft. long pieces. Picture below shows (roughly) how it will be laid out, but there will be some tricks built in. I can't wait to get it together and share it with everyone 

It smells as wonderful as it looks too! (that's a first!)










I've also picked up a bunch of factory trim pieces from my local auto wrecking yard to replace some of the stuff I've torn up and broken, for example I can now flush mount the midbass into the doors again. The Eclipse CD7200mkII radio lost some of its magic smoke the other day, so I have a service manual on the way to troubleshoot and repair it.

More progress coming over the next few days...


----------



## Justin Zazzi

Stopped here for the night. This section will rest at the front of the cargo area, where the rear seats used to be. It will float on a frame leaving a storage pocket underneath for amps, processing, jumper cables, first aid kit, etc.


----------



## req

damn dude. looks like that wood was cut with a laser 



you ever get into the doors and look at that roxul?


----------



## stylngle2003

love it. super cool idea!


----------



## Darth SQ

Got some for the outside? 


Bret
PPI-ART COLLECTOR


----------



## Justin Zazzi

req said:


> you ever get into the doors and look at that roxul?


Nope, never did get around to it. I'll be rebuilding the doors again to get the midbass flush mounted like they used to be, and plan to look at the roxul and post some photos then.


----------



## Justin Zazzi

Front half of the floor is cut, fit, and screwed. I'm using grey 1/8" thick polycarbonate strips to fill in the gaps between the wood planks. I asked TAP Plastics cut them to be just a bit taller than the Mangaris wood, so now that it is all assembled the polycarbonate sticks up just a bit taller than the wood. Tomorrow I'll be belt sanding the whole thing with something like 100 grit, then 400 grit to smooth it all out. Then I can finally stain it with teak oil, and begin on the rear half.

I would like to thank my sponsors. Okay not really, but this guy has lent me so many of his nice tools I gotta thank him for it. Papasin, I owe you one!

If anyone wants to see this project in person, I'll be a the MECA competition in Sacramento in a couple weekends, August 4th. Details are in this thread here.


----------



## bbfoto

Looks beautiful, Jazzi. Glad that you're back at it.  Are you going to use the Soss hinges as well?


----------



## Justin Zazzi

Thank you bbfoto. It looks even better now after the teak oil staining, I mean ... wow!

I wanted to use the soss hinges, but decided on something a little different. It should make sense in a couple days when I'm done and take some more photos.

Back to the garage......


----------



## req

yeah dude. that looks a million times better than the "wood floors" i have seen at H20 VW show in ocean city.

rock on bro!


----------



## Darth SQ

Will the wood layout disable the rear seat?
Sorry if I missed this earlier.


Bret
PPI-ART COLLECTOR


----------



## quietfly

Jazzi said:


> Thank you bbfoto. It looks even better now after the teak oil staining, I mean ... wow!
> 
> I wanted to use the soss hinges, but decided on something a little different. It should make sense in a couple days when I'm done and take some more photos.
> 
> Back to the garage......



can't wait to see how this turns out. looks like a fantastic start.


----------



## req

PPI-ART COLLECTOR said:


> Will the wood layout disable the rear seat?
> Sorry if I missed this earlier.
> 
> 
> Bret
> PPI-ART COLLECTOR


yes.


----------



## FLYONWALL9

That, is going to be SWEET.

This is a boat I bout to help rehab after my accident. Though this
is mahogany and not teak. I milled each and matchbooked. Fun process
really rewarding.
Bateau Photo Gallery: Click image to close this window


----------



## Justin Zazzi

FLYONWALL9 said:


> That, is going to be SWEET.
> 
> This is a boat I bout to help rehab after my accident. Though this
> is mahogany and not teak. I milled each and matchbooked. Fun process
> really rewarding.
> Bateau Photo Gallery: Click image to close this window


What a beautiful boat! I too am really enjoying this process. It's very slow because I'm such a perfectionist and doing a lot of learning as I go, but also therapeutic in a way. What did you do, or what did you use to get the white lines between the planks? Is it something similar to grout or caulk? Is there also cotton (?) smashed between the planks? I've seen that done on other wood decks but I'm not sure exactly what the purpose is.


----------



## FLYONWALL9

Jazzi said:


> The beauty of this method is if I manage to scratch or damage it, all I have to do is lightly sand the damaged area and wipe some new teak oil onto it ... good as new.
> 
> -J


THANKS FOR THE COMPLIMENT

One of the best kept ole sailer/boaters trick is to 
use a damp cloth and hot iron. We do the same 
with hardwood gunstocks. Just keep the rag damp
and the steam will pull the dent out. 

I'm guessing you have read a great deal about sanding
this stuff? and what not to do


----------



## FLYONWALL9

Well, as you have said several methods of filling those gaps. Most boats that you have seen use that black stuff, its a calk, it does have some give to it so that it flexes with the planks. What I used is thickened slow cure epoxy with fiberglass fibers, microballoons, and epoxy pigment. You can tint it any shade you wish. The way we get the gaps is to use whatever size screw gives you the width your after and finder washers to hold down the edges of the planks. This is only after you butter the back side of the plank with epoxy to hold it to the subfloor. So once the planks are glued to the subfloor you pull out the screws and finder washers, use toothpicks to plug the holes left by the screws in your subfloor. 
EXAMPLE
Bateau Photo Gallery: Click image to close this window

Bateau Photo Gallery: Click image to close this window

After the first coats of filler, the decks have a milky looking finish. You have to be really careful sanding. I wouldn't go as strong as 100 grit. I would start with your 400 and just take your time. Reason why is it will be very easy to sand a divot. Always hold the sander flat and work in the direction of the grain. 

I don't want to go too in depth because I don't know how much you already know and don't want to take up too much of your thread. If you have questions I'll be happy to answer any. I've done several planed decks from various materials, even the faux stuff on the market.


----------



## Justin Zazzi

Thanks for all the info! I wish we could have talked a bit earlier haha.

I've done some woodwork before, was taught by my "big brother" from Big Brothers Big Sisters (its a youth mentoring thing, and I loved it so much I became a "big" recently too). The thing that threw me for a loop was trying to evenly sand down the polycarbonate to the level of the wood planks (that were perfectly flat after running through the planer) without making divots like you mention. In the end I'm happy with the result and learned some tricks to finish the rear half much cleaner.

I could use a suggestion on what to fill in the small gaps with, the tiny errors where I cut something a hair short or something doesnt line up perfectly. Wood filler comes to mind, but I doubt I could get a good color match or it might be too thick to fill in the tiny voids. Something that dries matte black would be my first choice.

I love the trick about inflating dents with an iron, ill have to try that with a scrap piece.


----------



## Justin Zazzi

Almost done!

Each of the long planks were cut and numbered to preserve the order they are laid out so the front and rear halves match. Also, each board has a piece of 1/8" polycarbonate nailgun'ed to the side to keep it flush on the top.










The front half is stained and complete. The rear half needs about a half hour more worth of power tools, but it's late and I'd rather not upset the neighbors. Some final cutting tomorrow and then staining, and it's done!










More details to come ...


----------



## sydmonster

this is just simply nice!! I can't remember the last time I saw something like this in a hatch back! Great, lush work!


----------



## jon w.

beautiful design and craftsmanship! for a while, i thought you might surprise us by making it into a slatted Helmholtz absorber


----------



## eisnerracing

sure beats a vacume - just need a swiffer !!

or have a rumba running around the back end - lol 

looks cool


----------



## Justin Zazzi

I have not given up on the idea of a panel absorber, there is certainly enough room under the rear half for one. I could not however make it one piece, this floor weights a lot as it is! Acoustic treatments are at the front of my mind though, and hopefully I'll have time enough to explore some ideas.

The floor is complete, stained, and drying now. I'll install it later today and hopefully have some last photos for you all. There is one last part unfinished, but I have not yet decided how I want to do it, so that will wait a little while longer.

Below is the detail of how the front and rear halves are joined. There is a piece of 1" angle iron bolted to the underside of the rear half that sticks out just high enough to engage the slot I cut into the front half. This forces the two halves tightly together to keep them aligned and (hopefully) give the appearance of one continuous piece.










Unrelated, but there are a pair of enormous carpenter bees that live in my apple tree. I finally had the camera ready this time. Larger than a penny, larger than my thumbnail, and completely docile.


----------



## BigRed

Lookin good!

Let me know when we can tackle those other expirements


----------



## Justin Zazzi

BigRed said:


> Lookin good!
> 
> Let me know when we can tackle those other expirements


Thank you Jim!

Those other experiments will require a tutor in horns/waveguides, and another tutor in 4th order bandpass enclosures (or maybe some brute force experiments in both subjects). I've not seen either of these ideas done before, so if you want to try something completely new, let me know!

One more coat of teak oil on the rear half tomorrow and then the floor is ... done. What a fun project this has been!










(the color balance is true, those colors are lush!)


----------



## req

looks bitchin!


----------



## BigRed

4th order band pass is nothing new unless u are speaking of something else

I'm always down for new experimenting


----------



## Justin Zazzi

Do you (or anyone else) know how to make a 4th order bandpass play about 3 octaves from 50hz through 300hz? The only information I can find relates to subwoofers and very limited bandwidth near 40-80hz.


----------



## captainobvious

req said:


> looks bitchin!



I'll second that. VERY nice work.


----------



## papasin

Just saw this in person...looks even better than the pics .


----------



## FLYONWALL9

Jazzi said:


> Thanks for all the info! I wish we could have talked a bit earlier haha.
> 
> I've done some woodwork before, was taught by my "big brother" from Big Brothers Big Sisters (its a youth mentoring thing, and I loved it so much I became a "big" recently too). The thing that threw me for a loop was trying to evenly sand down the polycarbonate to the level of the wood planks (that were perfectly flat after running through the planer) without making divots like you mention. In the end I'm happy with the result and learned some tricks to finish the rear half much cleaner.
> 
> I could use a suggestion on what to fill in the small gaps with, the tiny errors where I cut something a hair short or something doesn't line up perfectly. Wood filler comes to mind, but I doubt I could get a good color match or it might be too thick to fill in the tiny voids. Something that dries matte black would be my first choice.
> 
> I love the trick about inflating dents with an iron, ill have to try that with a scrap piece.


Sorry I am just now coming back to the party. IHope not too late, then again if so you may have the info needed if you run into the short wood issue again. You have found it is nearly impossible to stretch wood once its too short.  I did see where you had it together so, I am late, wish you had sent me a PM. I don't always get updates for some reason, perhaps it is something to do with AOL. 

My suggestion would be to use epoxy and wood flour (the saw dust used when you sanded it with the belt sander. Inherently once mixed it will be a bit darker, so you may need to play with the same dust from the wood and some flour from some lighter colored wood. Something like clear pine mixed with this wood, but in doing so you would want to measure out ratio's in teaspoons or something like that. It can be done. The other option would be to make the gap's the same on each piece. I may be misunderstanding the problem.

If you still have some scraps try a bit of TUNG oil thinned with mineral spirits for the first few coats. This will penetrate a bit farther into the wood for the first couple coats then go straight Tung oil. As you know the issue with teak oil over time will turn, its just the nature of oiled teak. Tung oil tends to last a bit longer, but try a piece of scrap wood to see if the color is up to snuff. The best part of Tung oil is the smell, its just got that great natural wood smell. I'm not saying you would need to redo what you have, it looks wonderful! It may just last longer once you see that you only get a few months out of teak oil as another option. 

I think the big bro's / big sis program is awesome. Sounds like you had a great brother and you'll end up being the same. More people should do that program, I applaud you....

Cheers,
Scott

edit:
How did the sanding go? were you able to take it down and keep it fairly even? Keep the sanding
marks down to a fair minimum? In time and with use you'll see it needs some refreshing. You'll 
want to use a long block I would say 8-14 inches. Get some block sand paper from Harbor Freight
and glue it to your wood block. You can use a smaller block if needed to get into those tight places,
wrap it with a piece of Scotch pad then wrap your paper around that. This will keep pressure marks
from your fingers off your nice flat floor. 

I gotta say, for this being your 1st attempt at planking I can tell you did a ton of reading and 
research. It shows. GREAT WORK!!


----------



## Justin Zazzi

sydmonster, jon w, eisnerracing, bigred, req, captainobvious, papasin,

Thank you all for the warm comments. I'm glad you and others here enjoy and appreciate this whereas most of my family and friends' first reaction is ... "why did you do that?"

BECAUSE I CAN, THAT'S WHY



(also I have that _new boat smell_ for life)

edit: and flyonthewall too!


----------



## req

its just awesome to see more like minded people around the world. i will have to say to you, thank you for posting your progress - it really makes me want to get out and work on my crappy install


----------



## quietfly

that looks phenomenal!!!


----------



## Justin Zazzi

An update on the to-do list:
-remove the rear seats (done)
-re-run all the electrical (done)
-mount the amp and 6to8 and leave room for a 3rd amp for later (done)
-build a hardwood floor to fill the entire rear of the car *(done!)*
-install auxilliary lighting to the cargo area *(done)*
-goto pick-n-pull and replace all kinds of factory trim I've torn up*(done)*
-build curtains for the rear cargo *(done)*
-experiment with turning the curtained-off cargo area into a bass trap *(done)*
-re-mount the midbass in the doors behind the factory door card instead of on-axis like they are now (in progress)


Some new ideas I'm working on:
-examine roxul rockwool in the doors to see how it is holding up
-dash horns (utilize windshield and dash as a horn, throat in the corner)
-bandpass enclosures for midbass (triple chamber for opposing drivers, no tactile feedback)
-convolution and artificial rt60 reinforcement in midrange/treble
-active bass trap (to make up for lack of room available for passive traps)
-try linear-phase eq (because it's supposed to be better?)
-aligning channels to eachother using phase in addition to time delay


and some dreams:
-building custom audio processor using a carPC
-trunk monkey
-cable lacing
-automated false faceplate
-vu meters built from the speedo and tachometer


----------



## req

-aligning channels to eachother using phase in addition to time delay

how do you plan on doing this? the issue is once anything is adjusted, the phase at that point can change. EQ, time alignment, crossover, etc. 

just a little reading for you, if you have not read it already. i am waiting on a power supply for my arc ps8 to use in-home. i am going to perform an expierement or two with speaker placement based on this thread with a pair of tweeters, closed back midranges, and midbass' speakers in the OPSODIS arrangement. then im going to try some 1\4 wavelength tube expierements with midbass speakers to mount drivers real far away based on the second thread.

http://www.diymobileaudio.com/forum...ussion/150134-crazy-imaging-stock-system.html

http://www.diymobileaudio.com/forum/hlcd/121185-mounting-drivers-really-far-away.html


----------



## HondAudio

Jazzi said:


> I want to aim the L3SE wideband drivers as on-axis as possible to my listening position in the driver's seat (hopefully to get excellent high frequency response), but also geometrically symmetrical relative to the car too (for aesthetics and hopefully to get a similar frequency response from the passenger seat).
> 
> Some measurements with the tape measure and a little trigonometry later ....
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Hopefully this will help if you want to do something similar.
> 
> 1) measure the three distances L, R, and W
> 2) plug them into the formula I derived and grind it out
> 3) draw an imaginary line from the midpoint of the two drivers to your head at the listening position. This will be the angle to the aiming position relative to the floor (lower left corner of drawing).
> 4) measure distance (A) from the midpoint of the two drivers, at an angle relative to the floor from step 3, to a point in space in the center of the interior. This is where you aim the speakers.
> 
> .........
> 
> I'm excited to be judging during MECA California State Finals this weekend and hope to see lots of you there!



Without taking out my TI-85 to run theoretical numbers, are _angle a_ and _angle B_ supposed to be the same?


----------



## TOOSTUBBORN2FAIL

I believe that was his goal. The idea was to get both drivers equally off axis to the driver and passenger seat. For example, in my car, I can get my midranges at about 17 degrees off axis, at both seats, for both the left and right mid. This should give the best chance of a two seat car, and even help with a one seat car, since at the same angle, the response should be similar shaped.


----------



## Justin Zazzi

HondAudio said:


> Without taking out my TI-85 to run theoretical numbers, are _angle a_ and _angle B_ supposed to be the same?


Good question. Angles alpha (α) and beta (β) should be different because this is not assumed to be an isosceles triangle, and all three sides should be different lengths (sides L, R, W).

The angles that should be the same are the ones in blue below. The angle between left speaker axis and the listening position should be the same as the angle between the right speaker axis and the listening position. This is the goal.
(however in my hand drawing they are not quite the same, so it is misleading)


----------



## Justin Zazzi

req said:


> -aligning channels to eachother using phase in addition to time delay
> 
> how do you plan on doing this? the issue is once anything is adjusted, the phase at that point can change. EQ, time alignment, crossover, etc.
> 
> just a little reading for you, if you have not read it already. i am waiting on a power supply for my arc ps8 to use in-home. i am going to perform an expierement or two with speaker placement based on this thread with a pair of tweeters, closed back midranges, and midbass' speakers in the OPSODIS arrangement. then im going to try some 1\4 wavelength tube expierements with midbass speakers to mount drivers real far away based on the second thread.
> 
> http://www.diymobileaudio.com/forum...ussion/150134-crazy-imaging-stock-system.html
> 
> http://www.diymobileaudio.com/forum/hlcd/121185-mounting-drivers-really-far-away.html



Going to build a carPC for processing only. I see lots of people wanting to build a carputer with fancy touch screen, dvd playback, nagivation, bluetooth, wireless sync of audio library, engine diagnostics, etc etc etc .... and it is paralyzing the number of options and amount of work that goes into a build like that. So my carputer will have a motherboard, a tiny ssd hard drive, and an external sound card. It will run a VST plugin host with filters for whatever I want. A linear phase EQ will prevent me from having to realign the drivers to eachother if I change the EQ. Since there will be no keyboard/mouse/monitor, I'll use the remote management console for windows XP from my laptop via a crossover cable to the carputer to work with it.

That's the plan so far.

Also, I've been reading Patrick's thread on the OPSODIS alignment. That seems very interesting and I hope you can do something with it. For mounting drivers really far away, I know you've seen my attempt at it and I hope you can build upon that idea!


----------



## JayinMI

req said:


> -aligning channels to eachother using phase in addition to time delay
> 
> how do you plan on doing this? the issue is once anything is adjusted, the phase at that point can change. EQ, time alignment, crossover, etc.
> 
> just a little reading for you, if you have not read it already. i am waiting on a power supply for my arc ps8 to use in-home. i am going to perform an expierement or two with speaker placement based on this thread with a pair of tweeters, closed back midranges, and midbass' speakers in the OPSODIS arrangement. then im going to try some 1\4 wavelength tube expierements with midbass speakers to mount drivers real far away based on the second thread.
> 
> http://www.diymobileaudio.com/forum...ussion/150134-crazy-imaging-stock-system.html
> 
> http://www.diymobileaudio.com/forum/hlcd/121185-mounting-drivers-really-far-away.html


Looking at the first thread, I'm confused. He said the '13 Jetta he was renting, but it looked like the older door panel with the MB in the rear of the door. (Unless it was a Jetta Sport Wagon, from what I've seen in some of Bing's threads, the wagons still use the older locations), but then he shows a picture of the newer panel with the MB in front of the door and says it's a '12...You're both VW guys, am I wrong?

Jay


----------



## req

i dont know where he got the pictures, but his rented jetta - the speakers were in the aft sections of the doors.

the thing that gets me - is the phase information being forward seems to be a serious problem for off center seating causing the "angle of attack" for the wave front plus the diameter of our heads having a stupid effect of the phase hitting both ears at the same time (or close) instead of one ear at a time kind of deal.

this is why headphones work so damn well right?


----------



## captainobvious

req said:


> i dont know where he got the pictures, but his rented jetta - the speakers were in the aft sections of the doors.
> 
> the thing that gets me - is the phase information being forward seems to be a serious problem for off center seating causing the "angle of attack" for the wave front plus the diameter of our heads having a stupid effect of the phase hitting both ears at the same time (or close) instead of one ear at a time kind of deal.
> 
> this is why headphones work so damn well right?



Hmm, what I don't get about this is that sound from the left speaker is still going to hit your right ear in the 1st configuration, just at an even longer time delay. Headphones work well, but lack the sense of space that a typical home stereo setup provides. This is probably due to the total lack of reflections (direct vs indirect sound).


----------



## Justin Zazzi

captainobvious said:


> Hmm, what I don't get about this is that sound from the left speaker is still going to hit your right ear in the 1st configuration, just at an even longer time delay. Headphones work well, but lack the sense of space that a typical home stereo setup provides. This is probably due to the total lack of reflections (direct vs indirect sound).


The difference in time between sound arriving at the right ear compared to the left ear results in a difference in phase between the two ears, which is how our ear/brain localizes sounds in the lower frequencies. So the theory of OPSODIS (as I understand it) is to increase that delay to the maximum by placing the midbass driver to the far left and right of the listener, to create maximum delay between the left and right ears, to ensure maximum phase difference between the ears, hopefully resulting in the widest sound stage.

Headphones are unique because they have perfect interaural cross-correlation (zero), meaning the left ear _only_ hears the left channel, and the right ear _only_ hears the right channel. Ambiophonics attempts to create this effect, but the sweet spot for listening is very precise and not easy to setup in a car, and impossible to setup for a driver and passenger at the same time (unless one sits directly behind the other).

You are right that home stereo (and home theater) setups have more spaciousness due to reflections. Early reflections tend to broaden an image, and late reflections tend to give a sense of envelopment. The books I recommend on the first page go into this in great detail, and I cannot recommend them highly enough!

This thread has a lot of great discussion on the topic too:
http://www.diymobileaudio.com/forum...-discussion/117783-where-does-width-come.html

Look for more threads and posts by a member named Lycan. I wish he was still around, some of my favorite reading was in threads he started or contributed to.


----------



## Justin Zazzi

Equipment for the Carputer should be arriving today. It will consist of:

M-Audio Profire 610 external sound interface $175
Gigabyte Mini-ITX motherboard with Intel Celeron Processor $85
Mini-box.com's M3-ATX automotive pc power supply (crazy cool item) $65
SanDisk ReadyCache 32 GB SATA 3 Solid State Drive $43
2GB Kingston Ram DDR3 $19
Random PCI Firewire Card $15
random bits from the electronic surplus store $48
total: $450

So if I use free VST host and plugins, I'll have a system that costs less than my processor (6to8), but I'll likely pay for some of the software. It is certainly more effort, but not a ton more expensive. Hopefully it will be much more flexible, which has been the goal from the start.


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## req

rock on.

just to let you know;

http://www.diymobileaudio.com/forum...ve-multi-touch-all-one-7-10-inch-display.html


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## Justin Zazzi

I did see that and might keep an eye on it. But I have absolutely no plan to put a display in the car or run a front-end on the pc. Just processing for now, that is challenge enough!

Thanks for the tip though


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## mitchjr

Subscribe


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## Justin Zazzi

Thanks for your interest MitchJr

The magic smoke escaped from my head unit, but thankfully the service manual arrived and I was able to purchase and install some new smoke. Details about that are in this other thread below. All repaired now. I forgot how good it sounds : )

http://www.diymobileaudio.com/forum...clipse-cd7200-mkii-component-q704-melted.html

I'm moving for school this weekend, and likely won't be making much more progress on this build for a while. At least the Golf will have a garage to sleep in though. That's a first.


----------



## Justin Zazzi

So the Eclipse CD7200mkII is proving to be more difficult to repair than I thought. The details are all in the thread listed above, but I'm hopeful. 2nd round of repair parts are in the mail right now.

In the meantime, I've started working on building a carPC as a custom processor. What a nightmare this has been too.










The M-Audio Profire 610 was supposed to be the external sound card of my dreams. 8 balanced analog outputs with high voltage op-amps, a stereo pair of analog inputs, and digital input and output as well. However after spending the past couple weeks going back and forth with their support staff and trying every single trick there is (AND purchasing an expensive firewire card off of their "approved" list") I have completely given up on the thing. It works great on my home computer running XP, but not on my project computer running win7x64. So it's back for sale.













Then I found this, the Asus Xonar D2 (heh yeah the 1/8" jacks are lighted from the inside!). It has some equally impressive specs, has pretty high voltage outputs for a "consumer item", and does full duplex 24bit/96khz with 8 analog channels out, stereo analog in, and digital in/out as well (plus a mic input too, but I don't plan to use it). It also has built-in Dolby Digital Headphone and ProLogic IIx processing, and DTS Neo6 too. It's a pretty sweet package and not very expensive either (I lucked out and found a used one for $85).

But this has problems too. My M3-ATX power supply does not seem capable of powering the Xonar D2 sound card. The negative 12v power rail measures -12vdc on my multimeter when the card is not installed, but as soon as I put it in and turn on the computer, it rests at -3.6vdc !!! This is a serious problem because it supplies the negative half of the op-amps on the sound card and there is massive clipping at any volume louder than a whisper.

sometimes I wish computer stuff would just ... work


----------



## [email protected]

Buy a mac...




Jazzi said:


> sometimes I wish computer stuff would just ... work








haha.. sorry... I just wanted to beat "that guy" out to be "that guy" for today.. lol..
That is weird about the power for the card, I have never run across anything like that..


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## ErinH

I've wanted to use a carPC for a long time for the added benefits but the issues like you've found yourself running into combined with my minimal time to play with this stuff has kept me from doing it. The way things are with modern DSPs, I just don't really see the intrinsic benefit. Yes, there are some great features you can get (FIR filters being one) but I've found that less involved seems to be the end winner. I definitely wish you luck going forward and I'm sure you'll get it worked out. Keep us posted (no pun intended).


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## Darth SQ

Jazzi said:


> So the Eclipse CD7200mkII is proving to be more difficult to repair than I thought. The details are all in the thread listed above, but I'm hopeful. 2nd round of repair parts are in the mail right now.
> 
> In the meantime, I've started working on building a carPC as a custom processor. What a nightmare this has been too.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> The M-Audio Profire 610 was supposed to be the external sound card of my dreams. 8 balanced analog outputs with high voltage op-amps, a stereo pair of analog inputs, and digital input and output as well. However after spending the past couple weeks going back and forth with their support staff and trying every single trick there is (AND purchasing an expensive firewire card off of their "approved" list") I have completely given up on the thing. It works great on my home computer running XP, but not on my project computer running win7x64. So it's back for sale.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Then I found this, the Asus Xonar D2 (heh yeah the 1/8" jacks are lighted from the inside!). It has some equally impressive specs, has pretty high voltage outputs for a "consumer item", and does full duplex 24bit/96khz with 8 analog channels out, stereo analog in, and digital in/out as well (plus a mic input too, but I don't plan to use it). It also has built-in Dolby Digital Headphone and ProLogic IIx processing, and DTS Neo6 too. It's a pretty sweet package and not very expensive either (I lucked out and found a used one for $85).
> 
> But this has problems too. My M3-ATC power supply does not seem capable of powering the Xonar D2 sound card. The negative 12v power rail measures -12vdc on my multimeter when the card is not installed, but as soon as I put it in and turn on the computer, it rests at -3.6vdc !!! This is a serious problem because it supplies the negative half of the op-amps on the sound card and there is massive clipping at any volume louder than a whisper.
> 
> *sometimes I wish computer stuff would just ... work*








^^^^^^^^in bold^^^^^^^^^










One word.....................





j/k 



Bret
PPI-ART COLLECTOR


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## Darth SQ

I am however, loving that ASUS sound card.
They make amazing monitors as well. 


Bret
PPI-ART COLLECTOR


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## Justin Zazzi

[email protected] said:


> Buy a mac...
> 
> haha.. sorry... I just wanted to beat "that guy" out to be "that guy" for today.. lol..
> That is weird about the power for the card, I have never run across anything like that..


Hey JOey, nice meeting you at the training this afternoon!


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## req

did you think that your power supply does not have the strength for it?

are you using a dc-dc power supply on your bech for testing? or a real desktop power supply?

i gave up with trying to use a PC for a processor and im just using it for all the fun stuff that the pc can do other than DSP. it is SO much easier to bypass that stuff and use a standalone DSP than use the car PC for everything.

thats what i did to get around the problems lol - kind of a cop out, but whatever


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## Justin Zazzi

req said:


> did you think that your power supply does not have the strength for it?
> 
> are you using a dc-dc power supply on your bech for testing? or a real desktop power supply?
> 
> i gave up with trying to use a PC for a processor and im just using it for all the fun stuff that the pc can do other than DSP. it is SO much easier to bypass that stuff and use a standalone DSP than use the car PC for everything.
> 
> thats what i did to get around the problems lol - kind of a cop out, but whatever


I think the bench power supply I'm using is adequate, and I put a fair size capacitor across it just in case. The M3-ATX computer power supply should provide 0.15A on the negative 12v rail (confirmed by the manufacturer today). So the Asus card must be trying to pull more than that ... I think.

The more I bang my head against the wall with this carPC processor thing, the more I just want to give up and keep using my 6to8. But the stubborn side of me just refuses to give up, and the creative side of me still needs an outlet to experiment with stuff.


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## [email protected]

Jazzi said:


> Hey JOey, nice meeting you at the training this afternoon!


Nice meeting you too! Jazz"i" with an I! 

Were you going to the show on the 21st?


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## [email protected]

If you use your 6to8 you can add the AMAS board and stream high res files into it.. 

I just added that to mine, so we will see how it goes. I have some CD's I ripped to FLAC, I gotta do a head to head between the disk and the streamed FLCA and see what the difference (if any) is..


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## Justin Zazzi

Yes, I will be at the show on the 21st in San Jose.

I could add the extra board to the 6to8, but my trusty Sansa Clip+ plays all the flac I need surprisingly well. It also does audiobooks like Game of Thrones, The Inheritance Cycle, and The Wheel of Time.


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## ErinH

Jazzi said:


> I think the bench power supply I'm using is adequate, and I put a fair size capacitor across it just in case. The M3-ATX computer power supply should provide 0.15A on the negative 12v rail (confirmed by the manufacturer today). So the Asus card must be trying to pull more than that ... I think.
> 
> The more I bang my head against the wall with this carPC processor thing, the more I just want to give up and keep using my 6to8. But the stubborn side of me just refuses to give up, and the creative side of me still needs an outlet to experiment with stuff.


Here's a seroius question: what can the carPC DSP provide you that (this is key) you actually need? I know a few people who have had elaborate PC DSP and their system sounded no better than what can be achieved with common DSPs today. In many cases people have royally FUBAR'd their systems as well trying to make use of all the fancy features they have over others. Like I mentioned previously, I definitely think they're cool but in terms of real benefit, what is there? What is it exactly *you *are trying to achieve by going this route?


^ I say all of the above to try to help you put things in perspective. I hate to see someone beat themselves up over something with little to no realistic gain. If you can justify the effort and truly believe there's something to be gained from it, then by all means continue forward.


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## Jaloosk

Maybe there was a reason the person you bought it from got rid of it...it could be defective...

Other that that I would try a different power supply...an inadequate power supply can cause all sorts of weird stuff to happen in a PC.


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## Darth SQ

bikinpunk said:


> Here's a seroius question: what can the carPC DSP provide you that (this is key) you actually need? I know a few people who have had elaborate PC DSP and their system sounded no better than what can be achieved with common DSPs today. In many cases people have royally FUBAR'd their systems as well trying to make use of all the fancy features they have over others. Like I mentioned previously, I definitely think they're cool but in terms of real benefit, what is there? What is it exactly *you *are trying to achieve by going this route?
> 
> 
> ^ I say all of the above to try to help you put things in perspective. I hate to see someone beat themselves up over something with little to no realistic gain. If you can justify the effort and truly believe there's something to be gained from it, then by all means continue forward.


Dead on Erin.

However, let me say this about my friend Justin.
I've seen him so many times successfully think out of the box when tackling projects reminding me of my younger self and why I so wanted to be an engineer.

He possesses the gifts of a dreamer *AND* a doer; which rarely occur in the same person.

If there was ever someone with more patience, persistence, brilliance, combined with a love of our hobby that could finally work through and solve the car pc's problems and show us all how to do it,

he's the man.


Bret
PPI-ART COLLECTOR


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## ErinH

I understand. However, this forum is full of engineers. Just not degreed engineers but field engineers. People who are paid to do technical work and (most importantly) think critically. I don't doubt his capability. I simply am asking him the question so he can determine the merit himself. Just because you can do something doesn't mean you have to or should. Thats what I'm driving at. It's awesome to have FIR and IIR filters. Infinite parametric and variable phase are great. But how useful are they? When do the efforts outrun the worth? 

I'm like Justin in some ways: the engineer who wants to use his knowledge to further the hobby. Truth be told, however, we all are just following the steps of others before us. No one in car audio is doing anything truly innovative. We are rooted in the same theories of all the studies before us. The difference is simply the environment. This is where the efforts should be made. Unfortunately it took me a couple years worth of chasing my tail before I realized this.

Again, I'm not arguing just to argue. If anything I'm providing a supporting opinion in saying that if the carPC dsp setup is causing this much headache then maybe it's time to reevaluate why you started down the path and consider if its still warranted. There are some great DSPs already on the market. More than that, however, there are only a handful of cars that are truly awe-some. And they arrived at their level of performance moreso by being rooted in a solid install combined with understanding of sound and tuning time (not that you don't possess any of the above). In other words, the great cars aren't necessarily made even greater by adding a PC for processing. They are, however, made great by having a deeper understanding of the science behind the sound and MOST importantly: how the particular environment plays a role. There are a few things I just know about my car and the fact that I know it saves me a lot of time and energy when it comes time to tune. That aspect alone pushed my car to the 'next' level this year. 

Just trying to help. Honestly.


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## Darth SQ

bikinpunk said:


> I understand. However, this forum is full of engineers. Just not degreed engineers but field engineers. People who are paid to do technical work and (most importantly) think critically. I don't doubt his capability. I simply am asking him the question so he can determine the merit himself. Just because you can do something doesn't mean you have to or should. Thats what I'm driving at. It's awesome to have FIR and IIR filters. Infinite parametric and variable phase are great. But how useful are they? When do the efforts outrun the worth?
> 
> I'm like Justin in some ways: the engineer who wants to use his knowledge to further the hobby. Truth be told, however, we all are just following the steps of others before us. No one in car audio is doing anything truly innovative. We are rooted in the same theories of all the studies before us. The difference is simply the environment. This is where the efforts should be made. Unfortunately it took me a couple years worth of chasing my tail before I realized this.
> 
> Again, I'm not arguing just to argue. If anything I'm providing a supporting opinion in saying that if the carPC dsp setup is causing this much headache then maybe it's time to reevaluate why you started down the path and consider if its still warranted. There are some great DSPs already on the market. More than that, however, there are only a handful of cars that are truly awe-some. And they arrived at their level of performance moreso by being rooted in a solid install combined with understanding of sound and tuning time (not that you don't possess any of the above). In other words, the great cars aren't necessarily made even greater by adding a PC for processing. They are, however, made great by having a deeper understanding of the science behind the sound and MOST importantly: how the particular environment plays a role. There are a few things I just know about my car and the fact that I know it saves me a lot of time and energy when it comes time to tune. That aspect alone pushed my car to the 'next' level this year.
> 
> Just trying to help. Honestly.


Once again, well said and some excellent points made. 


Bret
PPI-ART COLLECTOR


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## quietfly

Just to add my own .02, I've found sometimes it's good to step back from projects and look at the ROI of each of the pieces. To figure out what each portion brings to the table and at what cost (in terms of what ever the cost is, time, money, sanity). I look at the Best case Scenario, then ask myself honestly if that is worth the effort. Then i look at my pride and ask it if it can take a step back. Admittedly sometimes it can't, and i end up going about things the hard way, Just because. I understand both sides of the discussion, and have lived through both. GOOD LUCK!!!


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## req

this is exactly why i went and kept my car DSP and just use my carPC for the fun stuff like internet browsing, streaming from google music and youtube. GPS, OBD2, VCDS (volkswagen interface), so on and so forth.

i can not see the benefit from using a VST platform when my helix p-dsp and arc PS8 can get me there with less hassle. sure, its not nearly as customizeable - *but like erin and everyone else who has competed in sound quality has said - the enviornment and seating position is what kills us*.


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## [email protected]

Jazzi said:


> Yes, I will be at the show on the 21st in San Jose.
> 
> I could add the extra board to the 6to8, but my trusty Sansa Clip+ plays all the flac I need surprisingly well. It also does audiobooks like Game of Thrones, The Inheritance Cycle, and The Wheel of Time.



Do you know about this software? Rockbox - Free Music Player Firmware I use it on an old Toshiba gigbeat player and it is awesome.

But your sansa clip can't play at a high resolution through your audio system can it? I didn't recall it having any sort of digital output?


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## Justin Zazzi

I love you guys, truly.

My goal from the beginning was to learn, always to learn, and it still is. I would much rather put my creative efforts into something like this than into video games where the payoff is completely intangible. So the return on investment (worst case) is I learn something by pushing my boundaries and trying something new. It might not be something new in the sense of expanding human knowledge in the car audio environment, but it will be new for me and I'll gain skills that I can use in other projects and later in my career. It's already paying off actually: my college has a few competitive engineering teams and all my 12v experience is invaluable when designing autonomous robots that run off batteries and are controlled by on-board computers.

So is all the effort and toiling worth it? Purely from a car audio point of view, maybe to doubtful. Like you point out very clearly, the processors of today are excellent at what they do and are really easy to use. But from a self improvement and educational point of view, all of this work is completely worthwhile. I know I'll have projects later in life both in my career and at home that will require skills I'm acquiring now. Learning how google like a pro to investigate, troubleshoot and repair from the "big picture" down to the circuit level like I am right now with my Eclipse radio and this (damned!) audio card are good examples. *Learning how to find knowledge I don't have is a priceless skill that all this backyard tinkering has taught me, and that alone is worth all the trouble.*

I too would love nothing more than to expand the knowledge of this hobby, but to do that I must have some practice experimenting with ideas and asking all those "what if?" questions. The one thing that the carPC processor allows me is more ways to ask questions, and more ways to try and answer them. So ....

-is having both phase *and* time delay any better than time delay alone? How much better?
-are FIR filters are better than IIR filters due to the constant phase of them? Is pre-ringing as bad as some people claim, or is the tradeoff worth it?
-what if I have a continuously variable loudness curve based on volume? What would that mean, and how could it be useful?
-what if I mount midbass drivers unconventionally and compensate using phase vectors like Lycan was once talking about?
-do electric crossover slopes combine with acoustic slopes of the enclosure, and are the sum of the two more important than either one separately?
-can the reverberation time (rt60) inside a car can be manipulated electronically using some form of convolution instead of passive diffusion panels?
-are active bass traps a possibility given passive traps require so much room that we cannot spare?
-is a simple 10-15ms of delay with bandpass filters and some attenuation adequate for rear fill channels in a car, or is longer time delay and more sophistication really needed as suggested in the books I've been reading?
-how does rear fill work? what is needed to get believable a sense of envelopment? how does this relate to RT60 times and artificial means of increasing reverberation times by using something like convolution?
-similarly, how does center channel steering work? is this something I could potentially do on my own, or should I trust the Dolby ProLogic (or DTS Neo6 or Logic7) built into the sound card I chose? (haha I'm pretty sure that is a whole can of worms I don't want to mess with)
-Is there a DSP filter than can compensate for group delay in an enclosure? If so, what kind of wild enclosure designs are possible if group delay is no longer a concern?
-Similarly, is there a DSP filter to correct phase vs frequency so the entire system becomes linear phase?
-and how does all this stuff relate to tuning, classical knowledge of acoustic perception, and what is worthwhile trying to improve upon? Which of these topics (if any) can be used to overcome the challenges of the car audio environment?


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## Justin Zazzi

[email protected] said:


> Do you know about this software? Rockbox - Free Music Player Firmware I use it on an old Toshiba gigbeat player and it is awesome.
> 
> But your sansa clip can't play at a high resolution through your audio system can it? I didn't recall it having any sort of digital output?


I have seen the Rockbox project. It is really fantastic and I'm very impressed with what they can do. However, the Clip+ comes with most of the features I care about already, and the one or two things that Rockbox can do better are not worth the effort. The _return on investment_ is not worth it to me 

And no, the Clip+ does not have a digital output nor does it do 24/96 high resolution files. But it does have an outstanding analog output stage that belies it's inexpensive price point.


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## [email protected]

Whew, that HUGE open source investment... lol.. I was sold when I saw I could play DOOM with it.!! hahah..

go ahead and learn all that stuff in your post and share the answers with me!


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## Justin Zazzi

Well I can't play DOOM on my Clip+, so therefore, not worth it haha!


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## [email protected]

Awe.. I didn't realize the Clip+ didn't have a color screen.. 
SansaClip < Main < Wiki <---there is some cool technical stuff about the clip on that page, if you haven't seen it..


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## captainobvious

[email protected] said:


> If you use your 6to8 you can add the AMAS board and stream high res files into it..
> 
> I just added that to mine, so we will see how it goes. I have some CD's I ripped to FLAC, I gotta do a head to head between the disk and the streamed FLCA and see what the difference (if any) is..


I would be VERY interested to hear your findings on this. Please let me know Joey.


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## Justin Zazzi

And today I feel a little bit like Heart surgeon Dr. Zbigniew Religa. His incredible story can be found here, but the below photo says it all. After an all-nighter marathon surgery he still keeps an eye on the monitors to ensure his patient is still doing alright.










*ZOMG IT WORKED !!!*

I successfully transplanted the vacuum fluorescent display from a spare Eclipse CD3200 faceplate purchsed on eBay into the the broken faceplate for my CD7200mkII. After two previous failed attempts at repairing the radio, this third time is the charm. Flying high right now ....

The radio is back up and running again, and all the details of that adventure are in my other thread here.

On a slightly different note, I look forward to seeing everyone this weekend at MECA California State Finals in my hometown of San Jose. If I can find enough spare time between now and then, the Golf will be ready to listen to again, finally. See you there!


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## deeppinkdiver

Your a courageous sole Jazzi. I commend all your efforts, I just read through this entire thread and my head hurts.. lol. An incredible amount of references and leads to never ending knowledge it seems. On top of what seems to be an endless bucket of self skill tools your sharpening. Great job so far.

It has been a joy the last few hours of reading, I apologize I didn't find this sooner!

Sub'd


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## quietfly

congrats!!! its awesome when you figure out issues like that!!


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## Neil_J

Wow somehow I missed this build log and just now had the time to read it from page 1 to the end... Nice job and great attention to detail.

As to your CarPC/DSP/filtering questions you asked back in September, I'll try to answer some of them as noone else did.



Jazzi said:


> -is having both phase *and* time delay any better than time delay alone? How much better?
> -are FIR filters are better than IIR filters due to the constant phase of them? Is pre-ringing as bad as some people claim, or is the tradeoff worth it?


Yes, FIR filters can be better than IIR if you are an expert filter designer  FIR filters can be linear phase which would cause pre-ringing, or they can be designed to not be linear phase depending on how you place the poles and zeros on the unit circle. I have been one of the people out there saying that pre-ringing sounds bad, if you're ever heard a crappy compressed MP3 you've probably heard it. Is it worth the tradeoff? Depends. In order to fully "correct" the environment (in this case the car), the environment would have to be minimum phase. The car environment, at best, in minimum phase in certain areas and totally not in others. So FIR filters will buy you a little bit here and there (if you know what you're doing), but only a bit more than an IIR minimum phase filter would be able to do. And as far as being able to delay phase, you can do that with an IIR filter as well, as long as you can manually enter the filter coefficients, as you can with the MiniDSP platform. As to whether it will sound better? Again, I think it's all up to the person coming up with all those filter coefficients 



Jazzi said:


> -what if I have a continuously variable loudness curve based on volume? What would that mean, and how could it be useful?


That was one of the main reasons I wanted to start my CarPC project. I think it's a worthy goal as any, because there's not really any commercial platforms that support it. This single item would be one of the only reasons I can think of to put up with a PITA that is the CarPC.



Jazzi said:


> -what if I mount midbass drivers unconventionally and compensate using phase vectors like Lycan was once talking about?


Can't really comment on this one, as I've never played around with midbass arrays.



Jazzi said:


> -do electric crossover slopes combine with acoustic slopes of the enclosure, and are the sum of the two more important than either one separately?


I do know that using an FIR filter to make up for the acoustic phase distortion at the bottom of a high-pass filter supposedly does wonders to low-end response. It supposedly gets rid of the "wooly" quality near the rolloff. Here's a great paper on the subject (Gerzen Archives). But basically the acoustic filter is modeled and the FIR filter coefficients are setup to correct the phase wrap.



Jazzi said:


> -can the reverberation time (rt60) inside a car can be manipulated electronically using some form of convolution instead of passive diffusion panels?


Not that I'm aware of, unless you've got multiple drivers dispersed around the car and you're doing phase steering to each driver.



Jazzi said:


> -are active bass traps a possibility given passive traps require so much room that we cannot spare?


Theoretically yes, but I don't think it's trivial by any means.



Jazzi said:


> -is a simple 10-15ms of delay with bandpass filters and some attenuation adequate for rear fill channels in a car, or is longer time delay and more sophistication really needed as suggested in the books I've been reading?
> -how does rear fill work? what is needed to get believable a sense of envelopment? how does this relate to RT60 times and artificial means of increasing reverberation times by using something like convolution?
> -similarly, how does center channel steering work? is this something I could potentially do on my own, or should I trust the Dolby ProLogic (or DTS Neo6 or Logic7) built into the sound card I chose? (haha I'm pretty sure that is a whole can of worms I don't want to mess with)


If you're going to use a center channel or rear fill, use Dolby Pro Logic II or Logic7, or some active matrix processing algorithm. RT60 times would go up, I guess. But by doing so it would add width and maybe a bit of depth. I've had mixed results with rear fill, and am currently not using it. In the end, keep it simple was the way to go. How does center channel steering work? That's a loaded question, there are quite a few different algorithms out there. Left+Right / Left-Right will only give about 3 dB separation which is barely audible. Active matrix algorithms will give up to 48 dB of separation between channels, but they rely on clever, cpu-intensive, patented algorithms to do it. Check out the forum SurroundByUs, they make a Plogue Bidule plugin that uses FFT's and the center cut algorithm to do surround sound on a windows or mac box. 



Jazzi said:


> -Is there a DSP filter than can compensate for group delay in an enclosure? If so, what kind of wild enclosure designs are possible if group delay is no longer a concern?
> -Similarly, is there a DSP filter to correct phase vs frequency so the entire system becomes linear phase?


Theoretically speaking, yes to both. But I can't say for sure that the results would be enjoyable to listen to, as there could be plenty of artifacts that would color the music (same goes for the filter rolloff phase correction mentioned above). And you would probably need a very long FIR filter (in # of taps) to make that work. Everything in audio, as they say, is a tradeoff.



Jazzi said:


> -and how does all this stuff relate to tuning, classical knowledge of acoustic perception, and what is worthwhile trying to improve upon? Which of these topics (if any) can be used to overcome the challenges of the car audio environment?


In my purely biased opinion, I think 98% of the people here are using fairly conventional techniques to produce audio that sounds pretty good to excellent. I think anything specialized added on to that will improve to the sound, but in no way make up for the aforementioned conventional techniques that seem to work so well. In my experience going over the deep end in CarPC and multi channel stuff, I learned that it's not even worth thinking about that stuff until the basics like sound deadening, install related stuff, proper speaker placement, and conventional dsp are completely worked out. Oh and just start with Left/Right channels and a sub. Anything added after that is just icing on the cake.

Two great books on filters and dsp that I think anyone should before jumping down the rabbit hole:

Digital Filters for Everyone: Second Edition by Rusty Allred 

and

The Scientist and Engineer's Guide to Digital Signal Processing


----------



## Justin Zazzi

Wow Neil, thank you for stopping by and for your comments! I've been following your work for a while in both your Mini and your FrankenDAC too. I'm going to ask a few questions because it is rare to find anyone with knowledge about these ideas.




Neil_J said:


> FIR filters can be linear phase which would cause pre-ringing, or they can be designed to not be linear phase depending on how you place the poles and zeros on the unit circle.


This unit circle concept comes up time and time again, and I have no idea what it's all about. Perhaps I'll find it while reading some of the resources you mention near the bottom.




Neil_J said:


> And as far as being able to delay phase, you can do that with an IIR filter as well, as long as you can manually enter the filter coefficients, as you can with the MiniDSP platform.


I always thought that phase and frequency response were directly related in an IIR filter, and one cannot change without the other. Are you saying that a parametric EQ can change phase without affecting frequency response? I do not think so, I think you are saying the MiniDSP platform can be used to write custom filters (which is beyond my current knowledge). My tools right now are either the Mosconi 6to8 in my current build or VST plugins in my future build.




Neil_J said:


> I do know that using an FIR filter to make up for the acoustic phase distortion at the bottom of a high-pass filter supposedly does wonders to low-end response. It supposedly gets rid of the "wooly" quality near the rolloff. Here's a great paper on the subject (Gerzen Archives). But basically the acoustic filter is modeled and the FIR filter coefficients are setup to correct the phase wrap.


I was more interested in the phase interaction between the two speakers near the crossover point because physically there is always a rolloff in frequency response (first order, second order, etc) and a corresponding phase shift that accompanies it. My goal was to investigate if the phase shift caused by the physical qualities of the enclosure (for example first-order sealed) were stacking with the phase shift induced by the electronic crossover (commonly 4th order 24db/oct). Does that mean a 90 degree shift caused by the enclosure is stacking with a 360 degree shift caused by the electronics resulting in a system with a 5th order behavior (30dB/oct and 450 degree phase shift) ??? If so, then we should try aiming for a system with either 2nd order or 4th order behavior, and matching our electronic crossovers to our physical enclosures (such as a 3rd order crossover on a 1st order sealed enclosure).

I'll take a look at the paper you linked, it looks full of good stuff. Thanks.




Neil_J said:


> Not that I'm aware of, unless you've got multiple drivers dispersed around the car and you're doing phase steering to each driver.


Regarding convolution and artificial RT60 times, what do you mean by phase steering for each driver? How does this related to creating a diffuse sound field with the perception of a longer decay time in midrange and treble frequencies as an alternative to adding something like binary diffusion panels?




Neil_J said:


> If you're going to use a center channel or rear fill, use Dolby Pro Logic II or Logic7, or some active matrix processing algorithm. ....... Check out the forum SurroundByUs, they make a Plogue Bidule plugin that uses FFT's and the center cut algorithm to do surround sound on a windows or mac box.


After investigating further the sound card I purchased has Dolby ProLogic IIx built in but I do not believe I can manipulate the signal downstream of the decoding process (adding EQ, time delay, phase etc to each channel before the amplifiers). I think something like the Plogue Bidule plugin or a similar VST module that does ProLogicII or Logic7 decoding is the only way I can accomplish both a matrix and manipulate each channel at the same time. Thanks for the suggestion, I'll check it out.




Neil_J said:


> In my purely biased opinion, I think 98% of the people here are using fairly conventional techniques to produce audio that sounds pretty good to excellent. I think anything specialized added on to that will improve to the sound, but in no way make up for the aforementioned conventional techniques that seem to work so well. In my experience going over the deep end in CarPC and multi channel stuff, I learned that it's not even worth thinking about that stuff until the basics like sound deadening, install related stuff, proper speaker placement, and conventional dsp are completely worked out. Oh and just start with Left/Right channels and a sub. Anything added after that is just icing on the cake.


Agreed 100%. Thanks again for all the ideas and reading material.

I hope to make some real progress on this over the winter break, university-level engineering courses ensure I have no free time for fun stuff right now


----------



## Neil_J

Jazzi said:


> This unit circle concept comes up time and time again, and I have no idea what it's all about. Perhaps I'll find it while reading some of the resources you mention near the bottom.


Yes, pretty much any introductory guide on digital or analog filter design will touch on the unit circle and poles/zeros at some point. It has to do with the Laplace transform (for analog filters), z-transform (for digital filters), which I couldn't begin to correctly describe. Both of the references I mentioned in my last post discuss the concept. It's not essential to know this to be a bad filter designer; however I think it is essential to know this to be a good filter designer.



Jazzi said:


> I always thought that phase and frequency response were directly related in an IIR filter, and one cannot change without the other.


I believe that to be incorrect. You can make an all-pass IIR filter that does not affect frequency at all, but modifies the phase relationships between various frequencies. It's easy to get the IIR filter confused with its common implementations (peaking filter, crossover, etc). There are other less-common implementations and the all-pass is one of those.



Jazzi said:


> Are you saying that a parametric EQ can change phase without affecting frequency response? I do not think so, I think you are saying the MiniDSP platform can be used to write custom filters (which is beyond my current knowledge). My tools right now are either the Mosconi 6to8 in my current build or VST plugins in my future build.


No. All I'm saying is that you can do it with an IIR all-pass filter. You can't do it with an IIR peaking filter or a butterworth, chebychev, etc. IIR is the family of all filters where the impulse response doesn't become exactly zero after a certain point, but rather continues infinitely. By specifying the coefficients to the filter (e.g. a1, a2, b0, b1, b2 for a 2nd order), you can end up with some completely wild filters, or your standard ones like Butterworth, Chebychev, etc. That's what I meant when I said it doesn't take much to design a bad filter (you just plug in numbers after all), but it takes a lot of skill to come up with a list of near-perfect coefficients. 



Jazzi said:


> I was more interested in the phase interaction between the two speakers near the crossover point because physically there is always a rolloff in frequency response (first order, second order, etc) and a corresponding phase shift that accompanies it. My goal was to investigate if the phase shift caused by the physical qualities of the enclosure (for example first-order sealed) were stacking with the phase shift induced by the electronic crossover (commonly 4th order 24db/oct). Does that mean a 90 degree shift caused by the enclosure is stacking with a 360 degree shift caused by the electronics resulting in a system with a 5th order behavior (30dB/oct and 450 degree phase shift) ??? If so, then we should try aiming for a system with either 2nd order or 4th order behavior, and matching our electronic crossovers to our physical enclosures (such as a 3rd order crossover on a 1st order sealed enclosure).


I'm not sure, but if you have Matlab or Labview or whatever, all of that can be simulated before trial-and-error in the car. You wouldn't even have to write a lot of code (all the low-level stuff is provided either in the base package or as addons that your college would have). As long as you understood all the things you are trying to model, it would be a pretty quick exercise.




Jazzi said:


> Regarding convolution and artificial RT60 times, what do you mean by phase steering for each driver? How does this related to creating a diffuse sound field with the perception of a longer decay time in midrange and treble frequencies as an alternative to adding something like binary diffusion panels?


Sorry, when you said "RT60 times be manipulated", I assumed you meant you were wanting to minimize them (as is the case when you have standing waves around 60-100 Hz in a car, that make it sound all muddy, e.g. the third bass note in spanish harlem that sounds really boomy in an un-eq'd car). If you have an multiple drivers spaced around the car, each with a different digital filter that could very likely have different phase relationships at key frequency points, then you can sort of "null out" any standing waves. But I've seen where even just having multiple subs around the car all playing exactly the same thing works great for getting rid of standing waves, no DSP needed. A lot of home audio guys are doing the sub array thing, Patrick Batemen has brought it up, I think he was quoting Geddes and others that have written papers about it.

But as for increasing RT60 times, yea you can do that too, without any multi speaker setup. That's probably the easiest thing to do in a digital filter. Just add some of the delayed output back in with the current output, at a slightly reduced volume. You can get somewhat realistic reverberations with IIR filters (again these aren't your typical peaking or crossovers) but they're just simulated and can only sound so good. If you want to sound really good, then you usually pick out a decent impulse response of a good sounding large room and convolute it with your audio stream in real-time (you need an FIR filter to do this). There are a ton of impulse responses out there of all types of rooms and halls. You can load these into any VST convoluter and hear what they sound like.



Jazzi said:


> After investigating further the sound card I purchased has Dolby ProLogic IIx built in but I do not believe I can manipulate the signal downstream of the decoding process (adding EQ, time delay, phase etc to each channel before the amplifiers). I think something like the Plogue Bidule plugin or a similar VST module that does ProLogicII or Logic7 decoding is the only way I can accomplish both a matrix and manipulate each channel at the same time. Thanks for the suggestion, I'll check it out.


You won't find them (cheap) unfortunately. There's a PLII VST plugin that runs $500 and I don't think anyone outside of Andy back when he worked at Harmann has access to a Logic7 plugin in VST form. The guy at surroundbyus was pretty adamant that his sounded as good or better than the older PLII and Logic7. I can't verify that but I can say that's it's infinitely more configurable, and easy to implement yourself.



Jazzi said:


> I hope to make some real progress on this over the winter break, university-level engineering courses ensure I have no free time for fun stuff right now


OK, I'll shut up here, the last thing we need is another college dropout to chase unicorns of the car audio persuasion  Do read the book at dspguide.com if you have time even if it's down the road. It will answer pretty much any question you have here, and other ones you haven't even thought of yet. It pretty much clears up any misconceptions one might have about filtering and DSP. And there are a lot of misconceptions in filtering and DSP that I've come across.

Oh, and I'll also say that you can save yourself a lot of time and money by holding off on the CarPC completely until you've actually fully learned and implemented your filter ideas. You can take an audio file in matlab, apply the craziest filters you can think of, let it chug for a few hours, and then record the output to a single or multi-channel audio file. And play that back through your Mosconi 6to8 or whatever, or directly into your amps. Then and only if it actually improves things would I break out the wallet for the CarPC stuff. You will not like how many times you get burned, it's a hard road to go down, trust me  If you really must use custom filters and don't want the headaches, I'd recommend two things: #1, a DSP development board (probably the same ones sitting in your college lab so you have access to the development environment), e.g. Analog Devices SHARC or Texas Instrument TMS or whatever their latest and greatest is. #2, a MiniDSP MiniSHARC kit, which is basically an Analog Devices SHARC DSP that will allow you to enter your own filter coefficients, no programming necessary thanks to their awesome GUI. Only $185 and none of the headaches that you'll get with a CarPC (admittedly there are certain things like volume-dependent loudness contours that you can't do on a MiniDSP). Face it dude, if you're an engineer (or soon-to-be one) and can learn the filtering stuff, the CarPC doesn't really buy you anything. The VST stuff is for musicians with liberal arts degrees  Go with a DSP that allows you to write high-level code with a development environment that provides all of the backend low-level code, and call it a day.


----------



## Darth SQ

Neil_J said:


> Yes, pretty much any introductory guide on digital or analog filter design will touch on the unit circle and poles/zeros at some point. It has to do with the Laplace transform (for analog filters), z-transform (for digital filters), which I couldn't begin to correctly describe. Both of the references I mentioned in my last post discuss the concept. It's not essential to know this to be a bad filter designer; however I think it is essential to know this to be a good filter designer.
> 
> 
> I believe that to be incorrect. You can make an all-pass IIR filter that does not affect frequency at all, but modifies the phase relationships between various frequencies. It's easy to get the IIR filter confused with its common implementations (peaking filter, crossover, etc). There are other less-common implementations and the all-pass is one of those.
> 
> 
> No. All I'm saying is that you can do it with an IIR all-pass filter. You can't do it with an IIR peaking filter or a butterworth, chebychev, etc. IIR is the family of all filters where the impulse response doesn't become exactly zero after a certain point, but rather continues infinitely. By specifying the coefficients to the filter (e.g. a1, a2, b0, b1, b2 for a 2nd order), you can end up with some completely wild filters, or your standard ones like Butterworth, Chebychev, etc. That's what I meant when I said it doesn't take much to design a bad filter (you just plug in numbers after all), but it takes a lot of skill to come up with a list of near-perfect coefficients.
> 
> 
> I'm not sure, but if you have Matlab or Labview or whatever, all of that can be simulated before trial-and-error in the car. You wouldn't even have to write a lot of code (all the low-level stuff is provided either in the base package or as addons that your college would have). As long as you understood all the things you are trying to model, it would be a pretty quick exercise.
> 
> 
> 
> Sorry, when you said "RT60 times be manipulated", I assumed you meant you were wanting to minimize them (as is the case when you have standing waves around 60-100 Hz in a car, that make it sound all muddy, e.g. the third bass note in spanish harlem that sounds really boomy in an un-eq'd car). If you have an multiple drivers spaced around the car, each with a different digital filter that could very likely have different phase relationships at key frequency points, then you can sort of "null out" any standing waves. But I've seen where even just having multiple subs around the car all playing exactly the same thing works great for getting rid of standing waves, no DSP needed. A lot of home audio guys are doing the sub array thing, Patrick Batemen has brought it up, I think he was quoting Geddes and others that have written papers about it.
> 
> But as for increasing RT60 times, yea you can do that too, without any multi speaker setup. That's probably the easiest thing to do in a digital filter. Just add some of the delayed output back in with the current output, at a slightly reduced volume. You can get somewhat realistic reverberations with IIR filters (again these aren't your typical peaking or crossovers) but they're just simulated and can only sound so good. If you want to sound really good, then you usually pick out a decent impulse response of a good sounding large room and convolute it with your audio stream in real-time (you need an FIR filter to do this). There are a ton of impulse responses out there of all types of rooms and halls. You can load these into any VST convoluter and hear what they sound like.
> 
> 
> You won't find them (cheap) unfortunately. There's a PLII VST plugin that runs $500 and I don't think anyone outside of Andy back when he worked at Harmann has access to a Logic7 plugin in VST form. The guy at surroundbyus was pretty adamant that his sounded as good or better than the older PLII and Logic7. I can't verify that but I can say that's it's infinitely more configurable, and easy to implement yourself.
> 
> 
> OK, I'll shut up here, the last thing we need is another college dropout to chase unicorns of the car audio persuasion  Do read the book at dspguide.com if you have time even if it's down the road. It will answer pretty much any question you have here, and other ones you haven't even thought of yet. It pretty much clears up any misconceptions one might have about filtering and DSP. And there are a lot of misconceptions in filtering and DSP that I've come across.
> 
> Oh, and I'll also say that you can save yourself a lot of time and money by holding off on the CarPC completely until you've actually fully learned and implemented your filter ideas. You can take an audio file in matlab, apply the craziest filters you can think of, let it chug for a few hours, and then record the output to a single or multi-channel audio file. And play that back through your Mosconi 6to8 or whatever, or directly into your amps. Then and only if it actually improves things would I break out the wallet for the CarPC stuff. You will not like how many times you get burned, it's a hard road to go down, trust me  If you really must use custom filters and don't want the headaches, I'd recommend two things: #1, a DSP development board (probably the same ones sitting in your college lab so you have access to the development environment), e.g. Analog Devices SHARC or Texas Instrument TMS or whatever their latest and greatest is. #2, a MiniDSP MiniSHARC kit, which is basically an Analog Devices SHARC DSP that will allow you to enter your own filter coefficients, no programming necessary thanks to their awesome GUI. Only $185 and none of the headaches that you'll get with a CarPC (admittedly there are certain things like volume-dependent loudness contours that you can't do on a MiniDSP). Face it dude, if you're an engineer (or soon-to-be one) and can learn the filtering stuff, the CarPC doesn't really buy you anything. The VST stuff is for musicians with liberal arts degrees  Go with a DSP that allows you to write high-level code with a development environment that provides all of the backend low-level code, and call it a day.


If you two keep this up, this thread will be the first build thread to ever be "stickied". 


Bret
PPI-ART COLLECTOR


----------



## Justin Zazzi

Neil_J said:


> ...Here's a great paper on the subject (Gerzen Archives). ...
> 
> ...
> 
> Two great books on filters and dsp that I think anyone should before jumping down the rabbit hole:
> 
> Digital Filters for Everyone: Second Edition by Rusty Allred
> 
> and
> 
> The Scientist and Engineer's Guide to Digital Signal Processing


I finally had the time to look these over, and the two free resources will answer all of my questions and more. Absolutely perfect, thank you very much Neil for the suggested reading!


----------



## Golden Ear

Yo Jazzi! Just ran into this build log. I wish I would have found it sooner for it has a wealth of information! I haven't read every page yet but I will. Just wanted to drop you a line. Hopefully will see you at the next gtg


----------



## Neil_J

Jazzi said:


> I finally had the time to look these over, and the two free resources will answer all of my questions and more. Absolutely perfect, thank you very much Neil for the suggested reading!


Glad that I could help.


----------



## Hoptologist

I no longer remember how, but I stumbled upon and spent the last hour or so going through this build log. Massive depths of information that I can't even pretend to yet understand. But if there's one thing this build log made me want to do, it would be to learn.


----------



## Hanatsu

Interesting build! Lots of tech stuff, just the way I like it. Subbed


----------



## Justin Zazzi

Hoptologist said:


> ........But if there's one thing this build log made me want to do, it would be to learn.


I will consider that a huge success!

Also Hanatsu, welcome here!

I wish I had more progress to share and questions to think about, but college is kicking my butt I feel guilty even taking the brief time to post this instead of studying right now


----------



## Chaos

This reads more like a doctoral thesis than a typical build log in places, but that is to the good. I don't think I have seen another thread with this many valuable references posted.

As for the car itself, the main thing I like about it is that you had the guts to actually implement some of the theory and test the real results.


----------



## 1998993C2S

subscribe


----------



## Justin Zazzi

So much fun ahead! I'll be in Las Vegas this coming January for three fun events: ALMA's winter symposium, The Home Entertainment Show, and the Consumer Electronics Show. I've met an awesome mentor who has experience with just about everything imaginable from designing home entertainment systems to designing PA a system for the flight deck of an aircraft carrier. Between all the new reading material I've been exposed to and the free time I have now that school is on break, it's time to tackle some of my questions.



Jazzi said:


> -do electric crossover slopes combine with acoustic slopes of the enclosure, and are the sum of the two more important than either one separately?


Turns out, yes. We should be considering _the acoustic sum of_:
the electronic crossovers (active or passive)
and the rolloff generated by the speaker with enclosure
and any interactions with the listening environment
and any EQ used
and anything else that affects frequency response.

Thankfully, this is easy. Measure the _acoustic response_ of one speaker at a time and attempt to match each driver's high-pass and low-pass response to the crossover slope you want. But what crossover slope do we want?

For our purposes, the 4th order Linkwitz-Riley crossover arrangement is one of the better choices because (as defined by Linkwitz in his paper from 1978) it has three main properties:
_1) The phase difference between the drive signals at the crossover frequency has to be zero in order to avoid tilting the radiation pattern.
2) The output amplitude from the high-pass and low-pass section has to be 6 dB down at the crossover frequency so that the sum of the two is unity and no peaking occurs.
3) The phase difference has to be the same for all frequencies so that the symmetry of the radiation pattern is preserved above and below the crossover frequency._

So the crossover alignment results in both the high-passed and low-passed drivers being in phase with eachother at all frequencies, and also the sum of their responses will have no dips or peaks. Deeper reading into his paper will reveal other benefits of the LR4 filter.

The general advice for car audio tuning has been to use the steepest crossover slopes we can to minimize interaction between speakers. There is almost never any discussion about the implications of each slope (1st order, 2nd order, 4th order etc) or what properties each shape has (Butterworth, Chebyshev, Bessel etc) in regards to transient response, group delay, phase response, and so on. If you want to spend some time and learn about all this stuff on your own, check out the links at the bottom of this post where I've gathered all my information from.

*So what's the big deal?*

Crossover slopes on our head units and processors are not one size fits all. The settings we use _need to be complementary to the natural falloff of our speaker enclosures so the resulting acoustic response looks like_ a textbook 4th order crossover (or whichever crossover you decide you like).

For example, the typical infinite baffle or sealed enclosure we use for our midrange and midbass speakers has a natural rolloff of 6dB/octave. To get an acoustic response of 24db/octave, we need to add an electronic crossover of 18dB/octave. In addition because nothing is ever straight forward and simple in real life, much finesse is needed to align the acoustic response as closely as possibly to the theoretical response.

I'm running through this process with my car now, and my next couple posts will have details on how I used Room EQ Wizard to accomplish this. For now, good night.



Resources:

Siedfried Linkwitz's paper revealing the Linkwitz-Riley Crossover
JAES papers

Rane Corporation's excellent overview of the LR Crossover
http://www.rane.com/pdf/ranenotes/Linkwitz_Riley_Crossovers_Primer.pdf

Elliot Sound Products - Phase, Time, and Distortion in Loudspeakers
Phase, Time and Distortion in Loudspeakers

The Crossover Design Cookbook Chapter 4: Theory
The Crossover Design Cookbook Chapter 4: The Theory of Crossovers

FilterShop Application Notes - Analog Audio Active Crossover
http://www.linearx.com/files/pdf/FilterShopApp_05.pdf

Texas Instruments - Basic Introduction to Filters
http://www.ti.com/lit/an/snoa224a/snoa224a.pdfhttp://www.ti.com/lit/an/snoa224a/snoa224a.pdf

.


----------



## BigRed

Jazzi said:


> So much fun ahead! I'll be in Las Vegas this coming January for three fun events: ALMA's winter symposium, The Home Entertainment Show, and the Consumer Electronics Show. I've met an awesome mentor who has experience with just about everything imaginable from designing home entertainment systems to designing PA a system for the flight deck of an aircraft carrier. Between all the new reading material I've been exposed to and the free time I have now that school is on break, it's time to tackle some of my questions.
> 
> 
> 
> Turns out, yes. We should be considering _the acoustic sum of_:
> the electronic crossovers (active or passive)
> and the rolloff generated by the speaker with enclosure
> and any interactions with the listening environment
> and any EQ used
> and anything else that affects frequency response.
> 
> Thankfully, this is easy. Measure the _acoustic response_ of one speaker at a time and attempt to match each driver's high-pass and low-pass response to the crossover slope you want. But what crossover slope do we want?
> 
> For our purposes, the 4th order Linkwitz-Riley crossover arrangement is one of the better choices because (as defined by Linkwitz in his paper from 1978) it has three main properties:
> _1) The phase difference between the drive signals at the crossover frequency has to be zero in order to avoid tilting the radiation pattern.
> 2) The output amplitude from the high-pass and low-pass section has to be 6 dB down at the crossover frequency so that the sum of the two is unity and no peaking occurs.
> 3) The phase difference has to be the same for all frequencies so that the symmetry of the radiation pattern is preserved above and below the crossover frequency._
> 
> So the crossover alignment results in both the high-passed and low-passed drivers being in phase with eachother at all frequencies, and also the sum of their responses will have no dips or peaks. Deeper reading into his paper will reveal other benefits of the LR4 filter.
> 
> The general advice for car audio tuning has been to use the steepest crossover slopes we can to minimize interaction between speakers. There is almost never any discussion about the implications of each slope (1st order, 2nd order, 4th order etc) or what properties each shape has (Butterworth, Chebyshev, Bessel etc) in regards to transient response, group delay, phase response, and so on. If you want to spend some time and learn about all this stuff on your own, check out the links at the bottom of this post where I've gathered all my information from.
> 
> *So what's the big deal?*
> 
> Crossover slopes on our head units and processors are not one size fits all. The settings we use _need to be complementary to the natural falloff of our speaker enclosures so the resulting acoustic response looks like_ a textbook 4th order crossover (or whichever crossover you decide you like).
> 
> For example, the typical infinite baffle or sealed enclosure we use for our midrange and midbass speakers has a natural rolloff of 6dB/octave. To get an acoustic response of 24db/octave, we need to add an electronic crossover of 18dB/octave. In addition because nothing is ever straight forward and simple in real life, much finesse is needed to align the acoustic response as closely as possibly to the theoretical response.
> 
> I'm running through this process with my car now, and my next couple posts will have details on how I used Room EQ Wizard to accomplish this. For now, good night.
> 
> 
> 
> Resources:
> 
> Siedfried Linkwitz's paper revealing the Linkwitz-Riley Crossover
> JAES papers
> 
> Rane Corporation's excellent overview of the LR Crossover
> http://www.rane.com/pdf/ranenotes/Linkwitz_Riley_Crossovers_Primer.pdf
> 
> Elliot Sound Products - Phase, Time, and Distortion in Loudspeakers
> Phase, Time and Distortion in Loudspeakers
> 
> The Crossover Design Cookbook Chapter 4: Theory
> The Crossover Design Cookbook Chapter 4: The Theory of Crossovers
> 
> FilterShop Application Notes - Analog Audio Active Crossover
> http://www.linearx.com/files/pdf/FilterShopApp_05.pdf
> 
> Texas Instruments - Basic Introduction to Filters
> http://www.ti.com/lit/an/snoa224a/snoa224a.pdfhttp://www.ti.com/lit/an/snoa224a/snoa224a.pdf
> 
> .


Hope to see you there Justin!


Sent from my iPhone using Tapatalk


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## Justin Zazzi

To make this all happen in the easiest way possible, I'm going to significantly change my tuning methodology and how I use the features of the Mosconi 6to8. My goal is to separate the technical tuning from the subjective. Currently, I am relying on the parametric EQ for each speaker individually to do just about everything at the same time, so making changes is absurdly difficult because I have to juggle everything at once. The graphic below should help explain some.










It might not be clear, but the new methodology means I can hopefully adjust the individual speaker EQ, time delay, and crossovers only one time ensuring the speakers play together nicely. Then using the input EQ (which is completely separate), I can fine tune the overall frequency response to suit my tastes while maintaining all of the critically important relationships between the speakers (because I will not be disturbing any of the relationships _between the speakers_).

Ok, so where to start? If you're still following along, go download this application note from FilterShop and read page 207, and pages 211 through 215 (lots of pictures, not too much reading). In particular, pay attention to how the acoustic response of the speaker interacts with the crossover being built, with the goal of the summed response matching a textbook LR4 crossover shape (FilterShop calls it a "Butterworth-6dB" but if you read any of the resources in my above post, you'll see that really means Linkwitz-Riley).

The FilterShop software does all the optimization and it's really slick, but that software package is not cheap and we still need a measurement program to get the speaker's acoustic response. Lets use Room EQ Wizard instead.

_(I'm assuming you know a lot from here on. It's a bit daunting to get REW up and running for the first time, let alone develop your own target curves and whatnot. I'm going to be skimming over a bunch of stuff quickly so I can reach the conclusion faster. Feel free to ask questions, and I'll do my best to explain.)_

Set the speaker to run wide open without any crossovers, eq, loudness controls, or other processing of any kind. We want to measure the natural response of the speaker as it is installed from the listening position. Here is what my front left fullrange speaker looks like:










The pink line is the speaker's frequency response. The blue line is the target curve I built in excel using the equations from the Texas Instruments page linked in my previous post. The equation is shown if you want to try this method too. Using that equation and Excel, create a "house curve" text file that room EQ wizard can use in the format shown on REW's help pages here.

The Mosconi 6to8 has a maximum boost of +12dB, so I placed my target curve 12dB above the lowest point of my speaker's response that I anticipate to be boosting. The crossover point will be 300hz, and you can see the target curve replicates the LR4 filter perfectly because it is down by 6dB at the crossover point, and maintains a steady 24dB/octave slope thereafter.

*So here's the cool new stuff.*

Notice the speaker's response is very similar in slope to the target curve without any tuning. This is interesting because minimal processing is needed to reach the target. I'll start with a 2nd order variable-Q high-pass filter in REW and watch what the "predicted" response will be in real time without having to re-measure the system again and again (very, very cool). By varying the crossover frequency and the Q, I arrived at the following filter and after measuring the speaker again, this is my new response:










If you look at those numbers, you might be thinking ... what the heck? The one filter I'm using is contrary to just about every "rule of thumb" out there. It's not the steepest one I can use, nor is it branded by some cool name like "Butterworth" because I'm using a Q factor that doesn't match anything in particular. Also, the frequency of the filter is about 2/3 of an octave _above_ the crossover frequency I was aiming for.

But wait a minute. With just a single 2nd-order filter and no EQ whatsoever, my speaker now resembles a textbook Linkwitz-Riley 4th-order. The response is even +-5dB up to about 1.5khz without any other tuning. How cool is that? One filter!

So I took it a little further and added very aggressive parametric EQ to get the response to match the target curve as close as possible (except for 8khz and above where I'll tune by ear later).










Next step, do the same with the left front midbass.
Then, compare the phase of each speaker and see what happens.
Maybe this is just a red herring, but I think I'm onto something here.
But then again, fools always think as much too.

.


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## Justin Zazzi

BigRed said:


> Hope to see you there Justin!


I hope to see you and a few others too!


----------



## Justin Zazzi

First thing you need to do is start this playlist of Lindsey Stirling and The Piano Guys on youtube. Their work is truly awesome, and I'm sure a bunch of you will enjoy the mashup of classical string instruments with dubsteb and other modern fusion music.

Ok, now that you have that playing, check this out. It totally worked!

----

After tuning the left channel fullrange driver in my above post, I went back outside and tuned the left midbass speaker using all of the same ideas and techniques. Below is (first) the acoustic response of the midbass without any processing and (second) the response after two 2nd order variable-Q high-pass and low-pass filters were applied along with aggressive parametric EQ to match the target curve as close as possible. Note, the target curve is created in excel using the same techniques as the post above, though this one is a little more trick to make.



















Just a quick recap. I built my target response curves based on the 4th-order Linkwitz-Riley crossover alignment at frequencies of my choosing (50hz and 300hz). Then using Room EQ Wizard, I applied minimal amounts of variable-Q high-pass and low-pass filters to shape my acoustic response to match the target curve. Then I aggressively used the parametric EQ to force the acoustic response to very closely match the target curve. Finally, I used the loopback feature of REW to estimate the impulse response delay of each channel, and delayed the rullrange speaker by 0.42 milliseconds.

Here are the results. The following two graphs say it all.



















So there it is. It worked. I'm really and truly happy with this result. I did not massage any of the data with the intention of creating this result, and in fact I had the time delays backwards at first and had a completely different (and disappointing) result. To have a hypothesis completely and definitively confirmed on the first try is beyond satisfying.

I hope this has been helpful. I've sure learned a lot.
Please ask questions because I know this isn't the easiest thing to describe!

*Conclusions*

1) Time delay should be used to align the first arriving waves from each speaker (as a compensation for time only) and not as I previously thought as a tool to find the optimum interference between speakers (as a compensation for phase).

2) Crossovers are not one-size-fits all. The electronic (or passive) crossover needs to be a compliment to the pre-tuned response of the system to result in an acoustic response that matches the crossover alignments we are all so familiar with. The 4th order Linkwitz-Riley is my preferred alignment in this case.

.


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## deeppinkdiver

You keep presenting more and more helpful information for the guys that want to truely understand the science behind making speakers work great together. I personally appreciate your efforts very much! As soon as possible ill be getting my front end into my car and will be on your post reviewing great references and asking learning curve questions as I take a different approach this time.. Thanks Jazzi


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## ErinH

Great posts, man. I know this info is sprinkled around but you've done a really good job of combining it all in to one useful set of posts! 

John Pionke (pionkej) started a thread here with this in mind a couple months back as well. Not sure if you saw it but if not, it ties in perfectly to your posts above. 

Here's a couple of his threads that are really worth reading if you haven't already. 
http://www.diymobileaudio.com/forum...ssion/155959-essque-vs-danger-6db-slopes.html
http://www.diymobileaudio.com/forum...js-06-nissan-murano-meca-modex-sq2-bound.html

His build log has some info on this as well. I know he's posted in car measurements somewhere... I just can't find them. 
http://www.diymobileaudio.com/forum...st1988211.html?highlight=Acoustic#post1988211


I also shot for a summed crossover at about 3khz in my car based on advice from a Kef engineer who designed the driver I'm using. He said their passives use an LR2 circuit combined with the acoustic tweeter roll off to target that frequency. The reason they didn't use LR4 was due to the additional materials cost. What was more interesting was just how different the natural acoustic roll off of the left vs right speaker was in the car. They weren't terribly off, but they weren't the exact same. I know what it is "anechoically" because I have measured it. But when they went in to the car and aimed at different axes (time/intensity trading), the two were not as close as I had thought they would be. Not sure if I ever got around to putting the graphs in my build log but I do know that I mentioned it in my build log. 
http://www.diymobileaudio.com/forum...n-v-my-full-disclosure-build-tune-log-10.html

Might be worth looking at but it's essentially what you've said here, just applied to my specific install.


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## decibelle

Jazzi,

Truly excellent build, sir. I'm late to the party, but I just now read through your entire build from start to present. I am glad I stumbled upon this build when I did. I am rebuilding right now, and using many of the same methods you have successfully applied in your Golf, so that tells me I am on the right track of thinking.

Love the whole build, but I am most impressed with your desire to experiment just for the hell of it, and that you are not ashamed of failure. Pretty neat stuff, man. Looking forward to some updates.


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## stylngle2003

Justin, my mind is blown. Awesome application of your idea. :toff: Very cool reading material you linked. Kissing this week's free time goodbye!


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## Justin Zazzi

deeppinkdiver, millerlyte, and stylngle2003,

Thank you for the kind words, and I'm really glad this is helpful for you!





bikinpunk said:


> Great posts, man. I know this info is sprinkled around but you've done a really good job of combining it all in to one useful set of posts!
> 
> John Pionke (pionkej) started a thread here with this in mind a couple months back as well. Not sure if you saw it but if not, it ties in perfectly to your posts above.


I've seen some of pionkej's work and briefly read the threads you linked, but they didn't make much sense at the time. After the "ah ha!" moment these past few days, I can now see his post about 1st order slopes is spot on.

You are also correct that this info really is sprinkled around the internet, but it seems only small pieces at a time and it was really difficult to connect all the dots together and see how all of these ideas interact (phase, crossover slope, crossover Q factor, crossover frequency, acoustic vs electric system response, and how to measure and make sense of it all). I'm not sure the best way to make this entire process easier to learn for other people, but it needs more "air time" because it has taken my tuning skills and my system to the next level.

---

I've finished tuning all the speakers in my car and the results are astonishing. I've always been proud of how "invisible" my subwoofer is, but I've never truly had "up front bass". There is a Smart Fortwo owned by MrsPapasin that has a subwoofer up front in the passenger footwell and it was the first car I could say without reservation that ALL of the bass was up front. I won't claim my car now rivals that setup (because it is phenomenal) but my car is very close, and certainly much better than before in terms of bass integration and imaging.

If you use any of this crossover technique stuff in one of your builds, please let me know how it works for you? I'm really curious if others can replicate this process reliably, and what steps are confusing or troublesome.


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## sinister-kustoms

Like everyone has already said, thanks a tonne for an extremely informative thread!

On a side note, Lindsey Stirling...holy crap! She's like a super sexy nymph  Will be listening to more of her for sure!


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## Darth SQ

Justin,
Amazing work you've accomplished here.
I have read the last few pages at least three times and am finally getting a grasp of most of it.
You've cracked the code. :thumbsup:

I can't wait the hear your car this spring. 
Happy New Year!


Bret
PPI-ART COLLECTOR


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## ansuser

Jazzi,

very good and usefull reading, indeed.

I am a bit concerned about "aggressive EQ" you mentioned to fit speakers response to the target curve. What about a possible phase shifts due to applying equalizer?
Can you show a Phase plot before/after application of filters/equalization?


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## Hanatsu

Post #251 could effectively debunk lots of those phase-mystical-thing threads. That post should be sticky'd in the tech forum. Informative posts indeed, Jazzi


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## Justin Zazzi

ansuser said:


> I am a bit concerned about "aggressive EQ" you mentioned to fit speakers response to the target curve. What about a possible phase shifts due to applying equalizer?
> Can you show a Phase plot before/after application of filters/equalization?


This is an excellent question, and one I really want to be able to answer. What you see above is the bleeding edge of my knowledge on this subject so I am not sure how to respond to your question. I could post what the phase looks like before and after my tuning steps, but after examining them tonight I'm at a loss to explain what is happening. I know for sure that as I smooth out the ripples in the frequency response, the ripples in the phase response become smoother as well. However, I need to better understand the mathematical relationship between frequency response and phase response to offer any other insight. I want to be able to see how a change in one will result in a change in the other.

For example, reading Room EQ Wizard's help pages regarding Minimum Phase (seriously, go read that page too) reveals that group delay is simply the derivative of phase:
_" The group delay plot shows us how much each frequency is being delayed - mathematically, it is the slope of the unwrapped phase plot, so anywhere that phase is dropping linearly corresponds to a constant group delay region (i.e. that region is delayed by a constant time)."_

I know there is a relationship between frequency response and phase, but I'm not sure how to find it. If anyone knows what it is or what it is called, please point me in that direction.


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## Hanatsu

The excess group delay will display the areas which ain't acting like minimum phase as peaks in the plot, the measurement is valid for one point in space ( as it cannot be spatial averaged ). All minimum phase region can be EQed as you please without any issues. Of course, the rule that "acoustic high Q" corrections shouldn't be made in the higher frequencies as there can be large deviations in frequency response just as you move the microphone an inch or two, still apply.

Sent from my Samsung Galaxy 3 via Tapatalk.


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## ansuser

Jazzi said:


> I know there is a relationship between frequency response and phase, but I'm not sure how to find it. If anyone knows what it is or what it is called, please point me in that direction.


Considering equalizer as a bandpass filter, phase shift strongly depends on it's implementation. 
AFAIK, only FIR-based equalizers do not introduce phase shifts (apart from group delay required to do all the calcs inside processor unit).
I know some head units introduce severe phase shifts with equalizer enabled. I don't know if Moscony unit or MS-8 do any better in this respect (i.e. I don't know if these units have linear phase or minimum phase equalization).

I would like to go a bit deeper anf try to explain why I am concerned.

Imagine you have left and right channels perfectly time aligned. 
Then let's assume you want to equalize left and right channels independently (which is almost a must in an acoustically unfriendly car envirionment). Most probably, cut and boost frequencies will be different for left and right channels due to unsymmetrical listening position. In this case, if equalization introduce phase shifts in certain frequency ranges (in area of central frequency of equalizer band), we will get additional group delay for equalization frequency band only for one channel (where equalization was applied). Finally, this can yield into image smearing in certain frequency range. So, it can be a tough trade-off between tonal accuracy and image focus and stability.


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## ErinH

This is actually why I use assymetric crossover points. More and more DSPs allow you the flexibility to do this rather than being fixed at 1/3 octave frequencies. Both mids' LPF and Tweeters' HPF are different from side to side and between in order to achieve the same acoustical crossover at the listening position. This cuts down on the need to EQ out of band to match the response curves.

I covered this in my build log s I'm gonna quote myself ...



bikinpunk said:


> It is cool to know that I didn't have to go in and start hacking away at the response to get it where I like it. And, of course, anyone can say they don't use any EQ but I think the real fruits of the work have been vetted by people who have heard it. Yes, I didn't place 1st in my class at finals, but the system response is no slouch (I did manage to pull down 3rd place in a heavily stacked INAC class my first year out, though). It can use work, of course, but I think it's head and shoulders above where it's been in the past, regardless of any competition. And, I'm a pretty humble dude so it's not really easy for me to pat myself (really, the engineering of the drive unit) on the back, if that's how you want to view it. I'm really just trying to relay everything I did that went in to this install and where it got me at the end of the year. Hopefully it's not misconstrued as boasting, because that's not the intent. I'm just trying to share and be open about what I've been doing.
> 
> Now that that's out of the way...
> 
> 
> If you look, you can also see I have different crossover points on the left side vs right side tweeter/midrange. Since the left mid falls off faster than the right mid does due to the aiming, I crossed the right mid and tweeter to match up with the left side response which saved me some EQ headaches as well.
> 
> The left midrange is low passed at 3000hz/24dB.
> The right midrange is low passed at 2673hz/24dB.
> The left tweeter is high passed at 3726hz/24dB.
> The right tweeter is high passed at 4000hz/24dB.
> 
> 
> When I measure the in car response without EQ, the two sides line up pretty well based on these crosover points alone. Took me a bit of time fiddling with it by ear and RTA to find the best points and slopes; the exact numbers are more swags in the 10hz increment than they are necessity, though. I've tried shallow slopes (12dB) and while it worked well, it didn't really do anything other than cause issues outside of the nominal passband of every driver. In a reflective environment, I think shallow slopes do more harm than good. Even the design engineer at Kef who lead the design of the driver I use told me they'd prefer to use a higher order crossover slope but the additional parts cost prevent that. He was the one who motivated me to stay away from "textbook" crossover points, which pushed me in to playing with Passive Crossover Design software (PCD) a bit and determining crossover points and slopes to toy with before zeroing in on where I'm at now. The benefit of the higher slope, besides having to worry about out of band response as much, is the additional SPL you can achieve without additional distortion.
> 
> Additionally, the horn loaded nature of the tweeters in their coincident state creates a rising response in all axes. You can see this in the picture below. This rise actually guides me in to crossing the tweeters over higher electronically than I would a standard 1" tweeter. At the end of the day, this means my system is able to get pretty loud without audible distortion.... obviously there's a point at which it becomes an issue but that point is considerably higher than it's ever been in any of my previous builds.


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## Justin Zazzi

ansuser said:


> I would like to go a bit deeper anf try to explain why I am concerned.
> 
> Imagine you have left and right channels perfectly time aligned.
> Then let's assume you want to equalize left and right channels independently (which is almost a must in an acoustically unfriendly car envirionment). Most probably, cut and boost frequencies will be different for left and right channels due to unsymmetrical listening position. In this case, if equalization introduce phase shifts in certain frequency ranges (in area of central frequency of equalizer band), we will get additional group delay for equalization frequency band only for one channel (where equalization was applied). Finally, this can yield into image smearing in certain frequency range. So, it can be a tough trade-off between tonal accuracy and image focus and stability.


I think I understand what you are concerned about. However, group delay is equal to the negative slope (negative derivative) of the phase response, with respect to frequency. In other words, The only way to create a trending increase or decrease in group delay is by having a phase response that is continuously getting more and more steep, or less and less steep. A constantly steep phase response (either increasing or decreasing) will result in a constant group delay. If you've taken the first class of Calculus, this concept might make more sense.

So in other words, the only way to drastically change the group delay over a large frequency range and have a large imbalance like you fear would be to have a phase response that is constantly more and more steep (or more and more shallow) over that same frequency range.

However, in all of my testing and reading, by coercing the acoustic response of the system to align closely with my target curves (which are smooth), the acoustic response is becoming more and more smooth. In every measurement I've taken, a smoother frequency response also results in a smoother phase response, which would make the above scenario less and less likely.

What I'm trying to say is, I strongly believe that the use of aggressive EQ and other filters _for the purpose of making the acoustic response more smooth_, should not result in a significantly worse group delay or phase response than existed before. However, the opposite is almost certainly true.

I found one exception though. The phase response beyond the crossover frequency becomes chaotic and the resulting group delay does as well. This is not as bad as it seems though because as the acoustic response of the system falls off after the crossover frequency, the signal-to-noise ratio of the system falls off a cliff as well and the resulting measurements become less and less dependable. So what appears to be a "problem" is actually the noise overcoming the measurements.

For more reading about this, I refer to the paper “Subwoofer Alignment with a Full Range System”, by Charlie Hughes and the matching case-study on Home Theater Shack that attempts to replicate Hughes' work. Both are a little bit tough to grasp at first, but after reading them a couple times most of this has become more clear.

Subwoofer Alignment with a Full Range System

Case Study: Sub Alignment using REW v5 - Home Theater Forum and Systems - HomeTheaterShack.com


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## funkalicious

Wow. Your approach, methodology and enthusiasm are inspiring and contagious. Thank you for the time and effort you put in to this :thumbsup:. How does the frequency response of your system compare between the passenger and driver seats?


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## Justin Zazzi

funkalicious said:


> Wow. Your approach, methodology and enthusiasm are inspiring and contagious. Thank you for the time and effort you put in to this :thumbsup:. How does the frequency response of your system compare between the passenger and driver seats?


I'm glad you enjoyed!

I have not measured the passenger's seat, but subjectively listening from that position (while someone else is demo'ing the driver's seat) I can say the imaging is awful but the overall tone is still pretty good. I'm not terribly interested in the passenger seat because this is designed to be a one-seat car, sacrificing all other listening positions to make that driver's seat as good as possible.


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## Justin Zazzi

Finally an update on the doors and the rockwool installation.
No problems, no mold, no decay or odd smells. All is well.


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## deeppinkdiver

Great to hear Jazzi! 

Where did you source that product again?


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## Justin Zazzi

I found it at Lowe's, called Roxul Safe'n'Sound. Home Depot and Orchard Supply Hardware do not carry it. I think was as around $40 for the package.

Beware though, it's only sold in large bundles of something like a dozen batts at a time. I hope you have need for lots of it if you guy buy any!


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## captainobvious

You could use extra for other areas of the car as well- between the headliner and roof, in rear quarter panel areas in the trunk around the wheel wells, etc. Should help absorb some of that noise too. It's much cheaper than 3M Thinsulate Acoustic so I'm going to give it a shot.
Thanks for updating us with the status of this. I've been very interested to see how it would weather.


-Steve


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## rton20s

Interesting. The rock wool or mineral wool insulation is exactly what we specify for our building projects when we are concerned about acoustics/sound transfer. (Standard fiberglass batt insulation is our standard spec for thermal insulation.)


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## req

im going to have to read this like 15 times now heheh 

if you dont mind me asking - what do you do to physically hook all this equipment up?

are you using a mic + laptop with a feed back loop? im just curious because i have everything to do this kind of measurement. dayton omnimic, REW, laptop, cables, DSP the whole 9. 

im interested to see what you do to actually hook it up to perform the tests you are doing.


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## Justin Zazzi

req said:


> im going to have to read this like 15 times now heheh
> 
> if you dont mind me asking - what do you do to physically hook all this equipment up?
> 
> are you using a mic + laptop with a feed back loop? im just curious because i have everything to do this kind of measurement. dayton omnimic, REW, laptop, cables, DSP the whole 9.
> 
> im interested to see what you do to actually hook it up to perform the tests you are doing.


Hey req, thanks for stopping by! I've read through much of your work and it has been influential in mine. Thanks a bunch for all that you share here 

I use a laptop with Room EQ Wizard software, a calibrated Dayton EMM-6 microphone from Herb at cross-spectrum labs (awesome guy to work with), and my preamp is an M-Audio Fast-Track Pro (with a loopback cable for the 2nd channel for REW). I aim for smoothing of 1/12 for most of my measurements as a balance between high resolution (to see what's happening) and keeping the "noise" in the higher frequencies from being misleading (sometimes I'll look at 1/3 or 1/6 for higher octaves). My measurements are made from a point in space where my left or right ears would occupy (while measuring the left and right channels respectively), while I sit in the backseat area. I aim the mic on-axis to the speaker being measured. I average 4 sweeps from REW for each measurement while moving the mic a tiny bit for each sweep in an attempt to use spatial averaging to smooth out the higher frequencies. Lastly, I only measure one speaker at a time unless I'm trying to verify that multiple speakers are not interfering with eachother, like in my examples in post #251.

I hope that helps! Please ask more questions if you like!

Also I do not claim credit for "breaking the code" with any of this crossover or tuning stuff, I'm just doing lots of reading and playing with stuff that people before me have discovered. However, I'm really glad that is is helpful for others.


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## Hanatsu

ansuser said:


> I am a bit concerned about "aggressive EQ"... what about a possible phase shifts due to applying equalizer?


Old post but that's an interesting question. An IIR based DSP will cause phase shifts inversely proportional to the amplitude gain. The main argument of not using "much EQ" is the so called "bad" phase shifts. In a minimum phase area (which can be seen as "flat" in the excess group delay plot) the phase/amplitude relationship will be proportional to each other when you EQ. If there's a peak in the frequency response and it's a minimum phase region, the phase shift of the EQ will "fix" the acoustic phase. 

Having said that, very high Q filters should only be used far down in the modal region where the response doesn't change over small distances. RoomEQ cascade weird filters to gain a optimal acoustic response, nothing bad with that, just don't use high Q parametric EQ in the midrange/tweeter range.


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## Joenaz2003

Man this is some great stuff you have going on in here. I read every post starting last night and think I understood 3 posts lol. My brain still hurts. I can only hope to be close to as technically knowledgeable about sound, placement and frequency one day. Great job man, and to everybody else in here that contributed all the great info reading material. I'm going to start reading all those books and links and hopefully it will help me and not just fry me out lol.


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## Justin Zazzi

I will be bringing the Golf down to Huntington Beach in about a week. Details on that meetup/competition are in the thread linked below. I hope to meet some new people and match some faces to the screen names.

http://www.diymobileaudio.com/forum...f-city-soundoff-6-28-huntington-beach-ca.html


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## damonryoung

Jazzi said:


> I will be bringing the Golf down to Huntington Beach in about a week. Details on that meetup/competition are in the thread linked below. I hope to meet some new people and match some faces to the screen names.
> 
> http://www.diymobileaudio.com/forum...f-city-soundoff-6-28-huntington-beach-ca.html


I look forward to meeting you and getting a chance to listen!


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## DLO13

Justin,
Very cool to get to meet you and catch the end of the clinic. I do have to say, while it may have been very elementary for you, it really cleared up a lot of questions I had/have - going into using a processor like the 6to8. 
Also, while I didn't get a chance to hear your car from the driver seat, the tonality was awesome. It blended so nicely! I asked Karisa where the sound was coming from and she pointed dead center 

And on that note - It was very cool of you to let Karisa have a listen while I was in Linda's Smart. Awesome meeting you, and hopefully we will see each other again!


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## Justin Zazzi

It was really nice meeting both of you (and everyone else too!) down in Huntington Beach, and I'm thrilled to have been a part of it. Thank you for the warm comments, and I hope to see you again sometime too.


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## rton20s

I agree with Karisa, Justin. Your car has a great center image. Thanks for providing that disc for the demo as well. I'd never listened to "Handlebars" on an SQ system, but I think I might add it to my regular demo material. Was that the original version from the CD?


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## damonryoung

rton20s said:


> I agree with Karisa, Justin. Your car has a great center image. Thanks for providing that disc for the demo as well. I'd never listened to "Handlebars" on an SQ system, but I think I might add it to my regular demo material. Was that the original version from the CD?


Are we talking about "Handlebars" from the Flobots??


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## rton20s

DRTHJTA said:


> Are we talking about "Handlebars" from the Flobots??


Yes. It was on the "vocals" demo disc that Jazzi had when I demoed his car. I was surprised at how clean it sounded and how well it staged. Honestly, I don't own the album, but have heard it in the past on the radio (pre system install) and when streaming on my phone.


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## Justin Zazzi

I will be bringing the Golf down to San Louis Obispo this coming Sunday for the MECA California state finals. I will not be competing so the car will be empty all day if anybody would like to take a listen.

Looking forward to seeing everybody down there!


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## papasin

Jazzi said:


> I will be bringing the Golf down to San Louis Obispo this coming Sunday for the MECA California state finals. I will not be competing so the car will be empty all day if anybody would like to take a listen.
> 
> Looking forward to seeing everybody down there!



Looking forward to hearing it!


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## BigRed

Looking forward to hearing what mike did


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## GTBqv.au

Holy Sh!t. I have just read this from the beginning. This is phenomenal. So much to take in.
For a start I am just laughing to Star Wars on the Cello. Thanks for introducing those two to me.
I will be putting a lot more effort into the sound treatments in my new car, incidentally also a Golf (Mk7). The recent stuff on crossovers was very enlightening. I have read a few of your crossover references and had also decided that Linkwitz at 24dB was the way. On my current car I however just assumed that I was far enough away from the natural rolloff to set the P99RS to 24dB and be done with it. Will not be happening next time! 
Inspirational stuff and really makes me want to be very active in getting the setup just so. Thank you.
My installer will curse you


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## Justin Zazzi

GTBqv.au, I'm glad you enjoyed the journey. Best of luck to you and your install!


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## Leekle2ManE

After your advice on my tweeter placement, I read through this build log and found it quite informative. There's a lot of engineering jargon that I have no clue on, but for the most part I can figure out what you talk about. Being that I'm more shade tree and not worried about perfection or competing, I will probably only actually use about a quarter of the stuff here, but the rest is just as important. I think it is people like you who have helped push Car Audio along over the years and I can't wait to see if your discoveries help push it along even more.

I have a few questions regarding your subwoofer placement from page 1:

In the post you quote Ingvar Öhman as saying that the sub shouldn't be more than 53 cm from an adjacent surface to help all reflections being in the same phase. You both then say that this means rear wall, side wall and floor, but don't include the ceiling. Would it be beneficial to have the woofer as high as possible to put the ceiling within this sphere as well?

I am also curious as to if this measurement should be taken from the center of the woofer's cone or from the edge. I am assuming the former, but would like clarification.

And lastly, while the post says to keep the woofer within 53 cm, I am curious if having the woofer equidistant from each surface would be better than having mixed distances? Or does it just matter that the woofer is within that 1/8th wavelength?

Thank you for sharing all your hard work.


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## Hanatsu

If you want to get rid of the first modal null place the sub close to the trunk facing backwards. 53cm is basically nothing in the lowest octave where the wavelengths are 10-20m long. Who said that again? 

Sent from my Samsung Galaxy S5 using Tapatalk


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## Justin Zazzi

Leekle2ManE said:


> I am also curious as to if this measurement should be taken from the center of the woofer's cone or from the edge. I am assuming the former, but would like clarification.


Measurements should be taken from the center of the woofer instead of the edge, because the sound does not come from the edge of the woofer but instead from the entire surface.



Leekle2ManE said:


> In the post you quote Ingvar Öhman as saying that the sub shouldn't be more than 53 cm from an adjacent surface to help all reflections being in the same phase. You both then say that this means rear wall, side wall and floor, but don't include the ceiling. Would it be beneficial to have the woofer as high as possible to put the ceiling within this sphere as well?


What a great question. In this example, we can only control the reflections off of so many adjacent boundaries. The three walls "touching" the subwoofer can be placed at any controlled distance (floor, side, and front) and the other three sides of the subwoofer (opposite side, rear, and ceiling) are indirectly controlled distances, which wind up at whatever they are based on where we placed the sub in relation to the first three walls. Obviously we cannot place the subwoofer right up against the floor AND the ceiling which would "ideal", so we have to choose a placement closer to one, the other, or somewhere inbetween the two. More on this below.



Leekle2ManE said:


> And lastly, while the post says to keep the woofer within 53 cm, I am curious if having the woofer equidistant from each surface would be better than having mixed distances? Or does it just matter that the woofer is within that 1/8th wavelength?


Another excellent question. The simple answer is it does not matter so long as you place the speaker "close enough" to all sidewalls so that all reflections are in phase with eachother, within the passband you are interested in. For a subwoofer, the passband is about 25-80hz so placing the sub within 1/8 wavelength of each surface (53cm) is easy.

The more complex answer is, if you cannot get "close enough" to each sidewall, then try to stagger the distances as much as possible. Each reflection off a boundary will contribute a set of reinforcements and cancellations in the frequency response at certain frequencies based on how far away the boundaries are. It is more desirable to have multiple small frequency response anomalies than to have one large one, especially because these reinforcements and cancellations caused by reflections off the side walls cannot be corrected with EQ or other signal processing.

For example the image below might show the reflection of a 160hz tone off a wall 53cm away. The red trace comes from the sub and travels towards the side wall where it bounces off and travels (yellow) towards the sub. The two waves are now out of phase and cancel eachother. What is not shown is the matching frequency reinforcement where the reflected wave and the radiated wave will be in phase with eachother, causing a rise in the frequency response at that frequency (1/2 wavelength or 320hz in this case). The frequency these phenomenons happens at is directly related to how far away the wall is from the sub. So by spacing the speaker at various distances from each wall, you can "spread the chaos" a little bit instead of having one very large cancellation that is impossible to correct with EQ or other processing.

This is also why it is common practice to avoid boosting when using an EQ because if you try to boost missing frequencies that are lost due to a reflection, you will never get them back and you risk damaging the speaker due to excessive power/excursion at that particular frequency.










_borrowed from teamrocs.com, though I am unsure who the original author is_


While we're on the topic, here's one more example.

Tweeters on speakers are usually placed centered between the left and right edges of the face of the speaker (see the speaker on the right of the image below). However, high frequencies have something called edge diffraction which essentially causes frequency response anomalies based on how far away sharp edges are from a tweeter (simplifying a little bit here).

The speaker on the right has some diffraction caused by the sharp edge to the left of the tweeter at some distance, and also by the sharp edge to the right of the tweeter at some distance. In this case, the two distances are equal, so the frequency anomaly is twice as bad at the same frequency.

Now look at the speaker on the left. The tweeter is placed off-center and the distance from the left, edge, right edge, and also the top edge are all different. This is an attempt to "spread the chaos" of the frequency anomalies because the edges cannot be placed "close enough" to control all the reflections to be in phase in the passband we are interested in (tweeters are likely in the many kilohertz range and have wavelengths of less than a few inches).












Anyhow Leekle2ManE, I hope that helps!
Thanks for taking an interest in my work, and best of luck with yours!


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## Hanatsu

Here's a measurement of different sub positions in a trunk. How much they differ from eachother. One against seat facing backwards (reference), one in the middle of the trunk facing upwards, one facing forward in the back of the trunk, one facing backwards 10cm from trunk in the middle. The placement in the middle of the trunk resulted in a null around 105Hz. As expected the difference gets larger as you go higher in frequency.


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## SO20thCentury

Thanks, Jazzi, for such an informative and enlightening build! You have managed to turn the lightbulb on in places I was completely in the dark. You are excellent at communicating in lay terms concepts that have been beyond my grasp.
Have you kept the rockwool basstrap in the back? 
Does the wood floor being a highly reflective surface cause any problems? My understanding was that soft, non-reflective was better. Or does your hatch cover and curtain mitigate that?

And as far as subwoofer placement goes, I've seen a lot of info on placement in a trunk but nothing about in a hatchback. The two do not seem similar enough to apply the same rules. (Especially if you never use the hatch cover or even have the seats up.)


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## Justin Zazzi

Hello SO20thCentury,

I'm glad you enjoyed the reading, and thank you for your warm compliments.

I do not have the rockwool bass trap in the car, and have not for a long while. I could tell it reduced road noise slightly, but could not definitively hear a difference with the stereo. The measurements say it makes a pretty drastic improvement though. Mostly it came down to convenience, and I use the cargo area frequently enough that I left it out for the majority of the time.

The hardwood floor being a reflective surface is also something I cannot perceive a solid difference on. It should make the treble a little bit more reflective in the car, but the treble has to get past the front seats first so there is likely very little high frequency noise left to bounce around in the back seat area. The hatch cover and curtain do cover about half of the floor though, so that will also reduce the reflections back there.

For subwoofer placement, all the same basic rules apply. Double check the past few posts that Hanatsu and I made about wavelengths and look at the pictures too. Aiming the woofer back towards the rear wall should be "best" for most people in both hatchbacks and trunks, unless you go infinite baffle style.


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## Justin Zazzi

An update.

The Morel Hybrid Ovation 6" have been real champs and I love them quite a bit. However, when I ran them hi-passed at 50hz they would run out of excursion pretty quick and I would get a lot of distortion. They have been hi-passed at 80hz for the past few months and they sound amazing, but I have lost a bit of the "up front bass" illusion I used to have when they were crossed lower.

Enter the Peerless SLS 6.5" driver. These are beastly compared to the Morels and should be able to play the lower frequencies without trouble (8mm Xmax compared to 5mm). However the Peerless won't be able to play frequencies higher than a few hundred hertz to maybe a kilohertz, so there is a tradeoff. I wouldn't recommend them to anyone running a two-way system because of this limitation.

I'll have initial impressions in a couple days and these should be ready to hear at the Elk Grove MECA competition this weekend. I hope to see some of you there!

Side note, my Morel Hybrid Ovation 6 component set is now for sale in the classifieds section. Details are over here.

Photos because photos are cool. The Peerless SLS is on the left.


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## captainobvious

Yeah the Peerless SLS' are pretty beefy. I ran the SLS 8" in previous installs. It's a fine midbass driver, but as you said- limited in bandwidth application.I didn't like to run mine higher than about 300hz.

The new SI TM65 might be a viable alternative down the road as well. With more xmax, higher power handling, a good mount higher sensitivity and easier mounting it's quite the good looking option. Granted it's about double the cost  But still very reasonable for the level of performance and quality they appear to have.

Looking forward to your impressions of the SLS6. I think it will serve you well.


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## Justin Zazzi

After a few hours of tuning on and off, I'm very pleasantly surprised with their performance. Gobs of bass and midbass.

New rattles everywhere though, that's the only downside


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## Lycancatt

I'm glad you went with these but..i'm not surprised about the rattles! good luck taming them, its a never ending story once you step up to a lot of up front bass.


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## Swaglife81

One of the better informational builds in this forum. Anyone should make the time to read this full thread if you wanna learn more. Acoustic performance theories, some Rew tips, crossovers, experimental placement. It was a good read. If anyone likes the scientific aspect of this hobby you will love this build. If your the magazine guy that just wants to see a whole glob of pictures this isn't for you.


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## JayinMI

Thanks to Photobucket, if you're the kind of guy who like gobs of pics, most forums aren't for you anymore. lol

Jay


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## Truthunter

Just read through this build log & wanted to thank you Justin for taking the time to document. Definitely learned things here & have a better understanding of concepts I have read/heard about previously but didn't fully grasp. 

Wanted to note about the Roxul: I'm in the process of installing some in my doors and I chose a product called Roxul AFB which is available in 1" thickness, is the same density/properties as the Safe n Sound and available in single 2x4' sheets at atsacoustics.com. It's more expensive by volume (still cheaper then the OC fg) but will save time as it will not need to be cut down thinner. It's also good to know that you did not have any issues with moisture compromising your in-door Roxul insulation.


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## Justin Zazzi

You're welcome! I'm glad you enjoyed the read. Thank you for the kind words.


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## Jscoyne2

Justin Zazzi said:


> _-build curtains for the rear cargo (done!)_
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> _When adding the bass trap the T20 time for my largest peak around 120hz is reduced from roughly 0.49 seconds to 0.37 seconds ... in improvement of nearly 25%. Is this audible? I'm not sure. The time required to remove it and listen again is too long to make a serious comparison. But I am happy to see it does make a measurable difference and works as intended._
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> _And finally 2x 250w heat lamps to dry fiberglass over the next couple nights. This should fix my drying issues ...._


All of this. Good lord lol


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## Justin Zazzi

Anyone know a decent way to copy/paste multiple posts from one forum to another? For example if I wanted to copy my posts from this build log to CarAudioJunkies without manually rebuilding every one of my posts, linking all the pictures, and so on.....

I bet a dollar there is a tool somewhere that can do this. Do you know where to find it?


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