# open baffle project



## alpinem

Here is a project that I have been working on for a while. It is an open baffle "hybrid" two-way design. Open baffle part is an 8" fullrange driver, there is also a 12" sub in a sealed down firing cabinet. The sonic characteristics of this design, after alot of experimenting and modeling, is incredible. The sound stage is massive. Much wider and deeper than the speakers are placed. The stage is also very focused and dimensional. It has layered depth like very few systems I have ever heard. These speakers make the room itself disappear. Bla bla bla......here is the build.




Here is a 3D model of the finished product.














Onto the construction.

A pile of CNC cut parts to be assembled.









First the sub. It is made up of 3/4"MDF layers. The wall thickness of the cabinet ranges from 1"-3 1/2" thick. Very STOUT.

Now for gluing, stacking, and clamping......



















Here is the sub cabinet.....minus the two layers that will make up the top.










Same process for the tower.










Here is one sub and one tower glued together and ready for sanding then fiberglass.










Here with the insert in place. The insert will eventually have an exotic veneer applied.










Now for the sanding......


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## alpinem

And some fiberglass.




























Next is some filler to make sure these are smoooooooth. After all they are going to be painted a high gloss black.










Starting to get a flat surface.











Here is the fit on the insert.



















And the sub insert.

Here is a close-up shot of the Bosse veneers grain.










Applying the veneer.

tower.....










sub......


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## alpinem

Here are the pieces trimmed and ready for a lot of clear to get a mirror finish.




























Finally attached the base for the tower.



















Here is the base for the sub cabinet. It has an extra "ring" to allow more room for the sub to load on the floor. Both the sub and the tower have spikes as well.










Here is one sub/tower ready for paint. The other soon to follow.










Notice the sub doesn't contact the tower anywhere. This is to prevent any vibration that the sub cabinet might have from being transmitted to the tower.


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## XtremeRevolution

Can't wait to see this when I get home. Images are blocked at work, but it sounds like you did a great job. Infinite baffle speakers have a way to make the sound stage sound...massive. 

I'm in the process of designing a line array using 12 drivers per side and one centralized tweeter using an open baffle configuration.


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## generalkorrd

Gorgeous! I wish I had a cnc at home, I could do so much! How many sheets of wood went into it?


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## Wesayso

Would love to see more, and more info on the drivers etc... they look stunning allready


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## ErinH

Guy, I heard an unfinished version of these about a year and a half ago and was hugely impressed. Honest to goodness the best speakers I've heard to date. The dynamicism was excellent. Tonality was my cup of tea. I can't recall my thoughts on staging because I spent the first 30 minutes constantly repeating "what the heck" everytime they'd do something nothing else I'd heard do. The day I heard these was the same day I had spent numerous outs at a local producers house listening to a multitude of setups including tube and solid state amps with $5k (the cheapest set he owns) speakers up to $12k speakers. I heard five different setups at his house. The ones Scott has bested them in every category. 
I suppose there's a whole lot to say for an open baffle setup and a good design. 

Scott, I didn't realize you were so far along but you have been at these for a while now. 

If you need measurements LMK. 

Oh, and DIBS!


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## SQHemi

Incredible workmanship. Very Inspiring...


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## wheelieking71

that is the single most awsome "speaker-build" i have ever seen! just awsome!


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## Ray21

Amazing!!


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## ErinH

bump for the most bad-assed project I've seen on this site.


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## bmiller1

Wow, that is some really impressive work. I'm jealous of your skill.


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## XtremeRevolution

If only I had a CNC machine.


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## ErinH

XtremeRevolution said:


> If only I had a CNC machine.


lol. You need more than just a cnc machine.


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## XtremeRevolution

bikinpunk said:


> lol. You need more than just a cnc machine.


Lol, I know, but there's no doubting that you can't get those kind of results without one.


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## ErinH

Well, you'd be surprised. I'm pretty sure Scott had someone do these cuts on a CNC machine, but if you're good you can make a single one and use a flush trim bit to make copies. Not saying I would... I'm actually thinking of getting the same folks he used to make me some rings for a build I'm considering in the future (assuming I don't just buy these).


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## ecbmxer

Fantastic build. I love builds like this that are built up of many cnc'd pieces. Thats one of these full range 8's right: Tang Band W8-1808 8" Neodymium Full Range Driver

Do you happen to have a link to the original design specs? Does it require a lot of EQ or any crossover design/construction?


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## XtremeRevolution

bikinpunk said:


> Well, you'd be surprised. I'm pretty sure Scott had someone do these cuts on a CNC machine, but if you're good you can make a single one and use a flush trim bit to make copies. Not saying I would... I'm actually thinking of getting the same folks he used to make me some rings for a build I'm considering in the future (assuming I don't just buy these).


Been there, done that, and it still requires some tools and time. The problem I have with it is that I either need to find a really good dust mask (the kind that looks like a gas mask with replaceable filters), or I need to have some good dust collection. Routing MDF with a reverse flush trim bit makes a gigantic mess. I usually take my work outside on a bench when I have to route MDF because of the dust it creates. 

Real wood though, that's a different story. Not nearly as harmful, and not nearly as cheap.


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## XtremeRevolution

ecbmxer said:


> Fantastic build. I love builds like this that are built up of many cnc'd pieces. Thats one of these full range 8's right: Tang Band W8-1808 8" Neodymium Full Range Driver
> 
> Do you happen to have a link to the original design specs? Does it require a lot of EQ or any crossover design/construction?


I imagine you'd need a contour filter to tame some of that top end and a BSC circuit to pick up the bottom end that will fall very rapidly in an OB. Without it, it will sound thin. Not terribly difficult to model. 

I've thought about doing something like this recently, especially given the prices available for some of these full range drivers, but the poor off-axis high frequency dispersion of larger full range drivers has prevented me from attempting it. This particular driver however is better than most, although the price reflects that.


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## alpinem

No bsc needed. Between the shape of the baffle, the design being open baffle, and the response of the driver I haven't found the need for it. The only xover is a simple 6db slope on the low end of the fullrange driver and a 6db slope on the top end of the sub.


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## chad

Are there any concerns about reflection off the top of the sub enclosure? Or is there actually an intentional level of reflection built into the design?


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## Pseudonym

pretty bitchin build. loving the stacked design.


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## PaulD

wow, looks like Scott has been busy 

is there a way to put someone on ignore, like most chat programs ?


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## XtremeRevolution

alpinem said:


> No bsc needed. Between the shape of the baffle, the design being open baffle, and the response of the driver I haven't found the need for it. The only xover is a simple 6db slope on the low end of the fullrange driver and a 6db slope on the top end of the sub.


Really? 

I'm curious as to what your frequency response will be south of 500hz. I know that's a great driver, but I haven't yet seen one that has any built in BSC and the frequency response seems to even further indicate a need for it. 

How low will you be crossing this?


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## ecbmxer

alpinem said:


> No bsc needed. Between the shape of the baffle, the design being open baffle, and the response of the driver I haven't found the need for it. The only xover is a simple 6db slope on the low end of the fullrange driver and a 6db slope on the top end of the sub.


Wow, thats awesome! So the baffle curvature was specifically chosen? Are there any other aspects of the exterior geometry designed with the frequency response in mind? Like the gap between sub enclosure and the baffle, the cutouts on the sides of the sub enclosure, or the shape of the baffle edges. I want to build an OB speaker one day, but don't wanna get this crazy with the construction. ALso, what sub drivers are in there?


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## alpinem

Yes there was a lot of experimenting in the baffle shape and size. The gap between the sub and the tower is just to prevent transmission of vibration from the sub to the tower. The shape of the sides of the sub is purely looks, not only to give the sub some character but looking from the front of the tower the sub behind it is not visible at all. In this configuration the sub is extremely transparent. It doesn't sound like there is a sub at all, but tonally everything is there. In fact with this configuration the fullrange also disappears into the sound stage. Everything is very focused and detailed but nothing appears to be coming from the speakers themselves. The system also does not have to be bi-amped. There are no extra xover components to "match" the output between the sub and the fullrange. I didn't want anymore in line than had to be. Just a simple 6db high pass on the fullrange and 6db low pass on the sub. In the end the network is very simple......it just took a lot of work to get there.


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## Wesayso

Great project! Does a setup like this need a lot of room around the speakers to sound good?
I would love to try open baffle but knowing my girlfriend it 'll be impossible to get speakers in the right position .


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## chad

Which sub driver are you using, if you don't mind me asking?


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## alpinem

sub is an SB Acoustics. 

SB Acoustics SB34NRX75-6 12" Woofer: Madisound Speaker Store


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## SSSnake

Scott,

First great work! I didn't realize you had these skills 

I guess I had the same question as Chad.



> Are there any concerns about reflection off the top of the sub enclosure? Or is there actually an intentional level of reflection built into the design?


It would seem to cause issues on the indirect sound. Just curious as to your thoughts.


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## alpinem

Hey Charles, 

I have tried the sub in several different configurations none of which caused any problems with the fullrange. Only changed the sound and transparency of the sub. Any reflections are either too high in frequency and/or too low in amplitude to notice a difference in the listening position.


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## chad

we are referring to the other side of the fullrange off the top of the downfiring subwoofer enclosure.


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## alpinem

Yes....so am I. Just stating that there are no ill effects from reflection off the top of the sub enclosure.


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## alabama_lowlife

That's one of the coolest things I've seen. I'd love to have that in my livingroom.


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## Stück

These look very interesting, eager for an update!


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## SQrules

I have to give props to Scott for his great skill and design work on these speakers. I to have heard them in the design phase, and they sound just as Scott has decribed them. Very impressive. Wouldn't have believed until I heard it.


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## ecbmxer

I really need to hear an OB speaker. I love the simplicity, yet insane intricacy, of this project.


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## alpinem

Well, it's been a while but I will be delivering these to the painter this week. We are going to do some samples first to make sure of the colors and finish. I think I have decided to go mirror high gloss finish on the wood inserts and black with a satin finish on everything else. I will post more pics as things progress.


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## highly

Inspiring. Truly inspiring.
Looking forward (as I am sure we all are!) to seeing them completed!

-Todd


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## alpinem

I decided to take things a step further. While the speakers are getting painted I will be building an amplifier for them. I bought a "class D audio" amp kit a while back and have never put it together. figured this would be the perfect application for it. The chassis will be made of aluminum. Here are a couple of pics of the wood mockup I made first in order to get the look and dimensions right.......plus wood is cheaper to experiment with than aluminum. There will be two amplifiers, one for each speaker.


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## Woosey

Respect!

Just gorgeous!!


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## 2010hummerguy

Awesome build, between these and the Orions I am leaning more towards the OB idea. How is overall SPL? Are these dynamic enough for serious home theater duty? I refuse to use a center speaker and these may seal that case for me.


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## RaunchyTheBug

Awsome building.


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## alpinem

I know its been a bit, but the parts are finally being painted. I should have them back in a week or two. I'll post pics of the paint progress.


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## chithead

Phenomenal work here! Can't wait to see the final product.


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## TheHulk9er

When can I get one of these?


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## hybridspl

Wow! In for finished pics and specs.


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## alpinem

outboard xovers.


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## alpinem

First coat of filler primer. They are looking very smooth. Now for some blocking, another coat of primer, then some paint.


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## minibox

alpinem said:


> First coat of filler primer. They are looking very smooth. Now for some blocking, another coat of primer, then some paint.


This is one of the most exciting builds I have ever seen on this site. Amazing work.


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## Wesayso

minibox said:


> This is one of the most exciting builds I have ever seen on this site. Amazing work.


The same could be said about his build log on his car


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## req

holy crap those are pretty!


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## alpinem

Thanks guys


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## alpinem

Paint is coming along. They are expected to be finished next week. I'm excited to get them assembled and doing some long listening sessions.


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## alpinem

Here are the latest pics.


Wet sanding.




























Nice!!!!!!





























Here is the sub.


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## alpinem

The inserts.




























Everything is very close. Hope to start assembly next week.


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## minibox

Beautiful! Will these be for sale or are you hanging on to them?


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## alpinem

A couple more pics


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## FlashJim

I need a towel.

Beautiful work. Are you on HTGuide, HomeTheaterShack, AVSForums, etc? I'm FlashJim on all of the audio related forums.


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## LBrines

Unbelievable craftsmanship, well done!


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## req

just post finished huge pics with the speakers installed and a review already >_<

i want to listen Q_Q


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## ErnstHenning

What Happened to this thread???


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## alpinem

Digging up this old thread for an update. My wife and I are getting closer to being empty nesters. One of our daughters got married and moved to Florida leaving a room that we had to find something to do with.









Set the speakers up in the room to see if things would work well enough to move forward with building a listening room. Worked great......onto the remodel.

The room is small and square.....I know both are not the best to make a listening room. Room is 10x10 so I will need a good amount of sound absorbing panels. I decided to go about this a bit differently than I have before. I just didn't want 4" thick panels hanging on the walls because it is such a small room. I decided to go into the walls.

First step was to get rid of all the unnecessary drywall.

























Then I ran conduit in the wall for the speaker wires.


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## ErinH

Oh, heck yes! 

Scott, it's great to see you back at it, man. Really awesome!


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## alpinem

Next I filled the stud bays with denim sound insulation......about 4" depth.









I wanted a simple clean look to the room so I decided to make a floating shelf for the gear to sit on. Here you can see the brackets mounted to the studs. I will also have outlets inside the shelf to keep the wiring neat and tidy.

















I also primed the wall. It will take a few coats to cover the dark color.


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## alpinem

The next step was to stretch fabric over the panels.


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## alpinem

More work on the shelf.


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## alpinem

Trimmed the panels with some simple molding.









































Trying to keep things nice and level.


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## alpinem

The gear that I will be using is Pro-Ject. They are more known for their turntables but the audio gear is fantastic.....plus I really like the simple clean look. I will be using the Pre Box DS2 analog, CD Box DS and Amp Box DS2.


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## alpinem

Finished trim paint and the room is complete. No visible wiring anywhere. Clean and simple look.
Really pleased with the results. The speakers are rock solid...the imaging is crazy precise...speakers perform much better with the room treatment.










All the gear in place and everything wired (the preamp is the wrong piece with the wood sides...it has since been replaced with the correct one that matches the rest of the gear).


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## alpinem

ErinH said:


> Oh, heck yes!
> 
> Scott, it's great to see you back at it, man. Really awesome!


Hey man......I know, it's been a while. You need to take a listen one of these days. Would love your input on the room.


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## ErinH

alpinem said:


> Hey man......I know, it's been a while. You need to take a listen one of these days. Would love your input on the room.


This build turned out awesome. I'd definitely like to hear it sometime.


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## seafish

OP, as one woodworker to another, I just want to say AMAZING SKILLS and BEAUTIFUL RESULTS!!!

On a side note, I would be very interested to know how much each of those bad boys tip the scales at??


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## alpinem

Thanks for the kind words..

Haven't weighed the speakers but I would estimate a sub/fullrange combo is in the 200lb range.


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## brett

i never come to this section and this is my first time seeing this. amazing job! the incredible amount of patience it must've taken for all of this. i'd be curious what they sound like in a larger room, but what you've done to that room and its presentation is equally great.


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## Electrodynamic

Wow, totally awesome build. Thanks for the all of the pictures and details. Excellent job!


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