# New Way to Increase Soundstage Depth



## Patrick Bateman (Sep 11, 2006)

For a few years I've been messing with ways to warp sound, and relocate sound. I've come up with something new and thought people might be interested in seeing the results.

It's hard to 'fake' soundstage depth. There's lots of processors that can make your soundstage sound wider, but depth is tough to fake. DSP processors can manipulate the location of the stage, from left to right, but manipulating it front to back is tough.

In a nutshell, our perception of soundstage depth is mostly dictated by how deep the speakers are actually located.

This varies with frequency; and it's easier to fake it at 5khz then 500hz. But in the two octaves from 500hz to 2khz, your perception of where the sound is coming from is basically going to be dictated by where the sound is actually coming from!










A tried and true solution is to use kick panels. This allows you to put the speakers further away than if they were in the doors, but it requires fabrication and it eats up precious room under the dash.









Here's my oddball solution that I designed for my Mazda6.









Looks a bit like a submarine.









The enclosure is basically a miniaturized version of the cabinet of a Kef 107/2. The Kef 105/3 also used a similar setup. There are two woofers in the cabinet. One pushes, one pulls, and all the air exits out of the port. Basically a push-pull bandpass box.


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## BowDown (Sep 24, 2009)

Where's it going? 

Sent from my Z30 using Tapatalk


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## Patrick Bateman (Sep 11, 2006)

There's a calculator here that I used to figure out the volumes:

Car Audio - BANDPASS SUBWOOFER Box Design Using Gain (Fourth-Order)









Here's a pic of it. Yes, it's ugly, I need to sand and paint it. Next to it is one of those 4" cubes from Cambridge Sound Works. I used that as a 'baseline' to be sure that my efficiency, output and distortion levels were within reason.


















This type of alignment is similar to this Polk subwoofer from the 90s, except the Polk is isobaric, and mine isn't. Push-pull mounting really nukes second harmonic distortion, to a level that's lower than what you'd see with a Scanspeak or Dynaudio woofer.


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## 94VG30DE (Nov 28, 2007)

Patrick Bateman said:


> I've come up with something *new *and thought people might be interested in seeing the results.


Careful with this, as some of the naysayers love pointing out how some of your ideas are re-packaging of already-existing concepts. I only care about new applications for old tech, so carry on


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## Hanatsu (Nov 9, 2010)

Gotta love your weird constructions 

Interested to see where you going with this...


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## Patrick Bateman (Sep 11, 2006)

94VG30DE said:


> Careful with this, as some of the naysayers love pointing out how some of your ideas are re-packaging of already-existing concepts. I only care about new applications for old tech, so carry on


Oh I steal stuff shamelessly. All of my best stuff was either a copy or a variation on something built by Kef, Danley, Dunlavy or Geddes.


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## sprocketser (Apr 18, 2014)

Looks interesting buddy !


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## Patrick Bateman (Sep 11, 2006)

Here's the predicted response of the enclosure. Using hornresp to do the sims, as usual. You're not going to get more than one to two octaves of output out of one of these.









Here's the measured response of the loudspeaker (green) and the Cambridge speaker for comparison (red)

The line at the bottom is the measurement of total harmonic distortion. You can see the bandpass is lower than the Cambridge. This is particularly noticeable in the measurement of 2nd harmonic distortion, which is reduced by push-pull mounting. (I'll post that measurement shortly.)









The woofers are Dayton ND91. Similar to the ones pictured here. (not mine.)

If you wanted to generate a lot of SPL from 200-400hz, there are a lot of 4" and 5" woofers that will do the job. Main reason I went with the Daytons is that a pair of them will move more air than most five or six inch woofers. And you can only do "push pull" with a pair of woofers. The Daytons also have a shorting cap on the voice coil, which reduces distortion further.

The CSW enclosure fares pretty well, particularly since the amp, sub and two speakers retails for under $100. Note how flat the response is.


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## Patrick Bateman (Sep 11, 2006)

Here's my favorite part of the design. *I stuffed a cylinder of closed cell foam into the port.* This measurement shows the response of the loudspeaker with and WITHOUT the foam 'bung' in the port.

This is another 'trick' I stole from Kef. They've been using this technology in their speakers for a few years now. Here's a description of the bungs from Kef's documentation:

_A pair of bungs is supplied with the X3OOA system for you to ﬁne-tune the bass output. When the speakers are positioned close to the wall, it is recommended that the bungs be placed into the rear port if you ﬁnd the bass output to be overwhelming or boomy. The bung can be separated into outer and inner for more bass reduction, you may put the full bung bungs. The use of the outer bung only will give less into port, bass reduction. It is recommended that you try the different bung conﬁguration to achieve the most optimal sound output for your environment._









"I need foam for my bunghole"















*Here's why the bungs are important.* All boxes with a port have multiple resonances. That goofy program WinISD won't show you this, but McBean's Hornresp will. All of the programs will show you the low frequency resonance, which is a Helmholtz resonance. *That's the resonance we're all familiar with,* and it's the one we tune with ports when we build a vented box or a bandpass box. But there are a bunch of resonances that are higher in frequency. *These are standing waves.* And the standing waves are actually louder than the Helmholtz resonance!









Standing waves are very powerful. The force of standing waves destroyed the Tacoma Narrows bridge. (I was born there, it's a big ol' bridge, trust me.)

The closed cell foam 'bung' reduces output by about three decibels; but it virtually eliminates the resonances caused by the standing waves. The peak at 800hz is reduced by about 50%, and the peak at 1500hz is reduced by about 100%.


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## rton20s (Feb 14, 2011)

In... just to see where this leads.


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## BigRed (Aug 12, 2007)

How does all this increase depth in the soundstage?


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## Patrick Bateman (Sep 11, 2006)

BigRed said:


> How does all this increase depth in the soundstage?


*You can make the apparent source wherever you'd like.*









For instance, a few years back I had midranges up on my dash. And I used the tiniest midranges possible, because I wanted to push them as far back as I possibly could, so that the soundstage would be wide and deep.

Using a bandpass enclosure for midrange is hardly conventional; in fact I've never seen anyone do it. *But it appears that it's possible.*

In a bandpass box, the apparent source of the sound isn't the loudspeaker box; it's the mouth of the port.









The Kef 105/3 is an excellent example of this. There are two woofers, buried about a foot into the cabinet. But the source of the sound isn't the woofers; it's the port.

This is because the wavelength are much longer than the dimensions of the port. Five hundred hertz is 27" long. So the wave can't even fit in the port. The wave forms at the mouth.

All of this allows for some seriously bizarre loudspeaker enclosures:

1) You could stick your midbasses behind the dash. As long as the exit of the port is against the firewall, and as wide as possible, the sound will emanate as if there was a speaker located where the port exit is.
2) You could get one of those 'thin' subwoofers and use it as a midbass. Put it under the seat, in the center console, wherever. The important thing is where you locate the exit.









Cars with a 'cab forward' design are good candidates for putting mids up on the dash, firing AT the windshield instead of away from it. Plenty of people have bounced tweeters off the windshield, but the process is a bit inexact. These enclosures are very specific though. They'll give you about one to two octaves of sound, and you can put it where you want it.


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## Mic10is (Aug 20, 2007)

just to clarify---Depth is a measurement of the distance from the FRONT of the Stage to the rear of the stage.

Soundstage relative to listening position is how far away the soundstage appears to originate from the listening position


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## SPLEclipse (Aug 17, 2012)

LMAO...that Beavis gif is killing me.

"2) You could get one of those 'thin' subwoofers and use it as a midbass. Put it under the seat, in the center console, wherever. The important thing is where you locate the exit."

I looked into doing this with my midbass. I was going to run them directly behind the drivers seat in the rear passenger footwell and use a port to route the output under the car and have it exit at the firewall. But...logic got the best of me and I went for the easy way out, plus I was worried about resonances from having that long of a port, but I like the idea of using bungs to take care of that. I can't wait until I retire this car as a daily driver. :evil:


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## danno14 (Sep 1, 2009)

you know, if this works, you're going to have to name it "Gertie"!

Tailing along


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## Patrick Bateman (Sep 11, 2006)

Here's a comparison of the frequency response of the sealed 3" woofer, and the bandpass box. The bandpass box has a foam 'bung' in the port to reduce the high frequency standing waves.

This measurements shows the second harmonic distortion; note that push-pull really nukes those harmonics.









To give you an idea of just how good this performance is, take a look at John Krutke's measurement of the Scanspeak 15W8530k00. The Scanspeak is $212; the Dayton is $29. Mounted push-pull, *the second harmonic distortion of the Dayton is lower.* Push pull is a no-brainer.


One other note - the drivers in my bandpass box are wired in series. That's why the output level is about five decibels lower than you'd expect. The 'raw' drivers are four ohm, but once you load them in a bandpass box, the impedance goes up about 50%. Wire them in series and you end up with a load that's about twelve ohms. I'm going to have two cabinets per side, wired in parallel, for a total load of about six ohms.


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## s4k4zulu (Mar 2, 2010)

Subd


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## quietfly (Mar 23, 2011)

in to see where this ends up.....


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## venki7744 (Feb 18, 2014)

Subd..waiting for more Bung


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## Patrick Bateman (Sep 11, 2006)

venki7744 said:


> Subd..waiting for more Bung


Not much left to do, except paint them 

Here's a summary of my findings:

It's well known that you can 'relocate' sound with bandpass subwoofers. For instance, there was a commercial sub in the 90s that put the enclosure in the trunk and connected it to the cabin via a tube.

It wasn't clear to me how high in frequency you can go. Can you do a bandpass that goes to 250hz? To 500hz? To 2000hz? *The answer was unknown.*

It appears that the answer is YES.

The limiting factor is the standing wave. A port has multiple resonances. Generally the lowest resonance is the Helmholtz resonance. That's the resonance that we're 'tuning' when we adjust the size of the port. But there are resonances higher in frequency : the standing waves.

















This simulation, and this measurement, show both resonances. The helmholtz occurs at 267hz, and the first standing wave at 986hz.

Normally, that standing wave might make this box semi-unlistenable. It's like having a distortion that's actually louder than the fundamental. Not good.









A little piece of foam - about 2" x 1.5" - is placed into the port. Similar to what Kef does in their LS50.

That little piece of foam lowers the efficiency a bit, but it knocks down the standing wave by nearly 50%. I tried using larger pieces of foam, and it IS possible to reduce the peak entirely. I settled on a 2" piece as it's a compromise between efficiency and smoothness.



And that's about all there is to it! The rest is just standard bandpass subwoofer theory, and the calculator at carstereo.com crunches the numbers nicely. (Car Audio - BANDPASS SUBWOOFER Box Design Using Gain (Fourth-Order))


Note that you can only get about 1-2 octaves out of the device. To go high in frequency, you'll need a driver with a high FS and a low QTS.









With something like a Faital 3FE20 or a Fostex I could reach 800hz, but I'd also have a higher F3.


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## Patrick Bateman (Sep 11, 2006)

Oh, a couple more things:










1) The foam bung should work on *all* types of boxes with a port. Bandapss, vented, etc. It should even work in horns; in fact I tried it using the reticulated foam that Geddes puts in his waveguides. I switched to closed cell foam over reticulated foam because the effect of the reticulated foam was too subtle. (Reticulated foam would probably work fine if you filled up the entire volume of the port. Basically you just need less when you use closed cell foam.)

2) One concern I had was distortion. That's why I did a bunch of distortion measurements, both THD and of the individual harmonics. I used fiberglass to stuff the ports on another project, *and the distortion went up significantly.* This did NOT occur with closed cell foam. (Check out the measurements I posted in this thread.)

So it looks like the foam has to restrict the air to a certain degree, but if you get carried away, distortion will go up. So reticulated foam doesn't increase distortion, and closed cell foam doesn't increase distortion, as long as you don't use a lot. In my experiments, fiberglass DID increase distortion, so I'd stay away from that.


One could use the foam to make a box that lives in a bit of a grey area between a vented alignment and a sealed alignment. It wouldn't be as efficient as a vented box, or as inefficient as a sealed box. It wouldn't roll off as quickly as a vented box, or as slowly as a sealed box. It would live in the middle. And, obviously, you could pull out the foam if you wanted to blast out the SPL.


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## venki7744 (Feb 18, 2014)

Thanks Patrick for the detailed explanation, so theoretically if I could manage 2 6.5" (or may be even smaller) midbass speakers in BP Isobaric configuration, I could easily fit these in my kicker panels considering here in India we have RHD cars which is almost always Manual making it almost impossible to place the midbass in the the kicker panel area...until now . 
However I still have one question that is..wont the BP box by itself change the phase causing it to lag the tweets and mids. Can you share your experience on how well it gelled with the other components.

Cheers,
Venki


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## Patrick Bateman (Sep 11, 2006)

venki7744 said:


> Thanks Patrick for the detailed explanation, so theoretically if I could manage 2 6.5" (or may be even smaller) midbass speakers in BP Isobaric configuration, I could easily fit these in my kicker panels considering here in India we have RHD cars which is almost always Manual making it almost impossible to place the midbass in the the kicker panel area...until now .
> However I still have one question that is..wont the BP box by itself change the phase causing it to lag the tweets and mids. Can you share your experience on how well it gelled with the other components.
> 
> Cheers,
> Venki


You just made my day! I wanted to discuss the topic of phase, but I figured that this thread was already a bit confusing and I didn't want to make it worse.

The short answer is that the enclosure basically behaves like a driver with an electronic bandpass filter. So, the phase isn't flat, but it's not supposed to be. Electrical, electronic, and physical bandpass filters change the phase of the driver. Filtering your woofer physically, like a bandpass does, will change the phase. But so will an electronic filter.

In my situation, this is actually a feature, not a defect. For instance, a passive bandpass filter would cost me about $15. Which is quite a bit, for a $29 driver. An active filter is even worse; I'd have to spend $80 for the active crossover and about $100-$200 for two more amp channels.

But I'm not going with a bandpass enclosure because I'm cheap, I'm going with a bandpass enclosure because it lets me hide the woofer enclosure. The fact that I can run without an electronic or passive crossover is icing on the cake. Note that a bandpass box reduces distortion also, while the other crossover types do not.

_Okay, that's the simple answer, here's the complex answer, hope this makes sense:_









Here's the predicted frequency response of two Dayton ND91s in a 0.18 liter sealed box, versus the same two drivers in a 0.36 liter box. Note that this is a TINY amount of air; 0.36 liters of air is about the size of a golfball. To be specific, it's a cube of air that measures 2.8" x 2.8" x 2.8".

The reason that my box looks a lot bigger is that I built it to take some serious punishment, I am running close to a thousand watts to an array of drivers.

In the predicted response, we see that the bandpass box has narrower bandwidth, but a lower F3, and a little bit more output.









Here's the *predicted* phase response of the sealed box and the bandpass box. The phase of the sealed box has some rotation, *but the rotation is slow and gradual.* The phase of the bandpass box rotates much quicker. This is definitely a valid complaint about bandpass boxes. I personally think that one of the reasons that bandpass boxes sound 'slow' is because they're phase response can get pretty ugly.

The trick to make this work is *to keep the bandwidth to a minimum.* For instance, the phase of the bandpass box is actually superior to the sealed box, if you restrict it to just 200hz to 400hz. Basically, the bandpass has flat phase response in it's passband.









Here's the *measured* response of the sealed box (Cambridge) and my bandpass box. In the measured response, *we see that the phase looks a lot better than predicted, for both box types.* The phase of the sealed box is basically ruler flat, from 300hz and up. Sealed boxes have really good phase response. The bandpass box is NOT flat; but it's rotation is less than 90 degrees over the span of two octaves.

A big factor here is going to be the frequency response. Basically the steeper the rolloff, the more the phase is going to rotate. Mating up another driver when the phase is only rotating ninety degrees is a piece of cake; but if you add additional filters into the mix it's going to get trickier.

If you went the opposite way, and flattened out the response with an EQ, the phase would get even flatter.












Here's one more thing to ponder. I have personally been thinking about this next thing for YEARS and one day I hope to wrap my brain around it:

If you look at the phase response of the bandpass woofer, you'll notice that in the two octaves from 400hz to 1600hz, *the phase is nearly flat.* But the response is falling at the same time. If you're clever, you could put another driver one octave above your first driver, *and the two drivers would behave as if they were one.* IE, you would have two drivers, and each driver is covering about one octave, but their phase response would look like the phase response of that sealed box. You would have two bandpass boxes that measured and sounded like a sealed box, but with lower distortion and higher output than a sealed box. I'll bet Jason knows where I'm going with this idea...


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## cajunner (Apr 13, 2007)

when you can mesh this bandpass re-location with the Unity design and get 250 hz out of ID full bodies using a PVC connecting pipe and hide your bandpass boxes under the center console, that would be pretty cool...

what, 2 ND91's per side, about 25 bucks in PVC plumbing, and getting 105 db @ 1watt from 250 hz to 18K, maybe it's a pipe dream?


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## quietfly (Mar 23, 2011)

cajunner said:


> when you can mesh this bandpass re-location with the Unity design and get 250 hz out of ID full bodies using a PVC connecting pipe and hide your bandpass boxes under the center console, that would be pretty cool...
> 
> what, 2 ND91's per side, about 25 bucks in PVC plumbing, and getting 105 db @ 1watt from 250 hz to 18K, maybe it's a pipe dream?


That was pretty punny....:laugh:


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## Patrick Bateman (Sep 11, 2006)

cajunner said:


> when you can mesh this bandpass re-location with the Unity design and get 250 hz out of ID full bodies using a PVC connecting pipe and hide your bandpass boxes under the center console, that would be pretty cool...
> 
> what, 2 ND91's per side, about 25 bucks in PVC plumbing, and getting 105 db @ 1watt from 250 hz to 18K, maybe it's a pipe dream?


Actually that's exactly what I'm doing.









In a Danley SH-25, the woofers sit about 24" forward of the tweeter. The midranges sit about 8" forward of the tweeter.

Part of the 'secret sauce' is that the mids and the woofers are in bandpass enclosures. The bandpass inserts a delay. *That's why Danley can get flat phase response, with the woofers nearly two feet in front of the tweeter.*










Here's the bandpass box in my car. About two feet in front of the tweeter


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## cajunner (Apr 13, 2007)

Patrick Bateman said:


> Actually that's exactly what I'm doing.
> 
> p://img100.imageshack.us/img100/5610/dssynergy25vi9.jpg[/img]
> In a Danley SH-25, the woofers sit about 24" forward of the tweeter. The midranges sit about 8" forward of the tweeter.
> ...


would you say that the larger the Le of the driver, the more it acts like a low pass filter, and that filter also creates a time delay that is phase-dependent?

and how does this work?

Linkwitz uses analog electronic all-pass to move his tweeter in the Pluto, to the same acoustic center or point source, as the omni midrange.

is this basically the same thing, but you're now having to either correct for, or benefit from the delay added with bandpass acoustic filtering, and that additional delay that is also frequency dependent?

like, does one cancel the other, can you add delay that rises with the time-shifting variable of a band-pass, using a variable delay design, because most time delay is static, or only works in the time domain and doesn't adjust for frequency and wavelength, or bandpass filter scenarios.


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## cajunner (Apr 13, 2007)

quietfly said:


> That was pretty punny....:laugh:


you don't want to know what I was going to say about that bandpass box, looking like a sump pump in a bung-hole filled world...


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## venki7744 (Feb 18, 2014)

Patrick Bateman said:


> Actually that's exactly what I'm doing.
> 
> 
> 
> ...


Few questions more from my end 

* How did you calculate the delay to align it 2' from the tweeter
* Based on the pic it looks like the sound is going to get reflected off the door pads before hitting the listener, doesn't this add more delay and early reflections as well.

Thanks,
Venki


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## Patrick Bateman (Sep 11, 2006)

venki7744 said:


> Few questions more from my end
> 
> * How did you calculate the delay to align it 2' from the tweeter
> * Based on the pic it looks like the sound is going to get reflected off the door pads before hitting the listener, doesn't this add more delay and early reflections as well.
> ...


Here's how you do it:

1) simulate the high frequency driver in hornresp
2) simulate the midrange driver in hornresp
3) Take a look at the group delay curve of the two drivers

Generally, as you go lower in frequency, *the group delay gets longer and longer.*

The net effect is that you generally want the tweeters as far from you as possible, because they have very little group delay. As frequencies get lower, it's possible to put the drivers close to you without completely wrecking the phase response.

We know this intuitively. Would you rather have your subwoofer close to your seat, or your tweeters? Which drivers will reveal their locations first?









Here's the predicted group delay of the enclosure. In the two octaves between 150 and 600hz, the delay is about two milliseconds, or 27".

I need to post some of the measurements I did this afternoon. I was able to get a Aurasound Whisper and this bandpass enclosure to 'blend' together by manipulating the gap between the drivers. When all was said and done, I got fairly flat response by putting the bandpass enclosure about 6" ahead of the Whisper. (In my car I'm using a lower xover, which is why I can get away with a 2' gap.)


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## quietfly (Mar 23, 2011)

cajunner said:


> you don't want to know what I was going to say about that bandpass box, looking like a sump pump in a bung-hole filled world...


That was more in line with what i was expecting....


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## req (Aug 4, 2007)

yeah i have been talking about doing something like this for a while pat.

the big question is, how does it sound in your car. not measurements, but application?


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## cajunner (Apr 13, 2007)

quietfly said:


> That was more in line with what i was expecting....


when a thread is already filled with semi-rigid filling of bunghole mass, I don't know if adding on is the right thing to do...



but seriously, it's nice that this concept comes around again.

I had the same ideas back in oh.. 2008, maybe?

If someone could easily explain the way an all-pass shifts phase as well as time, so that you could match the response pattern to null either an inductance of the coil that causes rotation, or the delay inherent in a well-devised bandpass, then it is assumed possible to use analog methods to create a time-coherent, phase-coherent, system in the car, using easy, or more likely, odd speaker locations and time-alignment for just left/right concerns.

Knowing how to do this, is a problem. I just don't have the math or the brain it appears, and/or the schooling, I have to be shown what to do, or how to build the circuit and then I'd have to be shown a measurement of the work, so I can believe that it indeed, is actually true, and a working model.

Someone who is familiar with how speakers tend, or trend, like say a 4" midrange with .4 mH of Le, should rotate the phase about 40 degrees starting from 60 hz and crossing the plane at 2400 hz, then...

see, I just don't get all the various parts of the equation. One might say I don't get any of it, but I believe that this all ties together, I think it may be psychosomatic in that general way, or genetic, who knows...


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## Patrick Bateman (Sep 11, 2006)

cajunner said:


> when a thread is already filled with semi-rigid filling of bunghole mass, I don't know if adding on is the right thing to do...
> 
> 
> 
> ...


Here is how it works:









When you have a loudspeaker in a sealed box with flat response, *it's phase is flat.* Companies like Dunlavy use that fact to create big speakers like this that basically act like one large full range driver. The Dunlavy SC-IV behaves like a six foot tall full range driver with response from 20hz to 20khz.









Here is a measurement of my bandpass and a cheap Cambridge Sound Works computer speaker. *See how the phase of the CSW is flat from 400hz and up?*

That's what guys like Dunlavy are taking advantage of. Put a speaker in a sealed box, limit the speaker to the frequencies that it's flat, and you get flat phase.

If you look at the measurement of the CSW, you'll see that the phase begins to rotate. As we go from 500hz to 250hz, it rotates ninety degrees. What Dunlavy does is that he 'hands off' to the next driver in the array when this happens. So a 5" woofer might 'hand off' to a 10" woofer at the point where the phase starts to rotate.

Now, you might wonder, *won't that phase rotation cause a problem?* Here's the key: the phase rotation at the LOW end of the midrange driver is exactly the same as the phase rotation at the HIGH end of the 10" driver. If that wasn't the case, this wouldn't work. For instance, if you tried to hand off from that 5" woofer to a 10" woofer that was playing up to 1khz, *the handoff wouldn't work.* This is because the FLAT response of the 10" woofer would mean that it's phase is flat, and we WANT the phase to be ninety degrees out of phase at the crossover point. The 90 degree rotation of the midrange matches up with the 90 degree rotation of the woofer, and the two sum as if they are one large woofer.

This works to infinity. If you wanted to, you could go tweeter-midrange-midbass-woofer-subwoofer. Dunlavy's biggest were tweeter-midrange-woofer.

So far, so good?

By the way, this exact same methodology is used by a bunch of the big names.









All the Thiel speakers work like this









Dynaudio does this too









And so does Vandersteens. (This is what I am listening to right now.)









If you wanted to do the same thing in the car, you would use locations that looks like this. In the pic above, we have a woofer-midbass-midrange-tweeter-midrange-midbass-woofer array.

The curvature is required to time align everything. Basically every loudspeaker must be equidistant from your head.

Dynaudio doesn't do this; you can see that if you look at the step response of their loudspeakers versus their competitors. It's good, but Dunlavy and Vandersteen are better. To my ears, it makes a difference. I heard Dynaudio back-to-back with Vandersteen in 2013, and that's why I bought a pair of Vandersteens. Dynaudio was good, but Vandersteen was noticeably better in the imaging department.



Sorry that was so long winded. In summary, here's how you do it:
1) Only use drivers in a range that they're flat. How you get to flat doesn't matter, they could be flat out of the box, or flat after EQ. But they have to be flat.
2) When their response starts to fall off, the phase will rotate. At that point, 'hand off' to the next driver in the array.
3) To get a really epic step response and the epic imaging that goes along with it, you're going to have to make all of the drivers equidistant from the listener.


The Danley Synergy horns work on a similar principle, but with a twist, due to the 'bandpass' nature of each driver. I'll get to that.


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## jdsoldger (Feb 14, 2012)

Forgive my newbness, but just a quick question. "Aligning" the the drivers using a time delay and aligning them physically (within reason, I am not talking one driver behind you and one in front, just drivers within say 2ft of each other or so) would amount to the same thing, right? So you could acheive the handing off of the phase with the drivers not mounted perfectly physically?

I am thinking along the lines of having the tubes from the bandpass box poking up from the dashboard, and the tweeters mounted near them and then using digital time alignment to get the phase handoff right?

Also, I love my Vandersteen 2ci, I have yet to listen to a speaker that would make me want to switch.


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## sqnut (Dec 24, 2009)

I find that people who are really picky about phase coherence love Vandys and yes not too many speakers image like them. I have heard the 2ce pictured above and they had incredible imaging. My issue was with tonality. I found them a bit dark and laid back in the mid range even more so than the dyns.


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## jdsoldger (Feb 14, 2012)

sqnut said:


> I find that people who are really picky about phase coherence love Vandys and yes not too many speakers image like them. I have heard the 2ce pictured above and they had incredible imaging. My issue was with tonality. I found them a bit dark and laid back in the mid range even more so than the dyns.


That is the other reason I really like them. I find most speakers far to bright for my likeing, and a lot substitute brightness for detail. They seem detailed, but it is all the tweeters, the Vandies are very detailed with no brightness at all. I have been fighting with my car system to get the brightness down and detail up. Even the HAT Mirus I put in my Miata recently (second car, just a simple set up for that one) I end up with the trebble on the head unit turned down to -8 out of 10 (whatever that works out too, need to measure sometime).


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## sqnut (Dec 24, 2009)

jdsoldger said:


> That is the other reason I really like them. I find most speakers far to bright for my likeing, and a lot substitute brightness for detail. They seem detailed, but it is all the tweeters, the Vandies are very detailed with no brightness at all. I have been fighting with my car system to get the brightness down and detail up. Even the HAT Mirus I put in my Miata recently (second car, just a simple set up for that one) I end up with the trebble on the head unit turned down to -8 out of 10 (whatever that works out too, need to measure sometime).


I hate bright speakers as well. The speakers I have heard from Klipsch, B&W, Focal, Paradigm, BA etc were all on the brighter side. Wilson is my benchmark for clear transparent sound but since they cost the earth, I settled for my scans .


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## cajunner (Apr 13, 2007)

Patrick Bateman said:


> Here is how it works:
> 
> Sorry that was so long winded. In summary, here's how you do it:
> 1) Only use drivers in a range that they're flat. How you get to flat doesn't matter, they could be flat out of the box, or flat after EQ. But they have to be flat.
> ...


crazy good post, Patrick.

this is advantage in 2-channel home audio, no doubt about it.

I see what bikinpunk is doing with his HT and it looks like Thiel flagship, circa 2008.

I understand the concept of this now without adding any crossover elements into the phase, and I wonder if that is going to be why the 1st order crossover networks these "phase-happy" designers put into the speakers, are so complex?

we still haven't entertained the delay of a large Le driver, with it's roll-off doesn't it also contribute to the phase rotation?

maybe instead of handing off at 90 degrees, the designers add in the roughly 45 degrees of a capacitor or coil, making a 135 degree, to 135 degree match-up?

I'm very happy to see that it is possible within a 3 way set-up, to get near perfect phase, or what? within 20 degrees from 50 hz to 15 Khz?

that would be all right by me?

so sourcing these special drivers that stay flat from near beaming down to almost resonance, or whatever, is it that difficult, or would just throwing one more driver into the mix going 4 way, do the trick with most off-the-shelf product out there in the Vifa PL line, or Peerless/Dayton price range?

and how does your little one-octave of band-pass low-mids, fit into a 3 way scheme without issue?

seems like your arc of drivers are about perfect save for that one little region that sits on top of the Schroeder frequency, maybe the nature of the bandpass can be utilized in corner-loading schemes, to retain the dynamics of the frequency region without causing issues with location?


this is promising on paper, anyway...


----------



## Patrick Bateman (Sep 11, 2006)

In my last post, I said I'd try to explain how the bandpass boxes change the phase situation.

Tom Danley doesn't post to this forum, but he does post to diyaudio, so I posted the info over there, in the event that he gives us a few hints. Here's the post:

Understanding Synergy Horn Phase - diyAudio


----------



## Patrick Bateman (Sep 11, 2006)

jdsoldger said:


> Forgive my newbness, but just a quick question. "Aligning" the the drivers using a time delay and aligning them physically (within reason, I am not talking one driver behind you and one in front, just drivers within say 2ft of each other or so) would amount to the same thing, right? So you could acheive the handing off of the phase with the drivers not mounted perfectly physically?
> 
> I am thinking along the lines of having the tubes from the bandpass box poking up from the dashboard, and the tweeters mounted near them and then using digital time alignment to get the phase handoff right?
> 
> Also, I love my Vandersteen 2ci, I have yet to listen to a speaker that would make me want to switch.


Unless I am missing something (and I may be), it would be theoretically "more perfect" to have the midrange and the tweeter very close together, and use DSP delay to line them up.









The driver overlap on speakers like Dynaudio and Vandersteen and Dunlavy is very very high. For instance, in this Stereophile measurement of the Dynaudio Evidence Temptation, the midrange is only 10dB louder than the woofer at 500hz. And at 70hz, the midrange is only 10db quieter than the woofer.









And this speaker is nearly eight feet tall!

The net effect of this is that sound from the Dynaudio just sound BIG.









The big speakers from Wilson and Focal don't do this. Because they use high order slopes, there isn't a hint of midrange coming from the woofer. At five hundred hertz, the output of the Focal woofer will be virtually nil, as much as sixty decibels down. When you hear midrange on a Focal, you're hearing the midrange driver only. On a Dynaudio or a Dunlavy, you're hearing a combination of multiple drivers, due to the shallow slopes.


Again, a lot of this is going to depend on personal taster. Personally, I was floored by the Dynaudio. It had dynamics like my Gedlee Summa, but the soundstage was just huge, like twenty feet wide and as tall as the room. But the thing that really grabbed me was that it had the articulation and intelligibility I've come to love from Synergy horns.


All of this comes at a cost : you have to sit in the sweet spot. If you stand up or crouch down, the imaging is gone. (They still sound pretty good, they just don't image as well.)

So it's basically a choice of whether you can live with a speaker that only images like a champ in one sweet spot, or a speaker that can't quite image as well, but can do it in a wide area (like the Focal and the Wilsons.)


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## UNBROKEN (Sep 25, 2009)

So theory and measurements aside...how does it sound in the car?


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## Patrick Bateman (Sep 11, 2006)

UNBROKEN said:


> So theory and measurements aside...how does it sound in the car?


Dunno. I have two Synergy Horns that are about 40% complete, a horn loaded sub that's about 75% complete, a bandpass midbass that's about 75% finished and one more that's about 25% complete.

The plan is to demo this at the show in Riverside in May.


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## UNBROKEN (Sep 25, 2009)

Awesome....I plan to be there. 
Your location saying Manhattan....do you mean Beach?


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## Patrick Bateman (Sep 11, 2006)

UNBROKEN said:


> Awesome....I plan to be there.
> Your location saying Manhattan....do you mean Beach?


The location is a goof. I actually live in San Diego.


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## HondAudio (Oct 19, 2006)

Oh Patrick, you so crazy


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## Patrick Bateman (Sep 11, 2006)

HondAudio said:


> Oh Patrick, you so crazy


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## Zippy (Jul 21, 2013)

I really enjoy reading your posts Patrick. I'm curious what your thoughts are on combining this new found spacial displacement with the OPSODIS setup to get your mid bass outside the vehicle for a more centered sound stage?


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## Patrick Bateman (Sep 11, 2006)

Zippy said:


> I really enjoy reading your posts Patrick. I'm curious what your thoughts are on combining this new found spacial displacement with the OPSODIS setup to get your mid bass outside the vehicle for a more centered sound stage?


Thanks!

The bandpass enclosure described in this thread inserts about 2-3 milliseconds of delay. That works out to about two to three feet. (One millisecond is 13.5")

So, yes, this works nice for Opsodis. With the midbasses to your left and to your right, the angle is right, but the delay is wrong. (Because they're too close.) The delay thats inserted by the bandpass tuning offsets the fact that the locations that are too close.

I posted a thread at diyaudio using these same ideas to figure out how it would work in a three way setup. (Understanding Synergy Horn Phase - diyAudio)

I also did some sims with dual reflex boxes, but that REALLY made my head want to explode. With a dual reflex box you're basically juggling two delays, one for the front of the woofer, and one for the back.

Ported boxes do the same thing, but in a ported box the time difference is much much larger than in a dual reflex bandpass.

If you juggled the length of the ports of a dual reflex it looks like you could get close to flat group delay in it's passband. But it's hideously complex because there's two tuning frequencies, and your crossover filter adds delay too. AND all of that is frequency dependent :O :O

Long story short, flattening the group delay of a dual reflex bandpass is best left to rocket scientists. Then again, Tom Danley DID work for NASA.


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## Hanatsu (Nov 9, 2010)

I will do some experiments with dual reflex BP (6th order). I've been wondering if you actually can archive flat GD, high efficiency and low distortion. With some processing and enclosure experimentation it might be possible... I'm always up for crazy ideas lol.


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## hakmazter (Jul 19, 2013)

I think you are grasping at straws when you are looking at these home speakers. The whole point of what they are doing is aligning the voice coils of the speakers to be equidistant from the listeners ear. If you put the tweeter on the exact same plane as a mid and a woofer, the tweeter response time will arrive at your ears slightly faster than the mid(s) and especially the sub(s).

This is true time correction from a mechanical standpoint coming from the hypothesis that the sound originates from the coil and radiates out. Considering the speed of sound is somewhat slow, it is noticeable and that is why the $$$ manufacturers do it.


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## Patrick Bateman (Sep 11, 2006)

hakmazter said:


> I think you are grasping at straws when you are looking at these home speakers. The whole point of what they are doing is aligning the voice coils of the speakers to be equidistant from the listeners ear. If you put the tweeter on the exact same plane as a mid and a woofer, the tweeter response time will arrive at your ears slightly faster than the mid(s) and especially the sub(s).
> 
> This is true time correction from a mechanical standpoint coming from the hypothesis that the sound originates from the coil and radiates out. Considering the speed of sound is somewhat slow, it is noticeable and that is why the $$$ manufacturers do it.


True. In a sealed box.
Not true in a bandpass box. A bandpass box has group delay that's 2-10x higher than a sealed box, depending on the tuning frequency and the port length.

Also, with first order filters, which I like to use, offset can make quite a difference in response. I've seen dips that were six decibels deep and half an octave wide disappear completely when I moved the drivers by an inch and a half. This is because the two drivers have a great deal of overlap, so if they're 180 degrees out of phase you'll get quite a null.


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## HondAudio (Oct 19, 2006)

Patrick Bateman said:


> Here's my oddball solution that I designed for my Mazda6.
> 
> The enclosure is basically a miniaturized version of the cabinet of a Kef 107/2. The Kef 105/3 also used a similar setup. There are two woofers in the cabinet. One pushes, one pulls, and all the air exits out of the port. Basically a push-pull bandpass box.
> 
> [/font]


Do you have some other pictures of your enclosure? Maybe an assembly diagram? Is that MDF fiberglassed to PVC pipe?


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## Patrick Bateman (Sep 11, 2006)

HondAudio said:


> Do you have some other pictures of your enclosure? Maybe an assembly diagram? Is that MDF fiberglassed to PVC pipe?


An illustration would help a lot.

Here's how it's set up:

1) There are three chambers
2) The middle chamber has a port
3) The left and the right are sealed
4) The woofer in one chamber is inverted. It's polarity is also inverted. This reduces second harmonic distortion for both drivers.

So a diagram would look like this:

sealed chamber -> woofer -> vented chamber -> woofer -> sealed chamber

It doesn't look like much, but it was actually very time consuming to build. This is because it's basically a miniature subwoofer. So it's like building a sub, only slower, because the tolerances are tight.

If I was going to change anything, I would make it out of PVC end caps and "tees". This would make everything go a lot faster. Drilling the hole in the center piece of the enclosure took about an hour! I had to cut it with a dremel because a hole saw doesn't work well when you're drilling into a curved surface. A PVC "tee" would solve all of that.

Another thing I did that made it slow to build is that the woofers are bolted to MDF plates. I could have glued the woofers to the enclosure, and that would be a heck of a lot faster. But by using bolts and an MDF plate, I can take it apart later if I don't like it.

If someone built this using PVC tees, PVC end caps, and epoxy, it would come together in about an hour. The downside is that the woofers would be permanently bonded to the enclosure, so you better be committed to it


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## darrenforeal (Jan 14, 2011)

hope to see/hear this sat...


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## sprocketser (Apr 18, 2014)

Your work s great mate . Keep it on . Lots of stuff to learn here .


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## FLYONWALL9 (Nov 8, 2009)

This is fascinating... 

In the late 80's to early 90's when I first started doing compititions 
and moved up into the higher classes, I quickly discovered that my 
extreme low budget system would not give me the image judges 
expected in that class car. So, I tried everything I could do get that 
wide image with placement. I could get it closer but it seemed the 
judges were not happy with just a pillar to pillar wide stage. Near 
impossible in a CRX until I heard the Sony XES demo car and saw 
where they placed various speakers. I became obsessed with TA, 
it seemed to be my answer. In the end it did solve my issues. 

I still have a very small car, but your solutions are enthralling. I 
would love to hear the vehicle once your finished, so, if you make 
your way to the Alabama Coast, or panhandle of Florida do send a PM. 

I'm wondering if you have ever made or played around with making 
a waveguide/horn with say a 4" component, in a kick panel? If it gave 
a better image than the standard volcano style panel?

Cheers,
Scott


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## captainobvious (Mar 11, 2006)

Patrick-

Interesting work. What consideration has to be taken with regard to port diameter size and relation to the size of the driver being used? Does it also hinge on the passband? I remember also reading about where a speaker was "relocated" to a different area and then a port cylinder was attached to the front of the enclosure over the driver, allowing the port end (wherever it was located) to be the point where the sound would emanate from. 

In your experiment here, does the port diameter limit the frequency response range propagating from the port mouth? Are you simply tuning for maximum spl for the given driver over the intended 2 octave passband, irrelevant of the port diameter? 


Thanks, interesting stuff.


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## Patrick Bateman (Sep 11, 2006)

captainobvious said:


> Patrick-
> 
> Interesting work. What consideration has to be taken with regard to port diameter size and relation to the size of the driver being used? Does it also hinge on the passband? I remember also reading about where a speaker was "relocated" to a different area and then a port cylinder was attached to the front of the enclosure over the driver, allowing the port end (wherever it was located) to be the point where the sound would emanate from.
> 
> ...


Thanks!

These boxes are simply bandpass boxes, so all the regular rules apply.










When we hear the phrase "bandpass box" we usually picture something that's the size of a large suitcase, but there's nothing stopping you from putting a 3" woofer in a bandpass. Which is what I did.


It allows you to put speakers in some weird locations, like under the seat. In this application, a bandpass has some advantages over a plain ol' sealed box:

1) bandpass boxes have lower harmonic distortion than sealed boxes, generally
2) bandpass boxes can have higher efficiency than sealed boxes

Basically if you're careful, a bandpass box can deliver the output of a larger driver in a sealed box.


Having said all that, a shallow 6" in a sealed box would work about as well 

I like to take the road less travelled


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## Patrick Bateman (Sep 11, 2006)

It looks like Alpine patented something like this:

US6868937B2

_"A sub-woofer system with a flat horn for use in a vehicle which is capable of achieving an improved sound reproducing performance as well as an excellent space factor by mounting the horn on the floor of the vehicle. The sub-woofer system includes a flat horn having a proximal end and a distal end where the proximal end is connected to a drive unit. The flat horn has a rectangular cross-section and is substantially uniform in thickness throughout while gradually increases in width toward the distal end. The drive unit is positioned under a front seat of the vehicle and the flat horn is placed on a floor of the vehicle, and wherein an end opening of the flat horn at the distal end thereof is positioned close to an inner front wall of the vehicle so that at least a part of the distal end contacts with the front wall."_


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## Elgrosso (Jun 15, 2013)

Patrick Bateman said:


> It looks like Alpine patented something like this:
> 
> US6868937B2
> 
> _"A sub-woofer system with a flat horn for use in a vehicle which is capable of achieving an improved sound reproducing performance as well as an excellent space factor by mounting the horn on the floor of the vehicle. The sub-woofer system includes a flat horn having a proximal end and a distal end where the proximal end is connected to a drive unit. The flat horn has a rectangular cross-section and is substantially uniform in thickness throughout while gradually increases in width toward the distal end. The drive unit is positioned under a front seat of the vehicle and the flat horn is placed on a floor of the vehicle, and wherein an end opening of the flat horn at the distal end thereof is positioned close to an inner front wall of the vehicle so that at least a part of the distal end contacts with the front wall."_


Awesome! 
Other pics are great to illustrate the horn

























Apparently a brutal change in section in the middle is ok.
And isn’t it strange that they patented this? I mean it must be super hard to define a sellable solution for all variations of cars


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## rton20s (Feb 14, 2011)

Elgrosso said:


> Apparently a brutal change in section in the middle is ok. And isn’t it strange that they patented this? I mean it must be super hard to define a sellable solution for all variations of cars


I don't think it is strange to patent at all. There are tons of patents that get filed that never have any real practical application. It is for protection as much as anything. 

And in my mind, if it functions well, it could easily be a salable solution. Manufacture of the horn wouldn't be much, if any different, than the plastic ducting used for routing air for HVAC throughout the vehicle. It is very common for the ducting to be unique to a specific vehicle.


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## Elgrosso (Jun 15, 2013)

rton20s said:


> I don't think it is strange to patent at all. There are tons of patents that get filed that never have any real practical application. It is for protection as much as anything.


I’m not an expert on these, but don't they have to at least start the production process for this patent to stay applicable? (2002/5 here)




rton20s said:


> And in my mind, if it functions well, it could easily be a salable solution. Manufacture of the horn wouldn't be much, if any different, than the plastic ducting used for routing air for HVAC throughout the vehicle. It is very common for the ducting to be unique to a specific vehicle.


Makes sense, but these pieces are sold by the millions with the cars.
Here it would still be a lot of effort for a small target probably.
(see the regular mid-range car horn market).


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## rton20s (Feb 14, 2011)

Elgrosso said:


> I’m not an expert on these, but don't they have to at least start the production process for this patent to stay applicable? (2002/5 here)


I'm not an expert either. But I am sure there are thousands, if not millions of patents that never get anywhere near production. There are even companies that develop/purchase patents just to make money from other companies through licensing deals and law suits.



Elgrosso said:


> Makes sense, but these pieces are sold by the millions with the cars.
> Here it would still be a lot of effort for a small target probably.
> (see the regular mid-range car horn market).


I am sure Alpine patented this in their role as an OE supplier for auto makers. I doubt it had anything to do with their aftermarket division. Similar to what we've seen with a ton of the Harman patents.


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## Patrick Bateman (Sep 11, 2006)

Elgrosso said:


> Apparently a brutal change in section in the middle is ok.
> And isn’t it strange that they patented this? I mean it must be super hard to define a sellable solution for all variations of cars


Oddly enough, "hard" bends seem to work better than "moderate" bends in a horn or transmission line. To get flat response you want all of the pathlengths to be equal. If you use verrrry gradual bends, you can do that. (This is why snail-shaped horns work.) But a "hard" 90 degree bend works too.

Unfortunately, sharp bends can generate obnoxious diffraction.


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## mitchyz250f (May 14, 2005)

Patrick couldn't this be called 'how to make your sound stage wider' if the horn exit was between the door and the seat and right below you head? Similar to what you wrote about in this thread:

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


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## Elgrosso (Jun 15, 2013)

Patrick did you ever try something like that? (car or home)
They describe something that is half open and use the floor/carpet as one side panel of the horn. Seems really strange to me, if not solidly fixed it must be quite hard to avoid leakings all the way up to the mouth.
Also what kind of driver size do you think they had in mind? With this lenght it must be a 6 or 8" max no?


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## Orion525iT (Mar 6, 2011)

mitchyz250f said:


> Patrick couldn't this be called 'how to make your sound stage wider' if the horn exit was between the door and the seat and right below you head? Similar to what you wrote about in this thread:
> 
> http://www.diymobileaudio.com/forum...ussion/150134-crazy-imaging-stock-system.html


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## Elgrosso (Jun 15, 2013)

Orion525iT said:


>


Wow really cool! I think I missed this thread: http://www.diymobileaudio.com/forum/4290346-post75.html

How is the final result?


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## Orion525iT (Mar 6, 2011)

Elgrosso said:


> Wow really cool! I think I missed this thread: http://www.diymobileaudio.com/forum/4290346-post75.html
> 
> How is the final result?


Don't know yet. Construction has been a pain in the ass, but getting there.


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## Elgrosso (Jun 15, 2013)

I can imagine!
Next step is to fit a shallow 10 in here?


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## Elgrosso (Jun 15, 2013)

Look at that: 

TS-WX70DA - <b>NEW!</b> - Compact Powered Subwoofer | Pioneer Electronics USA




























TS-WX70DA

I have no idea if this is old news, but seems interesting.
It's a bit confusing between the TS-WX70DA or the TS-WX710A
Two versions or just two code names for US/JP?


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## DC/Hertz (Nov 27, 2011)

It's just a transmission line


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## Elgrosso (Jun 15, 2013)

DC/Hertz said:


> It's just a transmission line


Yeah just, like it happens all the time!
(looks more like a back loaded horn but I’ll let the experts talk)


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## DC/Hertz (Nov 27, 2011)

Is the sub firing out the bottom?


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## Elgrosso (Jun 15, 2013)

DC/Hertz said:


> Is the sub firing out the bottom?


Not sure, it’s not super clear, maybe the bottom left mouth on the first & third pic?


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## DC/Hertz (Nov 27, 2011)

I can't tell. Either way it is different and not a bad use of space. 
You do see a lot more T lines these days


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## rton20s (Feb 14, 2011)

They had it at CES 2017. I believe there are a couple of Youtube videos about it. 

https://www.youtube.com/watch?v=JX_Rii8g1S0&index=29&list=PLxoBfIbvFUYUp275BYI8AIGXHvUQe2vUW


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## Jheitt142 (Dec 7, 2011)

Sooooo back loaded horn with 2 6" woofers. Hmmmm I can build that for nearly free.. I may have to try one for the gfs car 

Sent from my SM-G930W8 using Tapatalk


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## Focused4door (Aug 15, 2015)

DC/Hertz said:


> I can't tell. Either way it is different and not a bad use of space.
> You do see a lot more T lines these days


It is interesting and lots of appeal for those that don't DIY, but seems like anyone on this site could make a T-line that custom fits the space and for less money. 

You could get a shallow mount 12" sub in that much thickness and volume though. With more power handling and likely higher driver efficiency as well.

Seems far more interesting as a midbass concept than a subwoofer, assuming you could get a midbass T-line to exit where you wanted,

So far simulating bandpass midbass I have yet to come up with something that I think is worth building.


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## Elgrosso (Jun 15, 2013)

So apparently the TS-WX710A went out in 2013, and the TS-WX70DA just came out.

old:









new:









They changed a bit the folding layout but both are back loaded horns:









But honestly I’m note sure of the difference here, is it just about length/mouth size proportion and related box tuning?





Focused4door said:


> It is interesting and lots of appeal for those that don't DIY, but seems like anyone on this site could make a T-line that custom fits the space and for less money.
> 
> You could get a shallow mount 12" sub in that much thickness and volume though. With more power handling and likely higher driver efficiency as well.
> 
> ...


Yes it’s cool that they work on more exotic stuff like that. Also it can be found for not that expensive online. I almost want to try but I’ll wait for the first reviews.
As you said, more used as midbass since it’s good up to 250Hz, 2 could be cool under front seats if they fit.

For the shallow 12", won't it need a much bigger volume?


----------



## Patrick Bateman (Sep 11, 2006)

I've built transmission lines, tapped horns, sealed boxes, front loaded horns, back loaded horns, bandpass boxes and vented boxes.

Hoffman's Iron Law still rules the day. The main advantage of the Pioneer box pictured above is that it's height is very very low. Basically they're using a horn to raise the efficiency of a pair of sixes so that their output is competitive with a ten or a twelve. But the twelve will still offer more output, due to higher displacement, due to higher SD and xmax.

But if you wanted to make a low profile subwoofer that doesn't cost too much, this would be an interesting option.


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## Elgrosso (Jun 15, 2013)

Patrick Bateman said:


> I've built transmission lines, tapped horns, sealed boxes, front loaded horns, back loaded horns, bandpass boxes and vented boxes.
> 
> Hoffman's Iron Law still rules the day. The main advantage of the Pioneer box pictured above is that it's height is very very low. Basically they're using a horn to raise the efficiency of a pair of sixes so that their output is competitive with a ten or a twelve. But the twelve will still offer more output, due to higher displacement, due to higher SD and xmax.
> 
> But if you wanted to make a low profile subwoofer that doesn't cost too much, this would be an interesting option.


Thanks Patrick, 
So you mean a 12*in this configuration (volume/size) could still work and give more output than 2x6, or can a too big woofer be detrimental here? 

By the way I found more, also a carrozzeria version (probably just esthetic): 










carrozzeria | ????????????TS-WX77A

and even Alpine did the same thing:










ãƒ‘ãƒ¯ãƒ¼ãƒ‰ã‚µãƒ–ã‚¦ãƒ¼ãƒ•ã‚¡ãƒ¼(å°‚ç”¨ã‚³ãƒ³ãƒˆãƒ*ãƒ¼ãƒ©ãƒ¼/å°�åž‹ã‚¢ãƒ³ãƒ—ä»˜å±ž) ã€�SWE-2200ã€‘ï½œALPINE Japan

Less details here, not even sure it's a horn, and 2x8"

Must be a trend for small vehicles in Japan


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## 92blacktt (Dec 18, 2008)

I had a 10" carrozeria powered subwoofer in my toyota soarer that I imported from japan. The output was good, and had the same low profile as the dual 6" powered subwoofer. If the output is the same, what is the point of the loaded horn? Can just use a 10"...


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## Elgrosso (Jun 15, 2013)

92blacktt said:


> I had a 10" carrozeria powered subwoofer in my toyota soarer that I imported from japan. The output was good, and had the same low profile as the dual 6" powered subwoofer. If the output is the same, what is the point of the loaded horn? Can just use a 10"...


This one? ƒpƒ��[ƒhƒTƒuƒE�[ƒtƒ@�[ - TS-WX99A

(500w/100db/ported 10 apparently)

I would imagine that, after the volume/shape advantage, efficiency and low power requirement of the horn can be interesting.


----------



## Patrick Bateman (Sep 11, 2006)

Elgrosso said:


> Thanks Patrick,
> So you mean a 12*in this configuration (volume/size) could still work and give more output than 2x6, or can a too big woofer be detrimental here?
> 
> By the way I found more, also a carrozzeria version (probably just esthetic):
> ...


Back in the day, the owner of Stereo Integrity and I used to argue about horns. His opinion was basically that a sealed or vented box of equal volume was less hassle. I was of the opinion that horns could be more efficient.

It took me a few years of building and measuring, but he was right: If you have two boxes with the same F3 and the same volume, their low end efficiency will be similar. Doesn't matter if it's a bandpass, transmission line, horn, vented box, even a sealed box.

So, the Pioneer box is cute, but I wouldn't expect it to outperform a sealed or vented box of comparable volume.

Now that doesn't mean that it's a bad idea. For instance, this is a great way to create an efficient loudspeaker that's also very shallow.

In fact, I've been doing the exact same thing for years, for my midbasses:

I take a midbass and I put it in a bandpass box. The bandpass loading requires a larger box, but it also raises the output. (Again, box size and output are tied together.)

So for me, it's a way to make an exceptionally loud midbass that's just 3-4" tall. My car stereo has changed in many ways over the years, but bandpass midbasses have been a constant. (I stick the bandpass box under the front seats, and the exit of the bandpass goes to the side of the car, to maximize the width of the stage.)

Now, obviosuly, there's an alternative here, which would be to use one of those 'shallow' subs. But I'm not a big fan of them for a number of reasons:

1) They're hideously expensive. Even the cheapest 'shallow' subs are $80 and you can spend $300 easily
2) For what you spend, they're not competitive. For instance, a $150 Dayton Ultimaxx will walk all over the shallow subs priced at $150.
3) The biggest problem by far is that their F3 is way too low. Most of the 'shallow' subs are true subwoofers, and they have low F3s and low efficiencies.


Put all of that together, and I tend to make a lot of boxes that look like this thing from Pioneer. Mine are usually designed for midbass duty.

Also, from a manufacturing standpoint, this is a way for Pioneer to make an affordable shallow sub. A couple of 6" woofers can be had for about $40, and in the right box they will outperform the shallow subs that cost 2-3x as much.


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## 92blacktt (Dec 18, 2008)

it looked like that, don't remember the exact model. This was back in 2008 and I sold it after importing the car.



Elgrosso said:


> This one? ƒpƒ��[ƒhƒTƒuƒE�[ƒtƒ@�[ - TS-WX99A
> 
> (500w/100db/ported 10 apparently)
> 
> I would imagine that, after the volume/shape advantage, efficiency and low power requirement of the horn can be interesting.


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## Patrick Bateman (Sep 11, 2006)

Here's some pics of my new bandpass midbass enclosures for my car. They use an AuraSound NS3 woofer, which is currently on sale at Madisound.

The 'gap' in the enclosure is just there so that I can assemble it. Basically i screw the driver in, I cover the entire enclosure in mortite, and then I wrap it in fiberglass. This is to create a constrained layer damping enclosure.


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## I800C0LLECT (Jan 26, 2009)

Is that installed under your dash?


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## Patrick Bateman (Sep 11, 2006)

I800C0LLECT said:


> Is that installed under your dash?


I haven't decided yet. I need to 3D print some horns. If there's enough room under the dash, then these will go there.

My original plan was to try and cram an 8" midbass and a tweeter onto a Unity horn, but I just couldn't make it fit. So the current plan is a Unity horn with a ribbon tweeter, a 5" midrange (on the horn) and then as many midbasses as I can find room for.


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## Elgrosso (Jun 15, 2013)

Patrick Bateman said:


>


Nice, what kind of output do you get from it?


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## Focused4door (Aug 15, 2015)

Elgrosso said:


> Awesome!
> Other pics are great to illustrate the horn
> 
> 
> ...



Looks like Bose is doing this or something very similar, can't tell if it is a Transmission line or a horn. 

THE SOUND OF 34 VOICES SPEAKING - The curious listener's guide to the Bose Panaray System in the Cadillac CT6 | LA Car

http://www.lacar.com/2018ct6/34-speaker-cadillac-ct6-bose-panaray-audio-system.jpg

Gary Summers posted about the Bose Cadillac system in the best OEM thread.


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## Elgrosso (Jun 15, 2013)

Maybe just a small bandpass P.Bateman style?


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## Patrick Bateman (Sep 11, 2006)

How come I never though of that?

That's a midrange horn. That's pretty clever.

Sound can't expand until a duct is large enough for it to expand. IE, if you have a waveguide that's sixteen inches wide, but only an inch tall, the wave will only bend in one axis. (13,500hz is one inch long. So in a 1" tall duct, everything below that frequency will love unable to expand until the duct becomes large enough.)

That's how Bose gets away with those bends.

The other 'neat' part is that the perceived location of the speaker will be the mouth of the horn. IE, back by the firewall.

Gary told me about this system a few weeks ago, he wasn't a fan 

One thing that I see with speaker companies is that they're often obligated to deliver obnoxious systems, because marketing runs the show, not engineering.


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## I800C0LLECT (Jan 26, 2009)

I'm pretty sure you mentioned it before. I remember reading about it. Old news 

Sent from my SM-G955U using Tapatalk


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## Focused4door (Aug 15, 2015)

Patrick Bateman said:


> Here's some pics of my new bandpass midbass enclosures for my car. They use an AuraSound NS3 woofer, which is currently on sale at Madisound.
> 
> The 'gap' in the enclosure is just there so that I can assemble it. Basically i screw the driver in, I cover the entire enclosure in mortite, and then I wrap it in fiberglass. This is to create a constrained layer damping enclosure.


I am kind of curious if epoxy resin will dissolve water soluble filament. 

If not, you could 3D print a mold and then fiberglass it, then dissolve the print away. It would save some space for the enclosure.

Even if epoxy would dissolve the print, you could probably cover it in something that would come out or off when dissolved.

Might be interesting to try different resin types.


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## Patrick Bateman (Sep 11, 2006)

It doesn't. One of the things that I've battled constantly, when it comes to 3D printing, is making the prints airtight.

I'll post some measurements when I'm not buried with my day job, but basically I had two bandpass midbasses with identical enclosures and drivers and one of them was 3dB quieter! When I ran an impedance sweep, I found that the box was leaking.

This is something that I see year after year, and I haven't seen too many people ranting about it. My 'hunch' is that most people are using active crossovers, so they're not bothering to run impedance sweeps. But if you DO run an impedance sweep, you'll see that even the tiniest leak will cost you output.

And not a small amount of output; a difference of three decibels is like going from an 8" woofer to a 5" woofer. *It's a BIG problem.*

I go to ridiculous lengths to make the enclosures airtight. Back in the day, I used to seal them with Liquid Nails for Subfloors. (This is great stuff, it dries smooth and it's water soluble, so easy cleanup.)

Nowadays I do a CLD sandwidth of fiberglass, the 3D printed enclosure, then mortite, and then another layer of fiberglass. So it's basically an outside surface of fiberglass, and inside structure of PLA, and a layer of mortite for damping. I use System Three T-88 epoxy.

This might sound like a tremendous amount of work, but keep in mind that I don't have to screw with cutting boards at all these days. Back when I made enclosures out of wood I might spend eight hours cutting and gluing. Nowadays my printer does 75% of the work.

But I think that 'finishing' the enclosure is absolutely essential. In fact, my last set of waveguides wouldn't have melted in the sun if I'd finished them properly. I basically got impatient and wanted to hear them, so I didn't take the time to fiberglass them.


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## Patrick Bateman (Sep 11, 2006)

I've had these new bandpass midbasses in my car for about three days now, and I just can't believe these things. I need to do some measurements. 










When I measured them outside, their F3 is about 120Hz. I have no idea how much cabin gain I'm getting, because I haven't measured them, but they honestly hit as hard as a 12" sub. (Check my posts, I'm not into hyperbole!)

These things are performing beyond my wildest expectations, to say the least. Admittedly, the enclosures are an absolute p.i.t.a. to build, because they must be absolutely positively airtight. But I guarantee you, if you got in my car today, you'd think I was running a couple of eight inch midbasses. I'm guessing a lot of this is due to cabin gain. Cabin gain usually adds about 12dB at 40Hz, so the F3 on my 3.5" midbasses may be as low as 50-60Hz in the car.

But here's the fun part:

I have two of these in the car right now, but I never planned on running two. They're TINY; I planned on using as many as I could fit. I will be using at least four, and possibly eight.

That should get, um, interesting. It would be wild to do a car with no subwoofer, and an array of Aurasound NS3 midbasses. That would be a serious skullfuck. These woofers punch way above their size.


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## Elgrosso (Jun 15, 2013)

Looks impressive, disto seems a little high but did you measure max spl?


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## mh_mini (May 4, 2016)

Elgrosso said:


> Looks impressive, disto seems a little high but did you measure max spl?


I'd imagine using 4+ would lower the distortion while raising spl


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## Focused4door (Aug 15, 2015)

Patrick Bateman said:


> That should get, um, interesting. It would be wild to do a car with no subwoofer, and an array of Aurasound NS3 midbasses. That would be a serious skullfuck. These woofers punch way above their size.


You should model the Tang Band neo subwoofers, they have a 3" and 5" that look impressive at least on paper. Not cheap because they are neo magnets, but small boxes and pretty impressive looking. I looked at using one for a sub in a DYI boom box and ended up buying a set of the JBL Control X wireless instead.


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## SubOptimal (May 6, 2017)

Question about bandpass midbass.
I'm looking to try something similar with the Dayton ND91-4s. 
They model fine until I add in the port resonance.
If I bandpass with the DSP too, will that dampen the port noise?


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## Patrick Bateman (Sep 11, 2006)

Elgrosso said:


> Looks impressive, disto seems a little high but did you measure max spl?


I couldn't agree more. I came pretty close to throwing these in the trash before I even hooked them up. Because the distortion IS rather high.

But WOW do they sound fantastic.

I'm really starting to think that reducing distortion may be a fool's errand. 

Dunno.


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## Patrick Bateman (Sep 11, 2006)

SubOptimal said:


> Question about bandpass midbass.
> I'm looking to try something similar with the Dayton ND91-4s.
> They model fine until I add in the port resonance.
> If I bandpass with the DSP too, will that dampen the port noise?


I can post the STL file if you'd like. The Dayton ND91s are basically a drop-in for this box. I used the AuraSound NS3s largely because they're a couple bucks cheaper. The Dayton ND91 is a shameless clone, and the only real difference is a lower QES and lower LE, which isn't really important for a midbass.

Don Keele tweaked the ND90 and called it the "ND91" for his CBT speakers. But they're both AuraSound NS3 clones. 

I have both onhand, they're nearly indistinguishable.










As far as the port noise, check out my measurement, the port noise is fairly well behaved. You could put a little polyfill in the chamber to reduce it if you wanted to. Another option would be to wire an inductor in series.


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## SubOptimal (May 6, 2017)

Thanks for the offer Patrick.
Prices here are much the same, but the ND91 better fits my requirements.
It's a touch more efficient, and models as if it will give a bit more usable bandwidth.
It also requires a smaller enclosure, which allows me to use a longer port.
Reason being, I'm attempting to have the enclosure located where the OEM 6.5" would normally be, and route a long port (~45cm) up to the sail panel area.
The easy part is then mating that with an efficient 2-2.5" mid and probably an ND16 tweeter.

Was there any electrical filtering applied when you took those measurements?

This would be ideal...









This would be hopeless


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## Patrick Bateman (Sep 11, 2006)

I think I had a high pass set at 40hz, but that was all the filtering

Note that there's no real need to put the midbasses near the midranges. The frequencies are so long, it's difficult to perceive where they're coming from.

For instance, 200hz is 1.3 meters long.

What WILL affect your perception of the location are the harmonics.

For instance, the 3rd harmonic of 200hz is 600hz. That harmonic is well into the range of frequencies that are easy to localize.

That's one of the beauties of bandpass boxes; they filter out harmonic distortion. At 600hz, the harmonic distortion of my bandpass midbass is well under the noise floor.

Subjectively, my midbass sounds like it's at the firewall, even though it's under my seat. The mid-range is located near the firewall and it 'anchors' the stage.


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## Patrick Bateman (Sep 11, 2006)

Here's a video of the construction.

It's 3D printed, with mortite and fiberglass for constrained layer damping:

https://youtu.be/Ng0M3s0yqcY


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## Whiterabbit (May 26, 2006)

Interesting topic, and timely for my pre-planning.

Can you share the volumes and port geometry you elected to use for this project? I would like to duplicate your work in Q4 of this year for a center channel. I've predicted for years this kind of application would be excellent for excessive midbass routed up the door sills into the kickpanel area, however for a compact active center channel located inside the dashboard, I believe a bandpass solution like this represents an excellent solution for low frequency challenges given to us by modern OEM dashboard designs.


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## thechainrule (Feb 2, 2010)

Patrick, I’d love to try out your 3d printed design in my install, would you mind sharing your stl file?


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## Patrick Bateman (Sep 11, 2006)

I probably don't have the file any longer. I can take a look on my NAS, but it's been about three years and two laptops ago. I'll make myself a note to check this week.


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## Patrick Bateman (Sep 11, 2006)

Patrick Bateman said:


> Here's some pics of my new bandpass midbass enclosures for my car. They use an AuraSound NS3 woofer, which is currently on sale at Madisound.
> 
> The 'gap' in the enclosure is just there so that I can assemble it. Basically i screw the driver in, I cover the entire enclosure in mortite, and then I wrap it in fiberglass. This is to create a constrained layer damping enclosure.





If you'd like to print this, I uploaded the STL files here:






A Collection of 3D Printed Things - diyAudio


I've noticed that people have been printing out some of my waveguides, even though I never managed to actually finish a project. I've probably made fi



www.diyaudio.com


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## EricP72 (Mar 23, 2008)

Patrick Bateman said:


> If you'd like to print this, I uploaded the STL files here:
> 
> 
> 
> ...


I know this is an older thread, but I'm looking at doing an under the midbass. Have you come across any passive or powered under the seat subwoofer setups that work perfectly for midbass say 80hz-200hz and doesn't give away its location by excessive vibrations through the seats? I was thinking about the focal Isub twin or the JBL FUSE.


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## Focused4door (Aug 15, 2015)

On paper the JBL looks better

I am curious if the JBL fuse can be tuned higher by removing weight from the passive radiator if you are only using it as a midbass. 

It may not have added mass, or it may not be removable though. Lots of products are hard to even take apart depending on the design as well.


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## EricP72 (Mar 23, 2008)

Focused4door said:


> On paper the JBL looks better
> 
> I am curious if the JBL fuse can be tuned higher by removing weight from the passive radiator if you are only using it as a midbass.
> 
> It may not have added mass, or it may not be removable though. Lots of products are hard to even take apart depending on the design as well.


Now that would make it the front runner if the PR can be tuned


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## Patrick Bateman (Sep 11, 2006)

JBL Fuse looks like a no-brainer:









JBL Fuse compact 8" Under seat subwoofers -...


I just came across these compact 8" enclosed subwoofers from JBL/Harmon and was so entrigued I bought a pair for under seat midbass. They are "subwoofers" not a true midbass/midwoofer like I was looking to put under my seats but basically I can only fit shallow 6.5" mids in my doors so while my...




www.diymobileaudio.com





The key to the setup that's described in this thread, is that the use of multiple midbasses fixes the fundamental problem of midbass in the car.

At home, we can put a 7" woofer into a vented enclosure and we can get bass that's quite good. I recently measured my Behringer two-ways, and they play down to 30Hz in my living room! And they sell for about $300 a pair. That's just ridiculously good performance for the money.

In a car, it's a struggle to get a 7" woofer to play down to 60 or 70hz.

Basically, the sound from the RIGHT speaker is nullifying the sound from the LEFT speaker, and vice versa. This is because the interior of your car is about five feet wide.

112Hz is ten feet long.

56Hz is twenty feet long.

So when your left speaker plays 112Hz,when it arrives at the RIGHT speaker it's 180 degrees out of phase, creating a null. When you left speaker plays 56Hz, when it arrives at the RIGHT speaker, it's 90 degrees out of phase, creating a dip.

So you have this range from 56Hz to 112Hz, where your left and your right midbass are fighting each other.

That's the entire point of this thread: *If you spread your midbasses out, you can get away with midbasses that are much MUCH smaller.*

No exaggeration: when I was using this scheme in my car, I was using two 3.5" woofer per side, and it sounded "punchier" and "smoother" than using a single eight.

So the JBL Fuse looks like a no brainer. But DO NOT do this experiment with one midbass per side, that defeats the entire purpose. Use two per side, or more. I had one midbass under my seat, and one under the dash, per side. If you want to get fancy, you can align their outputs using DSP.

Even without DSP, it will sound better than you can imagine, because the fundamental issue with midbass playback in a car is that the geometry is all wrong. Best way to fix that would be to get a car that's ten feet wide, but that's impossible. Second best way to fix it is to distribute the wavefronts by adding a second midbass per side.

Also, please note that you DO NOT want them side by side.

I know that it seems like that would be a good idea; that you'd want them close because it will "sound better."

But it won't. The entire problem here, is that the left speaker is fighting the right speaker, and vice versa. If you put two midbasses side by side, they simply act like one giant midbass. You want them at least one quarter wavelength apart, at the upper limit of their output.

IE, if you have two midbasses per side, and each midbass is playing up to 250Hz, you would want them about 13.5" - 18" apart.

One midbass in the door, and one midbass under the seat is a good combo. Or one midbass in the door, and one under the dash. When I did it, I used the same midbasses for my pair, per side. But you could probably mix midbasses without a lot of downisdes. Such as having one JBL Fuse under the seat, and something different in the door, and they're wired so that they get the same signal.

If you REALLY want to go crazy, there's also a lot of good reasons to have one playing louder than the other.

This is about to get confusing, so I apologize in advance:

As noted earlier in the post, the reason it's hard to make midbass in a car is because of geometry. Basically, your right speaker is between 90 and 180 degrees out of phase with your left speaker in the octave between 60 and 120Hz. The exact frequency depends on the width of your car, but 60-120Hz is a safe bet, give or take about 15%.










Andy from AudioFrog published this measurement of cabin gain in various cars, and you can see a consistent dip at about 60Hz. The dip due to cabin gain isn't the same dip that midbasses experience, but the idea is similar. 

At about 110-130Hz, you get a really deep null, as much as 10dB. To put that in perspective, a TEN INCH WOOFER is about 10dB more efficient than a typical THREE INCH WOOFER. So that dip is REALLY bad. It's the reason that 7" woofers sound anemic in a car, and dynamic in a home.

If you are going to put two midbasses on one side of your car, and two on the other, ideally they should have the exact same frequency response and they should be carefully delayed so that they arrive at the same time, despite their disparate locations.

But if you're like me, and you like to tinker...

Keep in mind that it doesn't take a lot to fill in that trough from 60-120Hz. If you want to go gung ho, put a midbass under your seat, and put one in the door and tune the heck out of them. *That is ideal.*

But if you want to tinker, you may find that even a SMALL additional midbass can offer a lot of bang for the buck. Because the fundamental problem here is geometric. So an additional midbass, located about 13.5"-18" apart, will go a long way _even if it's not playing 100% as loud._

Here's the math:

Let's say we have a woofer in your left door, and it's playing 100dB at 60Hz. We have a woofer in your right door, and it's playing 100dB at 60Hz. The cabin is 4.7feet wide. This means that at 60Hz to 120Hz, your left and your right woofer are between 90 and 180 degrees out-of-phase with each other. This means you're losing between 6 and 94dB of your output at these frequencies, making the midbass sound very anemic. If you add an additional midbass, playing at 94dB, *it will significantly boost the levels* even though it's "only" playing 94dB. It's getting a small fraction of the power, but it's reinforcing these frequencies significantly, because there's a frequency where your left and your right are perfectly out-of-phase.

Besides making the midbass sound "punchier", it also sounds subjectively "smoother" to me. This is only logical; in the three octaves from 60 to 500Hz, there's a tremendous amount of reflections in our car. It's a really ugly range where the wavelengths are long enough that they're completely omni. (IE, there's no reason to "aim" a midbass.) But the wavelengths are ALSO short enough that the geometry of the car is wreaking havoc. (If the cabin of a car was 4X as big, what I describe wouldn't be nearly as much as a problem. Jon Whitledge famously used a Sprinter Van, due to these issues I describe.)

IE, if you're limited on space, or you just have a 4" or a 5" woofer laying around in the garage, you might get good results by just fabricating a sealed enclosure and sticking that under your seat, playing in unison with what's already playing in your car doors. Or put it under the dash. 

And you can get a 4ohm resistor and wire it in series, to reduce the voltage that's going to the additional midbass. The idea being that you'll reduce how much power it gets. (This assumes that your existing midbasses can handle about twice as much power.)

The idea here, is that you can tinker with this, without making the commitment to tearing up your car to figure out where two midbasses would be located, ideally. If you use a resistor to drop the input voltage to the second midbass, be sure to to get a decent one off of eBay or Parts Express. Or get a couple of 10W resistors and wire them in parallel.


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## Jheitt142 (Dec 7, 2011)

ok. So I find this post very relevant to me right now. I'm in the stages of just getting my wiring runs together and while i have my sub, and my widebands i have three potential midbass candidates sitting here.

2 - 6.5" 2ohm CDT drivers
2 - 6.5" 4ohm silver flutes
2 - Dayton audio dual 8ohm 8" subs, but having used them sealed i think they'd be great for mid bass duty Dayton audio 8" subwoofer

I have been mulling over my choice here endlessly, even considering things like mixed mono.

the CDT's are spec'd so that a box would be a pain to fit. the silver flutes however would be great in a small enclosure. I've also modeled the 8" in as little a 0.22 and the response in the 80 and up range is great. im pretty low on power in this install. but at 2ohms i do have a rated 80RMS from my good old sounstream. so i could run the flutes and the 8's together on the same channels. just put one set in the doors and the other on the floor 

From what im reading here i could achieve much greater output splitting up that power with 4 drivers vs feeding it all to the 2 CDT drivers.


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## Focused4door (Aug 15, 2015)

I have wondered if the next step to this is to add a band stop filter to the wider midbass at the null frequency, and play the narrower located midbass full range of the midbass passband. No point pouring power into a null.


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## EricP72 (Mar 23, 2008)

So then by Bateman suggestion, I could purchase 2 JBL Fuse and run 1 set under the front seats, 1 set under the dash, and keep the door midbass drivers as is. The doors would be the main output with the others being used to supplement the output and nullify any voids or dips thus not really needing more than say 100watts per "box". So I guess the next part is finding a 4 channel amplifier that has a bass knob that way I can level match on the fly without using a dsp channel. Am I correct or am I over thinking the process?


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## Bikey (May 15, 2021)

What frequencies would you send to the Fuses and which would you send to the door speakers? Depending on what they are playing, you may no longer need the door speakers.
If your DSP has no unused channels, you could use something like a Mini-DSP, to handle the 4 Fuses.


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## Patrick Bateman (Sep 11, 2006)

EricP72 said:


> So then by Bateman suggestion, I could purchase 2 JBL Fuse and run 1 set under the front seats, 1 set under the dash, and keep the door midbass drivers as is. The doors would be the main output with the others being used to supplement the output and nullify any voids or dips thus not really needing more than say 100watts per "box". So I guess the next part is finding a 4 channel amplifier that has a bass knob that way I can level match on the fly without using a dsp channel. Am I correct or am I over thinking the process?


Three 8" midbasses will be way more than anyone would need.

I used 3.5" midbasses and it worked great.

Keep in mind that the null that's created by the left and right speaker being out of phase is REALLY deep - as much as 10dB.

That's basically the difference between a ten inch woofer and a three inch woofer!

The null basically takes your 6" midbass in the door and makes it sound like a puny little 2" driver.

You can demonstrate this by going to any Best Buy - there are computer speakers with 3" and 4" woofers that have punchier midbass than what a lot of people have in their cars.

If it were me, I wouldn't use three midbasses to start with, I would use two. Certainly nothing _wrong_ with using three, but I'd start out by just experimenting with a single additional midbass.










When I first started messing around with this, I just bought a set of Cambridge Soundworks computer speakers off of Craigslist. It was basically a way for me to experiment and see what locations worked well, and what didn't. And you can get the entire set for about $20. These cubes measure ridiculously well, they're basically flat from 100Hz to 20khz. They can't handle a lot of power, so you'll want to put a resistor inline to reduce how much voltage they're getting. 4ohms is a good start. 

Or wire them in parallel with your midbass and just be careful not to do overdo it. Ten watts will get you about 95dB.


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## Bikey (May 15, 2021)

Hi Patrick - 2 questions:
1 - what is the math/reasoning on the recommended driver separation (13.5 to 18")? 
2 - in the post above, you said to try it out with a single additional midbass driver and in a prior post you said "So the JBL Fuse looks like a no brainer. But DO NOT do this experiment with one midbass per side, that defeats the entire purpose. Use two per side, or more. I had one midbass under my seat, and one under the dash, per side. If you want to get fancy, you can align their outputs using DSP." I really like this idea but I'm either losing count or not following the reasoning.


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## EricP72 (Mar 23, 2008)

Patrick Bateman said:


> Three 8" midbasses will be way more than anyone would need.
> 
> I used 3.5" midbasses and it worked great.
> 
> ...


Ok. So I will try 1 set of JBL Fuse under the front seats with the door mid-bass still running. 80hz-200hz for the Fuse. What I really would like is to find someone to print out that bandpass box you designed and id run those. Less chance of me feeling the bass in my seat. Or....maybe someone can design a similar band pass box for a pair of 6x9's? Ok that is over kill.


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## NW JLUR (Dec 3, 2018)

Can the midbass drivers be further away from each other? I have a 2018 Jeep Wrangler with 6.5” midbass 80-350 Hz in the lower dash. Would a 5.25” midbass in the sound bar behind the front seats playing the same range at a lower level work?


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## Picassotheimpaler (Sep 21, 2014)

Patrick Bateman said:


> JBL Fuse looks like a no-brainer:
> 
> 
> 
> ...


If you are using the second midbass to only send an out of phase signal that cancels out the room modes of the midbass, why would you want to run them across the entire range of the main Midbass? Why not just bandpass them right where the cancelation occurs so you can keep most of the signal coming from a single source, keep the phase interactions between the 2 minimal, and to allow you to adjust the phase interaction much more finely through TA?


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## Focused4door (Aug 15, 2015)

Picassotheimpaler said:


> If you are using the second midbass to only send an out of phase signal that cancels out the room modes of the midbass, why would you want to run them across the entire range of the main Midbass? Why not just bandpass them right where the cancelation occurs so you can keep most of the signal coming from a single source, keep the phase interactions between the 2 minimal, and to allow you to adjust the phase interaction much more finely through TA?



I think it makes more sense to bandstop the midbass in the position that creates a null and run the other midbass over the full midbass range It would lower distortion, if you have a null the driver is working hard to do nothing constructive.

The bandpass and bandstop filters will both alter the phase response. You can't TA your way out of a phase issue, since the phase isn't constant over frequency.

Whether you have one midbass, two, or many you can't tell where they are coming from if they are lowpass filtered low enough. You might get second and third harmonics high enough to localize, but not the actual midbass.

You can physically locate a midbass in a position that pulls the soundstage in, but with multiple midbass that isn't likely.


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## Picassotheimpaler (Sep 21, 2014)

Focused4door said:


> I think it makes more sense to bandstop the midbass in the position that creates a null and run the other midbass over the full midbass range It would lower distortion, if you have a null the driver is working hard to do nothing constructive.
> 
> The bandpass and bandstop filters will both alter the phase response. You can't TA your way out of a phase issue, since the phase isn't constant over frequency.
> 
> ...


Point being that if you play both midbass over the same frequency band than you have to deal with them interacting from different places. And the idea is to have them in different places.
So by using the secondary driver within only the range in which the phase issue created by the car is present, you don't have to worry about the interaction between the 2 drivers except for specifically where you want them to. You can then use delay to rotate the phase within that narrow band, giving more precision when attempting to correct the cancelation.


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## Patrick Bateman (Sep 11, 2006)

Picassotheimpaler said:


> If you are using the second midbass to only send an out of phase signal that cancels out the room modes of the midbass, why would you want to run them across the entire range of the main Midbass? Why not just bandpass them right where the cancelation occurs so you can keep most of the signal coming from a single source, keep the phase interactions between the 2 minimal, and to allow you to adjust the phase interaction much more finely through TA?


If you have a lot of amp channels and DSP channels, you would ideally:

1) equalize the response of all four midbasses so that they're identical when they arrive where your seated

2) use DSP delay so that the four arrived simultaneously

For instance, Gary Summers has a lot of amp channels and a lot of DSP. When he plays recordings that are five channel, the soundstage (as I hear it) is superior to what I've heard in a home.

Basically he has it SO DIALED IN for that one spot in the car, it's hyper real.

The "hyper real" thing is particularly effective with multiple midbasses, because you're basically optimizing the response at the driver's seat at the expense of everywhere else. By making the response chaotic everywhere else, it tends to make the signature of the room/car disappear more.

You can prove this idea with your own microphone:

A few years ago, I was measuring a speaker in my living room. The weather was bad and I couldn't measure outside. The response curve looked weird; it was smooth but the highs were rolled off. I came to realize that the reason the response looked that way, was that I had my gate set wrong. Basically *the reflection* of the loudspeaker off of the wall was SO GOOD, it was nearly indistinguishable from the loudspeaker itself! The wall was basically acting like an acoustic mirror.

We do not have the luxury of removing the ceiling and the floor from our cars. But one way to make things sound better is to distribute those reflections in time, so that they don't muddy the frequency response and the imaging of our stereo.

*Having said all that...*

I am a cheapskate, and the idea of dedicating a DSP channel and an amp channel to each driver seems silly to me. I would run them across the entire range because the sound that arrives at my ears, from both speakers, should ideally be identical. The reason that this can be achieved passively, with no DSP, is because the wavelengths are so long. 200hz is fifty four inches long. As long as the speakers are about 1/3 to 1/4 in wavelength apart, they will be close enough that they don't interfere with each other destructively, but far enough apart that it distributes the reflections inside of the interior of the car. This means that the two midbasses are about 17" to 22.5" apart. The distance is determined by your xover point; the higher your xover point is, the closer they need to be. And vice versa.

This scheme works particularly well if the speakers are distributed depth-wise. IE, if possible, have one midbass that's at one distance, and another midbass that's further away from you.

This entire scheme is largely based on the idea of an end-fire array:










"An end-fire array is an array that gives a radiation pattern whose main beam is along the axis of the array. "









The End Fire Cardioid Subwoofer Array Made Visible - ProSoundWeb


Getting loudspeakers to play leap-frog in the forward direction and demolition derby on the back side...




www.prosoundweb.com





Next time you go to a concert, look for this:










One sub in front of the other. At concerts they use DSP to line up the wavefronts.

This particular array is actually two dimensional:

1) The end fire array directs the sound towards the audience

2) By putting the subs in a row, it directs the sound towards the audience

I guess if someone was truly crazy, they could probably do this across their entire dash, or underneath the dash. Basically create a wall of midbass that would direct everything in just one direction. (Bass wants to radiate ominidirectionally of course, so we have to use geometric tricks to make it directional.)


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## ckirocz28 (Nov 29, 2017)

Patrick Bateman said:


> If you have a lot of amp channels and DSP channels, you would ideally:
> 
> 1) equalize the response of all four midbasses so that they're identical when they arrive where your seated
> 
> ...


So 38 midbasses should definitely fix the problem, right?


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## Focused4door (Aug 15, 2015)

Patrick Bateman said:


> I guess if someone was truly crazy, they could probably do this across their entire dash, or underneath the dash. Basically create a wall of midbass that would direct everything in just one direction. (Bass wants to radiate ominidirectionally of course, so we have to use geometric tricks to make it directional.)


You say you want directivity? How about this? I have simulated this a few times for sub and midbass frequencies, but never built it. I kind of forgot about it until now.

I have a pair of Dayton ND64 or 65, I forget which. I bought them for testing since they were small and easy to jam into spots, and are full range so can be a makeshift tweeter for testing or a midrange without having to swap out anything other than clicking crossover settings.

I bought the matching passive radiators almost on a whim, they can play low, but not very sensitive or loud of course but an array of them might be interesting across a dash, especially in a vehicle with a center console. The bass reflex box was so small it took a little planning to cram both the passive and the driver in the box

That said, a single large woofer playing a bandpass from say 80-160 Hz with multiple ports or passive radiators spread out on the dash would be even more interesting. I would consider a 6.5" large for that kind of setup, but still might keep a low profile especially if the vehicle had a center channel spot. Most recordings are mono that low down, not all but most.


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## lithium (Oct 29, 2008)

I was reading this thread and decided to grab the JBL fuse to try out in my car. I'll try to install them this weekend and give my impressions. I also threw them on the dats v3 fresh out of the box. 

This is both wired in parallel. 









here is just one side, they measure pretty close









Looks like the PR is tuned to about 40 Hz. The peak around 600Hz I would assume to be the suspension or surround as its not broken in yet.


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## Bikey (May 15, 2021)

I'm interested to see how they work out. It it possible to remove the drivers from the enclosure?


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## DaveG (Jul 24, 2019)

Focused4door said:


> You say you want directivity? How about this? I have simulated this a few times for sub and midbass frequencies, but never built it. I kind of forgot about it until now.
> 
> I have a pair of Dayton ND64 or 65, I forget which. I bought them for testing since they were small and easy to jam into spots, and are full range so can be a makeshift tweeter for testing or a midrange without having to swap out anything other than clicking crossover settings.
> 
> ...


This is interesting... I've toyed with the ND 65 and matching PR. Shouldn't you have 2 PR's per ND 65? And what kind of output can be expected? They don't take a lot of watts and most midbass are 6.5"/8"/6"x9" with plenty watts going to them so I was thinking 2 8ohm ND 65 and 4 PR per side. Still concerned my 8" midbass will never let these be heard except maybe in the null (which I suppose is the whole idea) but at a lower output. Thoughts?


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## lithium (Oct 29, 2008)

Bikey said:


> I'm interested to see how they work out. It it possible to remove the drivers from the enclosure?


It's mounting from the inside. I dont have a reason to take the enclosure apart right now.


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## seafish (Aug 1, 2012)

Bikey said:


> ...It it possible to remove the drivers from the enclosure?


I am curious as to why you would want to do that ??

I mean their response includes the enclosure and PR and also the enclosure, when separated into the 2 distinct drivers that it is also designed to be, is relatively thin and compact and would be relatively easy to experiment with, move around and tehn finally mount in a number of places (under dash, under seats,...) to try to achieve distributed mid bass in the effort to correct for any mid bass nulls and limitations due to vehicle dimensions.

So if you are simply looking for thin drivers, why not find some raw drivers with parameters that would suit your install instead of taking these apart and dealing with unknown acoustic response??


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## Focused4door (Aug 15, 2015)

DaveG said:


> This is interesting... I've toyed with the ND 65 and matching PR. Shouldn't you have 2 PR's per ND 65? And what kind of output can be expected? They don't take a lot of watts and most midbass are 6.5"/8"/6"x9" with plenty watts going to them so I was thinking 2 8ohm ND 65 and 4 PR per side. Still concerned my 8" midbass will never let these be heard except maybe in the null (which I suppose is the whole idea) but at a lower output. Thoughts?


I wouldn't mix box types covering the same frequency range unless you can correct for phase on each channel because you will get phase issues from the group delay of the ported box. 

What is your 8" location? I would rather have a few small drivers in ported boxes than an 8" in the door, but I really hate the tactile feedback from the door. 

You don't want watts, you want output. If you have a null, you don't have output, or not much. If you have low efficiency in one driver, and higher efficiency in another, comparing watts is kind of pointless. The ND65 aren't very efficient, but if you run ported you get box gain, and running multiples gets you where you want to be. How many you need depends on your listening levels

I had to dig through my closet, I have two drivers and four passives. You don't have to use the matching passives, often times an oversized passive will model much better.


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## DaveG (Jul 24, 2019)

Focused4door said:


> I wouldn't mix box types covering the same frequency range unless you can correct for phase on each channel because you will get phase issues from the group delay of the ported box.
> 
> What is your 8" location? I would rather have a few small drivers in ported boxes than an 8" in the door, but I really hate the tactile feedback from the door.
> 
> ...


What do you mean mixing box types? If I were to do it I'd use passive radiators. Do passive radiator enclosures exhibit the same kind of phase issue as ported? The enclosures would need to be as small as possible so 2 ND65's and maybe a 5.25" passive radiator would be better? 8" midbass are located in doors.


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## ophidia311 (May 3, 2021)

lithium said:


> I was reading this thread and decided to grab the JBL fuse to try out in my car. I'll try to install them this weekend and give my impressions. I also threw them on the dats v3 fresh out of the box.


Curious to hear how you like them used in that fashion. Have a set that were going to be installed under the seats in my last car with a wideband in the dash locations but since got rid of that car so nothing to use them in right now. Sticking with the bose in my new mazda for the time being as its actually decent while i ponder what i want to do now.


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## Focused4door (Aug 15, 2015)

DaveG said:


> What do you mean mixing box types? If I were to do it I'd use passive radiators. Do passive radiator enclosures exhibit the same kind of phase issue as ported? The enclosures would need to be as small as possible so 2 ND65's and maybe a 5.25" passive radiator would be better? 8" midbass are located in doors.


Yes, a passive radiator is a bass reflex design and has group delay.

The door is a box type, infinite baffle which is oversimplified to a large sealed box.

You intend to run an 8" midbass IB in the door, and then a ported box of a smaller driver to fill the null from the door location, correct? The ported box will have phase difference relative to the infinite baffle driver.


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## DaveG (Jul 24, 2019)

Focused4door said:


> Yes, a passive radiator is a bass reflex design and has group delay.
> 
> The door is a box type, infinite baffle which is oversimplified to a large sealed box.
> 
> You intend to run an 8" midbass IB in the door, and then a ported box of a smaller driver to fill the null from the door location, correct? The ported box will have phase difference relative to the infinite baffle driver.


So maybe 4 of the 8 ohm drivers and no PR per side? I guess that would still be mixing enclosure designs ( IB and sealed)? I don’t see away around mixing. Can’t do an enclosure in the door and won’t cut holes in my car. Can’t I shift the phase with an ultra? Thanks Dave


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## lithium (Oct 29, 2008)

ophidia311 said:


> Curious to hear how you like them used in that fashion. Have a set that were going to be installed under the seats in my last car with a wideband in the dash locations but since got rid of that car so nothing to use them in right now. Sticking with the bose in my new mazda for the time being as its actually decent while i ponder what i want to do now.


Heading out to tune them now. If they don't work out I might try them as under sofa subs for my apartment..


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## Bikey (May 15, 2021)

The Fuse enclosures would fit in 3 of 4 locations that I'm thinking of with nearly no work. The fourth would require a custom enclosure.
Going with off-the-shelf raw drivers would mean 4 custom enclosures.



seafish said:


> I am curious as to why you would want to do that ??
> 
> I mean their response includes the enclosure and PR and also the enclosure, when separated into the 2 distinct drivers that it is also designed to be, is relatively thin and compact and would be relatively easy to experiment with, move around and tehn finally mount in a number of places (under dash, under seats,...) to try to achieve distributed mid bass in the effort to correct for any mid bass nulls and limitations due to vehicle dimensions.
> 
> So if you are simply looking for thin drivers, why not find some raw drivers with parameters that would suit your install instead of taking these apart and dealing with unknown acoustic response??


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## seafish (Aug 1, 2012)

Bikey said:


> The Fuse enclosures would fit in 3 of 4 locations that I'm thinking of with nearly no work. The fourth would require a custom enclosure.
> Going with off-the-shelf raw drivers would mean 4 custom enclosures.


Like they say ... 3 out of 4 ain't bad !!!


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## Picassotheimpaler (Sep 21, 2014)

Patrick Bateman said:


> If you have a lot of amp channels and DSP channels, you would ideally:
> 
> 1) equalize the response of all four midbasses so that they're identical when they arrive where your seated
> 
> ...


Ahhh, that's an interesting theory. I like it.
Basically using the separate midbass' differing distances to reflective surfaces to attenuate down the reflections through phase interaction. Except for the one sweet spot set by delay where they combine just right, if I am understanding this correctly.
So something like a door mounted midbass and kick mounted midbass would potentially work well.

PS: Good to see you back on the forum. Your posts are one of the main reasons I started trolling the site


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## Jheitt142 (Dec 7, 2011)

can i just turn my center console into a bass trap and be done with it?


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## Picassotheimpaler (Sep 21, 2014)

Jheitt142 said:


> can i just turn my center console into a bass trap and be done with it?


If you make your center console, roof, and trunk a bass trap than most likely lol


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## Jheitt142 (Dec 7, 2011)

Picassotheimpaler said:


> If you make your center console, roof, and trunk a bass trap than most likely lol


well, im about to have a whole lot less head room! hahaha


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## Patrick Bateman (Sep 11, 2006)

Picassotheimpaler said:


> Ahhh, that's an interesting theory. I like it.
> Basically using the separate midbass' differing distances to reflective surfaces to attenuate down the reflections through phase interaction. Except for the one sweet spot set by delay where they combine just right, if I am understanding this correctly.
> So something like a door mounted midbass and kick mounted midbass would potentially work well.
> 
> PS: Good to see you back on the forum. Your posts are one of the main reasons I started trolling the site


That's exactly right.



















Parabolic reflectors (sorta) work on the same principle. If anyone's ever been to this one in Houston, or the one at the Seattle Science Center, you'll experience the effect. Basically you sit down, and somebody is fifty feet away from you. And the person who's fifty feet away can talk to you, and it sounds like what they're saying is inside of your head. Like a set of head phones.

It works because the geometry is constructed in such a way that the sound is out of phase everywhere, except at that one point in space.










Parabolic line arrays work on the same principle, but are 2D instead of 3D.

This stuff doesn't work great at high frequencies, because the wavelengths are so short. 2khz is 17cm long, so if your pathlengths vary by more than about 5cm (two inches) the illusion doesn't work.

But 200Hz is 170cm long, so you can achieve the illusion even if you move your head 50cm (20 inches).

With the parabolic reflectors in Houston and Seattle, you'll notice that the highs are rolled off. This is why; the 'trick' works best at low frequencies.

But, again, this isn't just about parabolas. It works on any kind of array where you arrange the elements to radiate the signal to a specific place. A lot of the stuff that's being used to do this in audio originates from military research into antennas and sonar.


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## thecrestedibis (Nov 13, 2021)

I did something like this awhile back, but never got too far with it.

Basically I used small mid/midbass speakers and placed them in sealed enclosures near the door glass right where the side mirrors attached. 

I then placed another more on the dash near the A-pillar and ran it band pass out of phase with the others near the glass. 

The idea was to use the reflected sound on the side glass as phantom speaker and the destructive interference of the out-of-phase dash mounted speaker very much like an end fire array. 

I don't remember the exact frequencies, or if I used any delay and how much, but the effect was interesting. It definitely pushed the sound stage outside the physical dimensions of the vehicle.


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## lithium (Oct 29, 2008)

Based on some of the convo in this thread I decided to pick up the JBL Fuse. One thing I really missed from my previous car was crazy midbass from my fiberglassed door enclosures. For whatever reason in that car, I had not large cab mode issue after building door enclosures. I'm not willing to cut my doors up yet so for now I've been playing around with distributed midbass and front subs. 

My front door drivers are Anachy 7s. Unfortunately I have a giant whole on the left mid below 80 Hz, so that's the limit for door midbass regardless of how much displacement the mids are capable of. Not to mention the doors cant handle it. 

I first tried out a pair of Peerless SLS 8s in 1/2 cuft enclosures behind each seat (car is a '15 honda accord coupe). The subs would face outward. This setup worked out Ok but I want to move to a 3 way front stage and the large enclosures took up too much space. I also didn't like the tactile feedback from the driver side driver. 

Moving on from here I wanted to try a front sub that could supplement the midbass. I got some concrete form (12") and tried out my sls's 8 in two configurations. Isobaric in about 0.75 cu ft. and then sealed (sub on each end) sharing the same enclosure. The isobaric setup measured well but didn't have as much output as I'd like from the front sub. Running both sealed worked out better but they didn't model great for a small enclosure and the construction of the enclosure blocked access to the glove box somewhat. 

This is a photo of the isobaric setup. I just wrapped the enclosure with some 1inch foam that I have on hand and wedged it under the dash... 


http://imgur.com/DreJs8J


After this experiment I wanted to try again with a better product. I saw the JBL Fuse recommendations so I grabbed a refurb and threw it in the car. I tried it as seperates under each seat and then together as a front sub. 

I only have 8 ch of DSP so I could only run the front 3 way plus L/R fuse sub and disconnect the rear sub (Infinite baffle). I never tried Mono under seats, figured it wasn't worth it due to reasons below. 

I think I agree with statements concern the limited bandwidth you can get away with from an underseat midbass, 200 Hz seemed about right. I tried running the underseat JBLs crossed straight to my 3 inch midrange drivers and it kinda worked, I can see why folks prefer this to door midbass. Only issue I had again was localization due to tactile feedback on the driver side. Maybe if I could deaden the seat and/or floor it would reduce the vibrations a bit. 

Finally, I tried the setup I'm going to stick with for awhile. Front sub (JBL Fuse), rear sub (Mach 5 mj18 or maybe swap back in the FI IB3 15 next year OR get a AE ib15au), and front 3 way. 

Front sub in this car seems to really help keep the bass upfront at high output levels. I couldn't quite get things to transition well with just a rear sub, maybe I'm bad at tuning. 

To mount the FUSE I just stuck some bolts thru my floor matts.. Maybe not the best solution but not any worse then the magnet mounts I'm using for my midrange pods.. 


http://imgur.com/5Z1Zwbk




http://imgur.com/yamkHJq




http://imgur.com/HwDUcJ7



Overall, the FUSE is a pretty sweep sub. Surprising output from pair of 8s in a very small enclosure. I think most folks could be happy with one of these as the main sub with some EQ work.


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## SloVic (Oct 1, 2016)

lithium said:


> Based on some of the convo in this thread I decided to pick up the JBL Fuse. One thing I really missed from my previous car was crazy midbass from my fiberglassed door enclosures. For whatever reason in that car, I had not large cab mode issue after building door enclosures. I'm not willing to cut my doors up yet so for now I've been playing around with distributed midbass and front subs.
> 
> My front door drivers are Anachy 7s. Unfortunately I have a giant whole on the left mid below 80 Hz, so that's the limit for door midbass regardless of how much displacement the mids are capable of. Not to mention the doors cant handle it.
> 
> ...


Nice, had similar ideas but was looking at the Focal ISUB TWIN to experiment with. So the JBL's can be Mounted together? Pretty cool, seams like it might give you the benefit of manifold mounting... drivers cancel each other out to drastically lower enclosure vibrations. Makes me feel better about my idea of using 2 Dayton RSS210HO-8 in the passenger footwell then a pair of RSS390HF-4 in the rear. From what I've read you get a ton of loading (around 12-15db) in the mid 30's to 90ish in that spot, at least in midsize sedan. Seams great for taking the load of midbass and allowing a very low LPF for rear subs, plus the killer efficiency for the front sub.


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## Bikey (May 15, 2021)

Did you end up overlapping the frequencies from the Fuses and the woofers in your 3 way?
Did you take ny measurements?



lithium said:


> Based on some of the convo in this thread I decided to pick up the JBL Fuse. One thing I really missed from my previous car was crazy midbass from my fiberglassed door enclosures. For whatever reason in that car, I had not large cab mode issue after building door enclosures. I'm not willing to cut my doors up yet so for now I've been playing around with distributed midbass and front subs.
> 
> My front door drivers are Anachy 7s. Unfortunately I have a giant whole on the left mid below 80 Hz, so that's the limit for door midbass regardless of how much displacement the mids are capable of. Not to mention the doors cant handle it.
> 
> ...


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## lithium (Oct 29, 2008)

SloVic said:


> Nice, had similar ideas but was looking at the Focal ISUB TWIN to experiment with. So the JBL's can be Mounted together? Pretty cool, seams like it might give you the benefit of manifold mounting... drivers cancel each other out to drastically lower enclosure vibrations. Makes me feel better about my idea of using 2 Dayton RSS210HO-8 in the passenger footwell then a pair of RSS390HF-4 in the rear. From what I've read you get a ton of loading (around 12-15db) in the mid 30's to 90ish in that spot, at least in midsize sedan. Seams great for taking the load of midbass and allowing a very low LPF for rear subs, plus the killer efficiency for the front sub.


I thought about trying the focal as well. Not sure if there are any US distributors. I was also considering a dayton HO 10 upfront instead but all the fiberglass work is a pain when I dont have a garage right now..


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## lithium (Oct 29, 2008)

Bikey said:


> Did you end up overlapping the frequencies from the Fuses and the woofers in your 3 way?
> Did you take ny measurements?


When I was running them stereo under each seat I had tried overlapping the door woofers. This actually worked well. It evened the response out (fixed a null or two) but I still had some underseat tactile feedback that annoyed me. Also some wiring under the seat was buzzing and needs wrapped in CCF. 

I'll see if I have any measurements saved. I had REW crash halfway through tuning.


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## SiW80 (Mar 13, 2019)

Did you try them mono under the seats?


Sent from my iPhone using Tapatalk


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## lithium (Oct 29, 2008)

SiW80 said:


> Did you try them mono under the seats?
> 
> 
> Sent from my iPhone using Tapatalk


Nope, I would have tried if not for the vibe issue with the driver side seat.


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## SloVic (Oct 1, 2016)

SiW80 said:


> Did you try them mono under the seats?
> 
> 
> Sent from my iPhone using Tapatalk


I think @dumdum runs his in mono. Under the seats crossed from 60-160hz I believe, seams to work well for him.


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## Bikey (May 15, 2021)

Regarding the tactile feedback - how was the Fuse mounted?


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## lithium (Oct 29, 2008)

It was just sitting under the seat on the carpet. Wasn't touch anything so just the pressure near the seat bottom was enough to excite the seat. Maybe if I raised the seat a bit more it wouldn't be so much an issue. Or just lowering the level. The enclosures themself are quite damp.


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## dumdum (Feb 27, 2007)

I had to build a ‘rabbit hutch’ under the drivers seat to reduce tactile feedback from the drivers side midbass and I also did a number on the seat frame with deadener


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## Bikey (May 15, 2021)

I didn't understand the rabbit hutch but now it makes sense - it is essentially to try to direct airflow to the front of the seat instead of directly up to the bottom/front of the seat?
Does it not just result in more tactile feedback on the back of your legs or is the front area wide enough that it dissipates to something not noticeable?


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## bugman72 (Feb 5, 2021)

I just stumbled across this thread and am very intrigued. I have been trying to figure out solutions to increase midbass response of my current system in my '91 Chevy Indy Pace Truck. I am trying to maintain the integrity of the interior as much as possible, so finding subtle/hidden solutions are a plus. I am currently running an active 3-way front stage with my midbass drivers located in kick panels that I made. They aren't giving me the desired results I'm searching for, which brings me here.

I am going to print out Patrick's enclosure for the Aura/Dayton driver. Since I have a pair of midbass drivers in kick panels currently, should I only do one of Patrick's enclosures, or should I do two? And how should I power it/them? I don't have any free channels on my DSP nor extra free channels of amplification? Not opposed to adding an amp if this proves to be beneficial, but want to get past proof of concept first.


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## lithium (Oct 29, 2008)

What drivers are installed in the kick panel?


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## bugman72 (Feb 5, 2021)

Currently I have a pair of Savard 6" Rap V2s. Part of my issue is that the kicks are a bit too small...I know that. I will more than likely, at some point rebuild them a bit larger. But even so, I don't think I will have the output I need with just the pair. And placing them or another pair in the doors is not an option. '88-94 trucks did not have any speakers in the doors and I do not want to cut up the original door panels.


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## lithium (Oct 29, 2008)

Are they sealed? before building them bigger you could vent them out the back. Where is the missing output? Have you tried bring the subs up higher to compensate? 

Other option would be to try underseat midbass like the JBL fuse or build something like patrick's enclosures. Wire them parallel off the midbass channels on your current amp to try out.


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## bugman72 (Feb 5, 2021)

They were sealed, but I have since vented them from the back. Helped, but not enough. Sub is crossed at 80Hz (8" Savard Rap D4 in 4th order bandpass). I have midbass response, just not as much as I want. At lower volumes, midbass response completely disappears. At reference/demo levels it's decent.

This is why I am wanting to do Patrick's enclosures for the Daytons. The question I still have is do I run a pair of his enclosures (one under each seat) or just one. My thought is to go with a pair for ease of wiring them up with the midbass channels. I hope to upgrade my DSP at some point to something with more output channels. At that point I could give them their own DSP channels and amplification.


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## lithium (Oct 29, 2008)

You would want to run a pair.


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## KillerBox (Jan 7, 2011)

I ordered the JBL Fuse speakers in a hope that I could figure a way to make them fit. But I haven't figured out a way yet. They are just too big for my Lexus LX 470.

So I wanted to see if anyone else had any ideas? I have Focal K2 KRX3 6.5" in my doors with 300w each available but, my midbass in the 100hz to 200hz is about 3 to 6 DBs too low. 

P.S. I have 3 Arc Audio xDI 1200.6 of power bridged down to 12 channels, so I have plenty of amplifier channels to choose from. DSP is JBL MS8 in 5.1 mode.


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## SiW80 (Mar 13, 2019)

KillerBox said:


> I ordered the JBL Fuse speakers in a hope that I could figure a way to make them fit. But I haven't figured out a way yet. They are just too big for my Lexus LX 470.
> 
> So I wanted to see if anyone else had any ideas? I have Focal K2 KRX3 6.5" in my doors with 300w each available but, my midbass in the 100hz to 200hz is about 3 to 6 DBs too low.
> 
> P.S. I have 3 Arc Audio xDI 1200.6 of power bridged down to 12 channels, so I have plenty of amplifier channels to choose from. DSP is JBL MS8 in 5.1 mode.


Would focal iSub Twin fit instead?


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