# Tapped Horns in the Car



## Patrick Bateman (Sep 11, 2006)

Someone sent me an email asking about how to go about making a tapped horn for the car, so thought I'd post some things that worked for me. I've been running one in the car for about a month, and at home for over a year. I built both of them myself.

If you have access to measurement equipment, tapped horns are difficult to beat. Compared to a sealed box, a tapped horn is almost six DB more efficient. But that's only half the story; due to the way they work, tapped horns work well with *insanely* efficient woofers.

For example, let's say you're looking for a subwoofer to use in your car, and it's going in a sealed box. You might wind up with something like this:










That woofer has an efficiency of 84db.

Due to the nature of a tapped horn, it shines with woofers like this:










That woofer has an efficiency of 93db.

Their power handling is basically identical. (750 for the first, 700 for the second.)

So the big difference is the subwoofer box. Because the tapped horn has output from the front *and* the rear of the cone, it has an SPL advantage of close to 6db over a conventional box. But the *real* bump in efficiency comes from the fact that you can use outrageously efficient prosound woofers in a tapped horn, woofers like the one I'm showing above, that have a 9db efficiency advantage over the JL woofer.

Put these two things together, and you have a sub box that can play about 10-15db louder than a sealed sub box. To give you an idea of how ridiculously loud that is, let's say you're running a tapped horn with 500 watts. If the JL is 13db less efficient, you'd need TEN THOUSAND watts to get to the same volume level 

Now someone will probably wonder, "why can't I just buy a more efficient woofer? Why use the JL?" The reason is Hoffman's Iron Law. Hoffman's iron law teaches us that efficiency and box size are related. The lower you want a woofer to play, the bigger box it will need. But that's the key to the tapped horn - they don't need woofers that play low. In fact they work quite well with woofers that would normally work better as midranges. The subwoofer that's sitting in my car _right now_ has a midbass in it. For sub duty. I could explain why it works, but it would take another page 

Before you run out and go build one, here are some things I'd recommend doing first:

Take a look at these pages:

Tapped Horn Experiments

diyAudio Forums - The Smallest Tapped Horn - Page 1

the mother of all tapped horn threads, 137 pages and counting:
diyAudio Forums - Collaborative Tapped horn project - Page 1

Then get some measuring equipment, and get familiar with cabin gain. In order to get these huge efficiency gains, tapped horns have a fairly ragged response, and cabin gain will affect that too.

Last but not least, if you think it's impossible to make a subwoofer that's 99db efficient, take a look at this tapped horn that's *110 db efficient.*

DANLEY | TAPPED HORN SUBWOOFER 812


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## ItalynStylion (May 3, 2008)

Patrick, thank you for doing this. I'm very interested in learning to design these things but I just needed to be pointed in the right direction.

My questions are more about the design than anything else. I know that you take the frequency, calculate the quarter wavelength, and your horn length must be that long to the tap/opening. Are there rules for how big the opening needs to be? Also, how wide does the internal area of the box need to be per woofer? How do you figure that out?

I've read repeatedly that adding more woofers will smooth out the response but where do you add the second woofer? Is it just higher up in the horn throat? Does the opening need to be made bigger for more woofers?

PS: That last link is dead


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## Patrick Bateman (Sep 11, 2006)

ItalynStylion said:


> Patrick, thank you for doing this. I'm very interested in learning to design these things but I just needed to be pointed in the right direction.
> 
> My questions are more about the design than anything else. I know that you take the frequency, calculate the quarter wavelength, and your horn length must be that long to the tap/opening. Are there rules for how big the opening needs to be? Also, how wide does the internal area of the box need to be per woofer? How do you figure that out?
> 
> ...


In a regular horn, as you make it smaller it gets peakier. Tapped Horns behave a bit strangely, as it's basically two horns in one. There's a quarter length horn, but there's also a half wave horn, in the same encolsure. That's why it's difficult to predict what it will sound like with computer simulations.

Thirty years ago there was a similar box called the transflex, but it didn't catch on because it wasn't possible to sim it (at the time.)

In my experience, tapped horns actually get smoother if you make them small, and tend to get peaky if you make the box bigger. But a lot is going to depend on the woofer's parameters.

As for the mouth size, I'd say 2X the woofer's cone size is a minimum. So for your typical 8" woofer with an SD of 35", I'd use a 8.33" x 8.33" mounth as a minimum. (8.33" x 8.33" = 70".) It's pretty difficult to make the mouth TOO big, and using a mouth that's too small has all kinds of drawbacks. Keep in mind that the woofer itself is sitting in the mouth, so take that into account too.

Probably the safest bet is to just take an existing box, and scale it up or down. I've published a couple, Volvotreter has, and a lot of the Danley designs are pretty easy to figure out by just looking at the published pictures. The impedance curve of the woofer can give you a lot of clues as to how long the length is.


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## finbar (Feb 1, 2009)

Patrick, very interesting.
I read of the sonotube horn, assembed in sections. It occurs to me that if the divider was dadoed where it contacts the tube wall, sealant injection holes could be drilled in the tube wall, from outside, at the dado. With the divider installed, inject sealant until it comes out adjacent holes, filling the dodo. This may avoid having to assemble in sections. I hope this makes sense. Thanks for the great food for thought.


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## annoyingrob (Aug 24, 2007)

This is one of the many projects on my "to do" list. MAYBE this summer..........


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## Brian Steele (Jun 1, 2007)

I'd like to see a good TH design that provides decent output, fits well within the car and doesn't take up a whole lot of trunk space to do what it has to do. 

It's kinda hard though to give up the convenience and simplicity and trunk space saved by using two 12" drivers in a sealed spare tire well sub... .

IMO, HornResp, while a great tool, would be so much more useful for modelling these things if it allowed real-time viewing of the modelled frequency response while changing the alignment parameters, rather than change parameters-calculate-view frequency response-change parameters-calculate-view-frequency response, etc...

Hmm... what about TH with an 8" driver folded up to fit in the spare tire well...


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## lilmike (Jan 4, 2008)

Check the latest version of Hornresp. 

It does what you're asking, and more.

The tapped horn wizard is much easier to use.


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## Brian Steele (Jun 1, 2007)

I've downloaded and looked at the latest version. It doesn't have the features I described.

Let me describe it another way - it would be nice if, in HornResp's SPL response window, we could vary the horn parameters and immediately see the effect on the SPL response. As an option to speed up processing, and option to reduce the number of data points could be nice too.


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## lilmike (Jan 4, 2008)

The tapped horn wizard can do this. I use it regularly.

To get there - open a tapped horn simulation, click edit, then select the tapped horn wizard from the tools menu.

To see response, select "Response" from the leftmost dropdown menu.

To change to a variable S2, select that from the middle dropdown.

Play with the sliders and watch the changes.


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## Patrick Bateman (Sep 11, 2006)

Brian Steele said:


> I'd like to see a good TH design that provides decent output, fits well within the car and doesn't take up a whole lot of trunk space to do what it has to do.
> 
> It's kinda hard though to give up the convenience and simplicity and trunk space saved by using two 12" drivers in a sealed spare tire well sub... .
> 
> ...


Brian,

On Sunday I measured my tapped horn with a 12", then measured my old sub too. The old sub uses dual twelves in a transmission line.

The data was interesting.

The tapped horn had an insane efficiency advantage above 60hz, but below there the two boxes were virtually identical.

Dan Wiggins is probably getting a chuckle out of this, since it's Hoffman's Iron Law rearing it's ugly head.


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## Brian Steele (Jun 1, 2007)

lilmike said:


> The tapped horn wizard can do this. I use it regularly.
> 
> To get there - open a tapped horn simulation, click edit, then select the tapped horn wizard from the tools menu.
> 
> ...


Ah, now I see. I was looking in the wrong location.

Thanks!


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## Patrick Bateman (Sep 11, 2006)

A few days ago I posted the measured response inside my car. (Which is where I'll use it.)

Here's the measured response outside:










The orange and the red graphs are the tapped horn. I took two measurements, at equal distances, to isolate high frequency peaks.

Note the SPL levels aren't calibrated whatsoever; I just crank up the volume to get plenty of clean signal.

For comparison's sake, the blue lines are my old sub, which is a transmission line that uses dual 12" woofers.

The interesting part is that they're practically identical below 50hz! Hoffman's Iron Law at work 

But check out the efficiency from 40-80hz. To get the same efficiency with the transmission line at the same power, you'd need to use 4-6 of them!!!

The transmission line uses dual woofers, and is built LIKE A TANK. In addition to the serpentine construction, it also has cross braces and it's metal plated!










The pic shows three of my subs. The old transmission line, the new tapped horn, and my bandpass subwoofer from my home theater.

The tapped horn is basically an unqaulified success. It's more efficient, uses one woofer instead of two, is easier to build, and weighs less than HALF as much. The TL is 73lbs, the TH is 35lbs. The bandpass clocks in at a svelte 28lbs, thanks to it's sonotube construction 

diyAudio Forums - Tapped Horn for Dummies - Page 3


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## chad (Jun 30, 2005)

The band is thinking about going at it again.. the last time we thought about it we had a successful 13 year run  I'm requesting new subs and thinking 4Xsingle 18" tapped horns.


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## Brian Steele (Jun 1, 2007)

Patrick Bateman said:


> For comparison's sake, the blue lines are my old sub, which is a transmission line that uses dual 12" woofers.


That's quite small for a TL. What's the impedance response look like? And what drivers are those? 

Any way you cut it though, that TL still a big-ass box for a 12" driver 

I'd like to see something similar done with a 10" or even an 8", with a target volume of around 2.5 cu.ft. or less. I was trying to model a TH with an 8" pro driver, and not getting very good results...


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## Patrick Bateman (Sep 11, 2006)

Brian Steele said:


> That's quite small for a TL. What's the impedance response look like? And what drivers are those?
> 
> Any way you cut it though, that TL still a big-ass box for a 12" driver
> 
> I'd like to see something similar done with a 10" or even an 8", with a target volume of around 2.5 cu.ft. or less. I was trying to model a TH with an 8" pro driver, and not getting very good results...


The bandpass is my fav, the MCM 55-2421. Best $25 woofer ever.
The TL has dual Dayton DVC 12s, which are basically a clone of the original Adire Audio Shiva. (At the time, Dan Wiggins had discontinued the Shiva, otherwise I would have bought those instead.)
The tapped horn uses a P-Audio SN-12MB. The response with 3-4 MCM 55-2421s is virtually identical, and cheaper.

Google "smallest tapped horn" for details on how to build this.

I prefer the P-Audio because it's weight is very low.


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## Brian Steele (Jun 1, 2007)

Patrick Bateman said:


> The bandpass is my fav, the MCM 55-2421. Best $25 woofer ever.
> The TL has dual Dayton DVC 12s, which are basically a clone of the original Adire Audio Shiva. (At the time, Dan Wiggins had discontinued the Shiva, otherwise I would have bought those instead.)
> The tapped horn uses a P-Audio SN-12MB. The response with 3-4 MCM 55-2421s is virtually identical, and cheaper.
> 
> ...


The Dayton DVC 12s look identical to the Shiva - I'll doubt you'd have noticed any difference in response. 

Here's my first attempt at a TH alignment - the FR graph looks ok, but I have no idea how to actually implement this in wood, LOL

Driver: Eminence Deltalite II 2510 Neo 10" Driver
Vas	=	53.8 
Qts	=	0.420 
Qes	=	0.450 
Qms	=	5.760 
Re	=	5.060 
Fs	=	53.0 
Le	=	1.00 
Xmax	=	4.2 

TH parameters (for HornResp)

S1=486 sq. cm
S2 = 124 sq. cm
S3 = 540 sq. cm
S4 = 705 sq. cm
L12=47 cm
L23=159 cm
L34=29 cm

Total length=235 cm

Target response = F3~ 50Hz, with shallow rolloff (better match for car audio environment. 

And yes, S2 is about half Sd 

Thoughts??


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## splicer (Oct 4, 2008)

I have a strong desire to see a Tymphany LAT based tapped horn. I'm not sure why. Probably for the wierdness factor.


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## Brian Steele (Jun 1, 2007)

Brian Steele said:


> The Dayton DVC 12s look identical to the Shiva - I'll doubt you'd have noticed any difference in response.
> 
> Here's my first attempt at a TH alignment - the FR graph looks ok, but I have no idea how to actually implement this in wood, LOL
> 
> ...


Another attempt, same driver.....

S1=400
S2=400
S3=400
S4=400
L12=22
L23=178
L34=11

Wider bandwidth, easier to implement, better low end, and a bit shorter as well...


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## lilmike (Jan 4, 2008)

Glad you figured out the wizard. 

Interesting idea - a tapped pipe. It would be an easy build.

When considering frequencies above 40 Hz, it looks like the driver reaches xmax at about 20 watts, xmech at about 100 watts. Admittedly, it will be making a fair amount of noise with that level of power (115 dB 2pi). 

The impulse response looks kind of rough (to see that - have the SPL window open, then open the tools menu, hornresp can calculate the impulse response, as well as export it as a wav file which is really interesting).

There is a ton of information about folding these up on the web, as well as over at diyAudio in the collaborative thread. The simplest tapped horn I've built only required 7 boards, - only one more than a typical sealed or ported box.


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## chithead (Mar 19, 2008)

This has me curious about a dual 8" tapped horn for a computer sub, and possibly a single 10" for my brother's car... I have quite a few 8" speakers laying around and some pretty beefy 10" subs.


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## Oliver (Jun 25, 2007)

chithead said:


> This has me curious about a dual 8" tapped horn for a computer sub, and possibly a single 10" for my brother's car... I have quite a few 8" speakers laying around and some pretty beefy 10" subs.


Fold that horn and tap those mothers 

Hell, even stuff something if you can


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## chithead (Mar 19, 2008)

a$$hole said:


> Fold that horn and tap those mothers
> 
> Hell, even stuff something if you can


I got me some reading to doooo.....


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## Patrick Bateman (Sep 11, 2006)

Brian Steele said:


> Another attempt, same driver.....
> 
> S1=400
> S2=400
> ...


The first tapped horn that I built had an undersized mouth, and not much of a taper. It didn't live up to my expectations. I'd recommend a generously sized mouth. Keep in mind the driver SITS in the mouth, so you need to factor that in too.

I really need to haul the old one outside and measure it, but that would require moving it up three flights of stairs...


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## Brian Steele (Jun 1, 2007)

lilmike said:


> Glad you figured out the wizard.
> 
> Interesting idea - a tapped pipe. It would be an easy build.
> 
> When considering frequencies above 40 Hz, it looks like the driver reaches xmax at about 20 watts, xmech at about 100 watts. Admittedly, it will be making a fair amount of noise with that level of power (115 dB 2pi).


A by-product of the driver's low Xmax. Perhaps pro audio drivers aren't the best match for tapped horns if you're looking for insane output levels or power handling. It would explain why Danley went for car audio drivers for his THs at one point, if I heard correctly.




lilmike said:


> The impulse response looks kind of rough (to see that - have the SPL window open, then open the tools menu, hornresp can calculate the impulse response, as well as export it as a wav file which is really interesting).


I'm not sure how relevant the impulse response would be to an alignment that's basically going to be bandwidth limited to 100 Hz and below. What's your view?


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## Brian Steele (Jun 1, 2007)

chithead said:


> I got me some reading to doooo.....


Bear in mind, TNSTAAFL. THs are still quite large compared to sealed alignments with the same driver. My example TH for a 10" driver takes up 3 cu.ft. net - enough space for three 12" drivers .


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## Brian Steele (Jun 1, 2007)

Patrick Bateman said:


> The first tapped horn that I built had an undersized mouth, and not much of a taper. It didn't live up to my expectations. I'd recommend a generously sized mouth. Keep in mind the driver SITS in the mouth, so you need to factor that in too.
> 
> I really need to haul the old one outside and measure it, but that would require moving it up three flights of stairs...


I was planning to widen the mouth right at the location of the driver, similar to what you did for your TH. 

I've come up with some pretty zany theoretical THs via HornResp, now the I know how to use the wizard properly. Like a tapped Voight-Pipe looking thingy for a low-Q driver, and another that has the driver mounted centrally, with a closed TL one one end and a cylinder with decreasing diameter on the other. Folding those should be fun, if I was to try implementing them in actual wood .


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## lilmike (Jan 4, 2008)

Brian Steele said:


> A by-product of the driver's low Xmax. Perhaps pro audio drivers aren't the best match for tapped horns if you're looking for insane output levels or power handling. It would explain why Danley went for car audio drivers for his THs at one point, if I heard correctly.


Honestly - it depends on the bandwidth and SPL you are after. Some pro drivers do very well. I am using a cheap dayton 6.5" pro midrange as the driver in my tapped horn in my shop. It is certainly limited by excursion, but works well enough that I have not bothered to replace it yet. Other pro drivers (the Eminence 4012 and 3015LF) are popular TH drivers, but require large enclosures. Car drivers tend to model pretty well, though I will admit I've not built a TH with a car sub yet. I have several ideas and drivers waiting, but the available time for making sawdust just isn't there now.



Brian Steele said:


> I'm not sure how relevant the impulse response would be to an alignment that's basically going to be bandwidth limited to 100 Hz and below. What's your view?


Based on all the subs that I have listened to, I really do think the lack of ringing in an impulse response matters, think a muffled thud versus a clean thump. Export the wavs of a good and bad impulse response from hornresp, then listen to them, it is revealing. The tapped horn I just designed and built has a particularly good impulse response (it was an accident...there was no way to extract impulse responses when I was designing that one). I came away very impressed with the tightness of the bass and the impact it created. All else being equal, if you can reduce the ringing in the impulse response, you will have a better sounding sub.


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## chithead (Mar 19, 2008)

I wonder how the DIYMA R12 would do in a tapped horn...


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## Brian Steele (Jun 1, 2007)

lilmike said:


> Based on all the subs that I have listened to, I really do think the lack of ringing in an impulse response matters, think a muffled thud versus a clean thump.


Did you run the exported impulse response through a LP filter to mimic how the TH sub would actually be used?


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## Patrick Bateman (Sep 11, 2006)

Brian Steele said:


> A by-product of the driver's low Xmax. Perhaps pro audio drivers aren't the best match for tapped horns if you're looking for insane output levels or power handling. It would explain why Danley went for car audio drivers for his THs at one point, if I heard correctly.
> 
> 
> 
> ...


That's one of the strangest things about tapped horns. It really took a while to wrap my brain around that. Due to basic laws of physics, no matter how efficient the enclosure is, the box with higher displacement will always play lower and louder.

Taken to an extreme, I was able to simulate a tapped horn which maxed out around one watt!

That was another mistake I made with my *first* tapped horn; I'd used a resistor to lower the F3 by raising the QTS of the woofer, but at the same time it nuked the power handling, due to a lack of excursion.

Despite all this, I still think tapped horns in the car make a lot of sense. We get free SPL at low frequencies thanks to cabin gain, which is right where we need it.

Note that cabin gain with a tapped horn appears to be a little bit less than it is with a sealed sub. There's probably a relationship between the efficiency of a particular design and how much cabin gain plays a role. (IE, an enclosure that has a high efficiency from 20-100hz will see less cabin gain.)


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## chad (Jun 30, 2005)

Brian Steele said:


> A by-product of the driver's low Xmax. Perhaps pro audio drivers aren't the best match for tapped horns if you're looking for insane output levels or power handling. It would explain why Danley went for car audio drivers for his THs at one point, if I heard correctly.


Meh, i think he just prefers those types of parameters... Note how well the Lab horn driver resembles a "car audio driver"


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## Brian Steele (Jun 1, 2007)

chad said:


> Meh, i think he just prefers those types of parameters... Note how well the Lab horn driver resembles a "car audio driver"


Yeah, but there's a very BIG difference in parameters between the MTX driver used in the TH with its high Qts and high Fs and the LAB12 driver with its mid Q and low Fs .

The common factor is Xmax, which is quite high for both (when compared to pro audio drivers), and his choice of drivers with this characteristic makes sense when you consider the smaller box size + lower F3 targets for his designs.


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## lilmike (Jan 4, 2008)

Brian Steele said:


> Did you run the exported impulse response through a LP filter to mimic how the TH sub would actually be used?


No, I did not. As I said - the impulse response tool came along after the horn was designed. It was purely luck (or excellent design skills - but I'm going with luck) that it sounds as good as it does. 

As I understand the impulse response tool (and I may be WAY off base - I'm no acoustical engineer) it it a tool to show us the resonance of the enclosure's response to a pulse input. In other words - the best output is a single pulse. If you model a sealed box in hornresp, you see a single large peak in the impulse response, with the remaining peaks (later in time) at 20% or less of the original and decaying with time. Tapped horns - at their best - will have a small initial pulse, then a larger pulse, then the decaying pulses at lower magnitudes. The TH I just did has these secondary peaks below 20% of the original, and are all but gone after 60 ms. Other sims I have show peaks at 50% of the original magnitude at 60 ms. Listening to the exported wav files of these two models is where the thump (good) vs thud (bad) comparison came from. As I understand it, the original impulse gets smeared out through time due to resonances in the enclosure.

While I have been working with tapped horn enclosures for a year or so, I am no guru. My understanding and assertions here may be entirely off base. I have had no formal training in acoustics or engineering, I'm purely a self-educated amateur.

I have figured a few things out, mostly by screwing stuff up. Measurements have helped me a lot. Accurate impedance and frequency response measurements are absolutely key in understanding what is going on, especially when things are not what what was predicted. Playing with hornresp is a good start, but it is ultimately just pushing pixels.


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## lilmike (Jan 4, 2008)

chithead said:


> I wonder how the DIYMA R12 would do in a tapped horn...


Not too well I'm afraid - Patrick Bateman has tried, I did too. Very peaky response. There are better driver choices, I tend to use 6's, 8's and 10's in mine, the boxes get HUGE for 12s and 15's.


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## chad (Jun 30, 2005)

Brian Steele said:


> Yeah, but there's a very BIG difference in parameters between the MTX driver used in the TH with its high Qts and high Fs and the LAB12 driver with its mid Q and low Fs .
> 
> The common factor is Xmax, which is quite high for both (when compared to pro audio drivers), and his choice of drivers with this characteristic makes sense when you consider the smaller box size + lower F3 targets for his designs.


Agreed, and again agreed on the X-Max thing which COULD be why he tends to look this direction in drivers... and also the possibility due to the proliferation of AFFORDABLE larger X-Max drivers. I'd be all about using a car oriented woofer live if I could trust myself with them but I'm still under the gross assumption that car audio drivers have grossly exaggerated power handling specs.


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## Brian Steele (Jun 1, 2007)

FWIW, I just did my first attempt at a "tapped pipe" this weekend. A tapped pipe is basically a tapped horn with a constant cross-sectional area (Sd). This makes it a bit easier to fold it in two dimensions. I used a cheap Pyramid 6.5" driver for the exercise (the prime purpose of the exercise was to test the accuracy of HornResp in predicting the response of these alignments). 


Results can be seen here: 
HornResp, tapped pipes.... - Techtalk at Parts-Express.com


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## Chaos (Oct 27, 2005)

Dammit. You're going to make me want to build one of these next


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## Patrick Bateman (Sep 11, 2006)

Brian Steele said:


> Yeah, but there's a very BIG difference in parameters between the MTX driver used in the TH with its high Qts and high Fs and the LAB12 driver with its mid Q and low Fs .
> 
> The common factor is Xmax, which is quite high for both (when compared to pro audio drivers), and his choice of drivers with this characteristic makes sense when you consider the smaller box size + lower F3 targets for his designs.


IMHO, Danley didn't understand all the variables when he created the "tower of power." If you look at all of his recent tapped horns, he's gravitated towards prosound drivers with a relatively high FS and just un-fcuking-believable power handling.

Based on my own experiments with tapped horns, they're a lot smoother than the sims predict, and they play remarkably low with high FS drivers. Unless you're putting a TH in a home theater, stick with a woofer with a high FS. And get one with gobs and GOBS of power handling, because tapped horns don't have issues with excursion like a sealed sub.

This isn't a diss on Danley - it's just a very VERY complex subwoofer. Even Akabak will only get you "in the ballpark." The real-world results are a lot different than the sims, particularly in respect to power handling and smoothness.


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## Patrick Bateman (Sep 11, 2006)

Brian Steele said:


> FWIW, I just did my first attempt at a "tapped pipe" this weekend. A tapped pipe is basically a tapped horn with a constant cross-sectional area (Sd). This makes it a bit easier to fold it in two dimensions. I used a cheap Pyramid 6.5" driver for the exercise (the prime purpose of the exercise was to test the accuracy of HornResp in predicting the response of these alignments).
> 
> 
> > I did a tapped pipe about a year ago... google "tapped horn for dummies."
> ...


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## Brian Steele (Jun 1, 2007)

Patrick Bateman said:


> I did a tapped pipe about a year ago... google "tapped horn for dummies."
> 
> Didn't turn out too well; it's not behaving like the simulation predicted. IMHO, the problem was that I didn't factor in the volume of the woofer into the model, and I used a mouth that was dramatically undersized. Combine these two things and the TH concept falls apart...


There seems to be a fairly decent match between what HornResp predicted for my pipe and what I've actually measured, particularly when I tweak the HornResp params to match the actual length of the pipe (I got the measurements wrong and the pipe ended up being 179 instead of 199cm). The FR is a good match in the passband (I didn't expect much of a match outside of that because of the effect the folds would have on the response in that area). The impedance curve is also a decent match in terms of frequencies - impedance is off, likely due to losses and the fact that my folded pipe is not a "perfect" pipe. 



Patrick Bateman said:


> My second try worked fantastic, very happy with it. google "smallest tapped horn."


I actually read both of those threads and many others, before attempting my P.O.C. I chose a high Sd to avoid the "magnet blocking the output" issue, and basically adjusted the length of the pipe in HornResp until I got something I was happy with. If I'd spent a bit longer, I might've gotten the length right before I started cutting wood . Interestingly enough, the Dayton 8" series II would be a direct replacement for the cheap driver I used for the P.O.C - if only I'd made one dimension of the cross-section more than 8"... 

I'd likely be making another attempt at one as soon as I get my hands on a suitable driver. This time an Excel spreadsheet will be calculating the dimensions for me... 

I aim to put up a page soon about the P.O.C., and comparing its output against simple sealed / vented alignments using the same driver. Just as soon as I can find the time...


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## thehatedguy (May 4, 2007)

Can you realistic subbass with the TH you did in the car? Will it play down to 20?


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## Patrick Bateman (Sep 11, 2006)

Brian Steele said:


> There seems to be a fairly decent match between what HornResp predicted for my pipe and what I've actually measured, particularly when I tweak the HornResp params to match the actual length of the pipe (I got the measurements wrong and the pipe ended up being 179 instead of 199cm). The FR is a good match in the passband (I didn't expect much of a match outside of that because of the effect the folds would have on the response in that area). The impedance curve is also a decent match in terms of frequencies - impedance is off, likely due to losses and the fact that my folded pipe is not a "perfect" pipe.
> 
> 
> 
> ...


Yes, in my experience hornresp works really well, unless you fail to take certain things into account... For instance a woofer that's covering up 75% of your horn's mouth 










Also, these things are still horns, so flaring the mouth flattens the response. Can't do that with a tapped pipe. Also, designing the mouth to "mate" with a boundary will lower your F3 by extending the mouth.


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## TJ Mobile Audio (May 6, 2009)

Patrick Bateman said:


> Yes, in my experience hornresp works really well, unless you fail to take certain things into account... For instance a woofer that's covering up 75% of your horn's mouth


Seems like that would make quite the difference, lol.

Here's one I'd like to build but it won't fit in the Sentra, lol. Outside dimensions are 48" x 32" x 24", and the mouth is about 2' x 4'. I'd probably put a brace in the mouth also. Path length would be 9 or 10 feet, I'd probably need a sub with a fairly high Fs. I doubt it's big enough to play below 30 Hz, though, I just drew it up for fun when I was brainstorming for an extended cab truck project. Any glaringly obvious mistakes? I know there's a bit of trial and error with these, but I think it's worth avoiding unnecessary errors if I do get the chance to build one of these some time.


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## Patrick Bateman (Sep 11, 2006)

Looks sharp. At this point I think it's easier to design the box first, then plug the numbers into Horn Resp or Akabak. Basically figure out what size box will fit, then start trying different woofers until the response is smooth.

Tapped horns also seem to like snail shapes, which minimize the number of bends. Kind of like the ol' Lab Sub.


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## Brian Steele (Jun 1, 2007)

Patrick Bateman said:


> Yes, in my experience hornresp works really well, unless you fail to take certain things into account... For instance a woofer that's covering up 75% of your horn's mouth


Ouch! Did you try flipping the driver around? Perhaps it would have less of an effect if the magnet was located in the throat, rather than the mouth.




Patrick Bateman said:


> Also, these things are still horns, so flaring the mouth flattens the response. Can't do that with a tapped pipe. Also, designing the mouth to "mate" with a boundary will lower your F3 by extending the mouth.


I'm wondering if it would actually make that much difference, as, unlike a real horn, a TH's "mouth" can be significantly smaller than 1/4 wavelength of Fc.


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## Brian Steele (Jun 1, 2007)

Brian Steele said:


> There seems to be a fairly decent match between what HornResp predicted for my pipe and what I've actually measured, particularly when I tweak the HornResp params to match the actual length of the pipe (I got the measurements wrong and the pipe ended up being 179 instead of 199cm).


Just want to correct this - I was actually quite close to the target length for the TH - it looks like a leak around the driver is what led to the incorrect LF measurements.


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## TJ Mobile Audio (May 6, 2009)

Patrick Bateman said:


> IMHO, Danley didn't understand all the variables when he created the "tower of power." If you look at all of his recent tapped horns, he's gravitated towards prosound drivers with a relatively high FS and just unbelievable power handling.
> 
> Based on my own experiments with tapped horns, they're a lot smoother than the sims predict, and they play remarkably low with high FS drivers. Unless you're putting a TH in a home theater, stick with a woofer with a high FS. And get one with gobs and GOBS of power handling, because tapped horns don't have issues with excursion like a sealed sub.
> 
> This isn't a diss on Danley - it's just a very VERY complex subwoofer. Even Akabak will only get you "in the ballpark." The real-world results are a lot different than the sims, particularly in respect to power handling and smoothness.


I've wondered the same thing, whether pro drivers with their higher Fs would work well. However, for some reason I got the impression Xmax was still an issue, could you clarify what you meant when you said "tapped horns don't have issues with excursion like a sealed sub."? I thought below a certain point the drivers would begin to unload. Would you just need a high-pass filter to avoid that?



Patrick Bateman said:


> Looks sharp. At this point I think it's easier to design the box first, then plug the numbers into Horn Resp or Akabak. Basically figure out what size box will fit, then start trying different woofers until the response is smooth.
> 
> Tapped horns also seem to like snail shapes, which minimize the number of bends. Kind of like the ol' Lab Sub.


I did try to utilize the snail shape for the last few bends in my design. However, it seemed impossible in my space constraints to get a long enough path length without those first two "switchbacks". The Lab subwoofer is 22.5"x48"x48" IIRC, while mine is only 24"x32"x48", they have an extra 16" of depth to work with.

Unfortunately, I have a bit of a personal vendetta against the Microsoft operating system, so it looks like I won't be using Hornresp or Akabak unless I borrow someone else's computer. Unless someone knows of a Linux or Mac equivalent.



Brian Steele said:


> I'm wondering if it would actually make that much difference, as, unlike a real horn, a TH's "mouth" can be significantly smaller than 1/4 wavelength of Fc.


That's good to hear, that has been one concern keeping me from building one, I didn't realize the mouth could be smaller. I was worried that the mouth on my design would be too restrictive, but if the "tapped pipe" concept works I should have no worries.



Brian Steele said:


> Just want to correct this - I was actually quite close to the target length for the TH - it looks like a leak around the driver is what led to the incorrect LF measurements.


Though I know you've been here longer than me, I'll still say it's good to see people like you frequenting this forum. I've been a fan of your webpage for a long time and have used it (and will continue to use it) as inspiration for several of my own projects. I've got a few too many questions for this thread, so I'm going to send you a PM momentarily.


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## Brian Steele (Jun 1, 2007)

TJ Mobile Audio said:


> I've wondered the same thing, whether pro drivers with their higher Fs would work well. However, for some reason I got the impression Xmax was still an issue, could you clarify what you meant when you said "tapped horns don't have issues with excursion like a sealed sub."? I thought below a certain point the drivers would begin to unload. Would you just need a high-pass filter to avoid that?


Below Fc, the driver unloads, so , the TH should be treated like you'd treat any over vented alignment below that point.

The TH also acts like a high-order bandpass system, there will be excursion minimums within the passband, including one at Fc. However, there are no miracles - to move air the driver cone must move . HornResp will also predict the excursion at your chosen input voltage. 




TJ Mobile Audio said:


> That's good to hear, that has been one concern keeping me from building one, I didn't realize the mouth could be smaller. I was worried that the mouth on my design would be too restrictive, but if the "tapped pipe" concept works I should have no worries.


It can be MUCH smaller. Have a look at the designs at Tapped Horns for example. Smaller mouths will reduce efficiency, but also smooth the response out - and of course you'll end up with a smaller box.

And here's another thing - it looks like you may not have to use a smooth conical flare from throat to mouth for a tapped horn - you can implement the increase in steps, as the effect of the steps will happen outside of the horn's pass-band anyway. See P.O.C. #2 - Compact Tapped Horn - diyAudio for current discussion. This allows for a bit more flexibility in the folding - for example, my "tapped-pipe" P.O.C. (The Subwoofer DIY Page v1.1 - Projects : A "Proof of Concept" tapped pipe** - introduction )can be easily modified to allow for expanding Sd, by simply moving the bottom internal separator and adjusting the connecting points accordingly.


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## Yepvegas (Sep 23, 2009)

I want to build a horn sub that will go low without and sound good with all types of music I do have a budget since I have four kids, I have little money to play with. I was interested once I read about the impressions and results that others have had. I have one channel left to use on my ADS PH 15.2 that will run at 2 ohms or 4 ohms bridged for a solid 150 watts RMS according to specs but I beleive it is putting out more than that. At one time I was using it to push 2 Solobaric 12's when they first came out. I do not listen to music at the same levels I did when I was younger but it is noce to be able to crank it up on a good song from time to time and it is nice to have a system that can play it loud enough that the need to go higer can be reached before the system starts to distort. I drive a 2009 suzuki sx-4 sports sedan and it has a spacious 15.5 cubic foot of space in the trunk. The rear seats do not fold down and it doest not have an armrest with a ski pass. The rear speakers are in the rear doors so I will have to cut an opening in the rear deck. I would like to build a box that can bolt to the deck and taper down to the floor of the trunk. where do I begin. any way to get some help with the design? I am willing to give up a portion of the trunk but I want to force all of the bass into the car through the rear deck.


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## Yepvegas (Sep 23, 2009)

Wow it has been a long day I should have checked for spelling errors!!!


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