Bass/tapped horn subwoofers?

I've built a couple of bass horns over the years. A bass horn can sound good or it can sound bad, same as any other design....

Bass horns take up lot's of space, you need a throat opening of 1/4 the lowest wavelength you want to reproduce. So for 20Hz you're need a 14' dimension or so. The main advantage over other designs is that they require less power from your amplifier to get to an equivalent SPL. Now-a-days the amplifier power is easy enough to get so why do a horn?

The closest you can come to hearing a bass horn for residential use is probably a Klipschorn (corner loaded horn). Other than that, go to any large venue rock concert. Either way you won't be hearing response down to 20Hz.

I really like the sound of horns.

I'd like AVS to have more discussion on this topic.

Here's a couple of links/pics for food for though:

http://www.diyaudio.com/forums/showt...threadid=97674
http://www.diyaudio.com/forums/showt...threadid=97620

I dont claim to be any rocket scientist/subwoofer designer but to me, the 25db drop from 20hz to 10hz would be the deal breaker for me with movies/ht use. Like scientest said, amplifier power is cheap, so inefficent isnt really a factor.

Some thoughts:

1) The fact that horns have their own sound isn't necessarily a good thing. Among the issues are uneven frequency response, all kinds of phase issues and problems crossing over to other drivers. Fortunately, if all you're talking about is the lowest frequencies these issues are of less importance.

2) Traditionally horns for home use have been mated with tube electronics and a lot of the what people commonly consider the "horn sound" might be associated with the 2nd degree harmonics from the amplification equipment. No problem with that; it's well understood that such distortion is pleasing, just as long as we don't consider it accurate.

3) The tapped horn is far from a traditional horn and has issues all of it's own. Danley might feel that the ability to drive a given driver to higher SPLs than the same driver in a vented enclosure is what you want but the wild frequency response would make me question that conclusion.

I agree it's an interesting topic!

basically uses constructive interference for a limited pass band to increase sensitivity. best case is 6dB over your current benchmark. (back wave + front wave)

Still does not overcome displacement issues of low frequency SPL as well as resonators could. For example, Two passive radiators that move as much as the active driver would in theory match any horn at full displacement vs horn peak SPL.

both of these concepts are limited to very narrow SPL ranges, but they are very efficient.

In theory, you could simply apply more voltage to an active driver and then use more ports or passives and go well beyond what a horn can do when it the driver reaches xmax. active drivers will still reach xmax at resonance, but it will take a retarded amount of voltage... rarely reached... only in SPL competitions perhaps.

but then again, you could in theory horn load the active driver into a resonator and do some serious damage! The possibilities are many!

Horns are certainly not as easy to design as a simple sealed or reflex (vent or PR) enclosure. I'm not really sure what phase issues you are referring to, as this is one area where an efficient horn excels at. Of course any horn large enough to operate below 80Hz will have significant size and length, adding some complications to the integration with other devices, but they just need to be accounted for.

Horns have definite strengths, although to have more significant advantages, they need to be relatively large for the bandwidth being covered.

I believe you're confusing a few concepts here with the horn loading and the higher order tapped horn system. Even in undersized bass horns there can be gain relative to driver volume displacement above the frequency where the horn is 1/4 wavelength long. Near this range there is also an excursion minimum which sets up a condition capable of a lot of SPL for very little excursion. The relative relationship of Hoffman's Iron Law still holds, but you do have more room to give and take, akin to a bandpass design, but with additional/variable loading on the driver due to the length and flare of the horn.

They're easy to get loud, they're tricky to make efficient and smooth, and they certainly aren't small, but bass horns can sound very good as well.

I doubled up on this complaint since I was mostly thinking of the issues of matching up multiple horns as I wrote that. That problem shouldn't be an issue for a single bass horn. However, with a tapped horn I had also assumed the comb shaped response was due to the front / back constructive / destructive phase issues? Oh, and I guess it's worth pointing out that bass horns are usually far from the ideal horn shape?

Lets not talk about used products...but are high power amps very cheap? Say I have an Acoupower be it sealed or with PR. Is there any cheap 4KW amp bridged? In dynamic HT/music power compression should be non-issue with such a driver.

Maybe there are other products but this is one which i am familar with.
http://www.danleysoundlabs.com/pdf/T...ec%20Sheet.PDF

Anybody in the know, perhaps may let me know of any small/box with PR/port assistance (whatever) that has this or near this kinda efficiency and SPL capability? Say Lambda TD15X w/PR.
No need to dig very low, as show here with 28Hz which is fine with music.

But then I guess in the US of A with 110V service, getting 4KW output means a 50A line?. (is there such a thing even if you can pay?)

This thingy uses a powercon. (is the PL380 using the 20 or 32A one)... IEC type 13 is 13 or 15A only right?
http://www.qscaudio.com/products/amp..._FullRange.pdf

First, the whole reason that thing has an efficiency of 102dB is because it's a tapped horn covering a very narrow frequency range. With modern amps theirs no need for that kind of efficiency and no, you don't need 4kW either. That thing is designed for Pro touring and really has no relevancy to the home theater DIY market unless you're just experimenting for the fun of it. In these forums you will find people running multiple drivers in rooms small enough that you will pick up room gain and have high efficiencies across multiple octaves. People here routinely go from 80Hz down to 10Hz and even lower. If they have extreme desires for lots of bass they may be running maybe a couple of Behringer Ep2500's with 2400 watts (bridged mono) but at $350 a piece they're not spending a fortune on the amplification side a nor do they need to.


You don't need 4000 watts of continuous power, that's peak power and comes from the capacitor banks on the amp. The EP2500 for example will draw less than 10 amps at 120 VAC, which even if the thing was 100% efficient is still less than half it's rated output. But yes, you can get a 50amp line, I have one running to my Hot Tub... :-)

I think you need to tell us why you're looking at tapped horns? Is it just for fun or do you have a real application for a sub woofer that you are trying to find a solution for? If it's the latter I'd suggest you take a step back and figure out what you really need for in room response and then go find a bass reproduction technology that matches those needs; I personally wouldn't expect it to be a tapped horn...

Since you mention the Acoupower driver spend some time on their web site. For example their article on Redfining the club subwoofer addresses the issues of a conventional horn versus a bandpass box. This is not exactly my favorite design either (and interestingly enough shares some design ideas with the tapped horn in a way) but probably makes sense in this application. The result is a smaller box, better extension and higher SPLs! The other article on the site: Pro audio example B talks about how they achieve 100dB with just 1W total input power.

One final comment, personally I wouldn't be spending my money on the Acuopower for home use. I'd consider it overkill, but that's a whole 'nother disucssion.

Scientest, it would be impossible to list out why I chose DSL products finally (fill up several pages probably), because I started to revamp/choose/build/model all drivers and stuff about 1 year ago with very specific goals in mind over here (basically the main reason would be I am not doing Home Theatre sweet and short ). And I don't think DSL subs perform in a narrow range, to be fair. In fact they sound really good up there in the upper bass region (never get that in my other subs or those which i experienced). I current still have a pretty flat sub which I have not sold, still gotta EQ.... there is no way of bass trapping several freqs and there is still the house curve to deal with you know.

You can check out my Behringer story. Considered that last year.

I have heard DIY horns and stuff, home visits and all that. I guess I know what are you saying as you experienced building them last time. The diff is that I interviewed and asked lotsa users not only from here. Bit the bullet...its history from then on. Short answer (1) Quality, (2) SPL if needed (3) lower overall cost if i were to get other alignments in multiples. Yes I might have bought blindly and without audition, but I would believe the results are ok and it was a pretty informed choice (check out the Danley vs Conquest thread in the other sub forum, perhaps you can say I had a small part in psychoing)

Thy is still right about that peak thingy in the amps. Hey there's lots of music program with sustained bass notes longer than half a sec. Unless the cap banks can store several tens of thousand joules.

We don't need a dissertation, just some idea of what you're trying to do. The fact that it's not for home use puts the whole question in a different light altogether, but you did say "HT" in post 10. I'd also like to know why the original poster was asking about tapped horns the question in the first place...


Looking at it again you're right I had misread the FR graph. Depending on how it's priced (and what you're doing with it!) it might be a reasonable solution.


Huh? Oh, I think I see what you're saying; 1) the largest organs can reach down to 10Hz or so, so you're going to need something other than the Danley no matter what; 2) in HT you get room gain you may not need as much power as you might expect to sustain a organ note at realistic volumes.

Not for HT use?

Have you seen what Danley Lab's has cooked up with the DTS-20

I believe some of the inspiration behind this thread has steamed from the recent thread over in the regular Subwoofer forum:
http://www.avsforum.com/avs-vb/showthread.php?t=1055559

"I didn't realize what I was missing until I heard this beast, and I've owned or heard all the usual suspects -- JL, SVS, Revel, Aerial, eD, ML. Detail, detail, detail amidst tremendous output. It's like the ribbon tweeter equivalent on a subwoofer -- the clarity and resolution are astonishing. Everything else sounds muddy in comparison. It is the bass equivalent of going from 240i to 1080p, or as another owner commented, like "going from a receiver to separates. This is how major this DTS20 is."
I do still want to hear a pair of Seaton Submersives some day, but I think I'm done for now.. unless I decide to pick up another DTS-20!

That's a completely different beast and has no relevance to the comment I was making about the TH215.

Edit: and it's still not doing the 10Hz thing that some people on these forums are looking for...

Not to mix things up, I have the TH-112. TH-215 is just an example. There are so many other famous/good bass horns for differing apps like 12pi, bassmaxx etc.
I listen to drums (chinese/jap/etc), trance, jazz, heavy rock/metal, boring audiophile stuff etc.... Organ music, too demanding to reproduce.

My original question is : Are there direct radiating + ported or PR solution which are high in sensitivity? I'm interested to know and to see if anybody has a secret recipe that I don't know of.

That aside, I actually have experienced a happening setup consisting of 7 subs in a ~ 1000 cu ft room (SVS 13Ultras, PB singles/duals + M&K5k)....all tuned and bass trapped/EQed. Happening HT experience. No $$$ to pursue deep bass at punishment levels like multiple LMS5400/PR + good powerful amps.....so next best thing is to push the freq up.

It's easy to amaze people on the commercial forums.
I lured one guy from there to DIY [his section]. Short story, he owned
various commercial subs including the DTS-20. His first sub project
with aid from people here beat out those products.
His project documented here if you don't believe.

Which thread is that?

i have some very large tapped horns in my substage right now. they're built around a 22 Hz wavelength, and with a tone generator, i've gotten very noticeable response down as low as 8 Hz. I probably could have gone lower, but i was beginning to worry about over excursion.

As far as how they sound, i can certainly tell there are some dips and peaks in the response curve (though i haven't measured and documented them, they're just quite obvious). I also have an intense room mode in the 40-45 Hz range that doesn't help. still, they have that "horn" sound, are very tight (accurate, do very well with percussive sounds), and don't sound boomy like many ported designs that try too hard to get more output than they're really capable of. the biggest drawback i've found is that theyre very, very large. here's a picture of me and four friends getting them into my room through a window because the doors simply weren't large enough-



intially i was very happy with them. they get brutally low and sound very good. i plan on building a set based on a 35 Hz wavelength with much heavier baffles geared more toward musical listening. However, i think that will be the last of my tapped horn builds until i find an application that will really benefit from it. I've really fallen in love with transmission lines lately instead.

Bro, seriously the DTS-20 is not a bad product in a form factor that is acceptable. They just have to give good discounts to the non-pro (ie not using it to make money) users. But being pro its not nice to underprice too. Even JTR is starting to raise their prices now.

BTW how much is the PR from TC cost? I wasn't from that "era". Looks like there are still some units floating around, all this talk is starting my itch again. But sheesh, shipping a driver from the US by an individual is gonna cost much more than even the much heavier TH-112 by DSL. Anyway, I'm glad i went this way, super flexible.

Since others have share pix, I'll share mine here. Its impt not to forget having fun in this hobby. Seriously, audio is just but a journey.

The frequency response curves of the AVS TH you show in the first post are not indicative of what these can do potentially. That thread (FR's are from the first post in a >2200 post thread where there have been many good designs posted and built. There are several other threads on diyaudio about these and due to David McBeans excellent software, which has been updated and improved upon due to suggestions from the Collaborative TH thread, they are much easier to design.

I'll be building a couple myself soon.

I didn't realize that. You're right that is a HUGE thread.

Got any good examples?

I'd like to keep this conversation moving on this.

I have a few spare LAB12 drivers, and whilst not ideal, I'm tweaking the designs published by Don Bunce (circa post 100) and MaVo (post 1400 ish) to use them. I've had exams so I haven't put much time into it lately. Two should be more than enough for the current room.

Also worth looking at is Erik's 3015LF design. www.volvotreter.de

Any further progress from anyone along the lines of a tapped horn?

unfortunately, no. Work and studies got in the way, and I just missed the cut off to get the mdf cut before Xmas. I'm hoping the first few weeks after Xmas will see them completed.