OMG, I can't believe folks on here are quoting Public Enemy
That's actually how I got into waveguides!
When I was a teen I had a bandpass box with a pair of MTX tens that I built. Didn't know the first thing about how they worked, so I bough bandpass boxmodel. The instructions in the program were awful, so I studied the AES stuff from Geddes. And that got me on the road to where I'm at now...
But it all started with Public Enemy, and my attempts to wring every last decibel out of a 50 watt Hafler amplifier in my car.
I built a back loaded horn, and a tapped horn, with the exact same woofer last year. The tapped horn was about 10-12dB louder, and played lower.
I'll concede that they're difficult to get right, but that's why Danley charges $3000 for his models. They're worth every penny, and I'd heartily recommend that people consider purchasing one, unless they're comfortable with the software, and willing to invest a lot of time to learn how to build them properly. It took me a few tries to get good at this.
Here's some pics.
Here's a pic of the woofers. That horizontal piece of wood isn't just a brace, it also forms part of the horn path.
The limiting factor on the horn's size was the entrance to the house! I couldn't use the front door because there's a ninety degree bend, and the horn's too big to make it. So I built it so that it would fit through the window of the living room.
My Summas are about three feet tall, so this gives you some idea of how big this tapped horn is.
Two horns? Same driver? Louder across most of the band for the same input? 12 dB? Why?
Seems inexplicable to me.
I'm too lazy to post the sims right now, but if anyone wants to build this with something beside the Diyma 12s, here's a great replacement:
http://www.creativesound.ca/pdf/CSS-SDX10-data-140408.pdf
Here's a comparison of the thiele-small on the SDX10, versus the Diyma 12. The latter's measurements were done by yours truly, since the published specs aren't consistent with the Diymas that I'm using.
Diyma12 / SDX 10
fs= 27.59 Hz / 26 Hz
re = 3.77 Ohms / 3.5
Qms = 7.625 / 4.0
Qes = 0.612 / 0.47
Qts = 0.567 / 0.42
Le = 2.03 mH / 1.42mH
Vas = 42L / 53L
xMax = 23mm / 18.4mm
The diyma12 has more displacement and is cheaper. If you're using a ton of power, the Diyma12 is the one to use. But if you're only using a thousand watts or so, the SDX 10 will work great.
An externally hosted image should be here but it was not working when we last tested it.
http://www.creativesound.ca/pdf/CSS-SDX10-data-140408.pdf
Here's a comparison of the thiele-small on the SDX10, versus the Diyma 12. The latter's measurements were done by yours truly, since the published specs aren't consistent with the Diymas that I'm using.
Diyma12 / SDX 10
fs= 27.59 Hz / 26 Hz
re = 3.77 Ohms / 3.5
Qms = 7.625 / 4.0
Qes = 0.612 / 0.47
Qts = 0.567 / 0.42
Le = 2.03 mH / 1.42mH
Vas = 42L / 53L
xMax = 23mm / 18.4mm
The diyma12 has more displacement and is cheaper. If you're using a ton of power, the Diyma12 is the one to use. But if you're only using a thousand watts or so, the SDX 10 will work great.
Where from?
I've been playing around with the SDX10 in Hornresp myself... models up pretty nice for me so far. But if I can do more damage to the house's structural integrity with the Diymas, I'd love to know where to find them 😉
I agree, that is why I asked earlier if he was using drivers that are discontinued or currently available. I thought that they were "blown-out" on DIYMobileAudio and ebay, but are now unavailable - but I could be wrong.
Yeah - I can't seem to find any for sale. Too bad - with a couple modifications and an addition to my Tang Band horn, they'd drop right in there, get 900W from my QSC, and I'd get to see what 125+ dB at listening position sounds and feels like 😀
Patrick - was that 12dB you claim a number arising from a simulation or from mic measurements?
Quote:
Originally Posted by Patrick Bateman
I built a back loaded horn, and a tapped horn, with the exact same woofer last year. The tapped horn was about 10-12dB louder, and played lower.
snip
Two horns? Same driver? Louder across most of the band for the same input? 12 dB? Why?
Seems inexplicable to me.
Add me to the not believing what I read.
Are we talking a brain fart here about a tapped hotn beeing 12 db louder than a front loaded horn?
Tissn't so my good man. THe properly designed FLH is the standard against which all are measured. A tapped horn is a way to circumvent the bulk for almost the same efficiency. But we are talking almost as in 2 to 3 db less. Even the latest proponent himself Tom Danley has posted that tickling the last few db past 7 db gain is not an easy thing to accomplish.
A good FLH will give you gain in and around 10db.
So same driver and reverse? Not makes sense .
Mark
These were measurement of the exact same driver in two different boxes. One was a very VERY small front loaded horn. The other one was a tapped horn. Even *i* didn't expect the tapped horn to have such a huge efficiency advantage - in fact I'd convinced myself that a plain ol' bandpass was superior, in a thread I published called "Tapped Horn for Dummies."
Anyways, the TH was 10-12dB more efficient for two reasons:
- Properly designed, you can get 6dB more output from a TH for the same reason you can 6dB more output from a vented box at low frequency - you're getting output from both sides of the cone.
- The other 4-6dB in gain was due to the fact that the woofer's fB isn't being "pushed up" by a sealed chamber. For instance, a woofer with an Fs of 100hz may resonate at something like 150hz in a sealed chamber. But in a tapped horn the Fs often goes DOWN. I've published some threads on how this works. Basically if you put a woofer in front of a slab of wood, the FS goes down and QMS goes up.
Basically, in a front loaded horn, there's a point where your low frequency output is going to drop like a rock. You can see this in the the measured response of the Danley Lab Sub; there's practically no output below 40hz. Now take the exact same woofer and put it in a tapped horn of comparable size, and you're going to get MUCH more efficiency below 40hz if it's properly designed.
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If anyone's interested in hearing a demo of the Gedless Summas and a couple of tapped horns, hit me on email. I may be doing a demo on Saturday near Portland OR.
I believe that a properly sized chamber will do this wonderfull thing called reactance annulling. Actually helping the low end . Not hindering the low end.
So your comparing the tapped monster you have in this thread with a way smaller FLH?
Mark
Patrick - you are making some of us more and more queasy about THs. "Very" small horn... like small enough that there was cancellation all over the place?
"Get more" from vented box... like at a few chosen low frequencies and much less at others and no difference at others and....?
I'm beginning to feel like you are cherry-picking the tones, ranges, etc. instead of talking about the full pass-band. Your write-up sure talks both sides of that street.
Yes, I am definitely "cherry-picking" the tones. This IS a subwoofer forum after all! And at very low frequencies, tapped horns are very hard to beat.
Of course, there are plenty of reasons to use a front loaded horn, or a sealed box. For instance, a front loaded horn offers almost unrivaled efficiency at high frequencies, and a sealed box is easy to build.
But if you want gobs of output at very low frequencies, and you know a thing about Akabak, tapped horns are tough to beat. In fact, I challenge anyone to show me a sub that can generate more than 120dB at 17hz with just two woofers.
From your fancy footwork in excusing yourself from data based evidence to rely on your personal proclamation, I gather you wish to withdraw your so-far unsubstantiated claims about 12 dB advantages of tapped horns, etc.?
No, I don't want gobs of output at any frequency if I can't get almost as much (as many?) gobs at ALL frequencies of interest.
"Excusing myself from data based evidence?"
Are you kidding me? Check out some of my threads. I *always* post measurements.
Also, if you don't like tapped horns, the "subwoofer" forum of diyaudio isn't the wisest place to hang out in.
I am underwhelmed by your democratic instincts and social courtesies.
Lemme see, this here place is only for TH adherents, you say. Then there's the place for constant directivity adherents, a particularly jovial place is for Karlson fans......
At least the ESL crowd is an equal-criticism and equal-support forum.
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