Collaborative Tapped horn project - Page 347 - diyAudio
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Old 15th April 2010, 03:13 AM   #3461
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Quote:
Originally Posted by Oklahoma Wolf View Post
No side to side bracing - something I should have employed. Would have, too, had I not gotten frustrated with the other bracing...
Not too late, you could use 1/2" - 3/4" hardwood dowels - just drill holes on either side, push them through, twist some glue in, then use like a Japanese handsaw to trim or such.
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Old 15th April 2010, 04:01 AM   #3462
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Yeah - I have some I was going to use for the bracing. The question is though... can I un-lazy myself enough to do it?
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Old 15th April 2010, 08:10 AM   #3463
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I was wondering about T-TQWT and "port" size/excursion.

What is the max excursion for a given frequency one should have?
And what size is minimum at any given excursion?

How will a smaller opening, say 200cm2 behave at 80Hz at high output, 30mm P-P or so. (around 114dB)
And 29Hz 88mm P-P (105.9dB)

What happens if you go down to 100cm2 with a more powerful driver?

Will we hit "port compression" like ported boxes at high SPL?
Loosing 3-6dB is not uncommon and I would like to avoid that.
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Old 15th April 2010, 10:59 AM   #3464
MaVo is offline MaVo  Germany
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I have build tapped horns with and without bracing... and to be honest, it doesnt seem to change much.
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Old 15th April 2010, 11:47 AM   #3465
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Bracing is probably less important in a 20Hz tapped horn than a 45Hz PA tapped horn.
For the 45Hz PA bracing was definitively required to keep it in one peace and at the same time keeping it from sounding ugly.

For LF you probably loose a little bit of output, if you even notice it.
The important part is the throat where the pressure is.
At the mouth you should be left with mostly velocity as the impedance of free air don't induce much pressure.

Just make sure that you don't get any ugly panel vibrations that are exited in the passband.
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Old 15th April 2010, 01:18 PM   #3466
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Quote:
Originally Posted by David_Web View Post
Bracing is probably less important in a 20Hz tapped horn than a 45Hz PA tapped horn.
For the 45Hz PA bracing was definitively required to keep it in one peace and at the same time keeping it from sounding ugly.

For LF you probably loose a little bit of output, if you even notice it.
The important part is the throat where the pressure is.
At the mouth you should be left with mostly velocity as the impedance of free air don't induce much pressure.

Just make sure that you don't get any ugly panel vibrations that are exited in the passband.
That's what I was thinking. I don't have my horn braced inside the throat itself, but the panels on either side of the throat are fairly well braced. I wanted to leave the throat as open as possible because the compression ratio was already about 3.25:1 and I was worried (needlessly as it turns out) about making it worse.

To be fair, that 80Hz dip is at the listening position - it could be something else in the room doing that too. It's right at the top of my intended passband, so that's why I'm so lazy about doing anything about it

The 50Hz and 30Hz dips are the room - had that with the old subwoofer too - IXL 18.2.2 tuned to 11Hz. I'm very pleased with the way the horn sounds so far. Also pleased I decided to put it on wheels. This thing is heavy.
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Old 29th April 2010, 01:58 AM   #3467
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Can anyone here suggest a design for the Eminence Delta Pro 18A? At $140, it's a really good deal. I'm looking for something (relatively) portable for PA use, if at all possible - a 30-35hz F3 would likely be just fine.
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Old 29th April 2010, 04:23 PM   #3468
FlipC is offline FlipC  United States
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Well first
Hornresp is really simple to use.
Second - search for the Live Sound thread here.
Third - TDA over on the Speakerplans.com forum has an 18" TH design that was built.
I am at work so dont have any links etc here.

Let us know what happens.
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Old 30th April 2010, 04:23 AM   #3469
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Quote:
Originally Posted by David_Web View Post
Bracing is probably less important in a 20Hz tapped horn than a 45Hz PA tapped horn.
For the 45Hz PA bracing was definitively required to keep it in one peace and at the same time keeping it from sounding ugly.

For LF you probably loose a little bit of output, if you even notice it.
The important part is the throat where the pressure is.
At the mouth you should be left with mostly velocity as the impedance of free air don't induce much pressure.

Just make sure that you don't get any ugly panel vibrations that are exited in the passband.
I remember an audio textbook that explained how panel output was measured with accelerometers, and also doing something odd like buying the box in sand apart from the suspect panel and measuring output with mic.
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Old 1st May 2010, 09:49 PM   #3470
PASC is offline PASC  Brazil
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Hi!

First tapped horn!?

Voice Coil of March, 2010, from page 18 on Shows article Acoustic Patents, by James Croft, and the figure 2 of a patent bellow mentioned (problably the FIRST tapped horn).
This is the patent 2,765,864 filled March 14,1955, granted Oct.09,1956, for W.E.Glenn, which describes the "tapped horn", with drawings, curves, ...

Patent Fetcher - Patent Fetcher PDF Processing

In page 20 James Croft writes:
"While all the items listed above are significant, US 2,765,864 appears to disclose the substantially SAME DEVICE that is experessed in the Danley application." ...

So TH is now public domain?

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