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Old 12th May 2010, 04:50 PM   #1
djn is offline djn  United States
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Default What the heck is a Tapped Horn???

I've read about and seen many Tapped Horns but have no idea why they work. Are they limited in how high they will go? Cheers.
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Old 12th May 2010, 06:24 PM   #2
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It's a bandpass horn where both sides of the driver diaphragm are used to contribute to the sound. How high or low they will go depends quite a bit on both the driver and the horn design. A good design can get you around 3 octaves - it's a little tricky to get them right.

My own tapped horn uses two Tang Band 8x12" woofers and has a bandwidth of 16-80Hz. Not perfect, but it was a first time effort. It will do above 80Hz, but not with the same sound quality you get in the passband. It's tolerable up to about 100Hz, but I don't usually let it play that high.
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Old 12th May 2010, 08:35 PM   #3
vadi is offline vadi  Austria
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I'd like to know if you can mount two woofers in one enclosure and get some impulse compensation? Would this still be 6dB louder than one woofer and do I have to double the crosssections too?
Those rectangular Tangband woofers seem efficient to put in pairs into an enclosure.

Last edited by vadi; 12th May 2010 at 08:38 PM.
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Old 12th May 2010, 09:50 PM   #4
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I haven't really tried too hard in modeling only one of the TB woofers, but I can say they like big boxes whether you use only one or two. I went with two because I thought if I didn't, people wouldn't think I was crazy enough

I did get slightly better modeling results using two for the 16Hz corner I was after, but I'm not sure if that's just because I gave up on only using one due to SPL and Xmax limitations.

Mine ended up being 74x42x17" - it's absolutely huge. I did everything I could to get the size down, but those woofers weren't having any of it. Got a design on the drawing table that does the same job at higher SPL in about 60% of the space.

I'll leave the impulse compensation part to those a little further down the learning road than I am. I've only tried the tapped horn thing once so far
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Old 13th May 2010, 03:49 AM   #5
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Quote:
Originally Posted by vadi View Post
I'd like to know if you can mount two woofers in one enclosure and get some impulse compensation? Would this still be 6dB louder than one woofer and do I have to double the crosssections too?
Those rectangular Tangband woofers seem efficient to put in pairs into an enclosure.
If I understand you, no. The impulse response is a function of the frequency response, of the whole system the tuned pipe included. In my mind the two woofers sum to be one synthetic woofer driving the pipe.

You could mount one woofer reversed to reduce some distortion products,frm memory the 2nd harmonic

Last edited by neddludd; 13th May 2010 at 03:51 AM.
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Old 13th May 2010, 07:38 AM   #6
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Yeah, that's right.

I used a similar technique to eliminate 2nd harmonic from my sealed sub - I mounted one driver normally, then one with the magnet outside.
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Old 13th May 2010, 08:11 AM   #7
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Chris661: interesting you mention this, since a sealed box causes 2HD by itself due to the compression of the air. There is an equation floating around which can give you an indication. I think the linkwitzlab thor subpages showed this. Whether or not it matters compared to the distortion of the subwoofer itself is another issue.
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Old 13th May 2010, 01:03 PM   #8
GM is offline GM  United States
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Quote:
Originally Posted by vadi View Post
I'd like to know if you can mount two woofers in one enclosure and get some impulse compensation? Would this still be 6dB louder than one woofer and do I have to double the crosssections too?
Those rectangular Tangband woofers seem efficient to put in pairs into an enclosure.
As already noted, in the horn's pass-band the drivers become a summed unit unless physically spread > ~1/3 WL apart.

Right, to get the extra 3 dB of acoustic gain you have to double the horn's net volume (Vb), i.e. double its cross sectional area (CSA).

GM
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Old 13th May 2010, 01:06 PM   #9
GM is offline GM  United States
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Originally Posted by Oklahoma Wolf View Post
Mine ended up being 74x42x17" - it's absolutely huge.
Which TB? All that I've simmed were tiny, requiring two drivers just to make them big enough to easily mount the drivers and get adequate acoustic gain out of them.

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Old 13th May 2010, 02:08 PM   #10
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Which TB? All that I've simmed were tiny, requiring two drivers just to make them big enough to easily mount the drivers and get adequate acoustic gain out of them.

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