Collaborative Tapped horn project - Page 5 - diyAudio
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Old 11th March 2007, 12:54 PM   #41
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G'day Paul,

Thanks for your clarifications

G'day William,
Also, horns as a rough rule of thumb if I understand correctly add 5 – 7 dB ~ don't know if this applies to bass horns.

What about tapped horns; what is the db or watts scale on your graphs?

Cheers
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Old 11th March 2007, 02:00 PM   #42
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Of pre-existing designs tapped horns are probably closest to Tapered quarter-wave pipes. I don’t know enough about each to say how they differ.

What are any differences?

Thanks
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Old 11th March 2007, 02:29 PM   #43
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I believe the efficiency is more if I understand correctly.

If I'm not mistaken, it's more like an undersized conical horn where a trick is used (the tap) to overcome the peaky response that would normally result. I believe a transmission line achieves a moderate improvement over a vented box in accuracy, but comparable output, but a tapped horn should create significantly more oomph. Apparenly the Danley tapped horn has more output than the contrabass to the tune of 10 db. The Contrabass used 2x high excursion 15" with two 18" PRS. This does more with a single 12" driver.
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Old 11th March 2007, 04:07 PM   #44
AJinFLA is offline AJinFLA  United States
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Quote:
Originally posted by paulspencer
Why ask for an opinion on whether something will work when you can simply try it and find out for yourself?
Because that (manufacturer) opinion might prevent damaging the system?

Quote:
Originally posted by paulspencer

I doubt I'll keep the Rythmik drivers in a tapped horn, more likely dipole
Unless much has changed since I asked (Brian) years ago, it's unsuitable for dipole use also.
I'm not trying to discourage you from trying it all, you paid for them, so they are yours to do with as you wish. I'm simply letting you know that the manufacturer has advised me previously against this. It might be based on his knowledge of his product or perhaps he was just being cautious.
Best of luck with your experiments, I'll keep an eye on them to see how they turned out.
BTW, which Rythmik kit did you get? He seems to have expanded the choices quite a bit.

cheers,

AJ
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Old 11th March 2007, 10:21 PM   #45
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G'day Rick

>On that note, what distance from the mouth were your measurements taken at?

The published graphs were taken with the microphone in the center of the plane of the mouth. The plots were taken indoors, and this was done to eliminate the effects of the room.

>Also, horns as a rough rule of thumb if I understand correctly add 5 – 7 dB ~ don't know if this applies to bass horns.

Yep, 5-10 dB gain seems reasonable.

>What about tapped horns; what is the db or watts scale on your graphs?

All the horns I measured measured between 95dB/2.8V/M and about 102dB/2.8V/M. As the mouth size goes up the efficiency goes up too. You get less efficiency than Hornresponse predicts.

With the right driver, the dip between the first two peaks will be eliminated.

Cheers

William Cowan
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Old 11th March 2007, 11:09 PM   #46
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An interesting idea...

I wonder if there is any real gain here... ?

gain over a 1/4 pipe? (for the freqs the pipe works)

Also, I wonder about the pressures on the drivers - especially the one that happens to be out of phase with the other at any given freq... thinking about the relationship between the peaks of the "main driver" being filled in by the "other driver"...

Also, it's a big box for 30Hz.
What's the relative differential with a 15" driver with the right specs in a similarly sized volume ported cabinet?

How about compared to one of the many bandpass cabinets?

...thinking out loud.

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Old 12th March 2007, 02:24 AM   #47
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AJ are you suggesting that this might destroy the Rythmik driver or amp or servo board?

I'll have to see what Brian has to say. As I understand, the main issue is getting the servo board to understand the frequency response so it can get it right in the nearfield. It may be some time til I settle on something that I'm happy to stick with for a while. A lot of "try things out" urges to use up first.

Bear, this is more like an 18 Hz horn with the right driver. The output should be more than a TL and distortion lower due to efficiency gain. Also the second driver is not what fills in the gaps, it is the fact that the rear output from each driver which is near the mouth loads the horn as a 1/2 wave horn - it does this by virtue of the fact that radiates from the mouth back into the throat, then back again. Effectively this allows the driver to behave differently across the frequency range in such a way that it overcomes the shortcomings of a too-small horn. I've tried sims of bandpass subs with my drivers and I haven't been able to model any significant advantage, even with a size-no-object box.

Will be very interesting to see how things turn out. The results here could either inspire or deter many other attempts.
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Old 12th March 2007, 02:51 AM   #48
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Greets!

FWIW, I visited DSL the other day to see the 'container' tapped horn, but unfortunately they were behind schedule due to stuff beyond their control, so didn't get a chance to experience forty horn loaded sub drivers, though a quickie audition of some their products using action scenes from 'Spider-man 2' left no doubt that the T-O-P delivers eyeball flattening bass in spades..........

GM
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Old 12th March 2007, 03:12 AM   #49
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GM, what can I say but I'm envious!

Quote:
no doubt that the T-O-P delivers eyeball flattening bass in spades..........
By tower of power are you referring to the DTS-20?
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Old 12th March 2007, 03:15 AM   #50
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Greets!

Right........

GM
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