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Old 10th January 2009, 06:27 PM   #1
MaVo is offline MaVo  Germany
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Default Double Driver Tapped Horn

Where is the benefit? How does it work? DSL calls their new horns with two drivers the next generation of TH. From another forum is this quote: "This is a slight devation of the tapped horn, same concept, but with a slightly different alignment using two drivers, each feeding the horn differently."

Here is some info on the TH SPUD, one of this kind: http://forums.audioholics.com/forums...d.php?p=492319

Any guesses or explanations?
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Old 12th January 2009, 11:44 PM   #2
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The addition of another driver can even out the response. The use of two tapped horns will do the same thing. Or two tapped horns with two drivers in each horn.

More subwoofers = smoother response.
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Old 18th January 2009, 01:25 PM   #3
JLH is offline JLH  United States
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Pictures 3, and 4 appear to show Tang Band W8-740 woofers. I own quite a few of those, so I should know. Interesting that the same woofers I've used in the past have found their way into a Danley product.

http://forums.audioholics.com/forums...6&postcount=66
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Old 18th January 2009, 01:53 PM   #4
HK26147 is offline HK26147  United States
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Quote:
"This is a slight devation of the tapped horn, same concept, but with a slightly different alignment using two drivers, each feeding the horn differently.
Pure Speculation on my part, hopefully Mr Danley will clarify:

A major goal of Pro Sound is SPL. Traditionally that means many large drivers in large boxes. They can't occupy the same physical space. The physical separation means there is less acoustic coupling, less of a point source. When drivers are separated by any distance, constructive and destructive interference takes place, until at a distance = 1/2 wavelength ( 180 degree cancellation ). Other frequencies/other wavelengths have other acoustic addition and subtraction relationships.
Delay can correct and optimize for a particular distance/frequency relationship, but it is a compromise.
Ideally get the sources closer ( in 1 enclosure ).
In my gross conceptualization of the original single driver TH, it is similar to 6th order bandpass box. With 2 driver in separate alignments, a higher order compound bandpass box.
Order?

Syd
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"If the doors of perception were cleansed every thing would appear to man as it is, infinite. For man has closed himself up, till he sees all things through narrow chinks of his cavern."
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Old 19th January 2009, 11:28 AM   #5
hm is offline hm  Europe
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Hello,
same times i think they will get a similar effect like my double horns.
reduce imp , more on the lower oktave, and ~2-3 oktaven over the flare rate a partiell delete to use it over 100 Hz and
easy crossover to the SAT.
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Old 20th January 2009, 02:22 PM   #6
JLH is offline JLH  United States
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Default Re: Double Driver Tapped Horn

Quote:
Originally posted by MaVo
Where is the benefit? How does it work? DSL calls their new horns with two drivers the next generation of TH. From another forum is this quote: "This is a slight devation of the tapped horn, same concept, but with a slightly different alignment using two drivers, each feeding the horn differently."

Here is some info on the TH SPUD, one of this kind: http://forums.audioholics.com/forums...d.php?p=492319

Any guesses or explanations?

After reading Tom’s description more carefully, I now understand why my attempts to model the TH-SPUD failed. I took the folding diagram found here:

http://forums.audioholics.com/forums...3&postcount=60

and blew it up and printed it on 11” X 17” paper. Then took a scaled drafting ruler to “measure” the horn lengths and calculate the areas. This is what I came up with for the various lengths and areas:

S1 = 490cm^2
S2 = 245cm^2
L12 = 21.67cm

S3 = 775.97cm^2
L23 = 497.74cm

S4 = 858.06cm^2
L34 = 92.28cm

I believe there is room for interpreting whether there is a chamber for the second woofer, or if it is a form of reverse taper. I took it as being a reverse taper. I selected L12 as the mid point between the two woofers. I did the same for L34. I now believe this is why the modeling failed. The TH-SPUD is more complicated than what it appears. I think some interesting phasing is going on to get a nice flat response. We cannot simply take the average, or mid point of the woofers and model them. I think this is like two tapped horns integrated together where the woofer offsets complement one another. A very interesting solution. I don’t think Hornresp can model it, but AkAbak should be able to.

Rgs, JLH
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Old 20th January 2009, 02:37 PM   #7
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JLH

I'm finding similiar results in my efforts with the live cab.
The set I am building shouldn't work according to hornresp.
I tried an intentional bounce and screwing up where the phase cancellations occur at the frequencies I need to have higher spl.
I don't know what I did but it seems to work.
So to second your suspicions...
There is a lot more going on in a folded TH than meets the eye.
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Old 20th January 2009, 03:13 PM   #8
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Default Re: Re: Double Driver Tapped Horn

Quote:
Originally posted by JLH



The TH-SPUD is more complicated than what it appears. I think some interesting phasing is going on to get a nice flat response. We cannot simply take the average, or mid point of the woofers and model them. I think this is like two tapped horns integrated together where the woofer offsets complement one another. A very interesting solution. I don’t think Hornresp can model it, but AkAbak should be able to.

Rgs, JLH

I spent some time generating some sims from the same diagram, and came to the same set of conclusions. Hornresp isn't going to be able to model the Spud properly due to the multiple staggered path lengths. Modeling in Akabak would be interesting, but since I don't have room for a 12 cubic foot sub anyway, I probably should just resist the temptation.
What really struck me though was not that the response wasn't flat - I expected that. Rather, it's that the efficiency wasn't even close. DSL's measurements show ~97dB in half space, which is significantly higher than my model (~90), or even the dual W8 that you put together. If they had custom 2-ohm versions of the W8 then this would account for most of the difference if we assume 2.83V input rather than 1W, but I sure got the impression the numbers were for 1W.
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Old 20th January 2009, 04:49 PM   #9
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I dont know if there are any impedance curves available on SPUD, but when i try to modell some of Danleys other designs i notice the impedance-graps are way off, and i mean _WAY off_.
Just trying to hit the same peaks and dips made some odd simulations.
There has to be more to it than meets the eye.... i wonder if the plastic tubes, wich appears in some photos, really are terminated... or if they act as an connection between frontchamber and the path.!?

Dag
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Old 20th January 2009, 06:45 PM   #10
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At 100Hz the two drivers are well within WL/4 so are acting as one.

I've built and measured a dual driver tapped horn and didn't see any unusual behaviour I could attribute to having a pair of drivers spaced along the line. One of my tests in a 30Hz TH had the drivers 450mm apart (which was still <WL/4 for the high cutoff for the horn).

Cheers

William Cowan
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