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Old 27th April 2008, 06:20 PM   #51
GM is offline GM  United States
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Quote:
Originally posted by MaVo
He build a Hifi version? Can you point me to some information about this please?
Officially, the lamentably defunct Lambda Acoustics was responsible for offering both kits and finished products, but even using the 'Wayback Machine' yields little useful info, though beyond careful throat, expansion contouring, cosmetics, different HF driver options and possibly 'audiophile' XO component options, they were otherwise the same as the prosound version AFAIK, but you'll need to ask folks who bought them such as WC: http://www.cowanaudio.com/

GM
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Old 27th April 2008, 07:03 PM   #52
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Thanks GM, i thought Williams horn would just be a regular one.
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Old 27th April 2008, 08:48 PM   #53
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G'day Mavo

My horn differs little from the one used in the Contractors Cube and other similar products that Servodrive released. The fill in the corners is a little different (cosmetic issue once a different crossover is employed) and the X/O components Nick used are first class, probably better than used by Servodrive. Apart from that, it's the same device. With a small amount of eq (+/- 1 to 2 db) in some points, the horn measures very flat within a huge listening area. I guess this is the ultimate beauty of the Unity Horn in a domestic environment.

Cheers

William Cowan
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Old 28th April 2008, 12:47 AM   #54
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Quote:
Originally posted by GM


Please elaborate as my experiments confirmed to my satisfaction what many other folks at Altec, RCA, etc. long before me concluded that the difference between round, square, and even low aspect ratio radials (< ~1:273) for a given BW/cut-off were so minor as to be moot for all intent and purpose.

GM
Mavo nailed it - in a prosound environment, the square mouth is superior because it maximizes the mouth size if your enclosure is cubic.

As for the cut off question, that gets into the ol' waveguide vs horn debate. The mouth size required for a waveguide is dramatically larger than the mouth size required of a horn with equivalent cut off. So in that respect, the researchers from Altec and RCA are looking at a completely different problem than I am. I am concerned with directivity control, not with how low I can play.
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Old 28th April 2008, 12:53 AM   #55
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Quote:
Originally posted by MaVo
Tom said roughly the following regarding HOM in unities: They are no concern, because the transition of round to square only affects the highest frequencies, since it takes place deep in the horn, where the internal dimensions are acoustically small for most of the audio bandwidth. Same goes for the entry holes. Only waves which WL is much longer than the horn dimension pass them, so no HOM are generated there. Regarding the square shape... i think a OS WG can also be square, as its only difference is in the expansion rate of the first throat centimeters, to smooth the transition between driver opening angle and horn angle.
Based on what I've read from Geddes, I do not agree with that statement. As I understand it, the first few millimeters after the diaphragm are the most critical in a horn OR a waveguide. The smallest deviation from "perfect" affects the waveshape all the way down the device. That's why Geddes is so obsessive about the entry angle, the match between the compression driver and the waveguide, and even the phase plug. In fact he owns a patent on interchangeable phase plugs.

Maybe he'll chime in on this thread and elaborate.
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Old 28th April 2008, 01:06 AM   #56
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Quote:
Originally posted by ttako
Hi Patrick,

I also plan to give a try to a UNITY horn.
I would like to get quite high efficiency, so I would like to use for example 8x 2" as mid and 2x8" as low beside the BMS 1"
Did you do experiment with configurations for the mid playing high to 2kHz?
Also did you try to build low extension like in the SH50? I mean with two speakers into the horn thru holes and the back chamber also goes into the same horn at a different location...

Thanks,

Tamas
Your suggestion *also* gets into the horn vs waveguide debate. The lil' two inch drivers from TB play down to 200hz. If you used a waveguide with a 30" mouth you could maintain directivity control down to 460hz. So why bother putting an eight inch woofer into the waveguide? You're not even running out of low-end with the 2" woofers, right?

Of course Danley is in a different situation; he has clients who are array four of these babies, which gives you a dramatically larger mouth.

Keep in mind that my endeavors are 100% focuse on home and car.
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Old 28th April 2008, 01:48 PM   #57
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Quote:
Originally posted by Patrick Bateman


Mavo nailed it...........

As for the cut off question...........
Nothing here addresses your assertion that a square mouth is a 'bad idea', so all things considered it's completely without merit IMO.

GM
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Old 28th April 2008, 02:09 PM   #58
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Quote:
Originally posted by Patrick Bateman

As I understand it, the first few millimeters after the diaphragm are the most critical in a horn OR a waveguide..............
If you study the early Bell Labs/WE, RCA, JBL, etc. designs you'll see that the pioneers of audio understood this and my 'adventures' in trying to optimize a pair of Altec 802D loaded 511B horns and later when DIYing horns/WGs finished convincing me beyond all doubt and while I wasn't willing to devote the time/patience to get into phase plug design I have no doubt that different phase plugs are required for different driver/horn/WG combos.

Not all that much new in horn/WG design and those who don't learn from history are doomed to repeat it.

GM
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Old 28th April 2008, 02:19 PM   #59
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Quote:
Originally posted by Patrick Bateman


Based on what I've read from Geddes, I do not agree with that statement. As I understand it, the first few millimeters after the diaphragm are the most critical in a horn OR a waveguide. The smallest deviation from "perfect" affects the waveshape all the way down the device. That's why Geddes is so obsessive about the entry angle, the match between the compression driver and the waveguide, and even the phase plug. In fact he owns a patent on interchangeable phase plugs.

Maybe he'll chime in on this thread and elaborate.

Hey John

First, the Unity horn is designed for extremely high SPLs and it is good at that. In the Pro market sound quality is not a major (or certainly not THE major) driving factor (from what I have heard of late its not even a consideration).

So are HOM an issue? No not really, there would be lots of them created by the midranges etc. and those from the throat would not be a big additive issue. But from a sound quality standpoint for lower SPL and smaller rooms, I would contend that the OS waveguides with foam would have a far better sound quality than the Unity. The unity will have lots more SPL. Its a tradeoff.

Someone asked about foam in the unity and yes I believe that the sound quality would be improved, but the SPL loss might be unacceptable as a tradeoff. HOM reduction via foam may not be very effective if serious attention has not been paid to reducing the generation of HOMs in the device itself.

Toms designs are optimized around max SPL, mine around max sound quality. He claims, and I don't doubt it, that his also work well in consumer applications, just as I claim that mine also work well in Pro applications. But make no mistake they are designed and optimized arround different criteria rankings.
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Old 28th April 2008, 02:23 PM   #60
gedlee is offline gedlee  United States
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Quote:
Originally posted by GM
Not all that much new in horn/WG design and those who don't learn from history are doomed to repeat it.

GM
I would take strong exception to this statement as my letter to the Editor of Audio-X-Press (see www.gedlee.com) will attest to. (This will be published - Ed Dell was quite impressed.) The understanding of waveguides will completely overturn and throw out all prior horn theory based on the Horn Equation. It may take some time, but it will happen. Its alrady started.
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