Wayne Parham wrote on Thu, 16 August 2007 18:29 |
Have you ever looked at the Renkus-Heinz CoEntrant horn and compared it with the Unity horn? They are virtually identical.
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Yes, and it's been years but I've read the patents. The base concepts with multiple drivers loading a common horn are very similar. IIRC the Unity patent added the opening spacings along the length of the horn, described how the physical spacing offset group delay in the speakers, and the improvement in phase alignment.
As a (non-audio) engineer, I really admired how this approach addressed phase at a basic physics principles level but I had no idea at the time whether the phase improvement would be significant or audible. Neat idea, but is it worth the effort. When I heard some TD-1s at a seminar I could hear the difference, and it wasn't subtle. Imaging I was not familiar with. I couldn't hear any gack in the crossover bands. Nearly inaudible coverage seams between two hard-packed cabinets. The cleanest coverage pattern I've heard. Pretty cool, definitely worthwhile.
From what I've read I gather that Tom and Ralph respect each other more than a little and see each other as on the same side as point-source advocates.
Wayne Parham wrote on Thu, 16 August 2007 18:29 |
Or how about the old Jensen Transflex? Any similarity to the Tapped Horn?
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Nope, I haven't looked at Transflex, and I don't know it's history. I like the physics behind the Tapped Horn, and there seems to be very few others (Bassmaxx is certainly notable) getting comparable output with comparable LF extension. I haven't heard either of these yet, but I'd like to.
Wayne Parham wrote on Thu, 16 August 2007 18:29 |
The 12Pi is completely different than the LABhorn. It uses a different flare, different throat, different front and rear chambers and different driver configuration. It uses the same drivers, but the drivers in the 12Pi are modified. It uses a spiral fold, but so did my 1970's 10Pi, which was a 40Hz basshorn.
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Hmmm. With reasoning like this, comparing the Unity and the RH Coentrant is like comparing apples and bricks.
From what I've read, those who have 12Pis are very pleased. Bigger in one dimension from the LAB so it doesn't meet the LAB design goals, but not a problem. Spiral fold, nothing new. A bit bigger, of course the design optimizition details will be different. A bit louder, cool. By all accounts an excellent sub.
What is bothersome is that your positioning of 12Pi comes across as a "better LABsub" due to push-pull and cooling plugs. If it did this in the same form factor I would agree, but it's not. It's bigger.
Wayne Parham wrote on Thu, 16 August 2007 18:29 |
So why then would you credit my work as standing on the top of Tom's work, any more than any other work stands on the top of work done before it?
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Tom never claimed the LAB was an end-all sub, just that it was a well executed conventional horn design that outperforms many big name commercial products, to specs driven by the user base, at very reasonable cost, and was within the capabilities of DIYers.
12Pi meets mostly the same goals, in nearly the same way. Same base concept, using all of the same criteria except one dimension. Again, by all accounts an excellent sub. But, done after the fact in "me too" fashion, and then placed in competition to the LAB.
Wayne Parham wrote on Thu, 16 August 2007 18:29 |
I "met" Tom Danley online in about 2001. Actually, my first encounter was with Mark Seaton. These guys were saying the Unity horn was better than any other horn, and attacking other designs.
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I think I ran across Unity a bit later than that. What I remember (my paraphrase) is Tom saying that he designed Unity in the quest for phase coherence because he was convince that phase was more important than the conventional wisdom thought, and that others would agree with him if they actually experienced it.
You were pretty adamantly opposed to this idea at the time, and it was clear that you hadn't heard Unity horns.
Wayne Parham wrote on Thu, 16 August 2007 18:29 |
Worse still, what I'm saying about the cooling plug and push-pull drive has great technical merit, yet they've done everything they could to squelch it. So please don't talk to me about rejecting concepts out of hand and publicly.
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I think your case for the cooling plug would be much better if you presented data that in a pack of four LABs (or 12Pi) that power handling improves by xxx watts, giving an increased max output of yyy dB.
BTW, how does the plug work with the reversed driver in the 12Pi? Are plugs on both sides still of benefit?
Same thought for push-pull, data would help. Theory says distortion should improve, you have said the improvement is measureable, but I haven't seen any numbers. My guess is that the audible difference going from 50% on a front load to 10% on a LAB is more significant than going from 10% on a LAB to even 5% if 12Pi gets there.
I have no doubt that the cooling plug moves some heat. Push-pull could lower distortion. Tom felt that the improvements wouldn't be significant. Data from you would help your case.