PMC clones

[Scottmoose]

Basically, with certain grey areas between them where people get into linguistic semantics over definitions.

All QW based TLs & their variations are ultimately 4th order; even max-flat impedance designs will ultimately transition from 2nd to 4th. Frankly, I don't think many of PMC's enclosure designs are especially good examples of the QW breed, but there are commercial considerations they have to work with, which is fair enough in itself. Most appear to be modestly damped QW pipes designed to use the enclosure resonance to extend the LF. They are certainly not critically damped / max-flat impedance TLs, or at least, none that I have seen are.

 

[boswald]

Clearly we are having "a failure to communicate". I in particular am having trouble with the language regarding the phase of a wave. To me 0 degrees is straight ahead,360 would be straight ahead behind or ahead one cycle, and 180 would be 'out of phase' and would cancel with the straight ahead. Am I missing something?

 

[pkitt]

I agree with your viewpoint on PMC enclosure designs. Those I've seen certainly are not optimized TL designs, for whatever reasons that happened. I just wish newcomers to TLs didn't get sidetracked by the several TL myths that prevail and promoted by people like Keilau.
Paul

Basically, with certain grey areas between them where people get into linguistic semantics over definitions.

All QW based TLs & their variations are ultimately 4th order; even max-flat impedance designs will ultimately transition from 2nd to 4th. Frankly, I don't think many of PMC's enclosure designs are especially good examples of the QW breed, but there are commercial considerations they have to work with, which is fair enough in itself. Most appear to be modestly damped QW pipes designed to use the enclosure resonance to extend the LF. They are certainly not critically damped / max-flat impedance TLs, or at least, none that I have seen are.

 

[planet10]

Clearly we are having "a failure to communicate". I in particular am having trouble with the language regarding the phase of a wave. To me 0 degrees is straight ahead,360 would be straight ahead behind or ahead one cycle, and 180 would be 'out of phase' and would cancel with the straight ahead. Am I missing something?

aaThe output of the rear of the driver is 180° out of phase with the front. One wants to delay it by a half cycle (180°) so that it is in phase. It will be time delayed by a half cycle. Horns might delay it more but ideally (at the "XO" point is an odd number of half-wavelengths behind.

dave

 

[boswald]

That's what I thought. When we read something that doesn't make sense, we sometimes question ourselves. There was a study recently which supposedly showed that those with absolute confidence were the clueless, most people were in between, and the most expert in a field were 60-80% confident.
Which reminds me of a story...At Temple University in Philadelphia, there were two professors;
Zalman Schacter knew everything......but understood nothing. Norbert Samuelsson knew nothing......but understood everything. Most of us are in between.

so thanks, Dave

best,David

 

[Ugg10]

Anyone tried to clone the PMC Twenty 22 large monitor ?

Looks like an interesting design and there are plenty of pictures of the internals to scale/copy. looks like a fairly simple build but I guess it is not that easy. Would consider making it with a minidsp crossover to assist in fine tuning. What would be the result if it were upright rather than at a slight angle? Anyone know of a calculator that can so the maths on this type of enclosure as I would be interested to model a 7" or even 8" version.

Audiophile Musings: Bristol Show 2014 - Bryston and PMC

From what I can tell the tweeter is a Seas 27TFFC, not worked out what the 6.5 main driver is yet. Anyone know ?

brochure shows the driver pictures - http://pmc-speakers.com/sites/default/files/attachments/twenty-series-brochure-nov16_0.pdf