Roy. thanks again. ^ Wouldn't using 2nd order cross-overs compromise the whole effort? |
IMHO, the first link is perhaps the best thread ever to appear on audiogon, Roy Johnson of Green Mountain Audio was especially generous in sharing his thoughts.
I've come to believe that some are more sensitive and/or prioritize these specific attributes more than others. Quite by accident, I've come to accept that these design principles are very important |
A good step response and square wave response can be a significant indication of wave form fidelity, things that any other piece in the system should readably be capable of.
Much of the need for correct listening position for the appreciation of such design principles is in regard to distance from the speakers for proper driver integration, typically such designs have something of a wide horizontal dispersion, sometimes there is concern for the listeners vertical position. Many of us do serious listening while sitting somewhat centered between the speakers. Such designs at least offer a very good semblance of wave form fidelity at some position as opposed to never providing any semblance of wave form fidelity from any position. You don't have to sit with your head in a vice to get the virtues of such designs! |
^Again good step and square wave response are indications of wave form fidelity (time and phase). Again, as to it's importance, well that's up to debate, with opposing opinions prevalent on both sides. I will say when I first began seriously auditioning speakers and without any real technical knowledge I was consistently drawn to those speakers that unbeknownst to me at the time shared those design properties, and those speakers designs continue to favorably impress. Others don't always seem to share the same sensitivity and/or priorities that speakers with these design priorities share. Only by listening to them yourself will you know for sure if it's important to you. Oh, btw, they usually share the similar quality of steady impedance loads, a subject of which I'm confident you will recall being discussed previously here on Audiogon. |
Just a word of caution regarding some speaker measurements one might come across. In an effort to avoid room interactions skewing measurements, very often speaker measurements are taken closer to the speaker than where one would typically sit. Most speakers designed for time and phase integrity need to be taken further away to allow for driver integration (approximately 8'-12'), where listeners typically sit. Unless these further measurements are taken in an anechoic chamber, the room will now contribute more measurable distortions than if the same measurements were taken closer to the speaker. Most people don't listen to speakers at the distances many speaker measurements are taken. If speakers with time and phase integrity aspirations are measured at distance ranges other than where they were intended to be heard from; their square wave and step response, though probably still better than competing speakers without such design considerations, will have their ultimate measurable potential be compromised. |
^+1:-)!!!!!
That's exactly how I've feel. |
Bifwynne, if you're in contact with DEQX, if you wouldn't mind, perhaps you might ask them why their system approach includes analog conversion rather than keeping the whole stream in the digital domain? |
Hi Roy, I don't mean to beat a dead horse, but I think that in a W M T M W array, it would be very rare indeed for any of the drivers to be equi-distant to floor and ceiling, and those surfaces would typically be different enough to reflect some frequencies differently as well.
I would have guessed that in an attempt at a staggered driver time coherent horn design that the horns themselves would get in the way of each other with the surrounding horns causing early reflections. Wouldn't a deep throat coincidental multi-driver have more early reflections than a flatter design? |
Roy. thanks again. ^ Wouldn't using 2nd order cross-overs compromise the whole effort? |
Hi Roy, thanks for coming back. Your contributions are most welcome.
I have few questions for you.
Could you explain the pros and cons of making a speaker time coherent either by analog/digital/active/passive means?
If one were to use digital eq that only deals with room considerations and not speaker refinement, would there be a chance (and if so how much) of altering the time coherence of speakers such as yours?
The late John Dunlavy seemed to be somewhat unique (there might be another but for the life of me I can't remember the name of the manufacturer that was once a regular contributor here) in that he used W M T M W driver, as well as down firing woofer configurations. He told me that because of his previous experience in military antenna array technology he had more experience than most in wave propagation technology. Others who tout their speakers as time coherent seem to stick with more traditional W M T arrays. Is this due to size and marketing considerations, or something else?
Though most manufactures of speakers designed for time coherence seem to make fairly similar placement suggestions, they do vary a bit, from equi-T, to equilateral triangle, to wider than near, etc.. Why would that be?
It would seem to me that ideally a speaker designed for time coherence would have a sealed box, yet none of your current offerings seem to be designed that way. Am I wrong? If not, why aren't they?
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Hi Roy, thank you for your response.
At the risk of appearing argumentative; here on Audiogon another speaker designer has suggested that placing multiple woofers in a room at different distances could be beneficial towards evening out standing waves, if that were the case; wouldn't W M T M W speaker arrays have some advantages? I'm not aware of any speakers that are touted be time coherent having more than one tweeter per channel, are there any?
As for sound bouncing differently above and below ones head, wouldn't that be typical during live musical performances? Wouldn't the wave size from midranges and woofers (and live performers) be large enough to extend above and below a typically seated listener's head?
Thiel's concentric drivers appear to be flat, so reflections should be minimized, no?
I have no direct experience, but I seem to recall that DEQX suggests that speaker correction should be first done close to the speakers and then followed with room correction at the listening positions.
Another question if I may; could horn loaded speakers be time coherent?
Thanks again! |
I just remembered the name of the old poster that started a time coherent speaker company; Karl Shuemann. To be fair to all here's a list of those companies that have made time coherent speakers that I'm aware; of starting with Karl's (which fortuitously falls into alphabetical order):
Audiomachina
Dunlavy
Greenmountain
Meadowlark
Quad
Thiel
Vandersteen
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^oops!
I forgot the original Ohms with genuine Walsh drivers
and perhaps their progeny from HHR-ExoticSpeakers, German Physiks and Huff might qualify too. |
Bifwynne, Dunlavy and Meadowlark are gone. I'm not sure if the newer Quads qualify. Some Thiels are, for the time being...the future looks glum. I have doubts that the newer Ohms qualify. I'd hazard a guess that the HHR ExoticSpeakers do, but I haven't seen verification. I would say the same for the German Physiks and similar Huffs, at least for the models that use their DDD drivers exclusively, I have doubts that their full range models qualify. FWIW, I have confidence that the others still do. |
Bombaywalla, unless this:
http://audiomachina.com/philosophy/
is out of date, I think they still are. |
Bombaywalla, you are correct we lost two great proponents of time coherent speakers and both gracious gentlemen as well, John Dunlavy and Jim Thiel. R.I.P.
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Duh, I forgot to add Duntech to the list. |
^Please forgive me, I was confusing DEQX with Holm Acoustics. |
