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In Reply to: RE: Relevant loudspeaker tests posted by Inmate51 on July 11, 2014 at 12:40:42
Heyser was indeed a giant albeit undereducated, like you i only met him once at an dinner at AES and i hardly said a word.
Dicks TDS / TEF machine has probably made more difference is my technical life than any other single item however. I was lucky to be friends with the guy who was in charge of the Heyser archives at Columbia college (Doug i mentioned, who was a friend of Dicks) and it was fun poking through Dicks stuff and reading some of his unpublished papers. The man was brilliant.
The generation loss recordings are getting old, 10 years now old but it remains that loudspeakers are far and away the weakest link so far as being a faithful reproducer, far worse than any other electronic part of the chain. Unlike measurements, one can hear the problems very clearly as the generations add up. try it!.
Follow Ups:
"The generation loss recordings are getting old, 10 years now old but it remains that loudspeakers are far and away the weakest link so far as being a faithful reproducer, far worse than any other electronic part of the chain. Unlike measurements, one can hear the problems very clearly as the generations add up. "Ya think?
I suppose that, on a personal or company promotional level, it was fun/useful to do the experiments. But from a body-of-knowledge standpoint, not so much. Everybody and their dog have known that speakers were the weak link in the reproduction/reinforcement equipment chains since forever.
Edits: 07/13/14 07/13/14
" Everybody and their dog have known that speakers were the weak link in the reproduction/reinforcement equipment chains since forever. "
While this is true, it is remarkable (to me as a loudspeaker designer) that the GLT hasn’t been used to improve the loudspeakers performance since it makes the flaws so much more dramatic / audible and in some cases easy to identify or as Dick wished, easier to tie the measurement to what you hear.
In our market, having a dramatically better sounding speaker / design was a large advantage as very often the potential customers compared the possible choices side by side and in that case, marketing budget or name recognition hardly matters at all.
While we don’t sell hifi speakers or to the hifi market, the principals are identical, the goal or my goal anyway is to have faithful reproduction and my thought was that many here are DIY’rs, many of which would be capable of doing a GLT.
It’s too late to refine design that has been purchased but this is a valuable tool for the developer or person doing R&D or for that matter if one wanted a fair way to evaluate how faithful the various choices of “weak links” were.
Now, I don’t know how many large spaces you have been in where state of the art big name “concert sound” is used for music but that is what was usually installed in stadiums and the sound is “concert like”.
On the other hand, the difference between concert sound and what can be done our way is pretty audible even captured by you guessed it, a microphone on a camcorder or Iphone.
Pop on your headphones and check a couple of video’s, you can hear loudspeakers in very large spaces which will pass several generations of audio in a GLT and sound totally different than “concert sound” for 75,000 - 100,000+ people and it sounds essentially the same everywhere.
Some samples;
A very powerful system located in the scoreboard.
https://www.dropbox.com/s/oyosfc3adc6j1du/20130723135350.mts
A smaller system in the scoreboard, recorded at 700 feet.
https://www.dropbox.com/s/tnsw5mb4v5vdlwq/20120726122124.mts
https://www.dropbox.com/s/lqeg3cf0daqv9ti/20120726114748.mts
A very cold distributed system converted to our loudspeakers.
https://www.dropbox.com/s/1nhx980w24ehxls/20131208154446.mts
"While this is true,"
" it is remarkable (to me as a loudspeaker designer) that the GLT hasn't been used to improve the loudspeakers performance since it makes the flaws so much more dramatic / audible and in some cases easy to identify"
Ya-da ya-da.
:)
well like i said
"It's too late to refine design that has been purchased but this is a valuable tool for the developer or person doing R&D."
And wouldn't be of interest to those not interested in making better loudspeakers i suppose.
Since John Dunlavy required his speakers to be in phase and time aligned, he looked first at the step response(which I guess would reflect time alignment most).
Hi
The Dunlavy's i measured (long ago) had first order crossovers which are the only "named" types that can sum into flat phase which can preserve / reproduce the input waveshape. . If /when the drivers are less than 1/4 wl apart, the DO sum into one single radiation (no lobes and nulls) as if it were a single driver.
In "hifi" time aligned usually means the drivers acoustic center or origins are aligned so that the origins are aligned but the sum has the all pass phase shift from the crossovers. With above first order xovers, the output of the LF section is behind the upper section in time and so does not preserve the input waveshape .
The best indicator of time vs frequency is not impulse or step response but is the Acoustic phase as defined by Heyser.
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