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Speaker Asylum General speaker questions for audio and home theater. |
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Speaker Asylum General speaker questions for audio and home theater. |
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In Reply to: Phase coherence in Von Schweikert and Spica Crossovers posted by misterjenkins on September 28, 2001 at 13:16:51:
Mike,Several years ago John Dunlavy and Albert V. crossed swords in public regarding their loudspeaker designs. I believe it started with John Dunlavy challenging the technical claims made on the Von Schweikert web site (the original web site, around the time of the VR-4/VR-4.5/VR-6 models). Here is a snippet of their rather long on-line debate, pertaining to your question:
John Dunlavy said:
".... Albert has frequently and emphatically claimed that his loudspeakers "exhibit phase-coherent performance using a 4th-order network". Not so, as several posters with excellent technical/professional credentials have explained. Phase-coherent (pulse-coherent) performance, on-axis, cannot be achieved using any type of passive, 4th-order crossover network. Period!
Nor can a passive 4th-order crossover yield accurate impulse, step and
phase responses. It is a priori impossible!"Albert V. replied:
"John, later technology refutes this, I'm afraid, such as in Baekgaard's paper on using "filler" drivers with 2nd, 3rd, and 4th order crossovers in order to achieve perfect pulse coherency. (See his paper in the Journal of the Audio Engineering Society, May 1977.) Also, I have never claimed that my crossover design replicates a pulse with first order behavior. Please reread my statement on this for clarification. I said that there are benefits of the 4th order crossover which are superior to a first order, and these benefits
are: 1) superior vertical off axis measurements, 2) superior power handling and 3) clarity due to lack of excessive driver interference in their stop band.Obviously, first order crossovers will pass a square wave, while 4th order networks exhibit approximately a 0.5ms delay in processing the pulse. I am not debating you further on common knowledge, and I am growing weary of your statements that I don't know anything about engineering.
You believe that a perfectly reproduced pulse is audible, and that this makes your design "automatically" superior. However, I and many other engineer who use steep order slopes have found that this delay is not audible and that the advantage of a perfect impulse response does not guarantee listening superiority...."
Etc.
Rich H.
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Follow Ups
- Re: Phase coherence in Von Schweikert and Spica Crossovers..HERE YA GO.... - Rich H 19:42:08 09/30/01 (2)
- Dunlavy- Von S debate- To Rich H - John Purys 19:55:10 10/02/01 (1)
- Re: Dunlavy- Von S debate- To Rich H - Rich H 21:22:22 10/02/01 (0)
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