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In Reply to: RE: Mr. Atkinson's discussion of loudspeaker sound & measurement.... posted by wangmr on December 29, 2014 at 03:19:08
The blending of listening and science, both presented properly in my view. I know it is not always possible, but I do like it when JA has the chance to measure them at his place which shows a more real world listener review. Measurements do tell a great deal and I appreciate him doing it.
Jim Tavegia
Follow Ups:
I just don't see how this is possible. I think such measurements are questionable at best for at least the following reasons:
1. There are few if any measuring standards.
2. JA admitted not long ago that one of his measuring instruments was out of production and long overdue for a check up / recalibration.
3. Is the platform for which the object to be measured the same or different than previous measurements with other similar products?
4. Is sufficient or at least similar warm up and settling in times alotted for the object in question prior to recording measurements?
5. Is the same measuring instrument used for all similar products?
6. It is well-known by some that our sensitive components are adversely affected by distortions induced by noisy AC and undercontrolled vibrations. Is the same diligence applied to the measuring instrument which may well be just as sensitive? e.g. What power cables and/or line conditioners and racking systems are used for the sensitive measuring instruments?
I recall a thread several years ago with Mark Levinson and John Curl participating where ML claimed he used SOTA-level professionally-calibrated measuring instruments, yet he and his colleagues claimed the measuring instruments failed them routinely when they could audibly discern things the measuring instrument could not discern. Curl also admitted that his measuring instruments failed him routinely in discerning certain audible changes.
Components, cables, and speakers all take a variable time to burn-in, warm-up, and settle-in. Shoot, I know some components that take upwards of 5 months to settle in.
Hence, without any potentially qualifying standards or consideration for any of the above, I'd have to guess that any such measurements have perhaps a greater chance of misleading the consumer rather than revealing truth.
No offense intended against JA as I appreciate his willing to take the time to perform this potentially valuable service. However, and I'm sure JA would agree, there's more involved than just taking measurements.
> JA admitted not long ago that one of his measuring instruments was out of
> production and long overdue for a check up / recalibration.
I was referring to my Audio Precision System One Dual Domain. However,
other than loudspeaker impedance measurements, for which it works fine,
this is now just used as a back-up to my Audio Precision SYS2722. This
is fully up to date and has just been recalibrated at the factory.> I'd have to guess that any such measurements have perhaps a greater
> chance of misleading the consumer rather than revealing truth.I disagree. The article referred to in this thread is now available at
the link below.
John Atkinson
Editor, Stereophile
Edits: 01/05/15
Thanks, John. However, I still could not see where any standards of any kind were adhered in preparation of or during your measurement recording sessions.
> I still could not see where any standards of any kind were adhered in
> preparation of or during your measurement recording sessions.
For electronics, I adhere to the old IHF standards, except where changing
the measurement conditions reveals something specific about the device
under test that I want to discuss. For loudspeakers, I use a
standardized procedure that I first developed a quarter century ago. See
the link below as well as my 3 articles on measuring loudspeakers at:
http://www.stereophile.com/reference/99/index.html
http://www.stereophile.com/reference/100/index.html and
http://www.stereophile.com/reference/103/index.html .
The only change in all these years was to substitute a chirp- and
FFT-based technique for the original spectrum analyzer technique for
the spatially averaged in-room response measurements. But I have now
published measurements on more than 750 loudspeakers under these standard
conditions, which is perhaps a unique situation.
John Atkinson
Editor, Stereophile
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