How much can be measured -- and how much cannot?


There has been a lot of discussion over the years on Audiogon regarding the measurement of components and other audio products. Some people claim everything is either measurable now or will one day become measurable with more sophisticated measuring equipment. But others say there are things in high end audio that will never me measurable and that measurements are really not that important.

Here is a typical example -- a quote taken from the Stereophile forum regarding their review of the Playback Designs MPS-5:

"JA 2/17/10 Review Measurements of Playback Designs MPS-5
Posted: April 13, 2011 - 8:42am

John Atkinson's 2/17/10 review measurements of the Playback Designs MPS-5 revealed less than stellar technical performance even though Michael Fremer really liked the player. I've included JA's closing measurement remarks below followed by the manufacturer's comments.

To my knowledge there was never any followup in Stereophile regarding the manufacturers reply the MPS-5 could not be adequately measured with traditional measurement techniques.

I believe Stereophile should respond to this reply in the interests of its own measurements credibility.

Len"

How important do you think measurements are? Are the ears really the only true arbiter?
sabai
Onhwy61,
I honestly don`t get your point. When I attend concerts it`s for the pure joy and involvement that music provides. With my home audio I attempt to come as close as I reasonably can and with my current system I`m extremely pleased with it. It`s that simple and straight forward for me.We just have different approaches and apparently different objectives.What ever works for you is the way to proceed.

Marketing has nothing to do with my choices, only the end result which is the sound and my response to it(it moves me or it does`nt).
I appreciate your different perspective.
Regards,
No, marketing is not driving what I think sounds good. I may be enticed to purchase a product, but after it is in my listening room the marketing is all over and forgotten. If it sounds good to me, I keep it. If not, I sell it or send it back.

Markering influences the buy decision, but never the keep and enjoy decision. Marketing's influence is very short lived in the end.
03-19-12: Ahendler
Actually I have never found measurements to help me in any audio decision to by a certain product. Measurements are helpful in the design process but do not tell you anything how a component will sound.
Let me supplement my previous response with some specific examples, that illustrate what I, Mapman, Roscoe and others have been alluding to:

1)Someone has read good things about the sound quality that SET amplifiers can provide. He or she is considering purchasing a SET amp and using it in conjunction with a speaker having a specified impedance of 8 ohms. JA's measurements reveal that the impedance has wide swings over the frequency range, including dips to low values at highly capacitive phase angles. Purchasing the SET amp would be an expensive and/or time consuming mistake.

2)Someone is considering adding a powered sub having only line-level inputs to his or her system, and driving it from a second set of output jacks that are provided on the preamp. As is commonly the case the two sets of output jacks are not separately buffered. The power amp is solid state and has an input impedance of 20K, the sub has an input impedance of 10K, and the preamp is tube-based and has a specified output impedance of 400 ohms. JA's measurements reveal that the output impedance rises to 3K at 20 Hz, which is not uncommon. Purchasing the sub would be an expensive and/or time consuming mistake.

3)Someone is considering purchasing a tube amp to use in conjunction with a speaker having a specified impedance of 6 ohms. JA's measurements reveal that the impedance is close to 4 ohms at low frequencies, and close to 8 ohms at high frequencies. That may work OK in some cases, but it definitely suggests the possibility that the speaker was designed with the expectation that it would be used with a solid state amp. The result stands a good chance of being an expensive and/or time consuming mistake.

Countless other comparable examples could be cited.

Disclaimer: I have no affiliation with JA, Stereophile, or anyone else associated with the audio industry.

Regards,
-- Al
My brother, who's a professional audio engineer, recently had to develop his own test gear, sensitive to smaller than picoseconds.
Al,
I agree with your clear reasoned examples, they will certainly have value in determining likely(or unlikely) compatability. They won`t help in determining the sound quality of various component matching.