Amir and Blind Testing

So in my vanity, I will take several readings on my bathroom scale but accept only the lowest reading.  I don’t do a statistical calculation of the group of readings.  That’s the very definition of biased testing, I think.  And what’s it matter?   When I go to the Doctor’s office they will not accept my weight based on my scale’s readout.  They take their own measurement on their scale.  No one believes the test data except for the one who took it…

Are you still going on about this? You don’t even expect measurements from 99.9% of audio companies, but you nit pick because a test site that produces likely accurate results within the framework of the measurements they are taking, produces results you don’t like?

My background is physics, so not an EE, but I understand most of the terms pretty well as we use similar measurements.

I personally don’t care if the amplifier I bought was 200 wpc into ohms or 195. I will never hear the difference and it is an acceptable margin of error or manufacturing tolerance. I would care about 170 because I paid for 200 and that is not an acceptable tolerance. In my industry, we specify batteries are either +/- tolerance or +/-0 (no lower than) depending on the product / contract.

Now if I am not mistaken, harmonic measurements, which are more important than power as long as power is close, is a relative measurement.

As well, as we discussed previously, it appears the test equipment in question both ships calibrated, as well as has a source and receiver. That provides a level of inherent feedback on current calibration.

Last, due to the relative nature of the critical measurements, the best measuring tested device, if available, could be used a 2nd reference to calibration to set a minimum benchmark. For example, if the best device you tested had a THD of 0.0010 %, and you test it again, 0.0010, you can be confident in the current operation of your system to testing devices with equal or higher distortion. We have a wide range of "reference standards" in our labs and production for validating current calibration, not to mention you are calibrating a whole fixture or system, not one item provided by a 3rd party vendor.

Jssmith, I appreciate your comments but I wouldn’t trust Amir’s opinion on judging the sound of anything. He’s obviously a horrible listener and the pure fact is he’s a measuring geek. He knows nothing about the quality of the sound of products. 

In the late 1970's I worked at a high-end audio shop in DC and they purchased what was then a "sophisticated" A/B switching unit, which allowed the user to switch back and forth between a pair of amplifiers (among other things).  I remember setting up a customer for an extended A/B comparison between a McIntosh 2205 and a Luxman LRS (Laboratory Reference System) power amp.  After a LONG audition the customer ordered the LRS amp, saying he thought that sounded "smoother" than the McIntosh.  I later found out that our tech had ordered a new main board for the switching unit, as it illuminated the lights for unit A and unit B when you pressed the button to make the switch, but the electronics inside the unit were not actually switching amplifiers...so my customer was actually only listening to the McIntosh amp.  When I found that out, I called him and let him know the situation, but he enjoyed the Luxman so much, he decided to keep it!

Haha, it’s placebo.