A question to the membership as a whole (I KNOW Bob can do it!): how many of you have the equipment and the ability to do rudimentary measurements on equipment? It has always been my procedure, after completing a modification, to check frequency response, even if only by looking at a sine wave on an oscilloscope at 50Hz, 1KHz and 10KHz, and checking proper signal level and power output (if the unit is a power amplifier). Rather than relying on ears, this is a better means of verifying proper circuit behavior, and more than once has revealed an error in a "wonderful-sounding" modification featured in a print magazine article or on a Internet site.
One such was a "wonderful-sounding" Dynaco Stereo 70 modification which was shown to output about seven watts. After verifying that the circuit had been built correctly, I took it to the next level on the test bench and found it produced gobs of low-order harmonic distortion, nearly 10%; but that wasn't necessary to reveal that something was seriously wrong with the "wonderful-sounding" design.
One such was a "wonderful-sounding" Dynaco Stereo 70 modification which was shown to output about seven watts. After verifying that the circuit had been built correctly, I took it to the next level on the test bench and found it produced gobs of low-order harmonic distortion, nearly 10%; but that wasn't necessary to reveal that something was seriously wrong with the "wonderful-sounding" design.