UNDERSTANDING: THD

PAUL McGOWAN / PS AUDIO

Zero calories? Went to cook some scrambled eggs this morning and first sprayed the pan with one of those spray oils. Always conscious of my weight I checked the calorie content: zero.  Zero?  Really?  It is, after all, oil and oil is NOT zero calories. Turns out the agency that regulates the measurement standards has set a minimum level where they figured if it’s below this level it doesn’t matter.

That got me to thinking.  Maybe it would make sense if we did the same thing.

I am absolutely convinced neither you nor I can hear the difference between 0.01% THD and 0.001% THD despite the fact one is 10 times lower than the other.  We may be able to hear the method used to lower the distortion (like applying more feedback) but all things being equal, I don’t think the difference between these two measurements matters.

Why publish it?  Why not make it easy on people trying to evaluate equipment, based on specifications that are basically meaningless to them?

For example: THD less than audibility.  Now there’s a spec I can live with.  The fact it may be 10 times lower than the next guy’s is a marketing man’s dream – but truly meaningless to the person it should matter to.

My apologies to the marketing guys.

Paul McGowan

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