Wednesday, December 2, 2009


xkcd 670

Actually PROPER volume knobs have units of -dB. My Yamaha goes from 0 to infinity with regularly marked intervals but they are labeled like this, from quietest to loudest.

infinity 70 60 50 40 34 28 24 20 18 16 14 12 10 8 6 4 3 0

The feedback circuit on the amp includes the potentiometer behind the volume knob. Maximum signal gain is achieved with the pot cranked all the way clockwise. As you turn it counterclockwise the feedback circuit changes the transfer function of the amplifier and the amplitude of the output goes down. So labeling it as a decrease from maximum makes good sense to me. There is actually energy burned off in that resistor that could be coming out of your speakers.

But apparently normal people don't think of it like that. They think of it like a speedometer I suppose. They think when they turn that knob clockwise they are giving it some gas. In that case I think it is a great opportunity for a smart engineer to change the silkscreen on that front panel and charge extra! Vive la ignorance!

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