[sdiy] Better testing techiques for audio circuits

[Justin Owen]

Thanks for everyone's input on this - some really good info, much appreciated.

Neil - can I just clarify...

>1/ The nulling technique, where you apply a stimulus (e.g., a sine
wave) to a circuit and then measure the difference between the input
and output using a true RMS AC voltmeter.

I'm measuring the stimulus at source (a) - e.g. a sine wave generator at its output, not connected to anything (except the meter), then I'm taking a second measurement at the output of the circuit under test (b) with the sine wave as an input to that circuit and from there I can assume that the difference between (a) and (b) is 'stuff' (noise?) that's introduced by the circuit?

How much more detail can I potentially get out of that other than e.g. seeing that a 5V AC input is coming out at 5.2V and therefore the circuit is adding 0.2V of 'stuff'? Does that make sense?

Thanks,

Justin