ceejay;192191 Wrote: > > Well, if not "obvious" then it is at least likely ... Noise introduced > by the amplifier after its gain control is of course irrelevant here - > it is whatever it is and nothing we do with the TP will change it. > Similarly, noise introduced in the TP *before* the attenuators is fixed > in relation to the signal and can't be affected by what we're doing > here. > > <snip> > > So, as you say, it depends on where the noise is being introduced: but > there isn't any place that SNR will be improved by lowering the TP > output level.
Hmmm - why not? I think you're making an error when you say the noise after amplification is irrelevant - we're comparing situations with different levels of gain, so it's very relevant. Suppose for simplicity there are only two types of noise - noise before amplification N_B, and after amplification, N_A. Then the total signal going to the speakers is something like g*(S + N_B) + N_A, where g is the gain, and S the original signal. The final signal to noise is g*S/(g*N_B + N_A) So if the noise is mostly from the TP, so that g N_B > N_A, the signal to noise is largely independent of gain, and attentuating S (and N_B) doesn't do anything. On the other hand if N_A > gN_B, so the noise is mostly from after amplification, signal to noise will improve linearly with gain, and so it's better to attentuate. Actually if this simple formula were correct it would always be better to attenuate, but of course there could be noise components that scale faster than linearly with gain, not to mention distortion. -- opaqueice ------------------------------------------------------------------------ opaqueice's Profile: http://forums.slimdevices.com/member.php?userid=4234 View this thread: http://forums.slimdevices.com/showthread.php?t=34140 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/audiophiles
