Attenuator Question

[greg788]

Paul, you mentioned using -10dB Rothwell attenuators at the input end of the Moreplay to cut the level of my DAC by 10dB lowered the distortion significantly. By how much again and why is that? Is it because the volume potentiometer is located behind the gainstage rather than ahead of it, for example? And what degree of distortion reduction should I expect with -20dB attenuators?

 

[Paul Joppa]

Reducing the level at the input of a gain stage reduces the second order distortion by the same factor, the third order distortion by that that factor squared, the fourth order by that factor cubed, etc.

You can experiment easily if you have Rothwell or similar attenuators. Compare putting the attenuator at the preamp input to the sound with them at the power amp input. At the Moreplay input they will reduce the distortion but increase the noise and microphonics.

(The 100Kohm atttenuators will be a slightly cleaner experiment than 10Kohm ones because they won't load the Moreplay output as much.)