Please help with aleph p 1.7 volume relay pops and click

[ostemaden]

Help

I am at the moment building an aleph p 1.7 preamp, and I am having problems with the volume relays.

When the volume goes from step 191 (10111111) to step 192 (11000000) I get pops and clicks in my power amplifier.

I can't determine if the pops and clicks are made by current interference due to the relays coils being turned off/on or if the pops and clicks are made by the in/out switching of almost every resistor in the volume circuit

Please give me some advice to solve this problem

Best regards
Ostemaden

 

[Holger Barske]

This is very common problem with relay attenuators, as you have seven relais switching at once and some unwanted settings may occur for a very short time, enough to cause that popping noise.
The "brute force" solution would be to mute the volume control very shortly before this condition occurs and turning it on again when the relais have settled.

 

[ostemaden]

Thank you for answering and you are quite right, I have tried some different things and the best so far is to mute for approx. 400 us before changing the volume settings.

There is still a little bit of clicks and pops, but it is much better than before.

Thank you for helping

Ostemaden