LSS Channel Switch "thump"

timmerel · Nov 28, 2008

If I switch from channel 1 at 30 watts (so no rectifier) to channel 2 at 5 watts (with rectifier), sometimes the amp makes a thumping noise. Presumably this is electricity suddenly hitting the rectifier tube.

Is there any way to avoid this noise when channel switching?

8d2studios · Nov 28, 2008

Just last night i was playing around with my LSS with this exact same settings and no noise or anything at all strange. maybe is your rect. tube that needs to be change, and always remember to use a power current protector with any mesa amp, they are just too delicate to plug directly.

timmerel · Nov 28, 2008

Never used a power protector - what would you recommend?

Any suggestions on replacements for the rectifier tube?

ja22y · Nov 28, 2008

My amp did that and I took it to be serviced. According to the tech, he checked w/ Mesa and the 'thump' is within spec and the explanation is since a pair of tube is being switched off, a low level thump is to be expected. But strangely, at somepoint later, that noise is gone. But I still get thump when engage the drive switch.

timmerel · Nov 30, 2008

I guess it makes sense, but wonder if there is any mod which could be done to temporarily switch the amp into standby mode while the channels switch - if I manually switch to standby, then change the channels and come back out of standby, there is no thump.

Probably a bit too complicated I suspect. I might look into a standalone standby footswitch being modded to the amp, which would enable me to do the same thing.

ja22y · Dec 1, 2008

timmerel said:
I guess it makes sense, but wonder if there is any mod which could be done to temporarily switch the amp into standby mode while the channels switch - if I manually switch to standby, then change the channels and come back out of standby, there is no thump.

Probably a bit too complicated I suspect. I might look into a standalone standby footswitch being modded to the amp, which would enable me to do the same thing.

I wouldn't do a standby footswitch since then you won't be able to switch the channels w/ a single step on.