PAB issues: too much bass, pop with footswitch

[greiswig]

In my build, the PAB really had too much bass to it, such that any attempt to use the 5th and 6th strings during a solo sounded really woofy. To try to deal with that, I did the typical thing of trying to put capacitors in series with the signal to make a high pass filter. I ended up with a .001uF silver mica cap and a 1M resistor across it. That is in the ballpark of what I'd like, tonally. And it's also in series with the .02uF entrance cap to the OD channel to tame the bass in OD mode, too.

However, I notice something else annoying with this setup: if there is any signal going when I flip the PAB on or off, there's a pretty loud pop. If there isn't any signal, the switching noise is negligible. I've tried various ways of making sure that the caps in the signal path aren't collecting DC between switches, and also making sure that the relay coils aren't causing a spike. But, like I said, the pop is still there if there is signal present.

I'm wondering if anyone else has dealt with this issue when using non-stock PAB boosts? Any ideas what causes the pop, and how to fix it?

IIRC, I read somewhere here (but can't find it again) that someone was suggesting series resistance (not capacitance) as a way of leaning out the bass in OD or PAB mode. Am I imagining that? I'm wondering if avoiding yet more series capacitance might help with the popping, so I'm looking for alternatives to what I have or advice on how to deal with i.

As usual, thanks in advance!

[dcribbs1412]

not sure if this will help.

https://tubeamparchive.com/viewtopic.ph ... t=pab+mods

what value are your resistors...22M
I know when I used a cap on my PAB it popped.....stopped after I
went to stock.

Darin

[Structo]

Never noticed it on PAB but mine pops on the OD.
I have a .01uF cap across the footswitch as well.

[greiswig]

Never noticed it on PAB but mine pops on the OD.
I have a .01uF cap across the footswitch as well.

You have a cap across the footswitch, or across the relay that the footswitch operates?

[greiswig]

Thanks for the replies so far. I wanted to emphasize: this pop is there ONLY WHEN THERE IS AUDIO. It isn't there if there is no audio. Is that fact diagnostic at all?

[Structo]

It's across the switch in the foot pedal.
I don't have any caps on the panel switches in the amp.