Valve Pre Amp and Separate Compressor

[Piers_Williamson]

I put up  my hand and say I am not an electronics expert!  I have a couple of Fender Custom Shop Jazz's which have relatively low output pickups and I find that pushing the signal through a Noble PRe-amp really gives that vintage sound.  I have added a Cali 76 Compressor to even out the response of the strings and to help between styles of playing.  At home I play the combination through a PJB set up including an Ear Box.  At some settings of the Compressor there is a wasp like buzz from the Ear Box.  I am pretty sure that I haven't bust one of the Ear Box speakers and I have changed over the valves in my Noble, in case one of them had gone.   Can the Compressor attenuate unwanted harmonics from Valves? And/or are there particular settings of the Compressor that Is should avoid?

[krispn]

If the noise isn’t there when the comp is off or out of the signal chain chances are it’s adding noise or highlighting some noise somewhere. There’s an expectation comps can increase the noise floor and while some comps do it in a less noticeable way than others it could be the culprit. As always remove what you think is the offending item from the signal chain and test then do the same with the next bit of kit etc. 

 

As for settings the best thing to do is set the unit to where it’s doing what you want with minimal noise (I know I’m stating the obvious). It’s always hard to give settings especially on a compressor as we all have a different touch/attack but on the Cali a 4:1 ratio and fine tune the attk/rel to taste for a nice gentle evening out is a good starting point.

 

Sorry I’ve just given the most generic reply ever on basschat 😀

Edited April 24, 2023 by krispn

[Osiris]

 

I've just googled the PJB ear box as I wasn't familiar with it, but it's two 2.5" drivers according to what I found so when you describe a wasp like buzz my first thought is that the compressor may be adding a gain boost that's pushing the drivers too hard so that they're distorting. Have you set the compressor - and the Noble - so that they're at unity, i.e. the same volume as when they're on and off? If you're using one or the other, or both, to boost the signal try backing off the volume to see if the buzz goes away.

 

The Cali76 is made with high quality components so hopefully hasn't developed a fault, my guess is that the tiny drivers in the ear box are struggling to reproduce sufficient low end at the volumes you want. Do you have any other speakers you can try swapping out for the PJB to help with the problem solving?