Quad Pre Outputs A & B: different sonic character

[HSL]

I checked my power amp and my cab and that isn't the problem. Output A on the Quad Pre has a more 'chunky' sound, while output B has less of that and more high frequency content. I'm not saying either sound 'bad', but definitely different. I switched the cables in the back of my rig to test and when I do that, channel B becomes the chunky one. I also switched around the power tubes with no difference, so it's definitely the Quad and not my cab or power amp.

I've got the schematics and tube layout printed out that I keep in a binder notebook, and it appears there's only one tube in the Quad that may change anything: V22 which is the FX return and output tube. I'll switch out the tube to see if that'll help any, but I doubt it will since it's for both outputs A & B.

Have you ever noticed this about the Quad, and is it normal?

 

[HSL]

Anyone know what this may be?

I'll probably be giving someone at Boogie a call tomorrow to see if they can help. I'm thinking about sending the Quad in to be looked at and fixed up.

 

[ando]

I think it's a good idea to get it fully checked over. With old pieces of gear you can't really rely on them unless they've been checked. The sound difference in your Quad could be any number of things - tubes are the obvious culprit, but if you have changed them already, capacitors are the other big one. They have a limited lifespan and when they go, they give symptoms like what you are describing because capacitors are used to filter certain frequencies. Pots can get old or full of dust, which can affect the sound.

If it's working ok, I doubt that anything that serious or expensive will arise when you get it checked. Good luck!

 

[crane]

Got exactly the same with my TA. It could probably come from V22 on the Quad, or any of the resistor or cap after it.
It's not a problem for me since I'm using different cabs. I like mixing different sounds/characters.

 

[HSL]

I've switched out tubes in the V22 slot, problem still persists. I bet it needs a recapping by now. I'm going to get a completely new set of tubes and check it out. If that doesn't fix the problem, I'll send off the Quad for servicing. I think it'll be worth it to have the Quad at 100%.

Actually, I'll still probably get it serviced just to be 100% sure even if the tubes do clear up the problem. I love it that much

 

[HSL]

I had a chat with a Boogie tech earlier. I'm going to completely retube the amp and see if it helps, but I don't think it'll correct the problem. After the retubing, regardless if it fixes it up, I'm going to be sending it on over to Boogie to have it looked over. Want to get it up and running 100%