New amp problems: Roadster

[Nazgul666]

Just picked up a mesa Roadster, used off of Craigslist. I read the entire manual and am messing with settings.

I'm getting a nice sparkly powerful distortion on channel 3. Now, when I turn to channel 4 there is a noticeable drop in volume and especially highs. Settings are absolutely identical. Every knob and switch.

Now what is supposed to happen, I believe, is that I should have even more highs on channel 4 because the only difference between channels is the taper of the presence knob. The presence knob on channel 4 is more aggressive so with identical settings it should be brighter with more grind.

I'm getting less sustain too.

Any ideas? Preamp tubes, perhaps? It's bumming me out on my new amp day!!

Thanks,

Mike

 

[gribbly]

Check out this thread.

I just picked up a Roadster combo and I had the exact same problem only with Channel 2.

It was a pre-amp tube. I switched out the 12AX7 in V2 with a new one, and boom Channel 2 was like new.

Since you're having an issue with Channel 4, I suggest switching out the 12AX7 in V3.

If Channel 1/2 sound good, you could try temporarily switching the 12AX7s to see if that fixes Channel 4 (although that will likely screw up Channel 2).

Hope that helps.

 

[Big_Al]

Does this happen on all modes for the channels? Reason I ask, I was using vintage mode on channel 3 and 4 but had to turn the presence up very high to get more treble on channel 4. Ends up that's the way it is.

 

[KH Guitar Freak]

Could be a number of things. In my case, it was a faulty treble pot on channel 4...

 

[joe web]

channel 4 is optimized for "modern" mode and sounds different in "vintage" mode to channel 3.