Walkabout sound question

[Vanceman]

I'm thinking about a tube swap in my Mesa Walkabout, if that indeed will help with my percieved problem. My rig consist of Fender dlx Jazz > Walkabout > Epifani ul410-2.

At lower volumes, the sound is perfect, but as things get turned up as the night progresses, the overall sound gets a little distorted. The Amp settings are basically flat, gain around 11:30, bass at 12:00 and mid at 12:30, treble around 11:00. I'm only using the master volume to go louder, not adding any eq or gain.

A question for the Mesa experts... Would it be safe to assume that gain drives tube #1 and the master drives tube #2? Going on that assumption, could I change out tube #2 for something a little cleaner in sound?

I've read the Walkabout mega thread but with over a 1000 replies, I got lost.

Any opinions and suggestions for that tube would be appriciated if you think that would help.

 

[RickenBoogie]

I believe tube #2 is the driver stage, so yes, that would be the one to change out. You want something with ALOT of headroom. But, I'm surprised you're getting distortion with the gain set where it is. Mine stays clean up to the mid point, no matter the volume. You might try cranking the passive mid knob, too. You'll get a little more juice that way. Good luck.

 

[pfschim]

I run my Walkabout with the Gain at 10:00 or so with the Master at 12:00. Slight push on the Bass and Treble tone, Mids cut to 10:00. EQ is basically flat. I also run my active 4s into the passive input switch setting on the WA.

When I run the combo by itself (4ohms) I don't have this issue, but when I occasionally add a 4ohm ext cab (like a Scout 15) and run the stack at 2ohms, I have gotten this problem after a long gig... I tend to think of it as thermal sag and not gain stage distortion, but that's just terminology,the issue is still there. It's not a huge issue and it does not happen to me until late in a long gig.

I just drop the Master a bit and perhaps even drop the active Bass EQ down a notch on my Bass. I have also just flipped the input to Active on the WA, but this tends to dampen down, or darken the tone, in ways I do not like. I also make a point to turn the amp off between sets, and in real hot environments, have actually brought a small fan to add airflow to the WA cooling vents.

I'd also be interested in hearing from others who have successfully tube rolled and found a higher headroom Tube 2 choice for the WA.

 

[quigg]

I can do almost anything to the EQ on mine short of turning the bass all the way up without making it distort at high volume. What does and will make it distort is the preamp in my bass, if I defeat the preamp, no problem, if I don't I adjust (the onboard preamp) carefully.