Roadster Question

[jhguitar1]

If this is posted in the wrong section I apologize. I have a roadster head and recently the high gain seems to be really muddy. Am I right to assume it is probably a preamp tube? I am familiar with boogies, so gain is not cranked, mids are not scooped, and bass is at a respectable level. If it is a preamp tube, which one should I start with?

Thanks

 

[Bill11]

Hi jhguitar1,

Which channel is experiencing this issue?

 

[primerib]

is it all channels, just one or two channels? disable loops also while testing

 

[jhguitar1]

It is on channels 3 & 4. I notice it when I turn the gain up. I use channel 3 as my hard rock tone so the gain is around 1-2 o'clock. Channel 4 is for medium rock and the gain is around 10 o'clock.
I had a great high gain tone at one time, and now it seems to have gone mushy.


Thanks

 

[thejay]

I would check the tube...

 

[jhguitar1]

I should check v1 - v3 correct?

 

[Bill11]

Hi

I don't have a tube chart here, but here are the functions as I remember them for the respective channels. Each preamp tube controls two functions:

V1A First gain stage of both channels (first side of preamp tube)
V1B Second gain stage of both channels (second side of preamp tube)

V2A Third gain stage, Ch1 & 2 (first side of preamp tube)
V2B Third gain stage, Ch3 & 4 (second side of preamp tube)

V3A Fourth gain stage, CH3 & 4 (first side of preamp tube)
V3B Tone stack driver CH3 & 4 (second side of preamp tube)

What I do, is buy a new preamp tube from Mesa, warm the amp up, put the amp in standby, replace one of the preamp tubes with the new tube, take the amp out of standby, test it with the new tube in place, and repeat this process until I have found the failed preamp tube.

If a new preamp tube does not solve the issue, I call Mesa.

Hope this helps and let us know what you find.

 

[domct203]

FYI-

The Roadster's Pre-amp tube functions are the same as the RKII:

V1 A = First Gain Stage (Input Stage)
V1 B = Second Gain Stage

V2 A = 3rd Gain Stage Ch. 1 & 2
V2 B = 3rd Gain Stage Ch. 3 & 4

V3 A = 4th Gain Stage Ch. 3 & 4
V3 B = Tone Stack Driver Ch. 3 & 4

V4 A = Reverb Return Buffer
V4 B = Reverb Send Driver

V5 A = FX Loop Send Driver
V5 B = FX Loop Return Buffer

V6 A&B = Phase Inverter

Hope this helps,
Dom

 

[jhguitar1]

Thanks guys. Basically, my amp sounds like someone put a blanket on it. The tubes are about a year old. If I just go ahead and retube all the preamps, do you think the "blanket" will be lifted? I have my first show with a new band in a couple of weeks and I am kind of freaking out about my tone.

Thanks

 

[domct203]

Preamp tubes will usually last quite a long time, especially with conservative gain settings. Try swapping V1 with one of the other pre's in the amp and see if that helps any.

If you play the amp 4-8 hours per week at stage volumes, it may be time for new power tubes. I change mine out about every 12-16 months, and the improvement in clarity is noticeable, but not extreme.

Hope that helps,
Dom