preamp tube tasks

[Tahoebrian5]

Ok, I'm experimenting with different preamp tubes and the tube task chart (pg 62) in the manual is cool but a couple things are unclear to me.

First, what is the difference between a drive stage and a gain stage?

Secondly, The task chart shows (for Ch. 3) V1a = input stage, V1b = 2nd gain stage, V3a = 3rd gain stage, V4b = 2nd Drive stage, V5a = 1st drive stage, V6a = 4th gain stage. Are all of these stages used for every mode of channel 3? If not how would one know which tubes are being used in which mode for each channel? This would greatly help me try out different tubes. For example If I’m trying to find the best tube for channel 1 clean sounds, obviously changing V2 is a waste of time.

Thanks, B

 

[MrMarkIII]

The bigger problem is the overlap. You can't just switch a tube and affect only CH3. For example, trying to get lower gain in CH1 will result in lower gain pretty much everywhere else. This is true for all the channels. Since CH3 is higher gain than the other two channels, it would be safe to think that the "Drive" stages are more cascading gain stages for CH3. Unfortunately, affecting with these will affect your Reverb, too.

This is not to say you can't experiment, and the basic logic and procedure is exactly the same:
Buy some tubes, and replace V1. Now run through the channels and determine if the sound is to your liking.
Repeat this process for V2, V3, V4, V5, V6, and V7.
One tube position at a time.
There's no magic formula, just use your ears. Enjoy!

 

[Tahoebrian5]

Actually V4, 5, & 6 only affect ch3 according to the tube task chart in the manual (disregarding reverb which I don't use, and effects loop).

I was able to talk to a mesa boogie tech support guy so thought I would share the info he left me with in case others are thinking of doing a similar experiment. I would like to add that I recieved a personal phone call from Mesa within a few hours of sending an email to the general mailbox.. I have to say their customer service is top notch!

Ok so what I found out..
1) Drive stages will typically have an affect on what they call "punch" rather than tone where as gain stages will more have more of a tonal affect.
2) Yes, all the gain and drive stages listed in the task chart are used all the time for each mode but are "rewired".
3) The overall suggestion as far as alternate tubes to try for this amp were of the chinese type. But suprisingly the mesa crew does not seem to dabble too much with different tubes.. at least that was what I got out of the conversation.