#1
Ok so I just got myself a bunch of new tubes for my Carvin X100B. Well I did a whole bunch of research on how to do it and all that good junk but to my dismay when I went to open the thing up it had no adjustable bias pot only a resistor in the place where the pot should be. The amp is biased extremely cold at about 18mA I just got a whole new set of JJ 6L6s that I was going to bias around 32-35mA.

I know its possible to install one easily, i just dunno how to go about doing it. I've looked up that I would need a sealed multi-turn trimming pot and I've found places to buy them, but I cannot figure out for the life of me what size resistance I would need.

This is where I got the idea from and pretty much exactly what I want to do.
X100B Bias Mod

Quick question, what is that white-ish goop he has all around the pot? There is some in my amp too but I dunno what the hell it is.


Here is the schematic if you need to look at it to help me out
X100B Schematic

I'm almost positive its R127 that controls the bias


Any help in this matter is greatly appreciated. I dont want to have to take it to a tech for something that is simple enough for me to do by myself, I just dunno where to start.

Thanks
--Clips in profile! comment please!--
Guitars
Schecter C-1 Hellraiser
Schecter Solo-6 Limited
Takamine G330H

Amps
Line 6 Vetta
Carvin X100B

Pedals
cmatmods Signa Drive, Brownie, and Boost
Morley Bad Horsie 2 Wah
MXR 10 band EQ
#2
Search my name on that forum (meanwiththedean) and you will find a thread where X100Bnut is explaining why it's better to use R126 for the bias. R127 is the positive side of the bias supply whereas R126 is the negative. For your tubes, it's safer if you use R126 and tie one of the legs to the wiper. The white goop is just hot glue to keep the pot still. If you can't find the link, let me know and I will help you out. I will take a picture tonight of my bias mod for you as well; I already have the amp out of it's enclosure. While you're ordering parts, I highly suggest beefing up the screen resistors and R121 to the values recommended by X100Bnut. That forum doesn't get too much traffic throughout the day so if you don't get an answer there, or you just want immediate help, feel free to PM me here.
Guitar:
Dean Vendetta 3 - Dave Mustaine Livewires

Amplifier
Carvin X100B - Bias Mod - Tungsol 12AX7's - JJ KT77's

I have built the most badass 212 that puts all others to shame
#3
Do you still need help with this? I've taken the pictures like I promised but I'm not going to bother if I don't hear anything from you. I'm hoping that no news is good news.
Guitar:
Dean Vendetta 3 - Dave Mustaine Livewires

Amplifier
Carvin X100B - Bias Mod - Tungsol 12AX7's - JJ KT77's

I have built the most badass 212 that puts all others to shame
#4
Oh sorry man I forgot to post a reply. yeah help would be great. I sent you a PM yesterday I dunno if you got it or not check your inbox to see if its there if not I'll just post here.

actually i just realized I sent it to your UG profile, but not the forum profile so thats why you probably didnt see it. I'll send the same message here.

thanks for your help man I definately need it
--Clips in profile! comment please!--
Guitars
Schecter C-1 Hellraiser
Schecter Solo-6 Limited
Takamine G330H

Amps
Line 6 Vetta
Carvin X100B

Pedals
cmatmods Signa Drive, Brownie, and Boost
Morley Bad Horsie 2 Wah
MXR 10 band EQ
Last edited by Dragonis at Jul 10, 2009,