New Carvin X100B tech note

[Twitch]

Well, the X100B just sounded amazing at practice friday!! Im very pleased, with the volume mod and the full JJ retube kit that I put in it, it just sounded sweet. However, Im still GASing for the V3, maybe Ill just order one sight unseen from Carvin next semester.

[Trussrod]

Not that this helps anyone, but this is just more proof that all these amps and sound equipment are a PITA. I wouldn't mind upgrading to a Mesa dual or triple rec but I've read too many stories about parts going bad. Glad you're happy, Twitch. At least you have the skill to fix the problem yourself. It's basically a necessity when dealing with this stuff.

[lerxstcat]

I bought it second hand, and Carvin is very aware of it and says they have "fixed" it for current production. What Ive done is something thats been done by others with no reported damage(this "fix" is all over the Carvin boards, though I performed mine in a more safe manner). I dont see how this will damage the amp as I have not added anything or removed anything, I have simply bypassed a cicuit. A circuit that is not essential for normal operation. The function of this switch originally was to correct the level of the effects loop for different effect types(ie rack or pedal). The circuit for the leveling while doing its job(correcting the level of the chosen effects) was also reducing the final output to the phase inverter, the mod simply bypasses the level correcting circuit.

Cool, sounds like you did your homework.

[Twitch]

Actually, my speculation was a little off. I ran this mod by my dad cause hes super tight with electronics and I wanted to know exactly what I had done. By disabling that leg of the switch I have left the OP amp the effects loop was using to correct the level un-biased. To bias an OP amp(to control its output level) you add a resistor in series to it to control its output. Since the OP amp is un-biased by the switch(Im sure its still biased by a stand alone resistor somewhere, as to be totally un-biased would create some degree of clipping which is not present) its allowed to have a higher output level than it would with a higher resistor value and therefore yielding a higher output level to the final stage of the preamp. This would also explain why when the effects loop is out of the circuit, the volume level once again drops as the OP amp in the FX loop is no longer in the path the audio signal takes. So there you have it, I boosted the top end volume with an OP amp. Didnt affect the tone any at all, still just as warm as it is with out the effects loop in the circuit, just louder. Maybe here sometime Ill do the proper mod by up-ing the resistor values before the phase inverter, but until then, Im pleased with the mod at hand.