Tube Amp Archive

A football field full of marshmallows, maybe?

Wait. I figured it out- voltage from power supply to anodes, right?

Duh. Was thinking backwards and not considering the whole schematic...

Ok. I've been going over the VC3112 for a while now, referencing the schematic while making notes for mods and also chasing this infernal fizz problem. I'm wondering if someone can enlighten me as to a portion of the circuit. Schematic for reference. It appears that part of the output from V2 and V3...

Clipping and/or parasitic oscillation "riding" those low notes. If you can watch the output on a scope, you'll see it right away. Although the model may mention "50" I doubt you'll see much more than 30W at clip and maybe less. Also EL84 tend to get rattly, and you might hear them shakin' their mar...

Mine's definitely not mechanical.

More of a fizz or buzz on low notes.

Ordered new power amp EL84 tubes yesterday. I'll start there and see how it goes.

Fwiw, that is the original transformer set. The stock speaker was a Greenback style from Eminence. The Mesa//Celestion C90 is an odd choice, imo, but may work. Obeid Khan designed it. From The Gear Page http://www.thegearpage.net/board/showthread.php?p=14477982#post14477982 The OT had a mechanical ...

If available, try another amp (not stacked on the VC's cabinet) into that speaker. Then the VC amp into a remote speaker. That other amp needn't be anything special - just have a 4- or 8-ohm speaker that's halfway decent, and have an output rating of at least 30W. Done! Swapped everything per your ...

Thanks for the reply! Could I get your opinion concerning the speaker buzz? It occurs only on the low end, with notes played on, say frets 1-5 of the E and A strings. A scratchy, almost-static, distinct buzz that sounds like the cone has debris trapped between it and the cab, or that the cone baffle...

Precisely as TT says-

The effect return is between the pre and power amps. When you jack an external preamp into an effect return, the amp's onboard preamp is out of the picture and only the external preamp is feeding signal to the power amp.

Hello- this is my first post, so thanks for putting together the forum and for taking the time to consider my question. I picked up a Crate VC3112 the other day purely as an impulse buy. Got it home and discovered it sounded pretty darn good, so of course I had to pull it apart and see what was in t...