I'm posting this in Amp Discussion as well- not sure which subforum it belongs in. I'm putting together a rack rig with a Peavey Rockmaster Preamp & Digitech GSP1101 fx processor, and am looking for a good solid poweramp. I've read nothing but good things about the old Mosvalves, but I can't decide if I want to go for the 982 (50w/side, 100 bridged mono), the 962 (80w/side, 160 mono), or the 942 (250w/side, 500 mono). It looks like I can find the 982s for about $220 used, 962s for about $150, and the 942s for about $340. I'd like to go with the 982 if I could, as it is only 1 rack space whereas the others are 2. Does anyone know if it would be enough power for clean headroom over a caveman drummer? If not, surely the 962 would be, right? If I'm going to be spending over $300, I'll just save for a Carvin TS100 or something. Thanks in advance to anyone who could answer my questions!

How bad of an idea would it be to close off the back of a tube combo amp? In sealing it, the amp could not vent... Should I even bother? Specifically, I'm talking about a Peavey Valveking 212 combo.
http://kensprosounds.com/shop/images/PeaveyValveking212_01.jpg
Here's a picture of the back.

Ok, I'm working on an 2 button A/B/Y switch so that I can select one, the other, or both of my amplifiers from my pedalboard with the push of a button. I'm using two 2PDT on/on switches and three mono (TS) phone jacks, like the ones you plug your guitar cable into.

As far as signal flow goes, I thought I had it all worked out. It does switch the path of my guitar's signal, but it also creates a good amount of hum noise. I was thinking maybe it was the two amp's inputs fighting to pull some current or something? Do I need to add some diodes? I really don't know. Oh, I also shielded the inside of the plastic casing I'm using with aluminum foil and have it grounded- I wouldn't expect this much noise from something like that anyway.

I'm attaching a quick diagram of my wiring. I apologize for now knowing schematic symbols. I tried to be as clear as possible.

Any ideas as to what could be wrong are greatly appreciated.

I'm trying to rip the preamp out of an old Randall RG200D combo amp, and I've got a few questions. The amp quit working a while ago, and I'm pretty sure the power transformer is shot. I don't know too much about amp anatomy, but I do know a little about electronics. That said, here are my questions. I know I'm quite novice, no need to flame- help is why I'm here.

1.) My ultimate goal is to remove the preamp section, and use it in conjunction with the poweramp of one of my other amps. To do this, I need to figure out all of the connections between preamp and the rest of the amp, and sever the ones I don't need. I've done almost all of that, but there are a few connections that I am unfamiliar with.
   -The first is a 3 wire connection between preamp and poweramp pcb's (3 pin clip on the poweramp end that separates into 1 red, 1 blue, and 1 black wire going to different places near eachother on the preamp end). This is separate from the preamp's line out that goes into the power amp- I know that is elsewhere. On the power amp pcb, the connection is labeled "CN2," and on the preamp side it's labeled "P101"(red), "P102"(black), and "P103"(blue).
   -I also am unsure which connections coming from the power transformer are which. There is a two pin (2 wire) clip that I'm assuming is kind of the "main power" right in the corner of the control pcb of the preamp, connected via the same clip on the transformer (labeled "CN1"). There is also one red wire going from transformer to preamp labeled "QC15" and "+15V" on the transformer pcb, and "P104" on the preamp pcb. (It's close to "P101-103" from earlier). There is also a black wire going from what seems to be the bottom of one of the huge capacitors (the size of a D battery) in the transformer section to somewhere underneath the preamp pcb. I haven't unfastened the preamp and taken it out of the chassis yet to see exactly where it connects.

If someone could let me know what these connects could be, I'd be very appreciative. Also, If you have any ideas on how to power this preamp once I've gotten it away from the poweramp and transformer, I could use that advice. I'm hoping it's as simple as figuring out how much juice it needs, and finding an AC adapter to patch in. Thanks in advance!