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Messages - Mattxorz

#1
Tubes and Hybrids / Mosvalves?
March 15, 2012, 03:20:30 PM
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!
#2
Yea, seems that way.
#3
It's not a protection thing- it's a speaker response thing that makes me want to do it. I got some Celestion V30's to put in, and they just don't sound right to me without a closed back cab. I may end up converting this amp into just a head, and build my own cab for the speakers, but if I can keep it a combo without screwing myself, I'd like to.
#4
Tubes and Hybrids / Close off the back of a tube amp?
October 14, 2011, 05:01:35 PM
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.
#5
I'm not going to do anything internally to my amps- I've got them for sale atm. I just decided to forget the "Y" functionality, and be content with an a/b switch for now. I got that working. Thanks for the advice, all.
#6
Nope- tried it. Apparently I don't have that great of a grasp on these things.
#7
Word.
#8
Ok- before I address Enzo's solution, I changed a few things. I had some bleed between the amps when one was selected but the other was not, so I routed the output signal of each to ground when they're not selected. I also disconnected these grounds with the other switch when it is set so that both amps are selected. That way Neither will be muted (if one was, it would mute both because of their connection). I attached an up-to-date wiring diagram.


Enzo, that makes perfect sense. And you're right. The scenarios you described are exactly what's happening. Instead of transformers, could I break the ground loop with a diode right before the output jack ground connection of each output? That way each amp's ground would only let juice through one way? Let me know what you think.
#9
I severed the ground connection from one of the outputs. That did seem to get rid of the amps loop humming, but it also un-grounds one of my outputs, so the amp plugged into that output hums even louder now.
#10
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.
#11
^bump.

In my (albeit relatively limited experience), boosting the input signal on a solid state amp has not generated positive results. I've had 5 or 6 solid state amps in my time, (a Fender Frontman 212R, a crappy Behringer, a Marshall MG (bad choice), a Peavey Bandit, a Randall RG200, and a few low wattage practice amps). Have you ever had to fart after eating Thai curry? On a clean channel of most of those amps, a boost like an Ibanez Tubescreamer seems to provide that sharp farty feeling sound. I have had good luck boosting distorted channels though; that Randall specifically, becomes much more defined with a boost on the lead channel.

+1 to the distortion stompbox + clean channel, if that's your thing. I seem to waver on my opinions of distortion pedals. I've never found one that could match the thickness of my 6505's lead channel distortion, but then again, most amps can't either. That said, you can't beat the clarity of well dialed in solid state amplification.
#12
OMFG. You're right. The fuse is built into the mains in. Imagine that. Let me now commence the kicking of my own ass.
#13
The fuse was the very first thing I thought about when the amp first crapped out on me. I checked all over. I don't see anything in this amp resembling a fuse. I'm still definitely novice, but I would hope I could identify a fuse. I had just shrugged it off. If that really is the problem, I'm going to have to kick my own ass. Any clues where it could be?
#14
Yea, I've got a multimeter. What should the direct transformer voltage read? I'll test it tomorrow when I get back to town.
#15
That's the thing. I'm pretty sure the transformer is the problem. The power switch and indicator light are wired across the transformer. They don't light. This amp was given to me, and I really don't want to invest too much money in it (seeing as how they go used for like $150 anyway). If I can fix it for the cost of some tiny parts, that's fine. If not, it's not worth my money. I'm a college student (no, not in electronics), and this is just kind of a free-time hobby.