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[Mattxorz]

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!

[J M Fahey]

Never used them, but 160W@U$150 sure looks better than 100W@U$220.
And never trusted much 1U power amps, just too little space for anything, specially the transformer.
jm2c

[mexicanyella]

I don't have any experience with the Mosvalve power amps, but I did use a Tubeworks Real Tube preamp into a ADA Microtube 100 power amp for awhile. This was a 50 watt/50 watt stereo 1-rackspace thing with a pair of 12AX7s in it, so not a real tube power amp.

We had a caveman drummer and a bass player who pushed his Hartke 350-watt bass stack pretty loud. I was able to keep up with this power amp, using one side to drive a 2 x 10 cab and the other to drive a 4 x 12. You might keep an eye out for used ADA stuff. It's light and compact.

[erokit]

I'd go with 160/80 x 2 so you have headroom for transients. You're going to depend on pedals or distortion from the DSP (if it has it). To compete with the rhythm section, I recommend at least a pair of 2x12" cabs. Go for stereo for that DSP. get cabs that match the lowest output impedance possible in any case. If you plan on bridged mono, use a 4x12" cab. To compete you need 4 speakers to push enough air.

[teemuk]

They are great amps, but be aware that they probably are not the best choice if you look for features like headroom or transparency because the MOSvalves are designed to colour the sound by having a somewhat non-linear response and especially to softclip the MOSFET outputs if driven harder. The latter feature will inherently limit the clean headroom, though it's something that certain people do look for from a power amp. They are not like your average transparent PA, which is either a good or bad thing, depending on each person's individual taste and preferences.

The rule of thumb is: if you want headroom then always choose the highest output power. Simple physics. Can't go wrong with that. Do also note that headroom translates to things like more authoritive bass response and overall signal clarity but it does not neccessarily equal greater perceived loudness or ability to cut through the bandmix any better. A low power amp outputting mid-range oriented signal that is compressed by clipping may sound far louder than a higher power amp that operates on a wider bandwidth and also reproduces all the signal peaks accurately instead of clipping them. The difference of headroom levels is often more a "feel" and overall "tone" thing than a loudness thing.

[erokit]

They are great amps, but be aware that they probably are not the best choice if you look for features like headroom or transparency because the MOSvalves are designed to colour the sound by having a somewhat non-linear response and especially to softclip the MOSFET outputs if driven harder. The latter feature will inherently limit the clean headroom, though it's something that certain people do look for frOom a power amp. They are not like your average transparent PA, which is either a good or bad thing, depending on each person's individual taste and preferences.

The rule of thumb is: if you want headroom then always choose the highest output power. Simple physics. Can't go wrong with that. Do also note that headroom translates to things like more authoritive bass response and overall signal clarity but it does not neccessarily equal greater perceived loudness or ability to cut through the bandmix any better. A low power amp outputting mid-range oriented signal that is compressed by clipping may sound far louder than a higher power amp that operates on a wider bandwidth and also reproduces all the signal peaks accurately instead of clipping them. The difference of headroom levels is often more a "feel" and overall "tone" thing than a loudness thing.

For me the tube style clipping will sound better. The guitar is not a hi-fi instrument. However for jazz or Grateful Dead tones I would Go the PA route. Jerry Garcia used a fender twin preamp and McIntosh audiophile grade amplifiers.

[mexicanyella]

They are great amps, but be aware that they probably are not the best choice if you look for features like headroom or transparency because the MOSvalves are designed to colour the sound by having a somewhat non-linear response and especially to softclip the MOSFET outputs if driven harder. The latter feature will inherently limit the clean headroom, though it's something that certain people do look for from a power amp. They are not like your average transparent PA, which is either a good or bad thing, depending on each person's individual taste and preferences.

The rule of thumb is: if you want headroom then always choose the highest output power. Simple physics. Can't go wrong with that. Do also note that headroom translates to things like more authoritive bass response and overall signal clarity but it does not neccessarily equal greater perceived loudness or ability to cut through the bandmix any better. A low power amp outputting mid-range oriented signal that is compressed by clipping may sound far louder than a higher power amp that operates on a wider bandwidth and also reproduces all the signal peaks accurately instead of clipping them. The difference of headroom levels is often more a "feel" and overall "tone" thing than a loudness thing.

What a great post! Good summary info, well stated. Good thread in general, really.