I rencently invested in some rack gear for my live rig, one of the items i bought was a Nady XA-900 Power Amp to drive my signal a little harder. Im running my guitar through a Marshall AVT150H Head and im trying to figure out how to setup the power amp to work with my AVT412 Cabinet.

The Cabinet itself can only handle 200 watts of juice, while the power amp runs at 300w per channel @ 4Ohms or 200W per channel @ 8ohms. Should I even try running the head output signal through the power amp and then run the power amp output into the cab? I dont want to risk overloading the cabinet and blowing the speakers.

The AVT150H head has a max output of 150 watts so im wondering if its even worth trying to run the power amp for just 50 extra watts of power. But if i do try to run it, should i use the line out on the amp or the regular speaker outputs to run it to the power amp?

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is your cab stereo?

if so you can just run your head into one side of it, and then run the line out from your head into the poweramp and then plug that into the other side of your cab.

as for blowing it.. don't turn it up enough to let the powersection's clip and you shold be alright.

and make sure you'r ohms are matched.

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150 Watts is plenty. You can rock a club with that. You should try to keep your speakers rated at twice the max output of your amp to be on the safe side. Connecting an amp that's rated for more power than the speakers is risky. Even if you keep the volume low, you might have transients at power up and power down or when connecting and disconnecting cables that could blow one of the voice coils in your cabinet.

well, i agree that 150w is alot.. and technically you could rock a club with a 15w amp, depending on your stye of music, how loud the rest of the band is and provided there is a PA.

but not all amps are the same volume, even if they are the same wattage.

alot has to do with usable headroom. take for example my fender rocpro.. it's 100w s.s., and it's loud as fuck... but after 5, it doesnt get much louder at all, just more distorted... and since it's s.s., all that rough breakup makes it almost unusable.

tube amps however, clip in a smoother fashion, which is pleasing... so it is usually desired to drive them all the way. not to mention, since they're "smoother". it puts less stress on the speakers. while s.s. will send hella squares at them and blow it.

so i find with s.s. i want headroom for days, thus in my rack i sport an 800w poweramp. so i can get loud as hell and not have to worry about shitty s.s. breakup blowing speakers(my cab i'm currently using handles only 300w).

you could go the opposite route and totally under power your cab, but that gives you much less headroom and a little less volume.


with tubes, headroom isnt as necisarry(maybe for tone is you want prestine cleans, but no danger of blowing speakers), so a simple 50w-150w-ish is plenty.


but, back to the avt, i find alot of people complain about them not being very loud. so you're not alone.

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Becareful cranking up that AVT. Those new Marshall SS amps have output sections that like to crap out when you run the amp hard. They aren't cheap to fix. I've replaced several power amp chips on MG's and I just had an AVT here last week, same thing. They all use the same crappy chip.
Jerry

totally, i've heard nothing but horror stories about anything hybrid or s.s. that marshall has put out recently. even the mode four.

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