Confused RE: Cabs, Ohm, Wattage..

D

dspry

Member
Hello!

As I slowly build upon my Axe-FX Ultra fund, I've been looking into all the necessary bits and pieces that I'll need to use it and I'm feeling stumped when it comes to the power amp details. I've gone through the forums but still can't really figure it out. :?

I want to eventually sell my 1984 JCM800 2203 to fund the majority of the switch to Axe-FX. It's a 100w amp and I run it into my Line 6 Vetta II cabinet which is a 300w stereo cab (which I'm assuming is 150w per side). You can select 4/8/16ohm on the cab.

I don't understand what Ohm is or what the wattage rules are with amps vs cabs. The Vetta II head (I owned this before selling to buy the JCM800) was rated at 300w so I always assumed the cabinet had to be the equivilent wattage or more.

Following what people have said on the forum with regards to picking an appropriate SS power amp, (wattage should be tube amp wattage x 3) I've round my power amp choices to the QSC RMX 1850 or the Carvin DCM1000 which do about 300w when in stereo 8ohm.

I basically want to know whether this is appropriate? Will it be 'better' if I buy a more powerful power amp? If I buy a power amp that outputs 300w in stereo, will I destroy my 300w cabinet? Are the differences between the two brands really MAJOR? From what I can gather it's simply input and output with a volume control (sorry if I sound incredibly uneducated).

I basically want a nice sounding power amp that is loud enough for gigging. I've heard that solid state poweramps are the way to go and I definitely want to play it through a guitar cab.

Any help would be fantastic!
Cheers :)
 
You should worry about too little power, not too much. As long as you don't play louder than the speakers can handle (AKA loud as f**k), you'll be fine. Better to have plenty of headroom available. I use a DCM1000, either into 1 or 2 cabs as the situation demands. No worries.

I haven't used the QSC, but a SS power amp is designed to amplify your signal without coloring it. I'd guess that either the Carvin or the the QSC will sound fine. The Line 6 cab, on the other hand...
 
dspry said:
I basically want to know whether this is appropriate? Will it be 'better' if I buy a more powerful power amp? If I buy a power amp that outputs 300w in stereo, will I destroy my 300w cabinet? Are the differences between the two brands really MAJOR? From what I can gather it's simply input and output with a volume control (sorry if I sound incredibly uneducated).

I basically want a nice sounding power amp that is loud enough for gigging. I've heard that solid state poweramps are the way to go and I definitely want to play it through a guitar cab.

Any help would be fantastic!
Cheers :)
Click to expand...

With solid state power amps, more is better - to a point. You want more power than you'll need to have plenty of clean headroom and not push the amp into clipping. With my Axe FX rig now, I'm running around 550 watts stereo into a 4x12 that can't handle that sort of power................................but I never come even close to full power power with it. I park the volumes on the power amp around 10 O'clock, and the output level on my Axe FX has never gone past 12 O'clock without it being VERY loud.

Clean headroom is the parameter to live by with SS power amps.
 
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