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Appropriate power amp

4

4string4ever

Guest
Apr 18, 2004
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Orlando, Florida
#1
I'm making the departure from an Ampeg PF800 head to a preamp/power amp rack set up, and as a newb in this regard, the terrain is somewhat less than clear to me. I will be using 2 8 ohm cabs, the lesser of the two rated at 350w. I obviously want to have comfortable head room without sizzling my speakers. I haven't decided if it really matters to me if I bridge two channels or not.

As always, the sage advice offered here is greatly appreciated.
 
#3
If you don't mind hauling some weight, you can't go wrong with the old QSC amps. But they are heavy.

I went this route for many years but just can't pick the damn thing up anymore. If I had stayed with a pre/power/rack unit, I'd probably get the new QSC digital power amp, because their stuff has never failed once on me. You can bridge or not as needed. You won't need to, but you might want to :)
 
#9
arbiterusa said:
You are technically correct, which we all know is the best kind of correct. I should have said "lightweight" so as not to give anyone a rash. No power amps are digital, not yet, anyway.

My old QSC900 (best power amp ever) is 34 pounds. I think the new QSC is 11. That matters.
Click to expand...

The point is about topology, not weight. You have never played a power amp section that is digital.
 
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#11
4string4ever said:
I'm making the departure from an Ampeg PF800 head to a preamp/power amp rack set up, and as a newb in this regard, the terrain is somewhat less than clear to me. I will be using 2 8 ohm cabs, the lesser of the two rated at 350w. I obviously want to have comfortable head room without sizzling my speakers. I haven't decided if it really matters to me if I bridge two channels or not.

As always, the sage advice offered here is greatly appreciated.
Click to expand...

Bigger question is will the output sensitivity be a good match to the power amp.
As I recall, the Alembic has a pretty stout output and could be used with any amp.
This is not the case with many Ampeg pre’s that require a .775V amp to reach full power.

Just down the road will be the conversation as to if a lightweight class D amp sounds as good as an old school lead sled.
A conversation that I will avoid.
 
#12
I believe that thr Crown xls's have a variable sensitivity selector to allow for .775v preamps as well.

Personally, whatever the sound differences may be, I dibt think that an audience cares much, and I'm more than hsppy to make the trade off for lighter weight and no tube maintenance concerns.
 
#14
So if I were to do that and I were judicious in how high I turned up the gain, it wouldn't adversely affect the speakers? It naturally always occurred to me that I could use a 1000 watt head with 400w speakers, for instance, if I was simply careful not to crank too much volume, but I never knew if that would still overload the design of the speskers in some way.
 
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#18
Why is the input sensitivity of a power amp significant as long as you have a preamp or mixer with enough voltage to drive it? The input sensitivity doesnt affect sound quality - only the input voltage required to drive the amp to full power.

My Powersoft K3 needs 1.88 volts input to deliver its 5,200 watts output - and it delivers 5,200 watts from a 1 rack chassis.
 
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