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Esitmate amp power output

8/10/1999 5:34 AM
David Axt
Esitmate amp power output
Is it possible to estimate the power output of an amplifier by the schematic diagram and tubes? Thanks.
8/10/1999 4:10 PM
Jim S.

Only in the most general way. For example, an amp that uses a pair of 6L6GC or EL34 output tubes could put out anywhere between 25 and 50 clean watts. A lot of it has to do with the size of the transformers and the amount B+ voltage put out by the power supply (which includes the power transformer). Also, keep in mind that two amps that have the same rated power output may not necessarily be perceived to have the same loudness. One amp may have a larger output transformer than the other; this would tend to increase the amps' bandwith (ability to deliver full power output at lower frequencies) and make it sound more powerful. Also, well-designed class A amps can often appear to be louder than what their output watts rating would suggest; this is because they tend to ease into clipping more gradually when pushed hard; the very even harmonic distortion that's produced might not be as readily perceived as the amp "breaking up".  
The bottom line to all this is: Don't get too hung up on output wattage ratings.
8/10/1999 4:41 PM
ken gilbert
Is this a rhetorical question in general, or do you have something specific?  
It is possible to ballpark output power, knowing a couple of things: class of operation, output transformer primary load, available electrode voltages, driver capability, type of output tube--that kind of thing. If much of this information is on the schem, then you're in luck. If not, you need to build it and see.  
So do you have a schem in mind?  

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