i was wondering how the gain factor of an amp is calculated...i was reading the ESP website, and rod said that for a 60W amp, the gain is about 27..how do you get this figure?
You would use normal op-amp gain calculations, Rf/Ri for inverting, 1+Rf/Ri
to get the gain in dB , 20Log(gain)
In the case of Rods amp ( I assume you were reffering to his P3A?)
It looks like Rf=22k and Ri = 1k which gives the voltage gain of 27dB
to get the gain in dB , 20Log(gain)
In the case of Rods amp ( I assume you were reffering to his P3A?)
It looks like Rf=22k and Ri = 1k which gives the voltage gain of 27dB
i understand the formula...its the same for inverting and non inverting op amp circuits...so am i to assume that it would be
gain = Vout(rms)/Vin(rms)
where Vin(rms) is approximately 1V (depending on desired sensitivity)?
gain = Vout(rms)/Vin(rms)
where Vin(rms) is approximately 1V (depending on desired sensitivity)?
The AVERAGE power into a load of resistance R for a sinewave is (Vpeak)^2/(2R).
So you work out the Vpeak you need for the average power you want (sometimes average power is incorrectly refered to as "RMS power" by the way - "RMS power" doesn't exist), then divide this by the Vpeak you have available at the input and this is the voltage gain you need.
Example: You want 100W average into 8-ohms at full volume and your CD player gives 2V peak as an input. The output peak voltage needs to be at least SQRT(100*16) = 40. So the voltage gain must be at least 40/2 = 20.
A voltage gain of between 20 and 50 is usual for domestic power amps.
So you work out the Vpeak you need for the average power you want (sometimes average power is incorrectly refered to as "RMS power" by the way - "RMS power" doesn't exist), then divide this by the Vpeak you have available at the input and this is the voltage gain you need.
Example: You want 100W average into 8-ohms at full volume and your CD player gives 2V peak as an input. The output peak voltage needs to be at least SQRT(100*16) = 40. So the voltage gain must be at least 40/2 = 20.
A voltage gain of between 20 and 50 is usual for domestic power amps.
cheers mate...i really appreciate everyones help 🙂..makes learning so much easier when you can read books and ask questions too 😀
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