Hi all,
I just purchased the PCB's to the F5T from the forum store an aiming to build monblocks. I have a big transformer (2.2 KVA) with 2x40V secondary that will aprox give 56V rails. Im thinking of to setting the bias to about 25-30W class A for each monoblock. What power should I expect in class AB then?
Im looking forward to your answers.
Br
I just purchased the PCB's to the F5T from the forum store an aiming to build monblocks. I have a big transformer (2.2 KVA) with 2x40V secondary that will aprox give 56V rails. Im thinking of to setting the bias to about 25-30W class A for each monoblock. What power should I expect in class AB then?
Im looking forward to your answers.
Br
Assuming the amp (which I'm not familiar with) can leave class A and continue to deliver increased output up to the point at which it clips (as it reaches the limit of the rails) then,
1. Your 40-0-40 tranny gives -/+56 volts.
2. In practice your amp might swing (say) -/+ 48 to 50 volts into 8 ohm resistive.
3. That becomes -/+48 volts peak to peak.
4. Vrms is Vpeak (48 volts) / √2 which is 34 volts rms
5. The "power" into 8 ohms is Vrms*Vrms/8 which is 144 watts rms
1. Your 40-0-40 tranny gives -/+56 volts.
2. In practice your amp might swing (say) -/+ 48 to 50 volts into 8 ohm resistive.
3. That becomes -/+48 volts peak to peak.
4. Vrms is Vpeak (48 volts) / √2 which is 34 volts rms
5. The "power" into 8 ohms is Vrms*Vrms/8 which is 144 watts rms
Consider using a choke input filter?
That will drop your power supply voltage from 1.414 x to 0.9 x the AC.
Likely will give a better overall sound from the amp, imo, and maybe permit full class A operation.
Mooly, I don't quite recall how close to the rails it can swing, but the F5T has a diode across the source resistors that permits it to swing closer than normal to the rails at peak outputs... fwiw.
EDIT: fyi, that will give you ~100w RMS into 8 ohms... regardless you need monster heat sinks for any F5t...
That will drop your power supply voltage from 1.414 x to 0.9 x the AC.
Likely will give a better overall sound from the amp, imo, and maybe permit full class A operation.
Mooly, I don't quite recall how close to the rails it can swing, but the F5T has a diode across the source resistors that permits it to swing closer than normal to the rails at peak outputs... fwiw.
EDIT: fyi, that will give you ~100w RMS into 8 ohms... regardless you need monster heat sinks for any F5t...
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Use dogpile.com(my favorite, or Google). Search on inductor input power supply. You will find better phrases to serach on from there? There is also another form of L input supply topology but I cannot recall the name. It involves the current in the inductor varying with the load cuurent???
MaybeZM has a comment???
Dogpile.com is better than Googrohh.com any day
MaybeZM has a comment???
Dogpile.com is better than Googrohh.com any day 
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