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
Use the maximum Vpk available from your rails after subtracting a bit for losses through the amplifier.
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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I been thinking of a CLC power supply. What value of the choke would be ok? I have a couple of Hammond 2.5 mH that would be total 2 pcs chokes and 4 pcs 47000uF/100V per mono block.
A CLC supply is a Capacitor input supply. What Bear suggested is an Inductor input supply as in LC. It would produce a lower output voltage and a ripple with less higher order harmonics 😀
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 Thanks everyone. I will consider the LC design, but what is the difference to CLC in performance.
One more question is if the rails that will be about 50-52 V, is that to high voltage for the F5T V3?
One more question is if the rails that will be about 50-52 V, is that to high voltage for the F5T V3?
I just found out that i bought the F5T V2 not V3, sorry my mistake. The recommendation is to have 32V rail voltage, but my rail voltage will be around 52V. Is that possible to run the V2 with that high rail voltage?
Best regards
Leif
Best regards
Leif
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