The standard F5 current is 1.3A pr device, 2.6A total pr channel, to keep the same total bias pr channel in a cascoded, dual output pair configuration you would need to reduce the bias for each FET to 0.65A( 4 x 0.65A = 2.6A pr channel)
As for supply voltage I am going for either 2 x 22 VAC or 2 x 25 VAC, havent decided yet. The 2 x 25 VAC would be nice, giving mere a decent power reserve of about 55 W Class AB in 8 Ohm.
(You might be getting an order tommorow, just have to sleep on it before I decide whether to pull the trigger or not)
The standard F5 is a one pair mosfet output stage.
Both mosfets are biased to 1.3A.
The total bias is 1.3A
Don't worry mate, those diodes heat up to 40C only with no heat sink, agree they will look smarter when mount on some handsome heat sink🙄
Hi.It looks good.Minimum value of gate stopper(gate stopper is a resistance to eliminate oscillations) is 47ohms and 150 ohms will not make a sensible difference.Do you know that you need a preamp to get full power with this player?Is there a preamp in the amplifier?Regards
Could you explain this statement please?
I thought it was at full power all the time without a preamp / attenuator. ?
Unless you were thinking of an active preamp which adds to the gain.
Ron
I forget what the sensitivity of the F5 is but it's only at full power if the source has enough output voltage to drive it to full power. Since it has 15db of gain some sources may not have enough output.
F5 amplifier has a gain of 5.5 so 2volts rms source signal multiplies with 5.5 and it makes about 11volts rms.F5 gives about 15volts rms max.So you can not get F5's max power with many sources without preamp(voltage gain)
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Just turn it up at full blast and you have all the power that would make any sense anyway, like maybe 20watt out of the possible 25watt (just a guess)
Voltage gain, not needed, but preferred,
that's what I thought you were talking about.
Thanks,
Ron
that's what I thought you were talking about.
Thanks,
Ron
It is needed if you do not have about 4volt rms source(to get full power from F5 amp)
Of course it is not needed if you preffer only 25watts to 8ohms
Of course it is not needed if you preffer only 25watts to 8ohms
And then you may be able to drive it to just above half attenuation, or overdrive it, with increased distortion
With a true rms voltmeter, set to measure instantaneous max voltage, connected on my speaker outputs -loud music/movie in a 25'x14'x9' room registered at 4.8Vrms and that is about 7Vpk (14Vpk-pk) or about 35% of what's available on a +/-24V or a +48V supplied amp. Lots of headroom using an LDR vol control...system is as posted on Pass projects thread.
Singing too loud does not mean you get full power 😉 If you use 100dB speaker it will sing much louder 😉 😀 If you think you get enough power there is no problem then.1212M's output is enough to get full power from F5 amp though.Some sources does not have such a high output swing.
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