Every now and then I must go and look at this F7 magic thing. I mean, mouser etc. must hate this amp it has so few part! I think this is just plain incredible! Wish I could give an ear to it...
What are the outputs? Does mouser has them? Or are you looking at Ihquam schematics?
The inputs are Tosiba Jfets and outputs are Alfet laterals, all NOS.
Looks like F5 but with positive current feedback.
Looks like F5 but with positive current feedback.
Don‘t get me wrong—I am totally fascinated by the minimalism of this amp, but I won‘t clone it. At least not as long as it’s still in production by firstwatt.
Thank you Nelson, for letting us know what it’s made of (since there doesn’t seem to be much more to it than 14 parts and your wizardry, it looks as simple as that—but…)
Thank you Nelson, for letting us know what it’s made of (since there doesn’t seem to be much more to it than 14 parts and your wizardry, it looks as simple as that—but…)
Mr. Nelson, are the alfet laterals lower distortion than mosfets in f5?
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Just wait for the upcoming F5L, it will probably not be waaaay off the discussed design. Got LATFETs?
If we look at the old Le Monstre amp it's a little bit like the F5 but with cascoded
Jfets and a sezuki pair ? for the output stage. But when it was being developed
Hiraga tried laterals for the output stage but didn't think it sounded good perhaps
he should have added some positive feedback. Oh I don't think it was called
" Le Monstre " because it was a small 8W amp but because of the power supply.
I think the power supply used a cap multiplier feeding a pair of 12V car battery's !
If someone was cloning the f7 instead of using the Alfet's why not just use the heat
sinks and outputs from an old Halfer DH220
Jfets and a sezuki pair ? for the output stage. But when it was being developed
Hiraga tried laterals for the output stage but didn't think it sounded good perhaps
he should have added some positive feedback. Oh I don't think it was called
" Le Monstre " because it was a small 8W amp but because of the power supply.
I think the power supply used a cap multiplier feeding a pair of 12V car battery's !
If someone was cloning the f7 instead of using the Alfet's why not just use the heat
sinks and outputs from an old Halfer DH220
No multipliers. Just banks of large electrolytics. Like 14 x 56.000 uF Mallory is what I had, and 1KW transformer. CL-RC, per channel. Don't have a picture anymore.
A cap multiplier reduces noise, yes, but also lags the power build up.
A good choke up front supplements any draw by setting its iron to work.
Nowadays you can get superduper FARADs (13V/ <.1ohm) from cars. The Supercapa's that were used at that time had an internal resistance in the ohms region; still that helped in the stage.
