You mean something like this?
https://www.diyaudio.com/forums/pass-labs/210538-f5-bjt-input.html#post2980905
With jfet as input it is an PASS F5.
If you want to use Latetal mosfet as output you need a more efficient way such as the USSA5. Or you can go with an F7 using positive feedback....
Fab
https://www.diyaudio.com/forums/pass-labs/210538-f5-bjt-input.html#post2980905
With jfet as input it is an PASS F5.
If you want to use Latetal mosfet as output you need a more efficient way such as the USSA5. Or you can go with an F7 using positive feedback....
Fab
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You are welcome.
I suppose you are referring to the USSA5 amp. For the distortion- if that really matters
- see below real measurements at 1W and 6Wrms for 1KHz. Note that with H2 possible cancellation (not the goal here) THD would be about 0.002% of only H3 at 1Wrms. The CFA topology has a poor PSRR so you need a very good PSU.
I have USSA3 with jfet input and USSA5 with bjt inputs. Both amps have their own different sound signatures, you choose which one you prefer.
One thing though is that jfet provides less gain than bjt as input stage so USSA3 has a lower damping factor than USSA5.
Fab
I suppose you are referring to the USSA5 amp. For the distortion- if that really matters
- see below real measurements at 1W and 6Wrms for 1KHz. Note that with H2 possible cancellation (not the goal here) THD would be about 0.002% of only H3 at 1Wrms. The CFA topology has a poor PSRR so you need a very good PSU. I have USSA3 with jfet input and USSA5 with bjt inputs. Both amps have their own different sound signatures, you choose which one you prefer.
One thing though is that jfet provides less gain than bjt as input stage so USSA3 has a lower damping factor than USSA5.
Fab
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