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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Thank you fab putting me on the right track. I couldn't find any measurements, any idea what distortion figure it exhibit? About the sound , is it better than jfets ?
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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