It's alive! 🙂
Nice work Andrewlebon!
Thanks for your quick work on this. Have you been able to do a max power stress test on a dummy load?
Nice work Andrewlebon!
Thanks for your quick work on this. Have you been able to do a max power stress test on a dummy load?
Hello
greetings in this version of sonals pcb MJE 350 pin outs have to be changed
see MJE350 on pcb otherwise no mistakes on pcb
warm regards
Andrew
greetings in this version of sonals pcb MJE 350 pin outs have to be changed
see MJE350 on pcb otherwise no mistakes on pcb
warm regards
Andrew
Hello xrk971
greetings played it at loud levels everything is super clear tomorrow i
will do some more testing and keep you informed
warm regards
Andrew
greetings played it at loud levels everything is super clear tomorrow i
will do some more testing and keep you informed
warm regards
Andrew
Good catch - I missed the fact MJE350 is ECB when switch made from MPSA92 (EBC). That would not have worked at all 😱
Can 1381/3503 work in place of MJE340/350 i like the sound of KSC1381/3503
warm regards
Andrew FX9 sound is softer
warm regards
Andrew FX9 sound is softer
I just ran sim with proper model for 1381/3503 and it works fine. I plan on using those as I like their sonic signature too. VHEX+ amp uses them to drive 2 pairs of IRFPs also.
Singing. Only testes with +-44V so far. Sounds fine through test speakers. I would like to have a trimmer for offset adjust. Hfe matched LTP and have 4mV on one channel and 20mv of the other. Not really an issue but still there. There also some turn-on noise. Will have to investigate that.
Edit: I used SMD for most of the small caps.
Edit: I used SMD for most of the small caps.
Attachments
Nice work Terry!
The SMT for small caps is a good idea. I have been pretty lucky with offset in the 1-3mV range when I match BC546C's spot on. Maybe 5551's are harder to get stable for matched Hfe?
You seem to have plenty of room for local heatsink on MJE250 - does it get warm?
I don't have any more time today to do testing. I only ran it for a few minutes and only at +-44V so I can't say if the little heatsink is necessary.
I could probably play around with different transistors and get the offset lower but a trimmer wound eliminate the issue. If I were serious about this amp that is what I would add. When I have the time I will hook up a bigger PSU and run it through my scope and test for clipping and square wave response. I'll check the heat of the small heatsink at that time.
Blessings, Terry
I could probably play around with different transistors and get the offset lower but a trimmer wound eliminate the issue. If I were serious about this amp that is what I would add. When I have the time I will hook up a bigger PSU and run it through my scope and test for clipping and square wave response. I'll check the heat of the small heatsink at that time.
Blessings, Terry
Nice work, use 100R trimmer instead two 47R resistors (R16. R17) for offset adjust.
Regards
hi, i built FH9 from the pcb posted while back.
1k bias resistor.
how do i adjust the bias with this?... thanks. 😉
oh and fh9 sounds verry nice, btw. smooth and warm unlike what i expected coming from vssa. similar level of performance none the less!
1k bias resistor.
how do i adjust the bias with this?... thanks. 😉
oh and fh9 sounds verry nice, btw. smooth and warm unlike what i expected coming from vssa. similar level of performance none the less!
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