I used another power supply and I have unused pcb power supply to the nx-amp. I want to replace it on the opa1642 may be the sample with TI. The proposal for those who want to do a dual-mono.
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Hi Andrew, hi All,
I'm new to this thread...
Thank you Andrew for this very nice amp, which I'm on the way to build (the sx), parts already ordered. Very extensive forum too...
I can't find the power supply circuit diagram (well, I know, it's not very complicated to reconstruct...). "figure 15" on the PDF page 29 appears in black, nothing to read on it... either online or downloaded !
Does anyone have this diagram ?
I'm new to this thread...
Thank you Andrew for this very nice amp, which I'm on the way to build (the sx), parts already ordered. Very extensive forum too...
I can't find the power supply circuit diagram (well, I know, it's not very complicated to reconstruct...). "figure 15" on the PDF page 29 appears in black, nothing to read on it... either online or downloaded !
Does anyone have this diagram ?
Wow, very fast answer, thank you Andrew !
@Bambadoo mmh, nothing commercial in fact ... just looking for a very pure cristal-sounding A-class amp for my own Linkwitz LX521 + ASP 🙂
@Bambadoo mmh, nothing commercial in fact ... just looking for a very pure cristal-sounding A-class amp for my own Linkwitz LX521 + ASP 🙂
As many, I come across the matching issue for the KSA1381E/KSC3503D, with the closest Hfe at 110/86 (I bought in 100 qty)
Not very close...
Is there still a reliable supplier for either pairs or only KSC3503E ? What is the feedback for Joshvi's transistors ?
Not very close...
Is there still a reliable supplier for either pairs or only KSC3503E ? What is the feedback for Joshvi's transistors ?
I heard good things via another poster on this thread about his transistors.
Your amp will still work with 110/86 - but the performance can be better with a closer match.
Your amp will still work with 110/86 - but the performance can be better with a closer match.
I have bought several from Joshvi. A very good member. I just measured and the KSC3503E is 150 -160hfe, KSE1381E 147hfe
there are still small differences between the BOM and the reality...
up to now, I found
- R4 should not be fitted, but is still on the BOM (as designation only)
- worse, C4-C5 and C7-C8 (1uF) are not on the BOM (nor on the schematics !) and should probably be fitted... I discovered them on the (very nice) Jims Audio PCBs, after all the parts were delivered to me...
In fact one can see them on the PDF on the underside of the PCB drawing, but value hard to read if at all possible.
I know it's a boring task to keep lists up-to-date, but it's a nasty situation to discover parts are missing once the orders have been put.
I don't mind posting an updated list once I'm sure everything is ok. Of course if you allow it, Andrew !
up to now, I found
- R4 should not be fitted, but is still on the BOM (as designation only)
- worse, C4-C5 and C7-C8 (1uF) are not on the BOM (nor on the schematics !) and should probably be fitted... I discovered them on the (very nice) Jims Audio PCBs, after all the parts were delivered to me...
In fact one can see them on the PDF on the underside of the PCB drawing, but value hard to read if at all possible.
I know it's a boring task to keep lists up-to-date, but it's a nasty situation to discover parts are missing once the orders have been put.
I don't mind posting an updated list once I'm sure everything is ok. Of course if you allow it, Andrew !
Sadhill,
Sorry about that - please go ahead and post your findings up.
I will come back to you with a detailed reply shortly - some components are not fitted anymore - like the small caps across the main reservoir caps for example.
Sorry about that - please go ahead and post your findings up.
I will come back to you with a detailed reply shortly - some components are not fitted anymore - like the small caps across the main reservoir caps for example.
I have the PCB layout in front of me
C4-C5 and C7-C8 - do not fit. Therese were originally placed in parallel with the main filter caps. I decided they serve little purpose - so they were removed from the BOM. The sx-Amp circuit diagram I posted up is therefore correct. I will add a note when I fix the PSU diagram in the write-up.
R4 - this is a 33 Ohm wire wound resistor and is part of the Zobel network (there are 6 of these on the board). That should be fitted. Can you check that designation again, or post up a photograph of the board?
C4-C5 and C7-C8 - do not fit. Therese were originally placed in parallel with the main filter caps. I decided they serve little purpose - so they were removed from the BOM. The sx-Amp circuit diagram I posted up is therefore correct. I will add a note when I fix the PSU diagram in the write-up.
R4 - this is a 33 Ohm wire wound resistor and is part of the Zobel network (there are 6 of these on the board). That should be fitted. Can you check that designation again, or post up a photograph of the board?