I will await your investigation Slav, as it appears there could be a voltage issue over the fet if we depart from the BF861C or 862.
IT ALSO seems that we may need to swap the 47R resistors to 68R if the 861c is to be used, to keep the valve in it's most linear state.
Alan and I were brainstorming this morning, over this very subject.
By brainstorming, I mean I asked loads of questions and Alan answered them lol
Unfortunately not with my Salas FSP back in play totally silent. Reconnected the Big Bottle everything turned on I turned up the left volume control and instant noise. Right channel is fine.
Feeling out of my depth with this So I will pm Alan and see if he would sort for me.
Feeling out of my depth with this So I will pm Alan and see if he would sort for me.
What’s the cartridge and tonearm ? Possibly it could be combination of mismatch when it comes to compliance and effective mass and not perfect alignment,also what was the frequency of output oscillation , how quick sine mapping ? would help if you had an oscilloscope or use some oscilloscope software.
Are both channels test same at DC condition?
I have no knowledge of the circuit so is just out of curiosity question , I'm certain Alan will sort it out
There seems to be BF861C available here: BF861C,215 NXP USA Inc. | Discrete Semiconductor Products | DigiKey
is it not what we need?
I will recheck all the voltages again in the morning.
Hopefully Alan will be able to help me out as I was very much enjoying what I was hearing for most of the three LP's I listened to. Safe to say I think that Oliver is on a winner with this phono stage.
Can you measure voltages on both channels for BF861C on all 3 legs as on one of attached earlier photos (photo on the left h/s) and check the outputs as well , thanks
I measured voltages at the jfet pins and have at the gate 0v; source 0.284; drain 2v. This is on both channels. All other voltages at the valves are as before.
I am looking forward to that very much. I will be sending it to Alan next week for sorting. Hope he won't be to critical of my smd skills or rather lack of
Lol, no he is far too much of a Gentleman to tell all.I am looking forward to that very much. I will be sending it to Alan next week for sorting. Hope he won't be to critical of my smd skills or rather lack of
Thanks , anyone could share what's the load resistor , I take 47R is source/biasing value?
