neville,
i havent tried many caps,
but i found obbligato gold to be very good
right now i have some russian ft-3 bypass caps and they are more revealing but a bit diferent sounding and they are not available in 10uf or so as far as i know.
i m using these right now as bypass on the f4 and i m ot using anything between it and my soundcard.
i m sure there are others but obbligatos have received praises and i would not hesitate to use them in a very high end system all around . i like their character very much.
at this level of performance, you can find any change in part quality at some key places
very dramatic and using good parts in this amp in general can be rewarding. For instance, i changed the output stage offset trimpot on f4 to a cheap resistor and removed the protection diodes and i was in awe at the difference it made(i would not recommend everyone to remove the zeners).
i havent tried many caps,
but i found obbligato gold to be very good
right now i have some russian ft-3 bypass caps and they are more revealing but a bit diferent sounding and they are not available in 10uf or so as far as i know.
i m using these right now as bypass on the f4 and i m ot using anything between it and my soundcard.
i m sure there are others but obbligatos have received praises and i would not hesitate to use them in a very high end system all around . i like their character very much.
at this level of performance, you can find any change in part quality at some key places
very dramatic and using good parts in this amp in general can be rewarding. For instance, i changed the output stage offset trimpot on f4 to a cheap resistor and removed the protection diodes and i was in awe at the difference it made(i would not recommend everyone to remove the zeners).
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Nor do I. It would have been good to see the output on a scope when I got it sounding just right but it was not to be. But the important thing is the sound.
I would adjust each channel using P3 until you hear what you are looking for and then adjust the mosfets again and the dc offset.
Need some help 
I installed my F4 and biased it without any issues. I then installed my BA-3 front end and have not been able to bias it at all. No matter how many turns I make on P1 and P2 I get very little mV. I then then took my voltmeter and checked V- & G and get about 23V and the same for V+ and G, but I noticed that when I took those readings, I have -23V on the V+ and +23V on the V-.......I have wired V- on BA-3 FE to V- on universal power supply v3 and same for V+.....should this be reversed?
I installed my F4 and biased it without any issues. I then installed my BA-3 front end and have not been able to bias it at all. No matter how many turns I make on P1 and P2 I get very little mV. I then then took my voltmeter and checked V- & G and get about 23V and the same for V+ and G, but I noticed that when I took those readings, I have -23V on the V+ and +23V on the V-.......I have wired V- on BA-3 FE to V- on universal power supply v3 and same for V+.....should this be reversed?
You definitely don't want to reverse the voltage polarity. The BA3 boards are correctly marked for +ve and -ve.
Check the mosfet positions. Looking at the BA3 board on the left (the side of the output cap) mine is marked Q4 (K2013) and on the right is marked Q3 (J313); I think there was a misprint somewhere that suggested they should be the other way round so that may be an issue. It was for me on my first build anyway.
The other issue is the Idss of the jfets. If they are low then you will find that nothing happens when you try to adjust P1 or P2 if they are rated at 500ohms. They would need to be 1k to do the job.
Check the mosfet positions. Looking at the BA3 board on the left (the side of the output cap) mine is marked Q4 (K2013) and on the right is marked Q3 (J313); I think there was a misprint somewhere that suggested they should be the other way round so that may be an issue. It was for me on my first build anyway.
The other issue is the Idss of the jfets. If they are low then you will find that nothing happens when you try to adjust P1 or P2 if they are rated at 500ohms. They would need to be 1k to do the job.
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lol thats funny Backbones. My jfets I got from Spencer and all were 8mA. Looking at Nelson documentation he also indicated upping P1 and P2 if jfets were low but I don't recall him mentioning a specific value. On another thought I did not get Bournes pots which I should have because they have a clicking sound I also am not quite sure which direction is min or max - will need to check with DMM, but if 8mA is low then I might as well get Bournes 1K pots now. If I dont plan to mess with P3, can I eliminate it all together?
I'm going to take my BA-3 out of the equation first and make sure my F4 is running. Not sure how much sound I will get with my DCB1 but its a process of elimination.
I also am not quite sure which direction is min or max - will need to check with DMM, but if 8mA is low then I might as well get Bournes 1K pots now. If I dont plan to mess with P3, can I eliminate it all together?I'm going to take my BA-3 out of the equation first and make sure my F4 is running. Not sure how much sound I will get with my DCB1 but its a process of elimination.
Good news is that my F4 is playing music, did not get to hear it much but its sounding very very nice. Could not hear its potential sadly...hence BA-3.
here is a pic of my BA-3 FE. Orange wires up front are V- and red wires in the rear for V+. I took the heatsinks off to remove it from the riser panel.
here is a pic of my BA-3 FE. Orange wires up front are V- and red wires in the rear for V+. I took the heatsinks off to remove it from the riser panel.
Attachments
Funny you mention that Backbones, I was just looking at it and realized that none of my ground wires were going to my power supply board. The ground for inputs is going to the input jack and currently the ground of "D" or output is going to the ground of the F4 input section but nothing going to my power supply board.