Sony VFET Amplifier Part 2

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Thanks Botte. Your response helps to clear up things. Mine is a new build so I will go with C1,C2 at 220uf and C3,C4 at 47uf, all the rest 220uf.
I realize that we all have different brand preferences for caps. What brand here seems to have worked best for you? Also what voltage should these be? Bypass or not since the board has provision for it?


Nash

I use the Elna SILMIC II Series 50V for the bootstrap 35 for the rest. I do bypass them with the vishay MKP 1837.
 
Been listening on the main system of a few weeks now. This to me is much better than the Version one. It has much detail without being bright sounding and the bass is better defined.


I will swap in my f3's, which have been my favorite amps and see how they compare.


I built both the M2 and Sony Ver 1 which both have the input transformers and they were just not to my liking, not bad by any means, just didn't capture my attention when I go through my music collection. Just my two cents worth?
 

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0.6V across R5 and R6 seems quite low. I guess it may be a combination of low Idss
jfets/high Vgs mosfets. I don't think you should select higher Vgs mosfets. (If
anything, that will likely make things worse.)

I think you need to increase the total resistance of R35+P3 and R34+P4.

1V offset at T18 is higher than Papa's recommendation of 200mV.

Also, are you really running the channels with just the brackets without
bolting them to heatsinks?

Hopefully others can chime in.
 
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Joined 2008
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0.6V across R5 and R6 seems quite low. I guess it may be a combination of low Idss
jfets/high Vgs mosfets. I don't think you should select higher Vgs mosfets. (If
anything, that will likely make things worse.)

I think you need to increase the total resistance of R35+P3 and R34+P4.

1V offset at T18 is higher than Papa's recommendation of 200mV.

Also, are you really running the channels with just the brackets without
bolting them to heatsinks?

Hopefully others can chime in.

I will be trying to increase 500ohm to 750. On both channels. As for the heatinks, I am not going over 50mV on R32 for now. Once fully installed in chassis, I will increase vfets bias.
 
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Well, the VFets don't need to be matched, but you need to know their Vgs at 0.5A Ids in order to safely bias the circuit. If you manage to somehow find the VFets, the Vgs grading can be done according to the attached schematic (courtesy of Nelson Pass).
 

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