Sony VFET Amplifier Part 2

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bk856er

bk856er

Member
Joined 2011
Does the Store kit include tubular insulators for the VFETS? I've seen several references to them by Variac, but my kit didn't have any - just all the nuts/bolts/washers/mica. Presumably we really do need those tubular insulators?

BK

*edit* Doh! The tubular spacers are packed in the silver mylar pouch with the VFETS, not with the other hardware. All good here.
 
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W

WalterW

Member
Joined 2012
Paid Member
nagini262 said:
Single pair version without local feedback but fixed global feedback, two pair version fixed local feedback and optional global feedback so I guess the sound of both are very close.
In the two pair version, the sound with global feedback is close to face of loudspeaker and you will heard the sound direct from your loudspeakers, the sound space is small. When you switch to without global feedback, you will heard the sound around of you, the sound come to your ear from anywhere in your room, it's very close surround sound so you can heard the large sound space. You must sit at your position and someone help you to switch the option, it's hard to find the difference if you come to your amp to take the switch and heard.
I built with the good parts without modify.
Click to expand...

Nagini, did you build the VFET pt2 with the new values for the resistors Nelson mentioned, or with the ones in the original schematic in the pdf?

Did you alter any of the 220uf capacitors to an other value? I heard people doing this, but can't find it anymore.

Do you use all the zeners as in the original schematic? because in the picture in the pdf you can see Nelson didn't use them on his PCBs.

Do you use 'the bootstrap' with R18/C8 R17/C7?

Thanks!
 
nagini262

nagini262

Member
Joined 2008
WalterW said:
Nagini, did you build the VFET pt2 with the new values for the resistors Nelson mentioned, or with the ones in the original schematic in the pdf?

Did you alter any of the 220uf capacitors to an other value? I heard people doing this, but can't find it anymore.

Do you use all the zeners as in the original schematic? because in the picture in the pdf you can see Nelson didn't use them on his PCBs.

Do you use 'the bootstrap' with R18/C8 R17/C7?

Thanks!
Click to expand...

Thanks about 2SK2013/2SJ313;)
I built VFET P2 with original schematic without any change. All capacitor is 220uF and I think that is OK; you can increase the value of C1/C2, the 19VDC will come up slowly and that is better for VFETs but 220uF still OK:rolleyes:
The schematic have Z1/Z5 and Z2/Z6 but the PCB have no Z5 and Z6 but that is no problem, you can running with only Z1 and Z2. The single pair version have no any zener protection and I think I will remove them when I upgrade my VFET P2:p
I used bootstrap as you see
 
Rodeodave

Rodeodave

Member
Joined 2004
Paid Member
WalterW said:
Nagini, did you build the VFET pt2 with the new values for the resistors Nelson mentioned, or with the ones in the original schematic in the pdf?

Did you alter any of the 220uf capacitors to an other value? I heard people doing this, but can't find it anymore.

Do you use all the zeners as in the original schematic? because in the picture in the pdf you can see Nelson didn't use them on his PCBs.

Do you use 'the bootstrap' with R18/C8 R17/C7?

Thanks!
Click to expand...

This should help:

http://www.diyaudio.com/forums/group-buys/285823-gb-pass-sony-vfet-version-2-al-boards-tea-bag.html

http://www.diyaudio.com/forums/blogs/tea-bag/352-sony-vfet-version-2-al-boards-build-blog.html
 
C

Cantilope

Member
Joined 2016
PS done for VFET

IMG_5744.jpg

I am on the heels of Wdecho. Here is my freshly finished PS for the VFET I will be building. It is a tight fit in the 5U, but can be done. I'll begin the audio boards ASAP.

Joe
 
Bones13

Bones13

Member
Joined 2006
Paid Member
Cantilope said:
View attachment 569653

I am on the heels of Wdecho. Here is my freshly finished PS for the VFET I will be building. It is a tight fit in the 5U, but can be done. I'll begin the audio boards ASAP.

Joe
Click to expand...

Looking good! I always enjoy seeing someone put something into the chassis in a different orientation.

Just a stupid question though, where do you put the motor run caps in the PSU schematic? Just across the rails somewhere after the resistors?
 
W

wdecho

Member
Joined 2014
Bones13 said:
Looking good! I always enjoy seeing someone put something into the chassis in a different orientation.

Just a stupid question though, where do you put the motor run caps in the PSU schematic? Just across the rails somewhere after the resistors?
Click to expand...

Easy, just put wires on one motor run cap and attach one to V+ and the other wire to star ground. Put wires on motor run cap and attach one to V- and the other wire to star ground. On the schematic you have just added two more caps.

The picture Cantilope posted does not show too well that he has 2 PS and 2 transformers in one big 5U case. I am envious. He is going to have monos but one case.
 
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Zen Mod

Zen Mod

Official Court Jester
Joined 2003
zenmod.in.rs/
Paid Member
dunno
some pooftah here is in recent years advocating their use , as main reservoir caps (when value is adequate for circuit) and as final bypass caps in rails ...... and as speaker xover caps
:rofl:

(frankly - just tip from Yore)

when selected from decent origin ( read - old factory , so pro quality guaranteed) , you can hardly find better cap for task
be aware that there are expensive audiophooll priced caps , nothing else than motor runs in disguise
 
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