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FS: Nelson Pass "VFET2" Front End PCBs
FS: Nelson Pass "VFET2" Front End PCBs
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Old 13th May 2016, 02:49 PM   #1
luvdunhill is online now luvdunhill  United States
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Default FS: Nelson Pass "VFET2" Front End PCBs

Here's the First Watt article in question:

http://www.firstwatt.com/pdf/art_sony_vfet_pt2.pdf

I have a few of these PCBs left-over that I'd like to offer up to the community. The price is $7.50/channel plus shipping. I'd expect shipping to run between $5 (US) and $15 (international) - but the amount will be payed after they ship for exact charges (so, two PayPal payments).

They are 2 layer, 1.6mm thick, 1oz copper, black with white silkscreen, ENIG plated. I'm including a BOM and supporting files in this post. The relay controls both the feedback resistor and the "second input" available via the Cardas dual RCA input connector. This is optional.

These can also make great preamp or headphone amplifier, but such applications would be community supported efforts, not by me
Attached Images
File Type: jpg vfet_fe_schematic.jpg (154.1 KB, 1134 views)
File Type: jpg vfet_fe_block.jpg (40.2 KB, 1114 views)
File Type: jpg vfet_fe_bom.jpg (301.3 KB, 1090 views)
File Type: jpg vfet_fe_top_silk_dimensioned.jpg (168.7 KB, 1061 views)
File Type: png vfet_fe_rendering_top.png (436.7 KB, 1069 views)
File Type: png vfet_fe_rendering_bottom.png (195.9 KB, 381 views)
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Old 13th May 2016, 02:51 PM   #2
luvdunhill is online now luvdunhill  United States
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Old 13th May 2016, 06:14 PM   #3
luvdunhill is online now luvdunhill  United States
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I have four of the previous version of the board that most notably have the wrong BJT pinout and some random other silkscreen mistakes and poorly thought-out interface with the output stage. Those are available for free, just pay shipping.

I now have 10 of the (fixed) version above.
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Old 15th May 2016, 01:36 PM   #4
luvdunhill is online now luvdunhill  United States
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8 boards left.
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Old 26th May 2016, 11:29 PM   #5
luvdunhill is online now luvdunhill  United States
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Old 19th September 2016, 02:45 AM   #6
wengtech is offline wengtech
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hello,
have you finished this vfet pt2.fe build?
how does the sound, compared to ba3 front end?

thanks.

Last edited by wengtech; 19th September 2016 at 03:15 AM.
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Old 19th September 2016, 03:04 AM   #7
syklab is offline syklab  United States
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Hi,
How do we use your module on top of the Vfet2 PCB provided by Nelson/Jason?
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Old 19th September 2016, 03:17 AM   #8
luvdunhill is online now luvdunhill  United States
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Quote:
Originally Posted by syklab View Post
Hi,

How do we use your module on top of the Vfet2 PCB provided by Nelson/Jason?


You don't you can use my PCB for output though. I think this more of an experimenters project than a turnkey one at this point. The FE does make a nice preamp / headphone amp though.
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Old 19th September 2016, 03:19 AM   #9
luvdunhill is online now luvdunhill  United States
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Quote:
Originally Posted by wengtech View Post
hello,
have you finished this vfet pt2.fe build?
how does the sound, compared to ba3 front end?

thanks.

I haven't used the BA3 FE, but I would guess this would sound better, depending on how hard you wanted to push the FETs. Also, no output capacitor on this build, which for some is a positive.
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Old 19th September 2016, 05:21 AM   #10
wengtech is offline wengtech
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Quote:
Originally Posted by luvdunhill View Post
I haven't used the BA3 FE, but I would guess this would sound better, depending on how hard you wanted to push the FETs. Also, no output capacitor on this build, which for some is a positive.
i plan to build BA3amp,
if this front end much better then i might use it for ba3 front end.

but i still confuse about the feedback output connection,
at your schematics, is it connected between the "output" and "vfet2 out" ??

because at the original schematic the feedback is connected to the speaker out.

thanks.
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