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FS: Nelson Pass "VFET2" Front End PCBs

luvdunhill

Member
2006-07-09 6:59 pm
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 :)
 

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luvdunhill

Member
2006-07-09 6:59 pm
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.
 

wengtech

Member
2012-02-27 12:13 pm
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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luvdunhill

Member
2006-07-09 6:59 pm
In this case, OUT connects to the output stage output. This relay controls whether feedback is enabled. The VFET2_OUT is the output of the FE. You can use these connections as you see fit, if you are using another output stage or application.

I am heading out on business, I return tomorrow and will count the remaining boards.