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FS: one pair of Nelson Pass A40 PCBs
FS: one pair of Nelson Pass A40 PCBs
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Old 5th March 2018, 01:40 AM   #1
alexcp is offline alexcp  United States
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FS: one pair of Nelson Pass A40 PCBs
Default FS: Nelson Pass A40 PCBs

UPDATE: a new batch of PCBs arrived! See post #17 below for pictures, post #28 for schematic.

The price is $10 per pair of boards plus shipping. Estimated USPS shipping prices are $5 for the continental U.S., $12 for Canada, $16 for Europe and Australia, and probably for most of the other countries. PM me if interested.

For details on the amplifier see the relevant article on FIRSTWATT web site and another one for substituting modern parts. The PCBs are double sided and follow the original 1978 design. Each 3"x3" PCB is for one channel front end only (power stage is off board), so you'd need a pair for stereo.
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Last edited by alexcp; 30th October 2019 at 04:04 AM. Reason: New batch of PCBs arrived
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Old 5th March 2018, 02:07 AM   #2
Eric is offline Eric  United States
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FS: one pair of Nelson Pass A40 PCBs
What a great project! This was my very first DIY amp - I chose this one because Nelson's article about it was available on his webpage and this PCB was for sale on the Sound Colony web page.

My write up is a bit old and definitely crude by today's standards, but I have some notes about my a40 build for anyone wishing to build this amp here: my a40 build. Still use this amp fairly regularly and it sounds great.
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Old 5th March 2018, 02:31 AM   #3
alexcp is offline alexcp  United States
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FS: one pair of Nelson Pass A40 PCBs
Quote:
Originally Posted by Eric View Post
What a great project! This was my very first DIY amp - I chose this one because Nelson's article about it was available on his webpage and this PCB was for sale on the Sound Colony web page.

My write up is a bit old and definitely crude by today's standards, but I have some notes about my a40 build for anyone wishing to build this amp here: my a40 build. Still use this amp fairly regularly and it sounds great.
Eric, thank you for sharing your experience and for the link! I could not agree more - after 40 years, A40 is still a great project, remarkable in both its simplicity and the sound quality it achieves. I built an A40 myself some years ago but have had an extra pair of boards hanging around. Hopefully someone (with a pair of large heatsinks) will build another one
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Old 5th March 2018, 03:02 AM   #4
exurbia is offline exurbia  Australia
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Old 5th March 2018, 06:15 PM   #5
alexcp is offline alexcp  United States
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FS: one pair of Nelson Pass A40 PCBs
Update: The boards have been SOLD. There was more than one person who wanted the boards, but I only had one pair.

If I get four or five people interested, I may be able to order another batch at about the same price. Until then, I am attaching the gerbers here. (I wanted to post them to my blog here on diyAudio.com, but could not do it for a reason unknown.)

I am also making the board available for order on OSHpark. Note that OSHpark is rather more expensive; they manufacture three boards at the price of US$5 per square inch of design, so with these gerbers, you'd get three boards for $45.

Acknowledgment: The A40 design, including the artwork of the PCB, was created by Nelson Pass. I only took his article (referenced in the first post) and produced an electronic version of Nelson's PCB artwork with the sole purpose of allowing PCB manufacture.
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Old 20th March 2018, 08:00 PM   #6
amp_guy is offline amp_guy  United States
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I would be interested in a few boards. Probably 4 pieces.
I have an A40 that I built long time ago, got it out recently and found about 8 volts of d.c. on the output.
My boards are rather crude as they were made using the laserprinter film and iron on method.
The A40 can be made using lateral mosfets instead of the darlingtons, I have not tried it but others have. Would like to try it as I have a boxfull of the old Hitachi's (2sj49 and 2sk134)

I actually had started laying out a new board when I saw your post here. Didn't think anyone else had any interest in this old design.
Deceptively simple design and sounds great.

Last edited by amp_guy; 20th March 2018 at 08:04 PM. Reason: added more
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Old 21st March 2018, 02:15 PM   #7
alexcp is offline alexcp  United States
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FS: one pair of Nelson Pass A40 PCBs
Thank you! I think there is enough interest for me to go ahead and order another batch. I will post here and contact you guys when I have the boards.
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Old 21st March 2018, 03:11 PM   #8
Dennis Hui is online now Dennis Hui  Canada
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FS: one pair of Nelson Pass A40 PCBs
Hi Alex,

I certainly would love to get a pair of boards when you have them available again.

Cheers,
Dennis
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Old 27th March 2018, 12:42 AM   #9
alexcp is offline alexcp  United States
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FS: one pair of Nelson Pass A40 PCBs
As is now posted in the thread's opening message, I got a new batch of the A40 boards made. As before, a pair of boards if $10 plus shipping. I estimate shipping to the continental US to be $5, Canada - $12, most of the other countries - $16.

If you're interested, PM me.
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Old 20th April 2018, 01:59 AM   #10
Freecrowder is offline Freecrowder  United States
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FS: one pair of Nelson Pass A40 PCBs
If there are boards still available I would like a pair.
let me know how to proceed.

Thank you
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