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GB for F6 Convertible Clone boards

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Hello,

By request ,

I am making some boards for the F6 amplifier board as Nelson has posted in the sixMoons article based on the F6 Second Harmonic.
Nelson has blessed a GB.

It's designed to be convertible in the sense that you can -

1. Swap transformers to your liking using a daughter board.
2. Move between the various schematical forms of the F6 without too much effort. A jumper here and there.

Since Nelson has been generous in yet another design for us, this board also reflects that.
-CRT spent a lot of time making the Gerber files. No payment accepted.
-All tooling expenses will be covered by myself.
-Anyone who purchases will be making a donation of $2.50 per main board and .50 per daughter board to DIYAudio via me when group buy is complete. If you don't like that, don't buy the board or complain on this thread.

Future sales will be given to DIYAudio if Variac deems the board fit for the store or Gerbers will be free. The future is unknown for many with the F6 with no SemiSouth R100's around to buy. So unless people make a good effort to note design changes for IRF240's etc, I suppose board sales will be limited.

Prototype boards are currently on order. Pricing is subject to change.
The sign up spreadsheet is in my signature. Payment is not accepted until prototype is functional.

Here is a picture of the circuit board.

An externally hosted image should be here but it was not working when we last tested it.


This post will be edited. Prices TBD. But ~18.00 for pair of main boards, 9.00 for pair of daughter cards.
 

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Do you have a schema of it?How is the inputstage set up?

Hi Ryssen.
Its based on the schematic listed here.

the only addition is for optional parallel pairs of buffer JFETs.
If one is not running source resistors on the JFets, then using 2xGR type will allow for higher dissapation, if BL grade <8mv IDSS or so is unavailable.
 

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Does the "primary" F6 board follow the UMS mounting spec? Ie. Will this fit on a diyAudio store stock chassis?

I'm signed up either way just thinking about what I'm getting into this time! Thanks for putting this together the layout looks great!
 
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This product is also under consideration. I have been chatting with one of the owners.
The Jensen designs were done by the same engineering group that they own now. So suspects a lot of overlap. I have ordered the 80 percent nickel version. It will barely fit the footprint, but I think do-able.

http://cinemag.biz/output/CMOQ-4.pdf

The pricing is less per unit.
$28.78 from manufacturer. I believe this is 10-11USD savings from Jensen.

The Onetics transformers have a great reputation, but the pricing is 50.00 each before any quantity discounts.
 

PKI

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Thank you so much, Tea-Bag! I am looking forward. Any details and comparison between Jensen, Onetics and Cinimag (did someone compare them in the finished prototype)? I looked through F6 discussion and could not find anything... Thanks!
 
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I don't have a comparison yet.
I merely wanted people to allow for this!
I have all of these transformers in my possession (some borrowed). But my opinion may vary from others.
The Jensen sounds like a safe bet, and costs less than the Onetics. But until I hear them both, all I can't speak for who I think is a clear winner, regardless of costs.
 
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Having fun so far.
It sounds really good with an just open air CHR-70 Mark Audio. I would not consider too much weight in making anyone else transformer decisions based on my own. I think tuning is second to just wiring up different options now - I must make sure the stuff works as a priority :)

Point is the IRF240 works, and gets current and offset under control, seems to have normal gain, but that I will compare better to R100s in the next few days.
If the IRF240 works, the R100 will work on this board.
 
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