DIY Front End 2022

On the new revision card with the C6, is this capacitor necessary or is it optional if you run the card single rail?
I can see this card is a jack of all trades. I won't be running any external feedback into it.

Also, can I just short the varistor, again running card as single rail?
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Have you read Nelson's post #686 yet?

He said that R13, R14, P1 and C6 are optional, and he explained their purposes. It has nothing to do with whether the power supply is bipolar or single ended.

If you do not need the add-ons, omit all of the optional parts. The only location that needs a jumper would be at R13. P1 (not a varistor by the way, it is a trimmer or potentiometer) does not need jumpers, but do install R6.

I have the original with none of the latest options and it sounds great. :)
I stuffed the resistors, placed and soldered the transistors. Is there anything more nerve racking than soldering all those tiny leads on 14 transistors and wondering if you blew it somewhere? I tested connections as best I could.

Just about the time I got the last transistors soldered was the time I finally got my technique down.

Waiting for caps to arrive then bench testing to see if they work. I will be running it single rail, so also placed the jumpers across R10 and R13, and placed R6 instead of pot, and will observe the polarities printed on the boards.
What? Nerve racking soldering? Get yourself a proper worklight with magnifying glass. Those are worth much more than their weight in gold 🙂👍
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I actually use one of those headband 'stamp collector' types - they relatively cheap, not exactly professional fitting, but do the job very well - I'm currently looking at those "Vision Aid" ones with the included led light at about A$60.

I find the 'work-light' magnifier a bit clumsy with larger projects, but perfectly okay for small ones - the more recent led versions far better than my old fluoro tube one plus an adjustable "Planet lamp".