B1 Rev. 2

Cool. Maybe something like this would be handy:
View attachment 1124487
Looking at the left side, you can use P1 to figure out what resistance would be needed for R3 and R4. Then you could jump P1 out of the signal path. And jump R5 if you wanted to.
View attachment 1124497
Mock up board layout. The GND pad is just an easy place to put your probe. It can be ran dual mono.

View attachment 1124498

Do you think the resistors to bypass the pot on JFETs that aren't matched to .01ma are worthwhile?
That is just about what I had in mind! :cheers: It would be perfect to have some options, to take into account both JFET matching level and downstream equipment needs (cap or no cap, etc). But I don’t know how to lay out neither a circuit or a board, Mike to the rescue. I tol thought about resistors instead of the pot, but you accommodating both is just splendid work. Very very nice!!

Your question was for Pico, but I think yes: resistor might very well be worth while, since the output signal is taken from the wiper. Might not make a huge difference of course, but it can’t hurt!
 
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1672389822678.png

Here it is with large areas for film caps and or a spot for a 10uf electrolytic like a silmic or something. A bunch of different pads for different sized films. I just started playing around with making PCBs so don't have too much faith yet... I am receiving my first order of PCBs that I drew up in about a week or so. If those don't create smoke then there is hope. :)

A mirror image layout would be much nicer looking and I could get the power in locations together as well as the inputs. I may do that. With this layout, I simply made one side and copied it to the other side.

1672390227526.png
 
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Cool. Maybe something like this would be handy:
View attachment 1124487
Looking at the left side, you can use P1 to figure out what resistance would be needed for R3 and R4. Then you could jump P1 out of the signal path. And jump R5 if you wanted to.
View attachment 1124497
Mock up board layout. The GND pad is just an easy place to put your probe. It can be ran dual mono.

View attachment 1124498

Do you think the resistors to bypass the pot on JFETs that aren't matched to .01ma are worthwhile?

This is good.
 
This is very good.

Potentially you could add regulators on each Chanel, something like whammy regulator design but a pair on each board, or we could just stop there.

Obviously if it’s on the board and you didn’t want to use that you could just solder links to bypass.

I can draw up some circuit idea if required.
 
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The ground planes are seperate. There is no connection between the two channel.

I threw them in my cart at JLCPCB. I will order them the next time that I have a few PCBs to order. Each channel has it's own ground plane. JLCPCB is quoting me around $10 + shipping with 5 of both of the PCBs in the cart.

You will see, one board has the output cap, the other doesnt. The Schematic below is the same for both other than C3 and C2 being removed in the no output cap board.
1672426247595.png
 

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  • Gerber_PCB_B1 R2 FAB NO CAP_2022-12-30.zip
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  • Gerber_PCB_B1 R2 FAB OUTCAP_2022-12-30.zip
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The ground planes are seperate. There is no connection between the two channel.

I threw them in my cart at JLCPCB. I will order them the next time that I have a few PCBs to order. Each channel has it's own ground plane. JLCPCB is quoting me around $10 + shipping with 5 of both of the PCBs in the cart.

You will see, one board has the output cap, the other doesnt. The Schematic below is the same for both other than C3 and C2 being removed in the no output cap board.
View attachment 1124711
Probably should add a resistor to ground at output to ensure the cap is discharged at switch off.
Just an optional component that people might want.
 
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Pico, Are you thinking of a resistor from the output of the cap to ground like how it is on the Korg Nutube b1? When I get the boards on my next order, I will play around with the 10uf signal output cap board and see if it stores energy in it. I guess it would cause a turn on thump or something like that. Maybe the protocol should be, turn on the preamp, then amp. Amp off, then preamp.
 
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