Linkwitz wm-61a mod preamp PCB, any comments?

[mrkva]

Hey guys,

I have designed a PCB for Linkwitz WM-61a mod preamp.
I went for a design with two gain options (x10 and x100), pseudo balanced output (hence 200ohm resistors). Also, I wanted to make it as-small-as-possible and all DIP based for easy beginners assembly.

Any comments?

Thank you!

 

[kaliwraith]

Hey, old thread, but I was searching for this exact thing. Did you ever make pcbs from this or find someone who makes them?

Thanks!

 

[AndrewT]

I wonder why he has connected the junction of R1 /R11 to -9V?
Is this a version of phantom powering?
Surely this junction goes to audio ground.

 

[infinia]

I wonder why he has connected the junction of R1 /R11 to -9V?
Is this a version of phantom powering?
Surely this junction goes to audio ground.

no it's correct
(the mic capsule mod, changes the FET inside it to a source follower.)

 

[infinia]

Hey, old thread, but I was searching for this exact thing. Did you ever make pcbs from this or find someone who makes them?

Thanks!

just use perfboard all the originals used perfboard.
perhaps use the PCB layout above for a parts placement/ wiring guide?

 

[AndrewT]

no it's correct
(the mic capsule mod, changes the FET inside it to a source follower.)

Thanks.