J201 for Chunk Chunk Question

[electricstorm]

Those of you who have built the Chunk Chunk (2012 version), did you match the J201's or just plug them in and set the bias according to the instructions?

If you matched the 201's, what Vgs value did you shoot for (low, high, in the middle, or whatever you could reasonably match)?

I have the improved JFET matcher circuit built and ready if I need to do some matching.

Thanks!

Jim

[DutchMF]

Just follow the instructions in the build docs and you'll be fine, no extra matching required! If you would like to lower the gain a bit you could swap out the j201's for 2N5457's (or only the first two), sounds really good as well, a bit more Marshall than Mesa, so to speak! Enjoy!

Paul

[pickdropper]

Yeah, if they bias correctly (and some won't) then you should be OK.

I agree with Dutch, the sound changes a lot depending on the JFETs used.  I almost always use a combination of J201 and 2N5457

[electricstorm]

Thanks Paul and Pick!

I don't have any of the 2N5457's, but I do have a few 2N5485's. Are those acceptable?

[alanp]

From what I understand, matched fets would only be needed if one trimmer was supplying bias to all four fets.

I wonder if a Phase 180 would be possible with nonmatched fets, using more than one trimmer...

[electricstorm]

That would be interesting!

Thanks for the info everyone. Haven't messed around with FETs much.