RunoffGrove Tube Emulators

[Arn C.]

In these circuits they call for J201 Fets, can any other fets be used and which ones are they?  2n?

Thanks!
Arn C.

[Mike Burgundy]

Guess what: it's in the DIY FAQ!
"From Jack Orman:

"This is a recurring question eventhough the information was in the Mini-Booster article at AMZ From the article: "The NTE458 usually has more gain than the J201, and the 2N3686 can provide gain of 500. The 2N5457, MPF102, and 2N3819 will produce less gain. Other substitute transistors include 2N5484, 2SK43, 2SK68, 2SK117, 2SK118, 2SK121, 2SK163 and BF245."

[Arn C.]

Thanks Mike!

Arn C.

[Jim Jones]

I've been using 2N5458's in my experiments.  The seem brighter and more sparkly than J201's, and not as gainy either.  I don't know if it's wise to make a sweeping generalization like that, but that's what I've found in my limited experimenting.

Thanks to Runoffgroove it's time to buy 100K trimmers by the truckload.  

Jim

[Arn C.]

And Thank you Jim for your input!!!

Peace!
Arn C.

[B Tremblay]

I've been using 2N5458's in my experiments.  They seem brighter and more sparkly than J201's, and not as gainy either.  I don't know if it's wise to make a sweeping generalization like that, but that's what I've found in my limited experimenting.

That's generally what I've found with 2N5457 and MPF102.  The gain is less than a J201, but the response is brighter.  It's really apparent in a single stage like the Fetzer Valve.

[Torchy]

So far I only built the Prof Tweed, but I have tried mixing 2N3819s and J201's coz thats all I had. Its a testament to the design that with a minimum of tweaking I can get an acceptable sound from both types.

Got some MPF's on order to bang in the Tweed ... and I cant wait to perf the Vox  

[Gringo]

I've done some experimentation with the mpf102 since almost every jfet based project calls for j201, but i can't get those locally (and ordering from steve is still unavailable for me). You can see a report of the results  here:

http://www.diystompboxes.com/sboxforum/viewtopic.php?t=21299&highlight=

i also have a few 2n5457 and bf245 (thanks Arn ), and i compared them with a mpf102, and the sound almost the same, a little bit less open than the mpf102 but with a tiny bit more "grit". So what i did to "warm" the mpf102 should apply to the 5457's and 245's.

If you like the sound of these "low gain" fets, but miss some more gain (i know i do!), you can try tweaking a little the gain stages to get where you want

[Jim Jones]

That's generally what I've found with 2N5457 and MPF102.  The gain is less than a J201, but the response is brighter.  It's really apparent in a single stage like the Fetzer Valve.

Hey Brian!

Cool, I've only messed around with the Fetzer so far so it's good to know I'm on track.  I've found you can make  a cool, simple little booster by building a Fetzer feeding a filter like at the output of your Princeton circuit.

I plan on doing way more experiementing with FET's in this capacity - thanks to you and Gary for the inspiration and topology's!  It's really nice for me (being mostly a tube guy), it allows me to breadboard familiar circuits without even referring to schematics.  

Jim

[bwanasonic]

Thanks to Runoffgroove it's time to buy 100K trimmers by the truckload.  

Speaking of that, can anyone provide the mouser part # for the trimmer shown in the runoffgroove Supreaux ? :

http://runoffgroove.com/supreaux.html

I'm looking for a trimmer with a small footprint that is easily adjustable from *above*, and that one looks to fill the bill.

Kerry M

[Fret Wire]

Kerry, I just posted a data sheet and Mouser part # for the 10mm Piher 100k trimmers. They are small. They have many different types, so the part numbers are long. Could you take a look at my thread, and double check that I have the right part number? Small and 40 cents apiece, not bad.

Thanks
http://diystompboxes.com/sboxforum/viewtopic.php?t=22168

[Lonestarjohnny]

I always order them from mouser, if you can afford to spend a few extra buck's they sell a kit  that goes from 100 ohm to 5 Meg ohm's that I find to be very handy, kit # 370-pth-10, you get 10 of everything,these are the Vertical Trimmer's, easy to adjust and take up very little room, you can get the price at Mouser's on line Catalog.
JD