Can I use 2N5458 jfets instead of the J201 for a Chop Shop?

[Barnshart]

Just bought the Chop Shop PCB and on the build doc it calls for J201 jfets.

I couldn't find any on Tayda in stock, same with on this site. So I did a brief Google search and was told the equivalent through hole part is a 2N5458 which PedalPCB did have in stock. So that's what I ordered!

But.... Will they work? This is my first build using jfets. I have absolutely no clue how to bias them. Figured I'd buy now and learn later. Just hoping they can actually be used! Any helpful tips would be appreciated when it comes to biasing.

Thanks!

 

[steviejr92]

Yes 2n5458s will work as a sub for J201s. Mind the pinout.

 

[szukalski]

Yes 2n5458s will work as a sub for J201s. Mind the pinout.

Have you tried a Chop Shop with the 2N5458?

I would recommend MMBFJ201 if you can find them.

 

[phi1]

I would also recommend j201s (Pedalpcb has smd and little conversion pcbs). When jfets are used as buffers, subbing shouldn’t be a problem. When jfets are the gain / clipping structure, then subbing them with significantly different parts will have a big impact of overall gain and the circuits ability to bias correctly.

 

[Laundryroom David]

Socket the fets and try. However …

Like @szukalski , I would encourage you to find mmbfj201 if you can. PPCB often has them, as does Aionfx.

 

[steviejr92]

Have you tried a Chop Shop with the 2N5458?

I would recommend MMBFJ201 if you can find them.

I actually haven’t! I just know you can use the 2n5458 as a sub! In that case let me scratch out my response!

 

[szukalski]

I actually haven’t! I just know you can use the 2n5458 as a sub! In that case let me scratch out my response!

In some places you can substitute them, I wasn't sure that the Chop Shop is one of them, hence the ask

 

[steviejr92]

Well id rather be safe and not lead him wrong!

 

[jimilee]

Just bought the Chop Shop PCB and on the build doc it calls for J201 jfets.

I couldn't find any on Tayda in stock, same with on this site. So I did a brief Google search and was told the equivalent through hole part is a 2N5458 which PedalPCB did have in stock. So that's what I ordered!

But.... Will they work? This is my first build using jfets. I have absolutely no clue how to bias them. Figured I'd buy now and learn later. Just hoping they can actually be used! Any helpful tips would be appreciated when it comes to biasing.

Thanks!

Guitarpcb.com always has quality stuff.

 

[lrgaraujo]

The jfet stages on the chop shop will probably work with a 5458 fet, but they're most likely not gonna sound the same as the original. Your safest bet is to use sockets, if you like the way the pedal sounds with the 5458s, that's all good. If not, it is simple to change fets down the road

 

[KR Sound]

You can use whatever the heck you want! If it sounds good to you, it works. If not, it doesn’t. That’s one thing I like about building- you can either try to emulate the source pedal as close as possible, or use it as a jumping off point and tweak it to how you imagine it sounding with your guitar and amp or to complement another pedal in your chain.

 

[temol]

Just bought the Chop Shop PCB and on the build doc it calls for J201 jfets.

Buy J201s. Why?



Of course it's possible to bias 5458 @ 6V but the resulting overall gain is quite low - see the ltspice simulation plots. It's the blue vs green plot. 24dB vs 40dB. As for the distortion - see the third plot. Squared edges of the green sinevawe vs rounded of the blue sinewave (no clipping = no distortion).
Red trace (5458+) - I increased value of the jfet drain resistors from 1k to 4k7. 1k stock value resulted in very low values of the drain resistors - around 3k. With 4k7 it's around 8k5 (Rd). Still lower than with J201 (around 13k). Gain has increased but still not much clipping compared to J201.

 

[The Gator]

I asked this question in my own thread not long ago. In the end, 2n5458 is a poor choice for substitution in this circuit. This circuit instantly became one of my favorites when I built it, and was given some proper J201s from a well known builder here, MichaelW.
And now, it is time to pay it forward.
I would be deligted to send you a pair of tested J201s for your chop shop.
If you are interested, just message me.
This is a great community that has always helped me. It would be great to be able to help someone.

 

[lrgaraujo]

Buy J201s. Why?

View attachment 42948

Temol, what kind of input signal are you using for this transient analysis?

 

[temol]

SINE(0 0.25 660 0.01 10)

 

[jhaneyzz]

I asked this question in my own thread not long ago. In the end, 2n5458 is a poor choice for substitution in this circuit. This circuit instantly became one of my favorites when I built it, and was given some proper J201s from a well known builder here, MichaelW.
And now, it is time to pay it forward.
I would be deligted to send you a pair of tested J201s for your chop shop.
If you are interested, just message me.
This is a great community that has always helped me. It would be great to be able to help someone.

Beat me to it...

I bought a couple dozen through hole J201s a while back when I saw they were in stock.

If anyone is ever desperate, give me a shout.

 

[Barnshart]

I asked this question in my own thread not long ago. In the end, 2n5458 is a poor choice for substitution in this circuit. This circuit instantly became one of my favorites when I built it, and was given some proper J201s from a well known builder here, MichaelW.
And now, it is time to pay it forward.
I would be deligted to send you a pair of tested J201s for your chop shop.
If you are interested, just message me.
This is a great community that has always helped me. It would be great to be able to help someone.

Thank you for the offer, I really appreciate it but Robert did actually message me and let me know he had some SMD 201 he could solder up for me so that's been sorted out. Thanks again though!

 

[The Gator]

Ok good deal. I was wondering if you were interested. Really, smd is the way to go with J201s. I did purchase some TO-92 package thru hole J201s that were in spec, but they are not as consistent as the SMD I have purchased and been given.
You're gonna like the Chop Shop.
And if you do, I also recommend tthe Champ Stamp.

Later,
~Gator

 

[Alan W]

You're gonna like the Chop Shop.
And if you do, I also recommend tthe Champ Stamp.

Later,
~Gator

Darn it! I never looked once at the Champ Stamp, and now it’s on my wishlist—Chop Shop has been by far my most favorite “gain stage” build, one that I seem to appreciate more the more I use it, rather than moving to the “try this again later” shelf. There’s something special in these two and three transistor design circuits.