J201 sub for a 2n5457?

[Dan0h]

Wrapping up the Pharmacist build and wondering if I can use J201s as a sub for the 2n5457s.

Thank you build gurus.

 

[Big Monk]

My immediate response would be no. J201, on average, will have much more gain than 2N5457. Here are values from the RoG "Fetzer Valve" article:



I'm not sure what the potential 2x boost in gain will do to the circuit.

 

[Dan0h]

Oh wow. Good to know thank you. Might have to order some more transistors….

 

[Mcknib]

Barry's got some not too expensive considering they're hard to get

(*) JFET 2N5457 - Guaranteed Genuine - GuitarPCB

(1) Genuine 2N5457 JFET Transistor from my own personal collection. Hand Tested and all are in the proper range for guitar pedals.

guitarpcb.com

Here's a stompville article on substitutes

Substituting the 2N5457 – Stompville

stompville.co.uk

 

[BuddytheReow]

I see you've got sockets ready to go. I agree with the above, but I also think you should try the J201s to see if you like it if you've got them lying around. You may be surprised. Or disappointed.

 

[temol]

We need a sticky subject explaining this.. J201 <-> 2N5457 topic is like a boomerang

 

[Dan0h]

Very confusing. Even on the link provided above it says “

Replacement and Equivalent:​

2N4339, 2N4340, J201, 2N4338, 2N4341, 2N5458, 2N5459, NTE458​

But I understand the differences in values will cause differences in sound. I can try my j201s and j112s and see if I like the sound and if not order some 5457s.

Thank you for the awesome feedback as always!

 

[Dan0h]

I see you've got sockets ready to go. I agree with the above, but I also think you should try the J201s to see if you like it if you've got them lying around. You may be surprised. Or disappointed.

Indeed!

 

[temol]

But I understand the differences in values will cause differences in sound.

In some cases you can expect a different sounding circuit, sometimes not. And sometimes you'll need to change a value of the resistor/trimmer or even capacitor here and there to accomodate for the different model of the transistor.
General rule - if it's a source followe (buffer) - you should not worry.
Gain stage - it depends. Take a look here for example.. this sould help a little bit.

 

[Diynot]

So I posed this question in another pharmacist build thread, but didn’t get any bites, so I’ll drop it here too. what if say you have 3 of the 4 5457s and a handful of j201s if you were to substitute 1 where would you place it and what would be the effect? My theory is if it were a Q1 sub it would be like a boost into gain, but at Q4, it would be more of a boost after gain. Thoughts? I’ll admit this is def a theoretical now since I went ahead and harvested a 4th 5457 out of another build, but would still like to know

 

[Dan0h]

So I posed this question in another pharmacist build thread, but didn’t get any bites, so I’ll drop it here too. what if say you have 3 of the 4 5457s and a handful of j201s if you were to substitute 1 where would you place it and what would be the effect? My theory is if it were a Q1 sub it would be like a boost into gain, but at Q4, it would be more of a boost after gain. Thoughts? I’ll admit this is def a theoretical now since I went ahead and harvested a 4th 5457 out of another build, but would still like to know

Great question because I have three J201s and three J112s. might just be a trail and error deal, glad I socketed.

 

[Dan0h]

SBP has some 58s. Maybe I will try those too.
Stomp

 

[Dan0h]

Barry's got some not too expensive considering they're hard to get

(*) JFET 2N5457 - Guaranteed Genuine - GuitarPCB

(1) Genuine 2N5457 JFET Transistor from my own personal collection. Hand Tested and all are in the proper range for guitar pedals.

guitarpcb.com

Here's a stompville article on substitutes

Substituting the 2N5457 – Stompville

stompville.co.uk

Wait is the the same Barry as Barry?!

 

[Mcknib]

Wait is the the same Barry as Barry?!

Haha no Barry at GPCB

 

[fig]

Haha no Barry at GPCB

Well, I'm almost certain Barry has 2N5457s from Barry.

 

[Kroars]

Wrapping up the Pharmacist build and wondering if I can use J201s as a sub for the 2n5457s.

Thank you build gurus.
View attachment 16804

Send me a message, I’ve got a bunch of SMD’s on adapter board, or just the smd whichever you prefer.

 

[Dan0h]

Send me a message, I’ve got a bunch of SMD’s on adapter board, or just the smd whichever you prefer.

Thanks dude, I decided to give Barry a try! I’ll try my J201s first then see what the difference makes when these arrive. Barry has LM308s too! Excited

 

[zgrav]

since you socketed the board for your transistors, feel free to experiment. put the j201s first, then last, then try to alternate them. it will be interesting to get your thoughts on the differences in the sounds.

 

[bowanderror]

since you socketed the board for your transistors, feel free to experiment. put the j201s first, then last, then try to alternate them. it will be interesting to get your thoughts on the differences in the sounds.

This is the real answer; you won't know until you try.

Especially for builds with sockets & drain trimmers, there is no harm in trying different JFETs. For pedals, where distortion is often a desirable trait, the effect of highly variable Vp/Idss specs, headroom & biasing of different JFETs is more art than science. Of course, there are good guidelines depending on what the circuit designer was shooting for, but you're not going to blow anything up by trying something different.

 

[Dan0h]

J201s work. Sounds full and fat at low volume. Kid is sleeping will be able to crank it tomorrow. Had an extra Mr. PedalPcb J201 smd conversion to add to my 3 iFCs. They all tested pretty close 129,132,136,139 hfe. I put them in that order. When the 5457s show up I’ll post an update.