# Sabbath Distortion Question



## Flipguitarist (Aug 29, 2019)

I’m trying to build this pedal and I’d like to ask before I solder the components if it’s ok to use  jfet 201’s in place of mpf4393’s on q2-q6 and a 2n2222 on q1? Thanks.


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## zgrav (Aug 29, 2019)

you could use sockets to preserve some options on transistors and give it a go.


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## Flipguitarist (Aug 29, 2019)

zgrav said:


> you could use sockets to preserve some options on transistors and give it a go.


I have two boards ordered the correct parts so while waiting I’m gonna build one with the mentioned replacements. Would they work? Thanks again.

I don’t have sockets lol


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## zgrav (Aug 29, 2019)

this might help:






						Substitutes for MPF4393 ?
					

Just bought the Bohemia pcb but it's hard to find the JFET MPF4393 transistors. So what substitutes can replace them ? Thanks !



					forum.pedalpcb.com


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## Jiuk (Aug 29, 2019)

If you want make your pedal like an original Catalinbread's, you have to choose 500 hfe transitor for Q1 and MPF4393 is must. J201 is NOT.


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## Chuck D. Bones (Aug 30, 2019)

The JFET gain stages are mu-followers and are pretty forgiving of FET types because the bias point is set by the resistor string connected to the gate of the upper FET and NOT by Vp.  Most N-channel JFETs will work, however the gains will be different.  There is enough variation between JFETs with the same part number that it's likely that pedal builders cherry-pick their JFETs to obtain the desired drain current and gain.  That being said, MPF4393s are easily obtained in the US.  Try Electronic Goldmine.  They sell a pack of 5 for $5.  That's where I get mine.  Any high-gain, low-noise Si transistor will work for Q1.  We'd be hard-pressed to hear the difference between BC184, BC550 and 2N5089.  I would not use 2N2222 because it is not a low-noise transistor.


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## Flipguitarist (Aug 30, 2019)

Chuck D. Bones said:


> The JFET gain stages are mu-followers and are pretty forgiving of FET types because the bias point is set by the resistor string connected to the gate of the upper FET and NOT by Vp.  Most N-channel JFETs will work.  That being said, MPF4393s are easily obtained in the US.  Try Electronic Goldmine.  They sell a pack of 5 for $5.  That's where I get mine.  Any high-gain, low-noise Si transistor will work for Q1.  We'd be hard-pressed to hear the difference between BC184, BC550 and 2N5089.  I would not use 2N2222 because it is not a low-noise transistor.


Thanks a lot once again! Will update once complete.


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## zgrav (Aug 30, 2019)

Electronic Goldmine is not showing any MPF4393s in stock right now, but that no doubt changes over time.


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## Flipguitarist (Aug 30, 2019)

Finished it with j201 and 2n2222. Not bad. This is version one I’ll build the other one with the right parts. But this one ain’t too bad. No issues whatsoever and fired up no problem. I’m happy ?.


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## Nostradoomus (Aug 30, 2019)

Theres definitely something special about 4393s in catalinbread circuits! The SMD versions are still plentiful if you’re ok soldering those tiny things.


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## Flipguitarist (Aug 31, 2019)

Nostradoomus said:


> Theres definitely something special about 4393s in catalinbread circuits! The SMD versions are still plentiful if you’re ok soldering those tiny things.


Oooohhh I don’t know how. I can try though. Link me where to get them? Thanks.


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## Nostradoomus (Aug 31, 2019)

https://shop.pedalparts.co.uk/PN4393_N-Channel_JFET/p847124_17055653.aspx Fuzzdog has some PN4393s as well if you dont want to bother haha. But if you want to try just search for MMBF4393 at mouser or DigiKey etc, you’ll need an Adapter board too but pedalpcb has those.


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## Chuck D. Bones (Aug 31, 2019)

zgrav said:


> Electronic Goldmine is not showing any MPF4393s in stock right now, but that no doubt changes over time.



Bummer.  EG deals in surplus, so not surprising that they eventually ran out.  Glad I bought some spares.


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## Flipguitarist (Aug 31, 2019)

Nostradoomus said:


> https://shop.pedalparts.co.uk/PN4393_N-Channel_JFET/p847124_17055653.aspx Fuzzdog has some PN4393s as well if you dont want to bother haha. But if you want to try just search for MMBF4393 at mouser or DigiKey etc, you’ll need an Adapter board too but pedalpcb has those.




How about these?


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## Chuck D. Bones (Aug 31, 2019)

Personally, I don't like SMTs.  You need a very good iron, a good magnifier (microscope preferred) and excellent solder skills to hand-assemble SMTs.  Mouser has PN4393s in stock for $1.13 ea.  Same electrical specs as MPF4393 and best of all, thru-hole!  That's what I recommend.


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## Robert (Aug 31, 2019)

I believe most folks are using PN4393 like Chuck mentioned, that's the one I've been recommending as well.


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## Nostradoomus (Aug 31, 2019)

Oh yeah those little buggers are last resort material haha. I’ve had to do it for 5457s because I’m not paying 5 bucks a pop or whatever it is for proper working ones.


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## Flipguitarist (Sep 3, 2019)

Nostradoomus said:


> Oh yeah those little buggers are last resort material haha. I’ve had to do it for 5457s because I’m not paying 5 bucks a pop or whatever it is for proper working ones.


So how did you go about installing them through hole without an adapter?


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## Nostradoomus (Sep 3, 2019)

I used an adapter board.


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## Flipguitarist (Sep 4, 2019)

So this is weird. I just finished the other pedal with bc184 and pn4393’s and it’s noisy compared to the one with 2n222 and j201’s. Used box capacitors on the new one too. The first one I built sounds better to my ears and not noisy using single coils. Anyone?


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## Nostradoomus (Sep 4, 2019)

Which is which in the photos?


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## Flipguitarist (Sep 5, 2019)

Ok I caught a capacitor installed wrong, removed and installed a fresh one the right way. Worked for a few minutes. Now no distortion and I hear crackles.


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## Flipguitarist (Sep 5, 2019)

Nostradoomus said:


> Which is which in the photos?


New one is with box capacitors.


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## Chuck D. Bones (Sep 5, 2019)

Can we see photos of the other side of the board?  Some of the solder joints don't look too good from the component side.


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## Flipguitarist (Sep 5, 2019)

Chuck D. Bones said:


> Can we see photos of the other side of the board?  Some of the solder joints don't look too good from the component side.


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## Nostradoomus (Sep 5, 2019)

Jeebus get a bottle of 99% isopropyl alcohol and a toothbrush stat!


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## Chuck D. Bones (Sep 5, 2019)

Indeed!  And reflow those solder joints.  Then inspect with high magnification and repeat as necessary.


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## Flipguitarist (Sep 5, 2019)

Chuck D. Bones said:


> Indeed!  And reflow those solder joints.  Then inspect with high magnification and repeat as necessary.


I did a reflow. I know I know I should’ve cleaned before posting. Anyway, same problem. What and how should I do to diagnose it? I have a digital multimeter from harbor freight. Thanks a lot to all of you.


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