# Substitutes for MPF4393 ?



## P51994

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


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## music6000

Look for Central Semi *PN4393.*
That is what I used for the Sabbath Distortion.


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## temol

Some people recommend 2N5457
You can buy MPF4393 on ebay


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## music6000

A chap at tagboardeffects  built the Sabbath vero version & tried J201, 2N5457, 2n5484 &* PN4393*.
He said they all worked but the* PN4393 *had the least Background Noise which is what I found.
There are 5 in that Circuit.


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## geargasstore

Hi,

Try here: https://www.mouser.com/ProductDetai...GAEpiMZZMuw1rG4%2BG7fpo0gMEgViPlHQXxsNV2UI18=

I just wish they weren't so expensive 

Thanks
Ernie


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## Chuck D. Bones

Electronics Goldmine has MPF4393, packet of 5 for $5.  That's where I got the ones in my Covert OD.


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## music6000

Chuck D. Bones said:


> Electronics Goldmine has MPF4393, packet of 5 for $5.  That's where I got the ones in my Covert OD.


Cool, Here's the Link :








						G21484 -
					






					www.goldmine-elec-products.com


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## mywmyw

music6000 said:


> A chap at tagboardeffects  built the Sabbath vero version & tried J201, 2N5457, 2n5484 &* PN4393*.
> He said they all worked but the* PN4393 *had the least Background Noise which is what I found.
> There are 5 in that Circuit.




Is the pin orientation the same?


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## Chuck D. Bones

Yes pinout for MPF4393 & PN4393 are the same.  When selecting low-noise FETs, devices with higher Idss and lower Rds,on are lower noise, all other things being equal.  However, we have to be mindful of Vgs,off because if we install a device with Vgs,off different from the one that the designer selected, then we may need to tweak the bias by changing the source or drain resistor.  I attached the MPF4393 & PN4393 datasheets for your reference.


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## mywmyw

Thanks for that. I tried substituting a 2n4393 from Tayda, was mindful of the pinout but still I get no sound on my DLS MK3 / covert OD build. Think I'll try this instead


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## Chuck D. Bones

2N4393 should have worked.  Maybe recheck the pinout.  If you still need help, try posting in the troubleshooting forum.  The first thing I'll ask is for you to measure the source voltages on Q2, Q4 & Q5.  They should all be around 5.5V, ±1V.


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## mywmyw

I'll do that and post pics etc soon. From what I read it should have worked fine crossing one of the legs over, so I was pretty disappointed. I guess it's also possible one of the legs is shorting out, even though I slipped heat shrink over them. I appreciate your help.


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## mywmyw

well it turns out there is a ground issue, not an issue with the Jfets... doh


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## Chuck D. Bones

They look and behave like the real deal.  Vp & gm are within spec.  Solderability is good.  Date code on all of the ones I've bought is 942, so they were probably made in September 1989.  I've used them in the Covert, BJFE Pink Purple Deluxe & ROG Double-D.  They work great.  Not everything at EG is a good deal, but there are plenty of good deals to be found.  Best way to find them is to get on their mailing list.  I bought 50 1N5817s for $4 and 500 FDH400 Si signal diodes for $7. Only complaint I have with them is sometimes they are slow to ship.


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## jejackson5

temol said:


> Some people recommend 2N5457
> You can buy MPF4393 on ebay


I tried this myself but not getting any sound. Is the orientation the same as the mpf4393? How would I verify that?


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## Harry Klippton

MPF4393 JFET, TO-92
					

The MPF4393 is an N-channel JFET, most notable within the DIY community for being the primary JFET used in Catalinbread® pedals from 2013 onward.




					aionfx.com
				




Aion sells them


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## carlinb17

Here are some 2n5457s there pricey but they have them.



			Pedalhacker Audio Grade Guitar Effect Pedal Electronic Components


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## Chuck D. Bones

2N5457 and MPF4393 have the same pinout.

Nothing special about MPF4393 except Catalinbread was designing them into their pedals when the MPF4393 was still in production.  You can buy legit PN4393 from Mouser, $1.17 ea in quantities of 10.  Don't risk your money on eBay when you can buy the real-deal from a trusted supplier.

Most JFETs will work as subs for other JFETs provide their Vp and/or Idss are in the right range.  The spec ranges between part numbers tend to overlap.  Some circuits are very picky.  Having the right part number is no guarantee a JFET will work in a given pedal circuit.


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