For JFET addicts

[RobA]

http://www.mouser.com/ProductDetail/Fairchild-Semiconductor/FJN598JCBU/?qs=sGAEpiMZZMv4z0HnGdrLjpo3FY8YkyPv%2foI%252b0yg3vWo%3d

I came across this through hole audio JFET, FJN598JC,  when looking around at Mouser. It's got decent specs for audio. It is end-of-lifed like every other through hole JFET. But, they've got 7000 of them in stock. I ordered a few and I think they are pretty nice. They work well for source follower buffers and overdrive nicely in tube simulation settings. The have an SGD pinout.

[culturejam]

The specs track fairly well close to 2N5457. But the pinout difference will mean a hassle when it comes time to solder them into a board that uses the more "standard" DIY FETs.

Good eye on that. 

[RobA]

Yeah, the SGD pinout would be a pain in most existing boards for pedals. But, they are cheap enough compared to most FET's now that it could be worth the hassle. I've been laying out the boards I do with JFET's on them using a part I made that is pinned out as DSGD with the two drain pins tied together so I can fit any type of JFET in it. It works pretty well.

[culturejam]

What I like about the different pinout is that it is the the same as most BJT trannies (base/gate) in the middle.

So have you personally tested these in a pedal build?

[midwayfair]

What I like about the different pinout is that it is the the same as most BJT trannies (base/gate) in the middle.

And as long as there's a pulldown base bias resistor, you can ditch the negative feedback base-collector resistor and plug them right into a BJT design. Fun!

[RobA]

What I like about the different pinout is that it is the the same as most BJT trannies (base/gate) in the middle.

So have you personally tested these in a pedal build?

Yeah, I'm working on the last stages of a the layout for a microcontroller based trem pedal right now that I've put these in as an input buffer. The design was setup so that it can take these, 2SK117, J201, etc and BJT's. Just change the biasing resistors and plug the right transistor in to the right holes and it works.

Other than that, I've used these in a preamp that I'm building for a Godin ACS nylon string and they are working well there. I'm not sure if I'll use these or the 2SK117's for this though. I've also breadboarded some JFET based amp sims similar to the runoffgroove ideas. In this setting, they seemed to have more in common with the J201. I was comparing the whole set off JFET's in the circuit, J201, 2N5458, 2N5457, 2SK117, 2SK30, MPF102, etc. I liked the way the FJN598JC's worked in high gain, overdriven positions. I thought they distorted nicely.

[culturejam]

Awesome, thanks!

[culturejam]

Got my batch in yesterday. I'll see about testing them out over the next couple weeks. I'll probably end up doing a layout just for these. 

[RobA]

I hope you like them then. I haven't tried them as a variable resistor yet. I should breadboard an Orange Squeezer and see how they work there.