2n5457's in minibooster circuits?

[Ed G.]

Has anyone tried alternative FETs in dual-minibooster circuits, specifically the BSIAB? I'm trying to reduce intermod on an updated BSIAB, and I wondered if the 2N5457 had better tone. I realize there's less gain, and that's OK with me.

[petemoore]

I'm a couple J201's short of having todays BSIAB build...it's working with some MPF102's, to fiil the gap, but upon swapping, I know the last two J201's will light it up more.
 Why not try some different Jfet types for a while...I would...I've had good 'Jfet' results using J201's, and many circuits call for them.
 J202's are a little higher gain I understand.
 Gotta get smore Jfets...

[Lonestarjohnny]

Ed, What I've been doing is Socketing my Bias resistor's and Tone cap's along with the Transistor's, I've been finding different combination's that sound better for what I want to hear out of my guitars, I've found on the boosters I've built so for, I like a little less gain, it really make's the signal cleaner for me and I still get the boost I want.
JD

[will]

Hi Ed,

Has anyone tried alternative FETs in dual-minibooster circuits, specifically the BSIAB? I'm trying to reduce intermod on an updated BSIAB, and I wondered if the 2N5457 had better tone. I realize there's less gain, and that's OK with me.

I have used 2N5457 in a minibooster they sound great.  I suspect the top FET can be replaced with a Mosfet like a bs170 or 2N7000 with no change in sound. The bottom FET determines the sound. The top transistor is really a current source so just about any n channel transistor should work. It's used to maximize the gain of the bottom FET.

Regards,
Will

[Ed G.]

Hi Ed,
I have used 2N5457 in a minibooster they sound great.  I suspect the top FET can be replaced with a Mosfet like a bs170 or 2N7000 with no change in sound. The bottom FET determines the sound. The top transistor is really a current source so just about any n channel transistor should work. It's used to maximize the gain of the bottom FET.

Regards,
Will

The main thing I'm wondering about is getting a 'tighter' sound, kind of clearer, when riffing on the neck pickup, it sounds a little murky. I was considering raising the source resistor on the bottom device and using a bypass cap to accentuate the higher frequencies, but havent' gotten around to it yet. I can't get any 2N5457's around here, I have to order some, so that's why I ask. Otherwise, I'd just pop in it, the circuit is on a breadboard right now.

[Lonestarjohnny]

I've tried the mpf's on 2 project's,  just got some 2n5457's in but have not used them, how much of a tone differation do you hear in them ED ?
JD

[Ed G.]

I believe the 57's should be higher in gain than the mpf102's, but less than the J201's.
I know I could tighten up the sound if I ran the pedal at 18V, but I like the convenience of 9V, so I'm going to keep plugging away at it.

[Jered]

Hi Ed, the 5457's might just be what you need, they are clearer, almost a little bright, but that might just be lack of gain.
Jered

[Gringo]

I compared a 2n5457 with a mpf102 side by side(dpdt switch for instant change) in a peppermill gainstage, and to my ears the gain and volume is quite even, with the mpf102 sounding a tad brighter. Same results using bf245's (they sound similar to the 2n5457).

I don't know how would they behave in a miniboost stage, gotta try that one on the board.

Hope this helps