How to reduce gain on BSIAB II

[DWBH]

I have a Bsiab I built last year. Now I'm going to build a FKR, and I don't want 2 distortion pedals. So I was thinking of reducing Bsiab's gain, so that it can be more like an overdrive, and when pushed, reach a slight distortion.
I read something about changing C2 and the J201... but what do you guys have to say?

oh, and i used GGG layout and pcb.

EDIT: and what does the trimmer do?

[Bucksears]

Don't want TWO distortion pedals??     BLASPHEMER!!!!!!!

Just kidding

How about just turning the gain down? If that's not enough for you, you could use MPF102's for Q1/Q2. That'll really drop the gain down.
To be honest, if that still doesn't do it, then maybe the BSIAB II isn't what you're looking for. For me, it's just an added bonus that I can dial the gain back for a nice Santana-esque, jazzy overdrive, then turn it up for Marshall burn.

While I think the BSIAB II using the stock transistor selections has PLENTY of gain for early VH/classic rock/80's metal, it's also the best low-gain overdrive that I've used, which is why I'm building one with two gain controls and a boost.
I'm looking at using a toggle for C2 to get an alternate selection with more upper mids.
But, peoples' tastes vary.
- Buck

[MikeH]

I just counted.  I own 14 distortion pedals... I think I might have a problem.

I don't have a schematic but, I believe this is a cascading transistor/FET type design?  The only thing I could think of would be to work in some resistor networks to limit the amount of signal going into each gainstage, in order to make them drive less.

[yertle]

J201's have alot of gain so switching to 2n5457 or mpf102 will get you less gain, you could also try to take away the bypass caps at the first gain stage but maybe that will mess with the voicing of the pedal.

[PaulC]

Those mu follower stages can be clipped with just a hot pickup.  It's easy to clip the input stage without any type of gain control (other than your guitar volume).  You might try putting a gain control on the front end so you can set it to kick in with the pedal instead of turning down your guitar volume the same time you step on the pedal.  Or you can change the input stage to something that can take a hotter input, and give less output to add headroom and reduce gain.  Something like the fetzer valve would work nice.

Later, PaulC
Heritage amps/Tim & timmy pedals

[Bucksears]

Sorry, forgot,
The trim pot is a bias adjuster (IIRC) for Q5. Max out the distortion and tune it by ear to its loudest setting.

- Buck

[John Lyons]

Type in BSIABII and there are a few threads about gain reduction.
Try 2N5457s for all the transistors and you should be fine.

John

[Ed G.]

The BSIABII does get good lower gain sounds, but replacing the J201s with 2n5457s might get you closer to what you are looking for as basicaudio said.
A larger resistor on the source of the 'bottom' fets like Q1 and Q3 will reduce gain but also likely change frequency response. Play around with those values. The source of Q1 is bypassed with a cap so those frequencies won't be changed.
You really have to get in there and start tweaking by ear, which is what I did. Adjusting one thing sometimes requires adjusting something else for balance.
But first I'd just try swapping out the fets. I really like J113s for lower gain sounds, but not all of them sound good. I think the Fairchilds sound OK. The National Semis sound good but are not available anymore.

[DWBH]

I'm getting some MPF102's and some 2N5457's and some trans sockets so I can swap them and see which one I like the most.