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Reducing Gain in minibooster stages

6/26/2000 5:24 PM
Matthew Springer
Reducing Gain in minibooster stages
So I got the entire Booster2.5 breadboarded out over the weekend and I am curious how I can reduce the in the first stage. It seems that the MB has way too much gain to be used in a bypass state since it would be too tough too match levels with tthe bypass mode.  
Any ideas?  
Ideally, I'd like to use on of these stages as a clean buffer but and tap off the Booster2.5 after the first stage to drive the clean side of the pedal board and use the subseuent gain stages to drive the dirty side.  
Sounds fantastic BTW. I haven;t gotten both stages up yet as I get some wild coupling between the first and second stages giving lots of oscillations.
6/26/2000 6:25 PM

Either adjust the resistor from the first Mini-Booster source leg to ground (bottom FET's source leg to ground) or voltage divide before hitting the first Mini-Booster.  
Try the source resistor first. Put a 1K to 10K there - or better yet, a trimmer.
6/26/2000 10:29 PM
Matthew Springer

I'm wondering if it wouldn't also be good just to throw a 100k resistor as the load of the first stage and use a purely resistive load as oppossed to an active load JFET.  
It's not so much reducing the gain I'm after as getting a little less clipping so I can use it as a pure buffer.  
I must say Aron, this pedal rocks!! It's got a lot of upper mids without being whinney and annoying. I can wait to hear what it sounds like with the second stage up and running. I had some severe oscillations getting the second stage up on the breadboard, but I think I had a wiring fault or needed to decouple the supply rail lines of the two stages with a 10 ohm resistor or something.
6/26/2000 10:46 PM

Just as easy would be to just leave the pedal as written and use another JFET booster stage to switch between.  
If you use R.G.'s board, there is no oscillation - it works fine.

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