BSIAB Gain q

[jimmy]

hi everyone

just finished buiding a brown sound in a box from GGG, after listening to the soundclip at diyguitarist.com. it worked after a few bugs were ironed out (i had two seperate ground points, and two components hadnt even been soldered together  :? )

end result - an overdrive pedal! problem is, it has very little gain. id say just less than a tube screamer, much different from the soundclip.

now ill put this down to the fact that i used MPF102s instead of the ever-evasive J201s. ive read the J201s are higher gain, but is there that much of a difference?!?!

if this is the case, any tips on how to supercharge it up to a higher gain beast? only idea i had was sticking bypass caps on the bottom fet in the minibooster stages. will that work?

cheers
Jim

P.S. also built Fetzer Valve - ROG strikes again! great work guys!

[Eric H]

now ill put this down to the fact that i used MPF102s instead of the ever-evasive J201s. ive read the J201s are higher gain, but is there that much of a difference?!?!

In general, yes. If you want to hear this effect the way it was designed --get j201's.

if this is the case, any tips on how to supercharge it up to a higher gain beast? only idea i had was sticking bypass caps on the bottom fet in the minibooster stages. will that work?

Yes, and you have a golden opportunity to learn something, too.  Try different sizes of bypass caps (,01uf to 22uf) to vary the bass content.  You can also add 100k (or so) trimpots wired as variable resistors inline with those caps to vary the gain.  You can lower the resistance (or remove completely) the 470k/470p between the boosters. Lower the value of the 100k going into the buffer.  Try one thing at a time, and have fun (get j201's)

-Eric

[petemoore]

And If I do, check GEO 'create your own Mu Amp'.
 That said, IIRC it's a 1k resistor between the bottom jfet's D and top Jfet's S that improves impedance and gain.

[jimmy]

thanks guys!

cheers
Jim

[YouAre]

Its a huge damn difference. I changed one of the j201's to what you had, just ONE out of the five, and i saw a considerable difference.

[Gringo]

if this is the case, any tips on how to supercharge it up to a higher gain beast? only idea i had was sticking bypass caps on the bottom fet in the minibooster stages. will that work?

Take a look at this too:

http://www.diystompboxes.com/sboxforum/viewtopic.php?t=21299&highlight=mpf102+supercharge

Hope it helps.