Experimenting with a Boss BD-2

[Andy73]

I have a BD-2 that I would like to have less drive.  It seems to be very 'grainy' or 'splattery'   and I'm not hearing too many harmonics.  I tried playing with the clipping diodes D7 - D10 for asymmetry as well as removing them altogether, but none of those changes had much impact on the overall sound.

My ultimate goal here is learning, a good sounding pedal is secondary to me.  So, how can I get less drive in this circuit?  Where can I smooth out the overdrive?

http://www.schematicheaven.com/effects/boss_bd2_bluesdriver.pdf

Most of the overdrive explanation that I could find on the web is for diode clipping.  How about affecting the transistors in some way?  Or change them?

Thanks in advance!

-Andy

[frequencycentral]

I think the BD-2 is basically the same circuit as the Ibanez Tube Screamer - a few component value changes.

There are loads of Screamer mods - do a search fo them!

[n8b]

One place to start is the section immediately following Q9. If you are familiar with classic tube amp tone stacks, then you will know what to do with it. If not, look up Duncan's tone stack emulator and play around a bit. Keeley has some mods listed on his site that are worthwhile. Beyond that, the rest of the pedal is a little over my head, and is definitely not a Tubescreamer.

[wampcat1]

I think the BD-2 is basically the same circuit as the Ibanez Tube Screamer - a few component value changes.

There are loads of Screamer mods - do a search fo them!

no... not so much. Maybe in the idea that it clips the signal via an opamp (though discrete) but not really like a ts at all.

As I noted in my book (http://www.amazon.com/Modify-Effect-Pedals-guitar-bass/dp/1434801063/ref=sr_1_2?ie=UTF8&s=books&qid=1212198834&sr=8-2 ) change c22/r31 as well as c24/r34. You could also just change the dual gang pot to a smaller value, say, 100k or so as well.

There are several different ways to smooth out the gain. One is by making C8 a larger value.

bw

[frequencycentral]

I think the BD-2 is basically the same circuit as the Ibanez Tube Screamer - a few component value changes.

There are loads of Screamer mods - do a search fo them!

no... not so much. Maybe in the idea that it clips the signal via an opamp (though discrete) but not really like a ts at all.

My mistake, I was thinking of the SD-1:

http://users.sa.chariot.net.au/~gmarts/ampovdrv.htm

[blanik]

try replacing D3 with a 3mm LED

[Andy73]

Thanks for all the replies!  That will definitely get my experiment started, hopefully I can learn more along the way!