Blues Driver Mods

[smallstonefan]

Hi all,

First, let me apologize if this isn't the right place to discuss mods...

I recently picked up a Boss BD-2 Blues Driver. Dang, what a sleeper! I'm not really into the blues, so I guess I've overlooked this pedal for years.

I really like this pedal, and I'm interested in performing some of the mods I've been hearing about. I found some info on Robert Keeley's page, but I was wondering if anyone knows of a site with more details on the mods for this pedal.

For example, does C1, C7, C6, C12, C13, and C15 ALL get replaced with a 10uF cap, or do the values differ for each cap? Also, I hear that silver mica caps should be used, but I'm not sure where or what values. The instructions I've found so far state (from Robert's site):

D3 Change this 1SS133 to a different (1N4002) diode for asymmetrical clipping. This adds second order harmonics. This adds to the tube type sound. I like the sound of this change.

D7 D8 D9 and D10 Change 2 of of these diodes from 1SS133 to a single 1N4002. More second order harmonic distortion. Although the change is slight, I like it. We actually take out one of the two pairs and replace it with a single 1N4001.

C1, C7, C6, C12, C13, and C15 Change this electrolytic capacitor to a 10uF tantalum. Tantalum capacitors sound better than electrolytic capacitors. I like these anywhere there is signal coupling at this high a value. Tantalum capacitors are easy to find in this range.

C14 Increase input coupling capacitor value to 0.1uF for increased bass response from your guitar.

C100 Here is where we can affect the tone control. I prefer a little more lower-midrange and bass frequencies through the tone section. You can increase the lower frequencies by increasing the capacitor value to 0.033uF. Install a switch to add a 0.068uF cap in parallel with this value for the Phat Mode!

All ceramic caps changed to Expensive Silver Mica

Thanks for any assistance you can provide,

[23]

Seems like overdrivespider might have done the BD also, I know he did the seeing eye mod and ultra mod for the DS-1... search for overdrivespider and see what come up, cant remember the exact site...hope this helps.....later

[Vaum]

Here's what I did to my Blues Driver, probably a few "stupid" modifications but whatever works, right? Really great sound for my needs.

C100: .033uf
C101: .022uf
C36: .01uF
C35: .047uF
C34: .44uF
C14: .1uF
C17: .01uF
C19: .0047uF
C8: .33uF
C9: Removed

D1: 1N60
D3: 1N4002

D7: 1N60
D8: 1N4148
D9: 1N4148
D10: 1N4148
100pF Silver Mica across diodes

Q9: 2N1303 Germanium
Q12: 2N1303 Germanium

R51: 50K pot (under footswitch to adjust mids for different amps)
R34: 4.7K
R26: 3.1K

Don't know the hFE of the germaniums, must be fairly high, drive actually increased when I swapped them for the stock PNPs.

[JDoyle]

Don't know the hFE of the germaniums, must be fairly high, drive actually increased when I swapped them for the stock PNPs.

Actually, most likely the drive increased because they have a LOWER hFE than the originals. Weird, yes, but true. Because of negative feedback, the higher the overall gain (differential amplifier input gain + output transistor gain) the CLEANER the output due to the restorative/corrective effects of negative feedback. If you lower the gain, there isn't as much gain to 'correct' the amplifier, and the drive and distortion actually INCREASE.

It's the negative feedback that flips the logic here.

Remember that the pair that share the emitter resistor make up the input to a discrete op amp and the germaniums your subbed make up the output stage. Those three transistors make up a dumbed down and limited (though really good for our purposes) op amp.

Regards,

Jay Doyle