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,

[Arn C.]

Smallstonefan(me too!)
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?    It appears that all of these caps listed are replaced by 10uF tantalums.

Also, I hear that silver mica caps should be used, but I'm not sure where or what values.
All ceramic caps changed to Expensive Silver Mica

I have the schematic in pdf form, it has all the values and the letter/number of each component.
Arn C.

[smallstonefan]

>>> Smallstonefan(me too!)

Sweet!   I have an original Small Stone. I transplanted it to a metal case with true bypass an an LED. I had a friend who makes custom pedals (Antech) add a gain circuit. It's switchable, so I can turn it off (stock) or boost it to get unity gain. I absolutely adore this pedal.

Anyway, now I'm digressing...

>>> I have the schematic in pdf form, it has all the values and the letter/number of each component.

Is this something you'd be willing to share? I think that would help tremendously! I've seen one hand-drawn schematic, but it didn't list the letter/number combination.

Thanks for the quick response (and for the confirmation on the tantalum caps) - I really do appreciate it!

[Arn C.]

Email me and I will send it to you!
Did you check out the mods you can do with the smallstone?
Arn C.

[LH]

Is it just me or does anyone else find this confusing:

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.

In the first sentence, Keeley says to replace either the D7/D8 pair or the D9/D10 pair with a single 1N4002. Then at the end, Keeley says he takes out one of the pairs and replaces it with a single 1N4001. Isn't he saying the same thing twice (but using different diodes)?

[LH]

Email me and I will send it to you!
Did you check out the mods you can do with the smallstone?
Arn C.

Arn,

Is your PDF schematic the same as

http://www.generalguitargadgets.com/v2/boss/BossBD-2.gif

or is the writing more legible?

[smallstonefan]

I agree. I know that he posts the specs as general info about what he does, not step-by-step instructions. But still, they're not all that clear...

[John G]

Smallstonefan
I have done the Kelley mods, plus several of my own, if you are interested.
John G

[smallstonefan]

Smallstonefan
I have done the Kelley mods, plus several of my own, if you are interested.
John G

Heck ya, I'm interested!

Any advice or info? I guess here are the main questions I have:

1. Was it worth it?
2. He lists using 10uF caps in about 6 different places. The current caps have various values. Do they all get replaced with the 10uF tantalum cap?
3. He mentions replacing all ceramic caps with sliver mica. I assume that this is all of the caps that aren't replaced with the tantalum? Do the replacements have to match the original values, or is there some 'special' value for them?
4. Can you clarify the diode issue brought up earlier?

I really appreciate you chiming in. I picked up the BD2 on a whim, and I think it's almost exactly what I've been hunting for! The idea of improving (plus the fact I love to use my soldering iron ) just make this too tempting to pass up!

[javacody]

He only says to replace electrolytics with tant and to replace the ceramics with silver mica, I'm guessing you would leave all of the other caps alone.

[Ansil]

zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz

the dreaded double post sleep

[smallstonefan]

zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz

the dreaded double post sleep

Why are some of my posts getting double-posted - any ideas?

[smallstonefan]

He only says to replace electrolytics with tant and to replace the ceramics with silver mica, I'm guessing you would leave all of the other caps alone.

Ah, this is probably where my ignorance comes into play: How can you tell which cap is ceramic and which isn't?

Thanks,

[Ansil]

ceramics are usually brown. and flat.. electrolytics are metal.   poly films are film

[javacody]

poly films are usually coated in plastic and look kinda like a chiclet. Ceramic are flat and round and usually pretty small. Electrolytics look kinda like a soda can.

[John G]

Smallstonefan,
First of all you will need the official boss schematic BD-2.  The previous repliers have hit the nail on the head only replace the 10 uF caps with the tantalms.  Similiarily the round brown shaped ceramic caps are replaced by the expensive silvered micas.  
My interpretation for the diode replacements is as follows - take out D6/D7 and replace with a single power diode (1N4001/1N4002) and the same for diode D3 replace with a single power diode.  
The diode orientation remains the same.  This gives the so called asyametrical clipping.  I found these modifications gave a slight overall clearer presence and the grainy gritty sound was reduced.  I found even after the mods the pedal to be way too bright so I removed C17 altogether.  The additional mods I developed are as follows;
Mod 1 - Do the Keeley mods, bridge R51 with a 22K Ohm resistor this has the effect of bumping up the bass and reducing mids and highs, remove C17.  The downside of this mod was that when using the neck pickup of a Strat the bass can become muddy.  The second mod which I prefer entails doing the Keeley mods, C17 is removed, R51 restored, C100 39nF - 47nF and placing a Ge diode across D1.  This gives the pedal a new sound more akin to an OD and now has a nice percussive edge when picking notes. Adjust C100 for suitable bass.  
Hope this is of some help,
John G

[smallstonefan]

ceramics are usually brown. and flat.. electrolytics are metal.   poly films are film

Thanks! This will help me a lot.

Oh, and Mary Jane on Christmas morning!  :shock: I thought that was for after the kids when to bed?  :wink:

[smallstonefan]

First of all you will need the official boss schematic BD-2.  The previous repliers have hit the nail on the head only replace the 10 uF caps with the tantalms.

Ah, so the 5 or 6 mentioned by Keeley all get replaced with 10uF. Got it.

Similiarily the round brown shaped ceramic caps are replaced by the expensive silvered micas.

OK, so I need to look at the guts of the pedal, identify the ceramic caps, look to the schematic to find their values, and order the exact replacement value for each ceramic cap. Got it.

My interpretation for the diode replacements is as follows - take out D6/D7 and replace with a single power diode (1N4001/1N4002) and the same for diode D3 replace with a single power diode.

Easy enough. Does it make much difference in sound if you use a 1N4001 or 1N4402?

The diode orientation remains the same.  This gives the so called asyametrical clipping.  I found these modifications gave a slight overall clearer presence and the grainy gritty sound was reduced.  I found even after the mods the pedal to be way too bright so I removed C17 altogether.

Very interesting! I'll will try this if the pedal sounds too bright.

The additional mods I developed are as follows;
Mod 1 - Do the Keeley mods, bridge R51 with a 22K Ohm resistor this has the effect of bumping up the bass and reducing mids and highs, remove C17.  The downside of this mod was that when using the neck pickup of a Strat the bass can become muddy.  The second mod which I prefer entails doing the Keeley mods, C17 is removed, R51 restored, C100 39nF - 47nF and placing a Ge diode across D1.  This gives the pedal a new sound more akin to an OD and now has a nice percussive edge when picking notes. Adjust C100 for suitable bass.  
Hope this is of some help

This is of a LOT of help - I can't thank you enough! I'll probably try the C17 change, but I don't think I want to change the overall character more like an OD, so I might skip the last mod. Not sure yet! I really love this pedal, and in some ways I'm hesistant to even change it. But then again, I've heard NOTHING but good things about the mod, so...

Thanks to all that have helped/are helping - you guys are great!

[smallstonefan]

PS I think I found what's causing the double-post. Sometimes, when I click Preview, it comes up with an error and then posts to the page anyway - without me doing anything...

[John G]

James,
I believe any of the 1Nxxxx series of POWER diodes will do the trick. Don't discount placing the Germanium diode across D1, all you do is tack solder it to the back of the board for trialing, and if you like it install it, if not then remove it and no harm done. When ever I need to reduce a value of resistor that is already installed I bridge it with a value as calulated by Ohms law (parallal resistance)to give the desired value. This is quick and easy and helps preserve the PC board.
John G