Boss Blues Driver Mod Question

[mcasey1]

I opened up my Blues Driver and followed the mod recommendations here:

http://www.freestompboxes.org/viewtopic.php?f=11&t=1062

Hi there,
I´ve been watchin this forum quite a long time to "learn" something bout modding pedals. I got infected by a Keeley DS1, which I bought used, 2 years ago.
I´ve bought the Monte Allums mod, to get an idea of modding the BD-2 and found the following description in a forum at "ultimate-guitar.com". So I played around with the Allums mod and the "ultimate-guitar" one, changed some diodes (I never thought, that 2, 3 or 4 parts could change a sound as much, as the diodes do

Here´s the description:

I am back once again to improve your stock Boss crap

This time a Boss Blues Driver it my bench. First impressions... No blues player would ever need the gain this unit puts out. Even the minimum gain was blowing my head off. This pedal was also a shrill dill, couldn't use the tone control at all, way too piercing. There was also fuzziness and crap when the gain control went past noon. One thing I was impressed by was the bypass system (all Boss pedals use the same elec switching). Though not true bypass it's still quite good, I could hardly notice the difference when I tested it using my looper pedal.

Anyways I like bright clear tones and fat tones. I am not a huge fan of gain. With this is mind I started modding the pedal.

I started with Robert Keeley's mod and went from there... I didn't like his mod but that's neither here nor there. If he modded the pedal like I did he would spend way too much time on an individual pedal... Anyways that being said I like my moddded tone better

A hint for removing Boss' industrial lead free (RoHs) solder... First heat up the joint so the solder melts, then heat again and apply a bit of your own lead (60/40 or whatever) solder. After this go about removing the solder with your desoldering braid or pump. I was quite proud of myself when I found this little trick out.

Here's what went down...
R21: 2.7K (contour control almost, you could replace a 5K pot. Tames tone pot)
R34: 5.6K (lowers gain)
R38: 220K (lowers gain)

C8: 0.0047mF
C14: 0.1mF (input cap, better start beefing up the tone from the start)
C16: 0.01mF
C17, C19: 0.01mF
C18: 0.01mF (use a good quality cap)
C19: I didn't touch this cap but for a mid boost remove this cap. More mids, more gain.
C27: 0.01mF
C34: 0.082mF
C35: 0.047mF
C100: 0.047mF

C101: This cap plays a huge part in the tone of this pedal. Look at the schematic and you'll see why... Anyways I have a SPDT switch on C101 to select between a MKT 0.033mF and a MKT 0.068mF cap. Fat switch! I am a sucker for fat tones and this switch delivers.

D3: 1N4002 (adding second order harmonics)
D6, D8, D9, D10: 3mm red LEDs (I like water clear high brightness) These are clipping diodes. LEDs make the pedal fatter, tighter and more compressed. I also find they add some dynamics to the pedal. They also clip much less than a standard diode so more headroom!

The next part of the mod is what I would call a Hi-Fi mod. No values of parts are changes. Instead the material (mainly the di-electric) of the capacitors is changed to a nicer better sounding material. Some cheap ceramic and electro caps but don't worry they aren't in the signal path. Don't cheap out here and not do this part of the mod. Without this part I seriously doubt the pedal would sound so good. It may not be the most interesting part of the modifications but it's worth it.

Use all Silver Mica caps here.
C26: 220pF
C21, C23: 47pF
C20, C25: 470pF

Use tantalum capacitors here
C1, C6, C7, C12, C13, C15: 10mF (16V or higher)

This part of the mod is great. All the fuzz and fizzeyness when the gain control was turned up was gone. Clarity was increased and the pedal had more dynamics and felt like it responded better to my playing.

It's a pretty extensive mod but well worth it. If you were only going to do some parts of it I would recommend the Hi-Fi part and playing with C14, C100 and C101. Its amazing how a few changes in a capacitors value and some changes to better quality parts can make a difference.

I like a big LED indicator... I use 5mm water clear high brightness LEDs on all my pedals. If you do use a bigger brighter LED change R39 to 3K or around there.


Final impressions of this pedal...
Great pedal accomplished exactly what I wanted. It is nice and clear and warm or with a flick of a switch it is fat and compressed both ways retaining excellent clarity though. The tone control is totally useful now and much more versatile. The gain control is quite useable and I can actually have a low gain sound now.

You can set the gain so low the pedal can be used as a straight up clean boost. It can still do some great crunch/post crunch tones but no more metal. It responds to my touch and feel. I tested this pedal with three different tube amps, one solid state and two guitars and it sounded great with all of them, mission accomplished.

Anyways another cheap pedal turned into a cheap very useable pedal...

I hope someone can put this mod to use.

The BD-2 is now an overdrive, not a fuzz anymore (IMHO).

Regards
a technical newbie  /quote]


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In the description he states that he installed a switch to change between two different capacitors for C101.  He suggests a .033uf and a .068uf.  Which value, lower or higher, will give more "fatness" as he puts it?  A .033 sounds really fat, and is great on the bridge pickup, but completely muddies up the neck position.  I think I will install a switch to compensate, because I love the .033 uf on the bridge, but need a less bassy tone for the neck.  For the neck position to be brighter, should I go lower than .033uf or higher?

Any help would be greatly appreciated.

Matt

[mcasey1]

I figured it out, just put a .022 cap in and it is less boomy on the neck pickup.  Something else that has happened though, is that when the pedal is bypassed, sometimes the clean sound gets gated and weak.  It comes and goes and when I turn the pedal on and off again it goes away, then comes back a little later.  Im not sure what the cause is.  Any suggestions?

[EATyourGuitar]

sounds like there is some capacitance building up or discharging very slowly. like when you bypass a couple times the cap discharges and its all good. then it charges up again. boss pedals are fet switched right. so start at the switch and probe it for dc changes when you engage and disengage.

[mcasey1]

Think it would be one of the electrolytic or tantalum caps?

[EATyourGuitar]

I would probe it with a dc voltmeter while recreating the problem and the fix. The parts you probe that have no moving voltage are of no interest. When you can figure out what parts of the circuit are affected, you should be able to find the short or break or bad part.

[mcasey1]

I just converted the pedal to true bypass.  Removed the transistors from the flip-flop and installed a 3pdt switch.  No more bypass problems.  New problem is, very little bass note definition on the bridge pickup or neck pickup definition at all.  I don't know if lowering the input cap from .1uf to .oquf would clean it up or if the output cap needs to be lowered, or if there is another cap in this circuit that significantly affects bass content/definition.  Considering that the gain was considerably lowered in the pedal due to the mods, it is strange that I get less bass definition now, and the neck pickup is barely useable.  Lowering input cap from.
.1uf to .05uf didn't seem to clean it up much in the bass register.  Any suggestions?  Much thanks in advance.  I feel like it is a few tweaks away from being a perfect overdrive for me.

[kurtlives]

That's my mod. Hope you like it!

[iiimonfire]

I just happened upon this mod and really like how it's made my Blues Driver usable in virtually any knob configuration! I did catch one bug, and I wanted to report it here in case anyone else tries this. Also, I'm not sure if it's behaved this way for anybody else, but here goes:

I noticed after replacing D6 with a red LED that when turning off the effect, the volume immediately mutes and then ramps back up to normal volume after about 1 second. I was able to reproduce this only the circuit was placed in the enclosure, and when I covered it up with my hand from the lamp at my workbench. After some poking around, I figured out that the LED I had placed at D6 was the culprit. I consulted the schematic and lo and behold, that diode seems to be in the output buffer's signal path, so it makes sense that it was preventing the proper flow of the signal when the effect was disengaged. What was so foreign to me was that I never considered that an LED could behave like an LDR, but a quick Google search seemed to confirm that as well. Science!

So I replaced it with the original diode. I'm guessing the original intention was D7 and not D6 as D7 is connected to the other 3 clipping diodes (D8, D9, D10) at the end of the BD-2's first gain stage. @kurtlives if you're still hanging about these forums, do you want to confirm?