Boss - BD-2 Blues Driver  [schematic]

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.

Re: Boss - Blues Driver (BD-2)

Postby austinhotmods » 12 Jul 2013, 14:24

New to the forum but a frequent visitor to the site, if I could pick a brain or two that would be a huuuuuge help. I have recently modded my BD-2 with LEDs in the D3, D7, D8, D9 and D10 positions...for some reason when I put the pedal in bypass mode the sound is there and then fizzle out to nothing...pedal works BEAUTIFULLY in on mode...like insanely awesome. just can't wrap my head around this sound fizzling out in bypass situation...anyone got any advice?! :scratch:
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Re: Boss - Blues Driver (BD-2)

Postby Barry » 23 Jul 2013, 23:54

Keith_A wrote:
Barry wrote:
maxzero wrote:
Barry wrote:Anyone familiar with the Machine Head Pedals mod for the BD-2?

Barry

Long overdue bump!


I've since ordered his kit, he paints everything, thank goodness for good multimeters

I don't color code everything - just the capacitors. Since the Galaxie Mod does more than just primarily change caps like many other mods, I needed a way to reduce the chance of the caps getting installed in the wrong locations. There are 7 resistor changes alone, some component slots are left open, one gets replaced with a jumper, some caps are swapped for resistors, and vice-versa. There are 10 capacitor changes, and none are like other mods that typically sub out one dielectric type for another, but of the same value.

The Galaxie Mod restructures the gain throughout the circuit so that all the diode substitution doinking is no longer necessary, as well. In fact, they are eliminated altogether. That should give a basic idea of why it requires a different approach than anything by Allums, Keeley, or the others.

In some ways, you have a different overdrive circuit when the mod is done. It's why the tone control actually becomes usable throughout its sweep. The op amp stage also contributes more than just a mild bass boost when the mod is done.

Just bear in mind that if you are posting the mod here, most people who read it will probably never understand the logic that went into it. So a simple component list will be a complete lack of a learning process. It will make it very easy for errors to occur, or even propagate across the net.

I don't mind the reversing and spreading of the mod so much as I do the the potential for being associated with an erroneous set of instructions. So if/when you post your component values here, please make sure you get them all correct. And if you don't know what a certain part of the mod does, please don't speculate - just say you don't know. Get help from forumites if necessary. I'd appreciate it.



I wanted the values for my own study, you can decide how much of your work you want to share and post here
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Re: Boss - Blues Driver (BD-2)

Postby Keith_A » 24 Jul 2013, 01:24

Barry wrote:I wanted the values for my own study, you can decide how much of your work you want to share and post here

Even though you omitted that you measured the values for your own personal use only, but did finally and clearly reveal that for all to read, I'll hold you to honoring your word.

Thanks for the much needed clarification - I am appreciative.
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Re: Boss - Blues Driver (BD-2)

Postby andymanicy » 26 Jul 2013, 13:36

Hi guys,

Sorry to pitch in after all your efforts, but I just need some advice on what I HOPE is a simple fix!

I love the BD2 stock sound - and am using it through a kit built Fender Princeton, with a DR output tranny, and a 12" Weber 12F150 speaker. The only thing I dislike when engaging the pedal is that it has a shrill top end, and lowering the tone control doesn't help - just tames it a bit whilst removing the other nice qualities.

Is there a simple 'single component' change to sort the tone control out and tame the top end a tad? Any advice would be awesome. I'm so happy with my setup apart from this one annoyance!

Thanks guys,

Andy
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Re: Boss - Blues Driver (BD-2)

Postby smackoj » 27 Jul 2013, 02:11

"The only thing I dislike when engaging the pedal is that it has a shrill top end, and lowering the tone control doesn't help - just tames it a bit whilst removing the other nice qualities.

Is there a simple 'single component' change to sort the tone control out and tame the top end a tad? Any advice would be awesome. I'm so happy with my setup apart from this one annoyance!"

Are you sure it is the BD2 making the noise? Do some trial and error trouble shooting before you go changing a pedal you like "as is" ... just one man's opinion mind you.

smacko jack :mrgreen:
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Re: Boss - Blues Driver (BD-2)

Postby aab0mb » 24 Oct 2013, 18:23

Yep. Gonna bump up this old one because....well...I have some ideas.

At one point I had a bd2 that i had been modding mostly like all the suggestions in this thread. Over at diystomp there was a suggestion to swap the outside lugs of half the dual gang gain pot so that one stage would increase in gain and the other would decrease. Kind of a cool idea....

So i tried all the normal stuff and still had some of the shrill top end and the splat sound that everyone complains about. I had also been looking at the od2 schematic quite a lot and the two pedals have a ton of similarities. Discrete op amps is mostly what i mean.

The od2 has the clipping in the normal section within the feedback loop. More of an overdrive sound that's compressed instead of the clippers to ground in between stages like the bd2. So! Remove diodes to ground and tack them in either feedback loop. I did the first one and used the second stage as makeup gain.

Now let me tell you.... This. Thing. SUNG! There's a LOT of gain to play with so it can get a little over the top but all in all the splat is basically gone. Feedback loop clippers people. Makes it a different pedal, I'll admit, but it retains a LOT of the full range clarity that it's known for. The mod tames the high end a bit and smooths the splat. bottom line. I really hope someone tries this. It's probably one of the most drastic and pleasing mods i've done to ANY pedal and it's relatively easy.

Note: easiest thing to do is use the little 100pf cap in the feedback loop as your tack on point for the diodes. One could make a mini board module to wire in diodes +cap if they chose. Whatever works for neatness as it's kind of a hack to the circuit. Nondestructive however which makes it TOTALLY worth it.
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Re: Boss - Blues Driver (BD-2)

Postby lespauldoc » 27 Nov 2013, 19:41

aab0mb:

i think i'm following you. You wouldn't happen to have a pic?

You're saying just pull the ground of all 4 diodes and put onto the 100pf cap? Doesn't make sense to me (but the change in the feedback loop explanation does). Trying to figure out the practical side of making that work.

thanks!
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Re: Boss - Blues Driver (BD-2)

Postby soupbone » 31 Dec 2013, 12:33

aab0mb wrote:Yep. Gonna bump up this old one because....well...I have some ideas.

At one point I had a bd2 that i had been modding mostly like all the suggestions in this thread. Over at diystomp there was a suggestion to swap the outside lugs of half the dual gang gain pot so that one stage would increase in gain and the other would decrease. Kind of a cool idea....

So i tried all the normal stuff and still had some of the shrill top end and the splat sound that everyone complains about. I had also been looking at the od2 schematic quite a lot and the two pedals have a ton of similarities. Discrete op amps is mostly what i mean.

The od2 has the clipping in the normal section within the feedback loop. More of an overdrive sound that's compressed instead of the clippers to ground in between stages like the bd2. So! Remove diodes to ground and tack them in either feedback loop. I did the first one and used the second stage as makeup gain.

Now let me tell you.... This. Thing. SUNG! There's a LOT of gain to play with so it can get a little over the top but all in all the splat is basically gone. Feedback loop clippers people. Makes it a different pedal, I'll admit, but it retains a LOT of the full range clarity that it's known for. The mod tames the high end a bit and smooths the splat. bottom line. I really hope someone tries this. It's probably one of the most drastic and pleasing mods i've done to ANY pedal and it's relatively easy.

Note: easiest thing to do is use the little 100pf cap in the feedback loop as your tack on point for the diodes. One could make a mini board module to wire in diodes +cap if they chose. Whatever works for neatness as it's kind of a hack to the circuit. Nondestructive however which makes it TOTALLY worth it.

Does this added 100pf cap take the top end shrill away?and if so,where are you tacking on this cap?(I've had the same problems with the OS-2,and the Blues Driver.) I wonder if this idea would work for those pedals too?Thanks!
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Re: Boss - Blues Driver (BD-2)

Postby astrobass » 12 Jan 2014, 21:09

The cap would go from the output to the inverting input on the op amp. Same as the diodes in the mod described there. I'm not 100% on what you're referring to as shrillness, but a cap like that will smooth the clipping, making the distortion less harsh.

Shrillness usually implies over-emphasis on the highs and is an EQing problem rather than a clipping method problem, so this may not address your issues, or it might. Depends on what you mean. If you have a really bright amp, harsh clipping can come off as shrill sounding.

Anyhow, any cap between 47p and 100p should actually work pretty good. You'll get a sweeter, more singing response from caps towards 100p and more grit as you get to the lower end of the range.
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Re: Boss - Blues Driver (BD-2)

Postby MoonWatcher » 12 Jan 2014, 21:36

aab0mb wrote:Feedback loop clippers people. Makes it a different pedal, I'll admit, but it retains a LOT of the full range clarity that it's known for. The mod tames the high end a bit and smooths the splat. bottom line. I really hope someone tries this. It's probably one of the most drastic and pleasing mods i've done to ANY pedal and it's relatively easy.

I've had this idea as a backburner thing, because this is how the diodes are handled in the OD-3, at least with its discrete op amp stage.

The OD-3 doesn't have the buzz or fizz, and it even eliminates the small-value caps (47pF, 100pF) in the discrete op amp that the BD-2 uses.

Thanks for reporting your experiences, because I may not wait so long to try what you did.
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Re: Boss - Blues Driver (BD-2)

Postby soupbone » 18 Jan 2014, 10:28

So,I've been checking out some of the mods on this thread.I've swapped some of the diodes to 1N4003's,and some Led's.I thought after I made these simple mods I thought this cut a lot of the gain,but this thing stil has tons of gain,even with the gain knob all the way down!Anybody have any ideas of modifying the gain stage(s) to have it where when you have the gain turned all of the way down,to have it as a clean boost?
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Re: Boss - Blues Driver (BD-2)

Postby floris » 21 Jan 2014, 11:17

For a gain reduction mod see my post here:
viewtopic.php?f=10&t=8277#p87613
... If you bypass R29 (22k) and R27 (33k) the minimal gain of each stage becomes 1.
Even better: First only bypass R29 and see how you like it. If not good enough then (also) bypass R27.

With "bypass" I mean put a wire over it, not remove it.
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Re: Boss - Blues Driver (BD-2)

Postby RhythmAce » 15 Apr 2014, 17:07

Hi everyone.

Could someone tell me what components are modified in the Galaxie mod?

Thank you,

Mich
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Re: Boss - Blues Driver (BD-2)

Postby stratogrrl » 07 May 2014, 00:14

RhythmAce wrote:Could someone tell me what components are modified in the Galaxie mod?


I traced it out a few months ago and posted it here:
http://www.scribd.com/doc/193173531/MHP ... Parts-List

There are 26 component changes in all, but a third of them are just part removals with those slots left open. The particular part numbers are:

Resistors: R9, R26, R31, R32, R34, R35, R38, R50, R51
Capacitors: C8, C22, C23, C24, C25, C26, C27, C34, C35, C100, C101
Diodes: D1, D3, D7, D8, D9, D10

It's a very transparent and musical sounding mod!!! You can either do it yourself (it's pretty easy) or send it in and have them do it. I ordered a kit from MHP, but I am not sure if they are still taking orders...their website said they are on backorder or something.
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Re: Boss - Blues Driver (BD-2)

Postby Keith_A » 22 Jun 2014, 01:08

stratogrrl wrote:
RhythmAce wrote:Could someone tell me what components are modified in the Galaxie mod?


I traced it out a few months ago and posted it here:
http://www.scribd.com/doc/193173531/MHP ... Parts-List

There are 26 component changes in all, but a third of them are just part removals with those slots left open. The particular part numbers are:

Resistors: R9, R26, R31, R32, R34, R35, R38, R50, R51
Capacitors: C8, C22, C23, C24, C25, C26, C27, C34, C35, C100, C101
Diodes: D1, D3, D7, D8, D9, D10

Some of those values are a little off. Since the cat is now out of the bag, I might as well give the official values. Also, a few things have changed in the last couple years. Nothing major, but different just the same.

R9 - 33K
R26 - 2K2
R31 - 10K
R32 - now left stock
R34 - 10K
R35 - 100K
R38 - 22nF CAPACITOR
R50 - 6n8F CAPACITOR

R51 - jumper

C8 - remove & leave open
C18 - 10nF (this was added a few years back)
C22 - 47nF (was originally 39nF - the new value s/b okay for most users)
C23 - 100pF
C24 - 100nF (this can be fine-tuned if you have unusual values like 82nF, or 68nF but is really more for finessing things)
C25 - 220pF
C26 - remove & leave open
C27 - 47nF
C34 - 10K RESISTOR
C35 - 100K RESISTOR

C100 - 33nF
C101 - 22nF

D1, D3, D7, D8, D9, D10 - remove all & leave open

...I tried to re-work things to use primarily common value components. The two exceptions in the list above are the 6n8F and 33nF capacitors - those two values should really at least be tried first. I originally had stuff that was values like 27nF, 39nF, 68nF, and 82nF, but going up or down to more common values seems to work just as well.

I won't bother to give a blow-by-blow as to what each change does. I think most folks would find it to be a lot more educational to print out the BD-2 schematic, mark it up for the changes above, and then it will probably give ideas as to what was done. It's probably more important to take note of what was left untouched - I see a lot of mods with all kinds of clipping diode swapping that IMO are primarily a waste of time. There's also the popular mods with 'premium' components of the same value that are supposed to give 'clarity,' which IMO is again a WASTE of time. If you want to change the sound and characteristics, you have to change component values. If you want to adjust the gain to make it more like an overdrive designed for the BLUES, you have to change some RESISTOR values. I'm just happy I figured out a way to keep it at SEVEN - you look at some other mods, and the only resistor that gets changed is the one for the ultrabright LED??? Seriously? :scratch:

stratogrrl wrote:It's a very transparent and musical sounding mod!!! You can either do it yourself (it's pretty easy) or send it in and have them do it. I ordered a kit from MHP, but I am not sure if they are still taking orders...their website said they are on backorder or something.

I don't offer the kits any more. I was spending more time putting parts in bags and packing things up to ship out than I was working on pedals. :shock:

I still offer the in-house mod, but now that someone can have it for free, I can't imagine anyone actually paying for it.

So there it is - from the horse's mouth, FWIW. All that I ask is that someone please double and triple-check their work to make sure the installation is correct. There are hundreds (possibly over a thousand) users who do seem to be very pleased with the mod. I just don't want it having a bad rep because of an error.

Have fun, boys and girls...

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Re: Boss - Blues Driver (BD-2)

Postby Dr. Pants » 14 Aug 2014, 01:53

I still offer the in-house mod, but now that someone can have it for free, I can't imagine anyone actually paying for it.


Did you thank stratogrrrllll for that?
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Re: Boss - Blues Driver (BD-2)

Postby IvIark » 14 Aug 2014, 02:51

Very good of you to share the info Keith. Unfortunately this is the nature of the beast, people hear mods which improves the pedals in a way they like, and the curious ones want to find out what has been done. The one positive is that I don't think too many people interested enough in the technicalities to subscribe to this kind of forum are likely to get their pedals modded by anyone else, so I don't think it will cost you too much business. But there are an awful lot of people out there who wouldn't even change an LED never mind perform a comparatively complex mod, so customers will still be there. Get them on TGP, they're giving money away there :mrgreen:
"If anyone is a 'genius' for putting jacks in such a pedal in the only spot where they could physically fit, then I assume I too am a genius for correctly inserting my legs into my pants this morning." - candletears7 - TGP
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Re: Boss - Blues Driver (BD-2)

Postby astrobass » 14 Aug 2014, 14:30

The value isn't in the secret sauce's recipe, it's in being able to offer people an opportunity to simply pay $X to receive a perfectly executed serving of secret sauce without any effort on their part.

Supermarkets do not put restaurants out of business.
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Re: Boss - Blues Driver (BD-2)

Postby MoonWatcher » 03 Sep 2014, 01:41

Dr. Pants wrote:
I still offer the in-house mod, but now that someone can have it for free, I can't imagine anyone actually paying for it.


Did you thank stratogrrrllll for that?

I hereby suggest thanks in that stratogrrl should receive one soggy and bloated tampon roughly shoved down the gullet, for such an excellent act of blatant douchebaggery. :twisted:

I don't really care if someone is going to lift something for their personal usage, or even for their inner circle or closest mates. But publishing it on a web page? And with just two fuckin' posts here? Scum-tacular! :applause:
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Re: Boss - Blues Driver (BD-2)

Postby DrNomis » 13 Dec 2014, 01:16

I just bought myself a brand new Boss Blues Driver yesterday, mine's stock-standard....obviously, and I quite like it as it works for me, if I were to mod one I'd probably do the mods to a second-hand one and keep my new one stock, I played it through my Focusrite Saffire Pro 40 with FL Studio 11 last night and found that the overdrive tone was quite smooth and amp-like, not sure why some people are saying that the note-decay is bad-sounding cause in my case it was smooth, maybe the circuit board in my Blues Driver is a revised version...I don't know, anyway, it works for me...... :thumbsup


I quite like the edge-of-breakup tones I can get with it..... :thumbsup
Genius is not all about 99% perspiration, and 1% inspiration - sometimes the solution is staring you right in the face.-Frequencycentral.

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