Boss - BD-2 Blues Driver 1995  [schematic]

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

Hi,
that´s nice: YOU need a proof of purchase? e-mail address?
To compare them, you gotta HAVE the address of purchase.....why don´t you send a mail to anyone, who bought your instruction to the date, you changed your instructions?

That´s business: I made a mistake, but as long, as nobody asks, I don´t care. Image

I just deleted your HP from my bookmarks :thumbsup

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roberttomasz
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Post by roberttomasz »

Looking for a picture (or drawing) plates Boss BD - 2 Very urgently needed! Thank you very much. Yours

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gruforevs
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my favorite amplifier: Fender Deluxe Reverb '65 reissue

Post by gruforevs »

Hey! (first post........ oooooooh :shock: )
I am a total newb at modding/building and was wondering if modding a blues driver would be a suitable first project? It would be cool if it sounded awesome in the end but I eventually want to mod my mxr classic 108 fuzz and maybe even build my own pedals, this is just for practice. I am not terribly concerned about breaking my blues driver (though obviously, I would prefer not to) but I am willing to risk it for some experience with a soldering iron. Your replies are eagerly anticipated!

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darscuzlo
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Post by darscuzlo »

Why risk your pedal?
I suggest buying your soldering supplies then just get your hands on some old circuit boards
and practice on them first. It can be any old broken radio, stereo, boom box.
get comfortable soldering and desoldering, THEN you'll have the chops to do the real pedal.

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gruforevs
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Post by gruforevs »

Thanks for your reply.

That sounds like a much better idea. I am just wondering, will it be very easy to see if I messed up on a broken radio? I mean, I will not be able to plug it in and see if it still works. Is it easy to see damage from bad soldering?

Thanks again for your help.

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darscuzlo
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Post by darscuzlo »

soldering is easy. de-soldering takes a little more practice.
If you get too hot you can lift the trace from the board.
It helps to have the right tools.
I have found that a regular 25 watt soldering iron from radio shack work well.
you want thin solder, soldering paste, de-soldering braid and I also like those little
bulb thingies that suck the solder out too.

The trick is to get the area you want hot enough to get the job done, before you lift a trace or cook a component. If you can get an alligator clip on the lead, for example, of the capacitor you are soldering, it will wick heat away it.

It takes more time, but when I'm doing mods I like to do the components one at a time
and then test to make sure the thing still works!

two things that have been helpful to me as well are a great little app for the iphone
that decodes the color bands of resistors. probably canb find the same thing on the net.
and also this site:

http://www.electronics2000.co.uk/calc/c ... ulator.php

when decodes the numbers of cap values.

good luck!

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gruforevs
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Post by gruforevs »

Sweet! I was just looking for something like that. Thanks for the help. I will make sure I get lots of practice desoldering all sorts of broken junk before I move on to important stuff.

Thanks allot for your help!

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darscuzlo
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Post by darscuzlo »

you might find this useful as well:


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roberttomasz
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Post by roberttomasz »

Can someone attach a photo or scan of the plate Boss BD-2? I am very urgently needed. Sorry for the spelling because I did not know English, and writing by the translator.

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gruforevs
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Post by gruforevs »

Hey,

Lots of guys in this thread talked about switching out diodes for LEDs. would any old LED work? Like, even infrared LEDs I stole out of old remote controls?

Thanks for your help.

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matt239
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Post by matt239 »

First only bypass R29 and see how you like it. If not good enough then (also) bypass R27.
Do we all agree that this would be the first option to try, for reducing gain?
- If bypassing R29 reduces gain "too much," then we'd just substitute a lower value for R29, yes?
& Does C22 then need to change?

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Post by floris »


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matt239
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Post by matt239 »

Thanks!
- So has anyone figured out what is actually causing the splatty - uneven decay?
Some of the mods reduce the gain drastically & apparently this helps, but how can we still get some overdrive & avoid the decay problem? I've reduced gain some by bypassing R29 & R27 as suggested, & I like the result,
- but if I cause the pedal to distort at all, then the distortion sounds great, until the end of the note, as it's fading away; splat!
- It seems to fade below the clipping threshold, then bounce back above it a couple of times..

- It seems like this has to be a problem with the first gain stage, before the main clipping diodes..
- Is this stage being overdriven, not recovering gracefully, causing a little amplitude fluctuation on the tail of a note, causing the clipping diodes to turn off, then back on etc?
- Would just reducing the gain more in the first section be the best way to attack this? & what would be the best way to do that? -- or is my theory all wet, & the problem is elsewhere in the circuit? :)

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cctsim
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Post by cctsim »

After the first gain stage there is a Fender-type tone stack that lets too much bass through before the clipping.

My suspicion is that this is the culprit for the splat. I have converted mine to a Marshall-type tone stack which evens the
frequency response a bit. I have never noticed the splat on fading notes in my case btw. These are the necessary changes
if you want to try them:

C26 -> 500p
C34 -> 0.022u
C35 -> 0.022u
R36 -> 33k
R37 -> 250k
R51 -> 25k

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matt239
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Post by matt239 »

floris wrote:What's the "terrible decay" in this pedal? Does that mean that while notes are sustaining and dying out (decaying) the overdrive sounds bad?
^^ That. ^^ :) -A common complaint with the BD2..
cctsim wrote: After the first gain stage there is a Fender-type tone stack that lets too much bass through before the clipping...
....My suspicion is that this is the culprit for the splat.
Hm.. - I don't know whether to just reduce the early gain more, or look at the pre-clipping EQ?

- I like the final EQ tone of the pedal OK, so if I were to reduce the bass before clipping, I'd want a complimentary bass-boost/ (or treble-cut) after..

Of course it's possible that the artifact I'm trying to eliminate is being created later in the circuit??

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Post by okgb »

Someone must make a BD style pcb ?
any opinions ?
byoc has a kit ?
looking for a bare pcb to try one , tia

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gruforevs
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Post by gruforevs »

okgb wrote:Someone must make a BD style pcb ?
any opinions ?
byoc has a kit ?
looking for a bare pcb to try one , tia
Blues Drivers have LOTS of components. Nobody makes pcbs cause it's a lot easier (and probably cheaper) just to buy one yourself (that's why this modification thread is so popular). I mean, there $70. Just go out and buy one.

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Post by matt239 »

Update:
- I replaced the 1MOhm @ R50 with a 22k. This changes the response of the "Fender style" pre-clipping tonestack to have only a slight bass boost, about +3dB @ around 100Hz, falling off rather than rising in the sub-bass region. (20-30Hz) (Stock there is a huge bass boost here.)

- placed a 1N4001 diode @(D10?), back in series with the single 1N4001 Keeley uses in place of one of the pairs of main clipping diodes.

- Changed R29 to 1k, & R27 to 10k. (They are 22k, & 33k stock, - I had had them jumpered..) These values give a sweep to the gain pot that I like. Can still get clean @ minimum setting.

With the EQ, & diode changes, the distortion is a bit milder, the splatty decay is less, but not totally gone.

- I still want to eliminate the splat, without just turning the pedal into a clean-boost,
- I want to boost the bass more, later in the circuit (post clipping)

(Can see some places to do it, not sure about calculating values.. used Duncan calculator for "Fender" tonestack)
Any suggestions?

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Post by matt239 »

MoonWatcher wrote: ... I like to start with the gain reduction, via R31 and R34 (first and second op amps). I've gone as high as 10K for both, but admit that it will lead to a serious gain reduction, and make the pedal very mild. ... Possibly 4.7K for both as a starting point might be good. Obviously be aware that C22 and C24 will have to be changed to keep the HP filtering the same, unless you want to change it.

... I've found that playing with the external compensation on the discrete op amps can work wonders, as well. The most effect can be achieved at R32 and R25, and a little goes a long way. Even a switch from 2.2K up to 3.3K s/b noticeable. I'd only fiddle with one at a time, and I wouldn't alter them by much.
Can you explain this a little more? - I don't understand this part of the circuit too well. :oops: - :scratch:
- R31, R34, R32, R25 look to me like they go from signal to ground so that decreasing them would reduce gain, rather than increasing them. - I'm sure I just don't quite get it. - I'm obviously missing something. :oops:
________________________________________________________________________________________________________
WhiteKeyHole wrote:Yeah, most of those modifications were brutally aimed at removing that nasty note decay...
Can you explain your theory here? What was your strategy? Which parts of your mod have the most effect on the splatty decay?

Thanks guys. :)

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Post by matt239 »

??
+ Do we know how the gyrator in the last stage is changing the EQ?

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