Boss - BD-2 Blues Driver  [schematic]

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Re: Boss - Blues Driver (BD-2)

Postby dta74 » 12 Apr 2012, 21:59

Thanks Floris,

Ironically, yours was one of the posts included in my spreadsheet of madness, though your changes (diodes only) seemed to mirror others I'd cataloged here and on other sites.

Yes, I love the distortion channel on the Valveking, which becomes even more impressive if you engage both the gain and volume boost buttons, which then become footswitchable. Running it thru a 16-ohm 412 cabinet does further wonders to the low end. Definitely a sleeper amp, especially considering I've paid only $200 and $250 for the 2 I've owned.

I understand why you would've wanted to see/hear some variation in the knobs and I'm gonna try to do that on the next demo (which was as much a test of the new-to-me Zoom Q3 as it was a demo). I've actually got some tape (miniDV) of a Fulltone OCD vs Danelectro Cool Cat Drive. I set the OCD with gain and tone straight up and the volume at unity, then set the CCD to match. With his back turned, my roommate (a semi-pro local player) couldn't tell the difference between the 2. Basically an OCD with a $100 discount, if you don't care about the name on the faceplate.

In regards to the shrill tone, the camera (2 mics in an XY pattern) was positioned approx. 3 feet from the cabinet, pointed directly at the cone, but off-axis, due to the fact that the amp was leaning back against another case. I was sitting just beyond the mic, so both myself and the camera were getting the tone straight off the speaker. Definitely NOT what you'd want to hear when mic'd thru a PA, but I think it gives a more accurate representation of the differences in pedals, by reducing the effects of the room. I guess I could really go nuts and plug the pedals directly into a recording device (I've got a Bass Pod somewhere...) and take the speaker and mic out of the equation altogether. I guess that's a thread for another day...
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Re: Boss - Blues Driver (BD-2)

Postby floris » 12 Apr 2012, 23:56

If I remember correctly, I posted on how to reduce the gain of the "opamp", made from discrete components, in this pedal. I can't recall anything on diodes ...
Keep those demos coming! :)
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Re: Boss - Blues Driver (BD-2)

Postby dta74 » 14 Apr 2012, 14:10

And finally, the Keeley mods (based on the unit I saw):

C14 0.01uF metal film
C20 100pF tantalum
C21 47pF tantalum
C22 .15/35T tantalum
C23 47pF tantalum
C24 1/35T tantalum
C25 100pF tantalum
C26 220pF silver mica
C100 0.033 metal film + 0.082 metal film (switched with a SPDT)
D7-D8 single 1N4001 across outer pads of D7-D8
Status LED 3mm clear blue
D11 replaced with 11k high precision resistor

https://plus.google.com/u/0/photos/1128 ... vNqom6POGQ
https://plus.google.com/u/0/photos/1128 ... vNqom6POGQ
https://plus.google.com/u/0/photos/1128 ... vNqom6POGQ
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Re: Boss - Blues Driver (BD-2)

Postby dta74 » 14 Apr 2012, 16:41

Again, based on Keeley's website (but not immediately noticeable w/o a magnifying glass) are the following additional mods:

D3 changed on website, looks stock on the pedal I had.
C1, C6, C7, C12, C13, C15 changed to non polarized electrolytic, same value.
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Re: Boss - Blues Driver (BD-2)

Postby dta74 » 19 Apr 2012, 04:17

Another modded pedal, another mediocre demo video... ;)

Partial Keeley mod based on previous post. Omitted any tantalum cap changes. C14 (input cap) value changed to 0.1uF. All non-polarized caps (C1, C6, C7, C12, C13, C15) are 10uF/16v. Clear blue 3mm LED stays dimly lit when bypassed - will correct later.

Same amp,guitar as previous demo: Peavey ValveKing and Peavey Generation w/ Seymour Duncan TB-11 Custom Custom bridge pickup.
Camera is Zoom Q3 positioned approx 2 feet from grillcloth.

Per request, more knob tweaking! After the 2:15 mark, the "phat" switch on the modded unit stays on (up position).
Volume knobs on both pedals set to unity gain the entire time (approx same volume engaged and bypassed).

http://www.youtube.com/watch?v=j2A8FhTHS7o
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Re: Boss - Blues Driver (BD-2)

Postby floris » 19 Apr 2012, 13:10

Thanks for the knob tweaking! The demo much more interesting this way.

Quite some intermodulation distortion and dirty fuzz with the chords at 1:33-1:53 due to the fat mode increased low freq content. I didn't like that.
Although I liked the modded version much better than the stock one at 4:13-4:37 even though the same settings are used.

I liked the minimal gain tone at 3 o'clock + fat mode of the modded one at 3:24.

On single notes, at 4:40, the fat mode was nice compared to the thin stock sound.
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Re: Boss - Blues Driver (BD-2)

Postby dta74 » 19 Apr 2012, 16:33

Some of that intermodulation might be the guitar going out of tune...

I concur regarding the phat switch with single note runs vs chords. Not something you could exactly define unless you heard it back to back. If it wasn't a major PITA to rehouse, I'd put it in a 1590BB-style case with dual footswitches: 1 for bypass/engage and 1 for "phat" on/off, like this pedal I built for a friend:

https://picasaweb.google.com/1128180730 ... 6659100450

Or spaced better, ala Visual Sound's dual-button pedals...

Roommate will be home tonight, so I'll try to get him to play while I tweak knobs... the difference in ability is humbling.

Don't forget, I DIDN'T do a full Keeley mod. Did NOT replace C20, C21, C23, C25 with the spec'd tantalum replacements. C22 and C24 appeared to be tantalum and were left as is. Not sure about the LED staying dimly lit when bypassed. I might just reverse the D11-to-11k resistor and see what happens.

At a bare minimum, I'd do the D7-D8 to single 1N4001 mod, the C14 to 0.1uF mod and the C100 .033/.082 (switched) mod. In fact, I still have 2 others lying around, so I might do that and compare to the current partially-modded version.

Total parts cost at Mouser came to something like $7 per pedal, plus shipping.
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Re: Boss - Blues Driver (BD-2)

Postby dta74 » 19 Apr 2012, 16:52

Component (PCB silk screen) Quantity per pedal, Manufacturer, Part name, Mouser stock number, cost per part (total per pedal):

D7-D8: 1x Fairchild, 1N4001, 512-1N4001, 0.08
C1, C6, C7, C12, C13, C15: 6x Nichicon, 10uF/16V non polarized electrolytic caps, 647-UVP1C100MDD, 0.12 (0.72)
C100switch: 1x Mountain, SPST toggle switch, 108-0001-EVX, 1.70
D11: 1x Vishay, 1/4watt 1% 11k resistor, 71-CCF5511K0FKE36, 0.09
LED: 1x Blue Water, clear 3mm blue LED, 593-VAOL-3LSBY4, 0.35
C14: 1x Panasonic, .1uF 250V 10% film cap, 667-ECQ-E2104KF, 0.34
C100a: 1x Panasonic, .033uF 400V 10% film cap, 667-ECQ-E4333JF, 0.63
C100b: 1x Panasonic, .082uF film cap, 667-ECQ-E1823JF, 0.61
C25: 1x CDE, 500v 5% 220pF mica cap, 598-CD15FD221JO3F, 1.22
C22: 1x AVX, .15uF/35V 10% tantalum cap, 581-TAP154K035SCS, 0.46
C24: 1x AVX, .1uF/35V 20% tantalum cap, 581-TAP105K035SCS, 0.35
Total parts cost per pedal: $6.21 plus shipping

If you're willing to dig thru Mouser's website, I'm sure you could find cheaper versions, like all 250V film caps, etc...
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Re: Boss - Blues Driver (BD-2)

Postby dta74 » 19 Apr 2012, 18:33

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Re: Boss - Blues Driver (BD-2)

Postby dta74 » 20 Apr 2012, 03:17

The latest demo, roommate playing same amp, early-80s Les Paul with Mojotone Customwound pickups:

http://www.youtube.com/watch?v=uMd_9WQ1hkM
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Re: Boss - Blues Driver (BD-2)

Postby dta74 » 07 May 2012, 20:09

Alright... beating a dead horse here, but I've built another partial Keeley Phat Mod. Remembered to take lots of photos (63, in fact). Uploaded and organized into a photo-essay tutorial with captions. Should be clear enough that even a drummer could do it (if they had soldering skills). Enjoy!

https://plus.google.com/photos/11281807 ... t7qo-3F1gE
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Re: Boss - Blues Driver (BD-2)

Postby floris » 07 May 2012, 23:24

Nice photo essay, thanks!
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Re: Boss - Blues Driver (BD-2)

Postby dta74 » 11 May 2012, 16:12

PCB from #4. Components to be removed are marked with a black Sharpie, 11 total.

https://plus.google.com/u/0/photos/1128 ... t7qo-3F1gE

Also, as an experiment, I used a 0.068uF as the switched cap for C100B. Definitely not as noticeable low-end boost as using a 0.082uF.
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Re: Boss - Blues Driver (BD-2)

Postby Barry » 06 Dec 2012, 05:13

dta74 wrote:And finally, the Keeley mods (based on the unit I saw):

C14 0.01uF metal film
C20 100pF tantalum
C21 47pF tantalum
C22 .15/35T tantalum
C23 47pF tantalum
C24 1/35T tantalum
C25 100pF tantalum
C26 220pF silver mica
C100 0.033 metal film + 0.082 metal film (switched with a SPDT)
D7-D8 single 1N4001 across outer pads of D7-D8
Status LED 3mm clear blue
D11 replaced with 11k high precision resistor

https://plus.google.com/u/0/photos/1128 ... vNqom6POGQ
https://plus.google.com/u/0/photos/1128 ... vNqom6POGQ
https://plus.google.com/u/0/photos/1128 ... vNqom6POGQ



D11 should be 1.2K
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Re: Boss - Blues Driver (BD-2)

Postby maxzero » 19 May 2013, 04:54

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

Barry

Long overdue bump!
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Re: Boss - Blues Driver (BD-2)

Postby Barry » 21 May 2013, 04:43

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
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Re: Boss - Blues Driver (BD-2)

Postby NOC3 » 21 May 2013, 06:20

I'll dig up my notes...


I remember just disconnecting the gyrator tone circuit :mrgreen:


If I went at it again I'd maybe try to up the voltages in the discrete fet op-amp... And add a resistor and cap in series with the diodes to ground.
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Re: Boss - Blues Driver (BD-2)

Postby chris1001 » 02 Jul 2013, 13:53

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


Old post I know, but how did the mod sound? Was it radically different from the usual Keeley/Monte type BD2 mods?
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Re: Boss - Blues Driver (BD-2)

Postby Keith_A » 02 Jul 2013, 15:41

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

Postby tonygrazioso » 03 Jul 2013, 05:20

here's my Dualie..both layouts from GM..(A) BD-2 (B) DR. BOOGIE..you can either have (A) or (B) or (A>B)....believe it or not, it's a really nice combo..they compliment each other very well.

Image
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