Boss - OD-3 Overdrive  [schematic]

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

Here are some guts of the Boss OD-3 (slightly modified):
https://cgi.ebay.com/Boss-OD-3-with-Mont ... dZViewItem

Anybody knows who or where is "Monte Allum"(inium ?) who changed some 47n capacitors to another brand ?
Maybe I should change my nick to "Monte Christo" ? :roll:

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Post by Igloo »

Ha!

Do you have schem for the OD-3?

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Post by analogguru »

Do you mean this one ?

http://www.axiomdrift.com/schematics/BossOD-3.gif

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Boss OD-3 Overdrive schematic
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Post by Igloo »

Super!
thx

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Post by analogguru »

Hey I found Monte Allum(inium) !!! This guy is cool !!!
He is selling 8 capacitors, 2 tantals, 1 Led and one resistor for only $21,90 !!! Have a look for yourself:

http://www.monteallums.com/Product_links.html#OD3Supra

And I bought instead of it :cry: this unit for EUR 12,50:

Image

with only 1x TL022, 1 x TL072, 7 x 4558 (old TS-9!), 2 x MN 3101, 2 x MN3007, 1 x MN 3011, 2 x LM 386, and a handfull of resistors and capacitors in it :cry:

So I think, I should at least have a look, which components will be changed :roll: Let´s have a look what Montezuma.... sorry, Monte Allum(inium) is doing:
He is changing the 1µF bipolar eleectrolytics (C15, C21 and C30) to tantalum caps :? , C9, C12 and C28 are changed from japanese film to european film capacitors and C11, C23 and C31 are changed to this brown caps....hmmmm

I think with time i will learn to live with the unit above instead of this mod kit.

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Post by indyguitarist »

If you want some mods for the od-3, maybe I could post some ideas?

Here's one of my favorite, looking at this schem:
http://www.indyguitarist.com/schematics ... 20OD-3.gif

r11: 10k trimpot set for treble
r15: 22k
c16: .033uf
c13: 1uf
c22: .1uf
c18: .22uf
d7: led/1n4148 in series
d11: 1n34a
c8: remove, don't replace


bw
Last edited by indyguitarist on 02 Jan 2008, 19:32, edited 1 time in total.

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Post by analogguru »

@indyguitarist
this looks more like a reasonable mod, thanks !

here are some other guts:

http://f.hatena.ne.jp/toy_love/20070102003632
http://f.hatena.ne.jp/toy_love/20070102003746
http://f.hatena.ne.jp/toy_love/20070102003021

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Post by markm »

Oh.
This is the fella that puts Ge Diodes in the Dynacomp.
Now I know who you guys are talkin' about.

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Post by cbriere »

is this one verified,
i'm not shure what happen at POINT A?
Image

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Post by cbriere »

here is schematics,
please verify , at point A ??

http://www.freeinfosociety.com/electron ... hp?id=2299

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Post by analogguru »

Point A in the first row right connects (only) to point A in the second row left - nothing else.

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Post by cbriere »

My guess is that PointA should connect between r38 and DRIVE.
That's because the collector of q11 is fixed, so it cannot pass audio signal.?

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Post by analogguru »

Q13 and Q14 act as a differential amplifier and Q11 as a buffer. The output signal is across R52. Drive/R38 + the diodes and R51/C33 act like in a tubescreamer.

Compare it with the Boss BD-2, FZ-2 and ODB-3 schematics.

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Post by cbriere »

tks,
what is partical about he OD-3 ? (if here are)

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Post by nooneknows »

I have a od3 and it reminds the bd2, at least as I remeber it. It has the same scooped mid type of sound and an boost on the bass side, in the band mix it doesn't cut through. To me it's a good unit at home, maybe with a transitor amp, but in live situation it's not that useful, if the frequency response was flatter the pedal could be more interesting.
The network between Q10 and Q13 it might be involved in part with the sccoped mid: if R48 wasn't there it could be similiar to a backward bigmuffpi tone control with the knob completely turned to one side... I didn't do the math, it could be interesting to analize.
I don't understand the part involving the opamp, it's shaping the tone but it's not clear to me the design. Any idea?
thank you

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Post by echodeluxe »

nooneknows wrote:I have a od3 and it reminds the bd2, at least as I remeber it. It has the same scooped mid type of sound and an boost on the bass side, in the band mix it doesn't cut through. To me it's a good unit at home, maybe with a transitor amp, but in live situation it's not that useful, if the frequency response was flatter the pedal could be more interesting.
i have to disagree. the od3 has been my main od for a few years. the response is pretty flat, with a small hump in the mids, but not near as much as a tubescreamer. i found it to cut like a knife. of course ive only used it with a vox ac30, a fender bassman (about 4 different types), a peavey classic 50 and 30, a marshall major, a gibson ga30, etc...


8)

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Post by nooneknows »

echodeluxe wrote:
nooneknows wrote:It has the same scooped mid type of sound and an boost on the bass side
i have to disagree. the od3 has been my main od for a few years. the response is pretty flat, with a small hump in the mids, but not near as much as a tubescreamer. i found it to cut like a knife. of course ive only used it with a vox ac30, a fender bassman (about 4 different types), a peavey classic 50 and 30, a marshall major, a gibson ga30, etc...


8)
Very strange: I use a Marshall Jcm800 combo and a peavey classic 30 (a little modified, cathode biased etc.), I tested the OD3 side by side in a chain with a YATS, a OCD clone, a Digitech Screamin Blues, a HAO Rust Driver and a DS-1 with my '70s strat and I'm pretty sure about the frequency response. The 'lack' of mid is quite evident compared to the YATS or even the OCD, much similiar to the Screamin' Blues, and so the bass hump.

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Post by PurplePeopleEater »

I've had a couple OD3's. I like them because they have a lot more low end than tube screamers, and sound more like natural amp overdrive to me. Everyone has their own opinion, but mine is that the OD3 is one of the best Boss ODs made.

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Post by nooneknows »

PurplePeopleEater wrote:I like them because they have a lot more low end than tube screamers
yes... too much low end for my taste :mrgreen:
maybe what I feel as a lack of mid it's just the low band enphasis and a flat response on the high band. That said my problem is then to tame down the lows...
any idea?

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Post by nooneknows »

so... my problem with this pedal is I have to much bass. C14 and R15 have a cutoff freq of 15Hz: replacing C14 with a 220nF the hipass filter would go to 723 Hz, a TS-territory, interesting...

another interesting point is the other half of the opamp chip:
C8 and R13 is a high pass with -3db at 4983 Hz paralleled with a 12K res
C7 and R11 is a high pass with -3db at 1598 Hz paralleled with a 12K res.
maybe we could flatten the band a bit

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