freestompboxes.org

Here's one of my Favorite Overdrives.
This circuit is a cousin of the Distortion + and it's rumored that the Distortion + is a variation of Dan Armstrong's Blue Clipper.

https://i17.photobucket.com/albums/b72/ ... LAYOUT.png
https://i17.photobucket.com/albums/b72/ ... ANSFER.gif

1977

https://i17.photobucket.com/albums/b72/ ... LAYOUT.png
https://i17.photobucket.com/albums/b72/ ... ANSFER.gif

Grey

https://i17.photobucket.com/albums/b72/ ... LAYOUT.png
https://i17.photobucket.com/albums/b72/ ... ANSFER.gif

The Grey version is from an "official' DOD service manual from circa 1977/1978 that a fellow from diystumpboxes e-mailed me requesting a layout. I am unsure of it's accuracy but, he was happy!!


***edit admin: here's schematic for basic reference***
http://www.generalguitargadgets.com/dia ... 250_sc.gif

The late grey is identical to the early yellow 250. The early grey and yellow have no Ra and no R8 (R8 only on the newer 250 from China).

JHS

I was a bit unsure of the schem and source but, hey....they sound good!
Thanks JHS!!

I personally LOVE the grey version; so transparant sounding...... although I use a schematic with the 1M feedback cap bridged with a 25 pF cap..... sound a bit nicer

Saw this values in some yellow ones also!

I added a switch for some germanium diodes; sound KILLER with a telecaster

Just tidied up a Dist+ Tonepad board, whipped into shape by lowering the bias R's from 1m to ~45k each, a few other things and a 'small' tone control.
It chews on the chord attacks deliciously.

Good to see you here Pete !

how good of a boost can the stock od250 do? I have seriously never heard an original.

Mine goes right past unity, not as hot output as my RAT Though, never gets set past 8.
+ it depends, and the diodes used to clip clip a lot of signal off, what's left after say Ge diodes are done shunting is'nt much, perhaps even around unity.
Use of >50k volume pot recommended.

polarbearfx wrote:how good of a boost can the stock od250 do? I have seriously never heard an original.

It's got some boost capability IMO.
I love the sound of this circuit.
BTW, Welcome Pete!!

Big, huge fan of the 77 circuit. It's my go-to OD. I changed the drive pot to a 500kC, seems to give it a more even sweep. And I changed C1 to .0047 to cut some low end... tightens things up a bit for palm mute chunking, and cuts through a full band mix perfectly. I use it with a cranked '80 Marshall 2203 and various P 90 Gibsons. The pedal doesn't do much. Just adds a little more grind, and adds a bit of "push", for lack of a better term, which gooses the amp for a bit more natural compression. Not like the artificial-sounding TS type compression, which to my ears is a bit too squashed-sounding for an already cranked Marshall.

a few different values makes this one a zoombox distortion, anybody tried both side by side?

I haven't gone into the 250 yet, but one of my first builds was a D+ followed by a Microamp in the same box, some minor changes to the D+ circuit were done regarding the pots (don't remember what values but by changing them I could get way more output and dirtier distortion) and germanium transistors (oops, edit: germanium diodes!!), that sound really killer on it.

Then came uncle Z and stole that idea from me
kidding

cheers

snail

It's late, and I'm waiting on my laundry to dry, so I'm going to start a list of any and all DOD 250 related circuits I can think of. Will I build them all if I can find a schematic and/or layout? Who knows. But it would be nice to have a grocery list!

DOD 250 ('77, grey, yellow, YJM).
MXR Distortion + ('76, Script)
Ross Distortion
Voodoo Lab Overdrive (I think).
Guyayone Zoom Box/Vox 1901
DeArmond Square Wave Distortion Generator (I made a layout in another threat, awaiting proofreading).
Fuzz Central Liquid Drive.

Surely there are more out there that I've missed or don't know about yet. Anyone?

Burglar wrote:It's late, and I'm waiting on my laundry to dry, so I'm going to start a list of any and all DOD 250 related circuits I can think of. Will I build them all if I can find a schematic and/or layout? Who knows. But it would be nice to have a grocery list!

DOD 250 ('77, grey, yellow, YJM).
MXR Distortion + ('76, Script)
Ross Distortion
Voodoo Lab Overdrive (I think).
Guyayone Zoom Box/Vox 1901
DeArmond Square Wave Distortion Generator (I made a layout in another threat, awaiting proofreading).
Fuzz Central Liquid Drive.

Surely there are more out there that I've missed or don't know about yet. Anyone?

CORON
MEMPHIS

I just realized I typed "threat" instead of "thread". Told you it was late.

what cool tricks and mods can be done to a DOD250/Microamp for some cool opamp clean boosts.

Sorry for bumping an old thread ..... but I am trying to track down the value of a resistor in the 77 gray dod 250 and have found conflicting information......

the resistor listed as R2 in markm's links in the OP above is said to be 470k in the grey spec layout and 1M in the 1977 Spec layout.....but I was led to believe that the DOD 1977 was the Grey....as in the GGG site instructions here https://www.generalguitargadgets.com/in ... &Itemid=26

Problem is there is a discrepancy on the GGG site between the values . On the schematic it says r4 = 470k and on the parts list it says 1M ....(r2 on markm's layout = r4 on ggg's schematic).......

so i emailed ggg and they responded that 470k is the correct value. I was fat, dumb, and happy till I ran into this thread...Now I'm even more confused.....


Is the DOD 250 od Grey version not the same as the 1977 DOD 250 od?
I have just about finished building this and I have socketed everything worth playing with later......so this question is more academic than anything.....but I'd really like to know which ckt is the venerable gray box that draws so much crazy money on ebay.

.....but I'd really like to know which ckt is the venerable gray box that draws so much crazy money on ebay.

None of them.....
as you can see here:
https://cgi.ebay.com/ws/eBayISAPI.dll?V ... :IT&ih=017
it´s an Mxr Distortion+ circuit housed in a Dod-case.
The variations came later.

analogguru

analogguru wrote:

.....but I'd really like to know which ckt is the venerable gray box that draws so much crazy money on ebay.

None of them.....
as you can see here:
https://cgi.ebay.com/ws/eBayISAPI.dll?V ... :IT&ih=017
it´s an Mxr Distortion+ circuit housed in a Dod-case.
The variations came later.

analogguru

this I knew......but it doesn't help.......
let me rephrase....what value for R4 would I most likely find if I opened up this?
https://cgi.ebay.com/ws/eBayISAPI.dll?V ... :IT&ih=007

8^)

wader2k wrote:

analogguru wrote:

.....but I'd really like to know which ckt is the venerable gray box that draws so much crazy money on ebay.

None of them.....
as you can see here:
https://cgi.ebay.com/ws/eBayISAPI.dll?V ... :IT&ih=017
it´s an Mxr Distortion+ circuit housed in a Dod-case.
The variations came later.

analogguru

this I knew......but it doesn't help.......
let me rephrase....what value for R4 would I most likely find if I opened up this?
https://cgi.ebay.com/ws/eBayISAPI.dll?V ... :IT&ih=007

8^)

Sorry that I don´t look at others people schematics - I draw my own.
Therefore I can´t say what is R4 or R2.
If you opened up this specific unit you must have bought it before .
But there is already a gutshot of the opened unit. From this gutshot I can tell you that it is most likely a 1979 unit, at least from the last weeks of 1978. Only during this period they used the 741´s from RCA in the grey 250.

Anyway, the feedback resistor was in all units from 1976 to 1979: 1M.
The bias resistor was in 1976 470k, in 77/early 78 510k, the rest of 78 and 79 it was again 470k. With a freeware graphic programm maybe you will be able to recognize the yellow and violet ring in the gutshot.

BTW, do you have a 741 from RCA ? I think this will have more influence on the sound than the stupid bias resistor - especially when the input coupling cap has a tolerance of 20%, like in this case.

analogguru