DOD 250 Grey 1977 and rare early '77 - new Veros.

[Toney]

 Steve's thread in the schematics section http://www.diystompboxes.com/smfforum/index.php?topic=86932.msg844578#msg844578 reminded me of a couple of Veros I did for this killer version of the good old DOD 250.
The first is Grey specs circa 1977.

                   

The second is a rare and great sounding 1977 transitional model as discussed in this thread - particularly the post of JHS:

http://www.diystompboxes.com/smfforum/index.php?topic=46548.0

A couple of notes: JHS used 1n4003 for his final build, so I have listed those.
I think the original may have had a linear 500k as opposed to the reverse log one which is usual for these. It is a good idea to socket the 2.2n Mylar from the input to ground as it may be a bit much (dark) for some. Oh and ceramic caps for the 47n and 10n do sound gritter to me - that's what the original had.

                   

[Steve Mavronis]

Toney, thanks for mentioning my schematic thread and good to meet another 250 fan!

The '77 model (based on veros like these) was the first I had looked at when I was deciding how to make my own clone. I don't know how I ended up settling on the last gray 250 model from late '79/80 to clone. Can anyone explain how the '77 sounds different compared to the '79 model? I'm sure the diodes make the most difference in sound.

Question: The later grays all have 5 caps., two of which are electrolytic. I thought the '76 and '77 had 4 or 5 caps but not having the 10uF polarized cap, even though there were holes for it on the original PCB? Those '77 veros both show a total of 7 caps so I'm curious. Does anyone have a photo of an actual '77 gray 250 circuit board?

[Toney]

From the linked thread and true with my own builds:

"From that info I built a '77 and '78 prototype, a member in the German forum did the same, the '78 sounded really good but the '77 was a killer, w tight focused bass and clear articulated highs. Changing the diodes in the '78 to 4001 was disapointing, the goal to great tone is the different circuit of the '77 w altered cap values + 4001. They use ceramic caps in the old unit, they give a bit more grit and clarity than the mylar caps in the later units"

Re the caps - I have C3 and C5 as power filters and the very rare one discussed has and extra 2.2n to ground at the input (an be omitted of course) and no 10uF cap in the BIAS-divider.

[Steve Mavronis]

Re the caps - I have C3 and C5 as power filters and the very rare one discussed has and extra 2.2n to ground at the input (an be omitted of course) and no 10uF cap in the BIAS-divider.

Yeah that extra cap to ground (different value) is what the old MXR Distortion+ has too. That explains the extra holes you can see in later gray 250 models. Don't know why I missed that in my 2010 research. I was curious on the number of caps, 7 in the veros. The gray DOD 250 usually had 5 and even including an extra cap to ground that would raise it up to 6.

[Toney]

 Steve I have added C3 and C5 as power filters and D3 as reverse polartity protection. I do it an all my builds thus on the Veros too, a habit I guess.
The JHS one has no 10uF in the bias divider but it does have an extra 2.2nf to ground.
Check out the thread linked above.

Really great sounding little circuit. Shows how flexible and multi-voiced the many incarnations of this thing are.