Super-bright OD250 Clone

[zombiwoof]

Hi,
I bought a "The Gray Speck" OD250 clone from Ebay, thinking it was an earlier version of the Chicago Stompworks pedal of the same name (except for the graphics, which look professional, it looks very similar to the CS version).  First, I noticed that it said in small print "Podals.com", a website that is now expired.  When I tried out the pedal, I was dissapointed to find it is extremely bright, not what I expected.  A check check of the internals showed neat wiring, an LM308CN opamp, and the caps seem to be the vintage values.  I haven't gotten around to checking the resistors, as they are all really small (1/8 watt), and it will take me quite a while to decode all the values.  I guess what I want to know is why would this thing be so overly bright?.  I'm sure the originals aren't that bright, and this seems to have the correct values as far as I've seen so far.  It is advertised as vintage spec.

I'm not sure what to do at this point, try to mod it for less treble?.  What components could be responsible for the brightness of the pedal, could it be an incorrect resistor value?.  I haven't looked at the back of the board yet, as it is glued to the sides of the inside of the enclosure at about a 45 degree angle, I'll have to break the glue bond to work on it.  Any ideas?.

Here's the auction:  http://www.ebay.com/itm/The-Gray-Speck-DOD-250-clone-overdrive-pedal-/331102750975?_trksid=p2047675.l2557&ssPageName=STRK%3AMEWNX%3AIT&nma=true&si=gdevMZtqpWivcK3lbCQqOBQfw6I%253D&orig_cvip=true&rt=nc

Thanks,
Al

[Kipper4]

Heres a thread on the grey spec with differant IC's used
it might be of use to you

http://www.diystompboxes.com/smfforum/index.php?topic=84918.0

[Mark Hammer]

1) An accurate replica of the 250 should have a 741 op-amp, not an LM308.

2) The design makes it brighter as the gain is turned up.  It uses a non-inverting configuration, which means that the low-end rolloff moves upward as the gain is increased.  At max gain, the "bass" rolloff begins around 720hz.  If you want it to have some heft to it at all gain settings, add a 100nf cap in parallel with the .047uf cap already there.  If you want to round off the edges a bit, consider adding a 22-33pf cap in parallel with the 1M feedback resistor.

People will often hear that this is the pedal that so-and-so uses for a terrific warm overdrive and then be surprised when they get an entirely different sound.  Bear in mind that it is possible to use the pedal to provide medium boost and overdrive to the front end of an amp on the edge of breakup.  At less than max gain, the 250, just like the MXR Distortion+, still had reasonable bass response.  As you approach max gain, that bass disappears.  So, if you have an amp that just needs a little push, this pedal may do a nice warm job.  If you are relying on the pedal itself to produce much of the overdrive tone, then you will likely be turning up the gain close to max, and forfeiting the bass to do so.

he suggested mod compensates for that.

[Gus]

Are you using a solid state amp or a tube amp?

[zombiwoof]

Sorry, my DSL has been down for the last 3 days, so I haven't been able to respond during that time.
First, I mistakenly said LM308CN, it does have the LM741CN.  Must have had Rats on my mind.
I'm using a Strat into a vintage '65 Princeton Reverb.
I have never played through a vintage OD250, but this one does seem to have the correct components, as I said I haven't checked all the resistors but all of the caps and the chip check out.  I do have a DOD YJM 250 pedal, and I have to say I prefer it in stock condition to this pedal that is supposedly built to original specs.  I did notice that they used almost all metal film resistors in this, the regular caps (other than the electros) are black box caps of some kind.  Could the use of metal film resistors have anything to do with the extremely bright sound?.  I'm sure the originals probably just used regular carbon film.  I have been meaning to mod my YJM OD to vintage specs, by putting in a 1458 (supposedly a dual 741), in a socket, and change the incorrect values to the right ones, and ditch the 25pf cap that DOD used with the 4558.  Just haven't gotten around to it.  I just can't believe that the originals are as bright as the new 250 clone I bought.  It seems to be bright throughout the range, not just as the gain is turned up.  I noticed that effect on the YJM pedal.  You can't get a warm sound out of this new one at all, like I said it sounds like a treble booster.

Thanks,
Al