I don't understand this DOD 280 Compressor

[loomis]

Hi. New user.

I picked up a first issue gray box DOD 280 compressor recently. I know pedal builders have reproduced the circuit.

I'm wondering if anything can be done to easily improve it, like different value caps or resistors?

Turn the compression up past about 20% and I get pretty annoying lowering of the volume when I strum a loud chord, making it pretty unusable.

Also, do you guys put these first in the chain or at the end of the line right before the amp?

And lastly, how do you convert these early DOD pedals to true bypass with an LED?

Thanks,
Loomis

PS - I scored an original tan Ross Distortion pedal complete in the box today at an estate sale for eight bucks!

[bagudan]

I have an orange dod 280.... Plenty of range left ón the volume, when sustain is cranked. It Can get Very loud actually. I put in a 3pdt, found the in and out wires from the board ( had to use an audio probe for this, as the markings and letters ón the board made no sense to mé) from this point it was easy. I Think it is a great compressor. Not subtle, but Very squishy indeed!

[zombiwoof]

Hi. New user.

I picked up a first issue gray box DOD 280 compressor recently. I know pedal builders have reproduced the circuit.

I'm wondering if anything can be done to easily improve it, like different value caps or resistors?

Turn the compression up past about 20% and I get pretty annoying lowering of the volume when I strum a loud chord, making it pretty unusable.

Also, do you guys put these first in the chain or at the end of the line right before the amp?

And lastly, how do you convert these early DOD pedals to true bypass with an LED?

Thanks,
Loomis

PS - I scored an original tan Ross Distortion pedal complete in the box today at an estate sale for eight bucks!

This is a common problem with many of the two-knob comps that don't have an "attact/release" control.  The best way to use this type of comp without the "pumping" effect you are describing is to keep the compression pot pretty low and turn up the level.  Anything higher than that on the compression pot and you get increasing "pumping", in other words when you hit a note or chord, the level of the note is low and slowly "pumps" up to the highest volume.  The only fix is to change out a couple of components that set the attack (which has been discussed on this forum in the past) to change the fixed attack, or to actually add an attack/release pot to the pedal.

P.S. The tan U.S.-made Ross Distortion is a great pedal.  It's a "better" MXR Distortion+.  Great deal on that one!.

Al

[Kesh]

You could try changing the compression pot. In some circuits this parallels the LDR side of the vactrol, which falls when you play loud notes. In others it takes the FB circuit to ground.

If the former then if this pot is set up high, then you get a bigger variation in volume between when compression kicks in, and when it doesn't. So just swap it for one half or a quarter or fifth its value.

If the latter then a fixed resistor will parallel the LDR and you could lower this by a half or a quarter instead of the pot.

There will be a gain loss either way, but the compression won't be so wild, so just up the volume control.

There is also a cap, maybe 47u, between the collectors of the two transistors. This controls attack release to some extent, you could try changing it. Also a smallish resistor after, which affects release more, and to some extent threshold.

[loomis]

Thanks guys. I really appreciate the advice thus far.

And yes, that tan Ross distortion pedal really sounds amazing. I can't get over how good it sounds.

Thanks,
Loomis