DOD 280 compressor mod

[Uma Floresta]

 

Originally posted by freeridstylee hummm weird, mines boards different then yours. Same orange casing sn 2806808. Its a much lighter board with only a small green tint and plastic pot knobs that are mounted on the opposite side of the components. I not sure exactly where to put the resistor, theres 4 legs, 2 are spread far apart, and 2 are close. Do i want to put the resistor inbetween the 2 spread apart legs or between the 2 close legs?

 

 

 

I don't have it with me now, but there are two legs that come from the top of the LDR and run down to the board, on the side nearest the edge of the PCB. The other two legs behind come from the bottom of the LDR and run into the board. On mine it

[Uma Floresta]

 

Originally posted by Web Surf This can be fixed as well, I suppose. First we looked at the minimum gain and increased it. The way we did it reduces the maximum gain. We can always calculate a different resitor to use in parallel to the LDR to get the same maximum gain as before. I could assist if you inform me the values that the LDR has at the beginning and the end of a guitar note ( when disconnected !!! )

 

 

I tried that at one point and I couldn't get a reading -- I am looking for a resistance value, yes?

[Web Surf]

Yes, resistance values

 

Disconnect one leg of the LDR

 

 

Put a Digital Multimeter across it

 

Read the initial value when no guitar signal

 

 

Read the value when you just hit a chord or note

 

PS : maybe you could also get some readings with the LDR in circuit

[Wilbo26]

 

Can anyone spot anything obvious here??? No matter what settings I put this thing it it starts out at a low volume and then swells up to a much higher volume...seems to be the opposite of Uma's problem.

 

 

 

 

Any help would be appreciated. I can take more pics of whatever if anyone thinks it might be helpful.

[AMZ-FX]

Can anyone spot anything obvious here??? No matter what settings I put this thing it it starts out at a low volume and then swells up to a much higher volume...seems to be the opposite of Uma's problem.

That seems to indicate that you are getting too much gain reduction when the signal first hits the circuit. The strong signals hit the transistors which turn on and light up the LED in the Vactrol when makes the signal soft. Then as the signal drops off, the LED is less brightly lit and the resistance of the Vactrol goes up, which increases gain (swells up).

 

You can change this by increasing the value of R10 (if it's doing this at most settings of R4).

 

regards, Jack

[Wilbo26]

That seems to indicate that you are getting too much gain reduction when the signal first hits the circuit. The strong signals hit the transistors which turn on and light up the LED in the Vactrol when makes the signal soft. Then as the signal drops off, the LED is less brightly lit and the resistance of the Vactrol goes up, which increases gain (swells up). You can change this by increasing the value of R10 (if it's doing this at most settings of R4). regards, Jack

Wow. You're good. I'll give that a try and check back.

[Uma Floresta]

I moved some files around in my photobucket account, and some links to images were broken. Just posting them again for reference. Looks like Wilbo has the older version.

 

 

[Wilbo26]

Thanks! Those should come in handy.

[Web Surf]

Wilbo,

 

Assuming you did the same mods as Uma,

 

A) Do you have active or high output pups ?

 

B) How does the box work when you reduce guitar volume ?

 

 

Uma, the remaining probs of less compression can be worked out. Remember my earlier post where I needed the data on the min and max resistance of the LDR so we can recalculate the min and max gain of the compressor. Right now, all we did is up the min gain so it does not choke up. If we up the max gain, you will have full compression again.

 

 

Another thing I would like to try out is to only compress the bass and let treble pass through unaltered. I read that this preserves some of the attack while still levelling average signal level

[keef riffers]

Hey i just wanted to bump this thread. I got an orignal one of these, the old gray one. It too has the same problem. I would like to do the mod if the schems are the same.

 

Also, I was wondering

 

if I get it true bypassed will there be a volume drop?

 

Is there a way to goose the volume up a little bit, perhaps by getting a different value pot for the volume? without adversely affecting tone?

 

thanks!

[keef riffers]

I'ma just bump this a bit

thx!

[PCjunket]

Having the same issue with the new 280 compressor reissue, sound fading in and out with level of strumming impact. Stumbled across this thread searching for known issues with the pedal. Very intrigued and handy myself with a soldering iron. Has anyone come across this thread with the reissue model and the same concerns as me.?

[AMZ-FX]

You may have to turn down the Comp knob since it is providing gain to the detector and the photocell. If it is too high, the compression clamps down hard on the signal.

regards. Jack