Flatline Compressor with CLM6000 opto isolators...

[isildur100]

Hi there!

I just bread-boarded John Hollis' Flatline compressor and tried to use the CLM6000 opto in there. It does not work as it should. It does compress a bit when I find the right sustain pot position. I believe I can't just replace the VTL5Cx opto with the CLM6000. I tried different CLM6000's some having Ron under 1k, others over 1k. It did not compress at all with those under 1k, although being under 1k is considered better for this component... Anyways...

Could anyone point me to what I should adjust in the circuit? I suspect it has something to do with biasing the current going to the led part of the opto....

cheers

[petemoore]

  There are resistora around most of those Photocell/LED [all the ones I've see] circuits which can alter the current through the LED.
  I was just messin' with a DOD280 compressor and Neutron Filter [both have LDR/LEDs'], the high brightness green LED's perked them up, but I changed other stuff [the light capsule and LED/LDR orientations]. I made the current controlling resistor a pot+Stop resistor [pick the stop resistor carefully so enough/not so much current to fry the LED is had]...Nice since I have room, extra control...makes it easy to pick the right R for current.

[isildur100]

Hi Pete, thanks!

I have tried putting a 1k resistor just before the anode of the the LED part of the CLM6000 and it works a lot better. I guess the best thing would be to put a 1k trim pot in series with a 330R and tweak it to perfection.

cheers

[petemoore]

  I like that one, had it on my DOD280 !
 Since it's homebrew Green LED/LDR, I put another RED LED behind the Green, shining right through it's body. Same thing for Neutron and whew nice control !
 So I don't burn the newly introduced RED LED [what color I had does it's job N/P], I used a 1k limiting resistor.
 To make RED adjustable down to very dim, I put a 500k [+ the 1k stop resistor] in the supply circuit [9V], I don't think it needs to go dimmer.
 Fixed the ripple and allows fine control of the DOD's sweep, since both designs are photocontrolled compressors...I almost hesitate to suggest dig out your fancy, closed/neat photo-unit and make the compressor ''floor'' adjustable in order to have more control over ripple, sweep range, ramp rates etc.
  ...wonderin' a bit how the Flatline differs, would have to actually look at it.
  I've had this comp first and last in chain, wouldn't mind another since the rackmount-on-floor offers additional room.
 Between the gain, output volume, and comp-floor-elevator adjustment, it's N/P now to get ripple-reduced, wildness-tamed compression sweeps.
 

[isildur100]

I will have to look at the DOD280. 

I am working on a mod for the flatline, incorporating Mark Hammer's punchline and other stuff. Will post it when I'm finished.

[isildur100]

Here is my mod for the flatline. I didn't use the Punchline mod. Basically, I added a compression level knob, compression type switch and changed some caps and resistor values. The compression level pot really makes a difference, you get a lot more control over the strength of the compression. I believe you could add it to the original flatline design without changing anything else but I had optimal results after tweaking some resistors and caps values. The compression switch type is there a bit by accident. At first, I had forgot to put the 10k resistor (where that 8.2k and switch are) and after some tweaking, really liked the sound which gives a more subtle compression with lots of sustain. When I realized that there should be a 10k resistor there, I decided to keep both compression types using a switch. The 10k resistor became a 8.2k, sounded better to me like that.

I used a 10uf cap instead of a 100uf at the diode bridge. Tried lower than 10uf and it didn't sound right. 100uf sounded more sluggish. 10uf was just perfect.

I used a 100uf instead of a 10uf right after the voltage divider. This made the whole sound more stable with less noise.

It works good with a CLM6000 but I guess it can work also with other optos or hand made led/ldr.

Here is the schematic: