Announcement
Collapse
No announcement yet.

Optical Compressor

Collapse
X
  • Time
  • Show
Clear All
new posts

  • Optical Compressor

    Bought an optical compressor on eBay. I was able to solder it up and get it working in about an hours work.
    not a bad little box for $19 and free shipping. No tone control, just sustain and volume but that's all you typically need anyway.

    Click image for larger version

Name:	00002.JPG
Views:	1
Size:	59.0 KB
ID:	32373116

    Click image for larger version

Name:	0001.JPG
Views:	1
Size:	53.6 KB
ID:	32373117


    Click image for larger version

Name:	00003.jpg
Views:	1
Size:	67.9 KB
ID:	32373118






  • #2
    Where is the compressor bulb?
    Originally posted by Unconfigured Static HTML Widget...








    Write Something, or Drag and Drop Images Here...

    Comment


    • #3
      It uses an LED and Optical resistor which form an opto coupler.
      This is actually superior to the older ones that used an incandescent bulb.
      A light bulb takes time to heat up and develop light. That allows too much music to get by before the compression begins.

      Some of the old opto compressors that used lamps were OK for program material, an entire mix, but too slow for individual
      instruments like a tight snare or guitar. LED's are much faster and will allow the attack to occur in the millisecond ranges where they benefit instruments like guitar.




      Click image for larger version

Name:	0001c.jpg
Views:	1
Size:	55.6 KB
ID:	32373276


      Comment


      • #4
        Oh. Ok. I was looking for something like that power light How does it sound?
        Originally posted by Unconfigured Static HTML Widget...








        Write Something, or Drag and Drop Images Here...

        Comment


        • #5
          Cool. Is it one of these? https://www.ebay.com/itm/BYOC-Build-...S!-1:rk:4:pf:0
          Official HCAG “Theory-Challenged Hack”
          Member of the IBANEZ ACOUSTIC ASSASSINS
          Proud Member of The Alvarez Alliance
          Member of the Schecter Society
          Person-2-Person on the Web

          Comment


          • #6
            Holy price difference.
            Originally posted by Unconfigured Static HTML Widget...








            Write Something, or Drag and Drop Images Here...

            Comment


            • #7
              I built it at work on my break. Then I took it home last night to try it out. It didn't power up or pass a signal right off. I failed to identify the Tip and ring properly on those cheap plastic jacks. A quick solder job to flip a couple of wires got the box working in bypass mode but no power when turned on.

              I didn't use the adaptor very long. When it didn't power up immediately I pulled the power plug and dug into it a bit deeper.

              Didn't take long to find the fault. The diagram has the power plug wired for a positive center adaptor. Standard adaptors these days use a negative center pin. I had to rewire the jack for a positive sleeve and the pedal powered right up.

              The only other thing, I had the pots mounted in the wrong holes. The sustain and volume were opposite. This was an error on how the box was labeled. The order of the wires coming off the board put the pots on the wrong sides according to the labels. Luckily the wires to the pots were long enough to remove the pots and crisscross their mounting without any major assembly issues. I was even able to stick the assembly picture they provided in the box over the circuit board in case I ever needed it again, it would be inside the pedal case.

              As far as sound goes, the fidelity/Frequency response was quite good. I'd easily rate that equal to any Boss pedal I've used. There was no Tone sucking and you had amble volume to use the pedal as a volume booster if you wanted. I was able to get a 1:1 volume boost with the volume pot on 1/4. Cranked up you'd begin to get a little hiss over 3/4 which you'd expect with a gain boost (at least 10dB in my estimation)


              The sustain/compression knob was fairly mild. you wont over-compress with this pedal. It seemed to clamp the volume down maybe 4db? That's enough to smooth the attack of choppy chords. The release was very long ( as with most optical compressors) and is what I wanted from it. It will likely do an excellent job on sustained leads notes.

              The Attack however, was a bit too fast for my liking. If I were to estimate its maybe 3~4ms which is more adapt to vocals or snare. For guitar I like having 6~12ms for chords and leads.

              I have a suspicion I can fix this by putting some distance between the LED and Photo Resistor. I have more volume then I need and separating the two should increase the attack times.

              If that doesn't work, I can also try putting a small capacitor in parallel with the photo resistor. As the resistance changes the voltage drop/rise will be slowed by the time the cap takes to charge and discharge. It would affect both the attack and release but that's not a big deal to me. I typically dial the attack and release to take about the same amount of time anyway with pedals that have separate adjustments.

              I could also put that cap in series with an additional pot so I can adjust how much capacitance is added. It would give me some control I don't have at the moment. Not sure if its something I want to add unless its necessary. I used to prefer more complexity as a kid. I figured the more parameters I had the easier it would be to set the ideal parameters.

              After years of using complex gear in live settings I reversed that opinion. It was fun to have all that stuff when I was young and learning. It let me find the ideal tones I prefer from all the possibilities. I'm typically too busy when performing to be bothered having to set a gazillion parameters, either on a guitar or pedals. At most I want to push a button and get the ideal sounds and not have to tweak anything.

              On pedals that have allot of setting I use rubber washers under the knobs which make the knobs hard to turn. Once the knobs are set they wont get bumped moving the pedal which makes them pretty much plug and play.

              Anyway, I think with a little extra tweaking I can get this pedal to do exactly what I want. Again, the diagram wasn't that hot on this one. If I didn't have 50 years experience in electronics I could have gotten screwed up building it in a few areas. The components were all fine but an actual schematic should have been included.

              If I were to advise someone with no experience building, you can just as easily buy one of these Monoprice Compressors for $19 https://www.monoprice.com/product?p_...SABEgI72vD_BwE
              Its an optical compressor and it has the added benefit of a tone control added.

              Comment

              Working...
              X