Monday, 30 May 2016

Korg CMP-1 / Yamaha CO-01 Compressor

Here is a layout for a vintage compressor.
Schematic is available on FSB forum here.
Couldn't find any good videos around.

It has been drawn to fit any common NPN trarnsistor but if you go for the original mind the pinout!

13 comments:

  1. I found what it seems to be a decent video here ;)
    https://www.youtube.com/watch?v=FJi8LD-0_wk

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  2. Thanks Alex. Will have to try this one out!

    Off topic and I'm sorry but I've no other way to contact you:

    I have the schematic for the Dr. Scientist Woofer Wailer and I'm desperate to build one but don't have the knowledge to make it into a Vero layout. Is there anyway I can get the schematic over to you for you to convert it?

    Thanks a bunch!

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    Replies
    1. Hi Mat!
      You could post it on the Forum/Requests where a lot of people would be able to draw a layout or, if you want to send it via email, you could still go on Forum and click on my name somewhere (always on the left site).
      It will give you the option to send a private email (for example you could go to Forum/Contribution/Unverified Layouts/ISP Decimator)

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    2. Hi Alex

      Yeah I tried the requests section a while ago but it never got picked up.

      I've emailed it to you now. Hope you can get to it via the dropbox link.

      Thanks.

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    3. Hi Mat.
      I've missed that one!
      I've added a layout in the Forum/Contributions section.

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  3. Alex...

    What makes the compression in this circuit - it is not optical. Is it the 13600?

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    Replies
    1. 13600 is a dual OTA - as in two CA3080s in a single chip.
      +m

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  4. Replies
    1. Oh - but I still don't know what makes this a compressor. I didn't see an optical component. Those 3080s are pretty cool chips, I guess they have built in buffers, as I understand it.

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    2. It is the 13600 that produces the compression in this circuit. 3080s do not have built in buffers, however the 13600 and 13700 do.

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    3. There's lots of different types of compressor circuits. Read about the Orange Squeezer here. It doesn't use an OTA like this, but uses FETs to change the gain/make compression? Enlightening http://www.diystompboxes.com/smfforum/index.php?topic=54308.msg414842#msg414842

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    4. OTA (Operational Transconductance Amplifier) is also known as VCA (Voltage Controlled Amplifier). This means that the envelope created by the signal strenght alters the voltage and this voltage is sent to control pin of the OTA/VCA - Which then controls the gain of the signal according to that envelope.

      13600 here is just an dual OTA/VCA with the other channel unused. This means that the compression is created basically in the same manner as it is in MXR Dyna / Ross Comp.

      Three basic ways of creating a compression, or envelope controlled amplifier, are optical (one you already noted), OTA (as i described above) and the third, FET compression (as Charles stated). You could achieve similar effet with DSP too, but as analog circuits go, these three are the ones tha have been around for decades.

      Buffered chip is just another feature of 13600/13700 that doesn't have anything to do with the compression itself.

      Does this answer your question what makes this a compressor? I think i may have explained what a compressor is...
      +m

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