This is a library of perfboard and single-sided PCB effect layouts for guitar and bass. I'm not an electrical engineer by any stretch of the imagination, just a DIY'er who likes drawing layouts. It is meant for the hobbyist (so commercial use of any of these layout is not allowed without permission) and as a way to give back to the online DIY community.

Monday, June 6, 2016

Keeley 4-Knob Compressor

The Keeley 4-Knob Compressor is a modified Ross Compressor and is highly regarded in the stompbox world. It's only down side is the use of the obsolete CA3080 chip. These can be hard to find and a little pricy. However if you're unable to find one, or unwilling to pay for one, use the LM13700 chip (which is 2 3080s in one) and this conversion daughter board. The schematic can be found here. If you have a hard time getting 150k pots, use a 250k pot with a 390k resistor in parallel (between lugs 1 and 3).


50 comments:

  1. Yaayyy! Another keeley!!
    What happen to "recent comments" fiture of this blog? It seems no longer working.
    Anyway, you are awesome as usual brother!

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    1. Yeah the code for that widget seems to be broken. *shrug*

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    2. one more, if I have to replace that B150Ks, what would you suggest?

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    3. Read the last sentence of the post

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    4. ah... how could I missed that last sentence... my bad

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  2. can i use this compressor with my active bass?

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  3. Verified! sustain is great) nice tapping :3

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  4. Great to see this one is verified. My build is 90% and still ongoing. Anyway, i replace the 150p ceramic with 100p and 47p in parrarel. Hope it would be fine

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  5. Just realize that the ATTACK on the perfboard is different to the pcb version. Which one should I stick with?

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    Replies
    1. I'll fix that. The PCB side is correct.

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  6. Hello! The solder side wiring pattern seems to be different from that of parts side around level pot connection point.For instance, 10nf cap connected to No3pin of 3080 is missing.Which should I stick with?

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    1. yea yea, I just realized it. perhaps this was the reason why my build didnt produce any sound..

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    2. Bericau,
      After my previous post, I figured out the issued solder-side also works.I have just confirmed it Sounds, not boxed yet though.Move the 10nFCap to below 15k resistor, and 1uF should be placed on the left side of the 15k connected to the ground via the hole on the left of 1M resistor.Minus pin to the ground.

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    3. Oh man, I must have had a massive brain fart. haha! It's fixed now and is consistent between the parts layout and the solder side. Sorry about that!

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    4. @shimaneko, from what I read, you only move the components and don't change the way they are connected, am I right?
      so my problem is likely bad component(s)..

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  7. UPDATE
    my build is now working, but I really get fuzzier sound as I roll the SUSTAIN pot up.
    for consideration, I use 100pF for the yellow cap instead of 150pF.
    any suggestion to fix my build?
    help me, anybody

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  8. most update
    my build is now perfectly working
    the problem was that my new strat's pickups were too close to string which made my gain was too loud
    done this one
    awesome like usual!

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  9. Could you please do the one with blend/ratio mod?
    Thank you very much bro

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    Replies
    1. use a blender. I'm about to try it though...

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  10. just curious, if the output gain is too loud, will changing the 10k resistor solve the problem?

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    Replies
    1. Yeah increasing that resistor would lower the output, but so would turning down the level pot ;)

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  11. I finished my foot today , big pedal this , in place of the potentiometer 150k put a de200K with a 680K resistor between pin 1 and 3 , it was great

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  12. It's working but I don't have compression :/ Sustain works, Clipping works and Level works, but the Attack pot doesn't work. Any Idea? I put my multimeter in the 1 and 3 lug and gives me 150k, so I assume it's working outside de circuit.

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  13. No encuentro el diodo 5817, reemplazo?

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  14. I got sound with the cable not plugged when i plug it i got no sound any ideas?

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  15. Hi, this compressor is like keeley bassist?

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    Replies
    1. No. The Bassist is based around a THAT chip I believe. This is just a modified Ross Compressor.

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  16. What type of capacitor is big 1uF to clip 3?

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  17. Hi, can anybody help me?
    If I have sound signal at pins 2 and 3 of the IC which are the inputs of CA3080 then I should have had sound signal at pin 6 too, which is the out put of this IC right? And if there's no any sound at pin 6 then probably my CA3080 is bad, isn't it?

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    Replies
    1. and I have something around 8V at pin 6

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    2. Yeah I'd say either your chip is bad or you've got a short that's letting voltage from pin 7 bleed in.

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    3. I've checked It one more time, now I have 2.4 V at pin 6 and 0.1 V at pin 5 which is the amplifier bias, but right before 27k I have smth around 8 V, can't remember exactly now. But that's interesting, before 27k there are let's say 8V and right after 27k which connects to pin 5 I have 0.1. seems like the IC sucks all the current :D

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    4. p.s at pin 7 I have 9V as it's supposed to be

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    5. So, I've changed the CA3080, With the first one, I had no sound at all, with the second one a have a mega fuzz-distortion pedal ))). It's even more distorted than may Box of Rock.

      So.. again a bad IC or I have something wrong in my circuit?

      Thanks.

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    6. Have you checked the rest of the build for faults? Run an audio probe through it any?

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  18. Hi! Please help me! Built it but it sounds distorted and there's no compression!
    I checked all the connections, they worked. no bridges. tried different transistors, tried 2 different 3080. nothing.
    Here you can see the pcb:
    https://ibb.co/e6xh9k
    https://ibb.co/mfsw25
    here you are my 3080 voltages:
    current 9.40

    1 0.02
    2 4.58
    3 4.55
    4 0
    5 0.01
    6 9.21
    7 2.85
    8 0.68

    thanks thanks a lot! it's months that i'm trying to get it working!

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  19. sorry I put the voltages in the wrong order. here you are the right one. thanks
    1 0.02
    2 4.58
    3 4.55
    4 0
    5 0.68
    6 2.85
    7 9.21
    8 0.01

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  20. This is a really great pedal compressor. Thank you again, David. You, sir, are a legend! =)

    One thing I noticed in my build is that clipping control changes the tonality a bit - the lower it's set the less low end I get at the output (with overall output level matched). Is it normal for this ciruit?

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    1. Not sure. I haven't built it. You'd have to compare it to a demo.

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    2. it does like it supposed to be. so I believe that's normal

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  21. I am the only one who got a lot of RF interference in this project even shielding the enclosure?

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