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Friday, 20 July 2012

Ross Compressor

As predicted! :o)

Although the layouts look different, this is extremely close to the Dyna Comp, I just rejigged things around to make the best use of space.  Unfortunately I needed an extra 3 rows, but c'est la vie. Here is a summary of the differences between the Ross Compressor and the Dyna Comp:

  • 1M resistor from Q1 base to vbias changed to 2 x 470K in series with a 1u cap from the junction of the two to ground.
  • 470K resistor from trimmer 2 to supply changed to 2 x 220K in series with a 1u cap from the junction of the two to ground.
  • Direct connection of Q1 collector to supply changed to 10K resistor with 1u cap from collector to ground.
  • Sustain pot 500K reverse log
  • Output pot 100K linear
  • There was also a 1u cap from vbias to ground but I'd already included a 100u in this position in the Dyna Comp as a more effective noise filter.





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21 comments:

  1. mirosol7 August 2012 at 12:45

    Tag it!

    Buit and tested these two (this and Dyna) simultaneously. These both are really good compressors. I think i have Mr. Squishy clone for sale :)

    They have some minor differences soundwise, but generally i'm leaning more and more to Dyna, as it sounds (in my opinion) a bit more simpler. Both are just great. Fat and round, just like good compressor should be.

    I'm seriously considering about boxing these two in the same box: "The latest attraction from Motown! - Dyna & Ross" :D

    Great builds both of them. Definitely a keepers.

    Thanks a ton!
    +m

    ReplyDelete
  2. mirosol26 December 2012 at 19:43

    Boxing day's boxings part 2:
    http://mirosol.kapsi.fi/varasto/boxes/rcomp.JPG

    Ross comp in large box. For a friend.
    +m

    ReplyDelete
  3. jeff12 January 2013 at 11:05

    hey I don't know if you guys take requests...but I'd really like to see a layout for the Ibanez CP9, Ross variant. Schem is here http://www.tonepad.com/project.asp?id=67

    ReplyDelete
    Replies
    1. jeff12 January 2013 at 11:08

      or http://www.cruachan-audio.pwp.blueyonder.co.uk/schems/Ibanez_CP9.gif

      Delete
    2. mirosol12 January 2013 at 12:25

      Request noted, but for the moment i can't promise anything. If i was to draw it, i would use just single CA3080 to make it sane sizewise...
      +m

      Delete
  4. JUAL KRIPIK SINGKONG5 February 2013 at 02:32

    can i use lm13700 instead of ca3080 with this doughterboard? http://2.bp.blogspot.com/-P7jqffl_ejk/UHVUB0pXl-I/AAAAAAAAC-k/p2HwRW-52S0/s1600/LM13700+Daughterboard.png

    thanks

    ReplyDelete
  5. Unknown9 January 2014 at 21:54

    Yo! This layout looks nice, my board lack a compressor so i might give it a try! I'm a bassplayer so what mods can I do to make it more suitable for bass? I think there are other bassplayers out there in need of the same info :) Regards

    ReplyDelete
  6. Unknown6 February 2014 at 15:00

    I only have a 100k reverse log. Do you think it will work with that instead?
    /Martin

    ReplyDelete
  7. Unknown31 October 2015 at 14:31

    HI guys .
    I tried this one but it doesn't work and Just can't see why.
    Is there something important I might have missed?
    How can I test my circuit?

    ReplyDelete
  8. Unknown10 March 2016 at 19:29

    Hi, I have a question about the trimpot. I read in the Dyna Comp build that the trimpot is for adjusting the input level for noise.

    What should the trimpot initially be set to, 2k or some other value? Has anyone found an acceptable range for an initial setting?

    Thanks you.

    ReplyDelete
  9. Unknown14 June 2016 at 01:56

    I just finished one of these last month. I tried to use some of the keeley values and tantalums for the power filtering. Its actually a little noisier than my MXR Dyna Comp anyone have any ideas as too why. It should be quieter by nature as the ross compressors modded theirs to address the issue. HMMMM?

    ReplyDelete
  10. Unknown14 June 2016 at 01:56

    I just finished one of these last month. I tried to use some of the keeley values and tantalums for the power filtering. Its actually a little noisier than my MXR Dyna Comp anyone have any ideas as too why. It should be quieter by nature as the ross compressors modded theirs to address the issue. HMMMM?

    ReplyDelete
  11. Kique18 December 2016 at 17:05

    Hi. In Q3,Q4,and perhaps Q5 low hfe is equal to more compression?
    I'd like to get more compression.

    ReplyDelete
  12. GTECH20 April 2017 at 19:34

    thank iviark

    https://youtu.be/07wyxlJG4bQ

    ReplyDelete
  13. Setenzak21 October 2017 at 22:32

    Hi all,

    I finished it many years ago. And found it great on clean.
    Just a little bit noisy but it's how ross compressor work.

    This compressor fix my problem on wahwah (thomas organ cry baby wah). I had a tone sucking with a Fuzz Factor'. I tried some output buffer but it dosent work as the Ross compressor.

    ReplyDelete
  14. Greedy_Fly8 July 2018 at 13:48

    2 x 100uF capacitors??? I can't find it on Ross Compressor schematic... maybe a mistake?

    ReplyDelete
  15. Greedy_Fly8 July 2018 at 14:01

    First 100uF cap... its a just filter! Ok!... Second???

    ReplyDelete
  16. cacopanda27 August 2018 at 15:06

    I built this without the 2x 100 uF caps as I cannot locate them in Ross schematic and other online resources. I included the mods described in Fuzz Central. Works wonders.

    ReplyDelete
    Replies
    1. cacopanda27 August 2018 at 15:23

      PS. I used metal film boxed caps for 1 uF. It was a tight fit I must say.

      Delete
  17. cctsim17 February 2022 at 01:26

    There are 2 errors in the layout around Q1. Coming out of the emitter of Q1, the 1M resistor should not connect to the 10k resistor but the other side of 1uF. A cut is also needed to prevent the capacitor connecting to the 470k resistor.

    ReplyDelete