Saturday, 21 July 2012

Keeley 4-Knob Compressor

So close to the Ross Compressor that the 2-knob versions seems to be essentially verbatim, but I thought the 4 knob version was worth adding for the additional Clip and Attack controls.  In the original the onboard trimmer isn't used and instead two 1K resistors were used between the bottom lug of the (top left) 220K and IC pins 2 and 3.  Rather than adding fixed resistors I thought it made more sense to leave the 2K trimmer and suggest leaving it in the dead centre position for the stock setting, and so allowing the Clip pot to perform that task, which would mean that you will have some additional tweaking capability to set the base input level using the trimmer which you wouldn't get from the Keeley.  So maybe this can be the 4½-Knob Compressor! :o)

Info from RK about the original:

The Keeley Compressor is the award winning industry standard for stomp box compression. The 4 Knob adds Input Clipping and Attack controls to the top of the the original Keeley compressor for easy adjustment. Perfect for those that often switch live between single coils and humbuckers. The sound alone will inspire your creativity.

All of our Compressors are hand built in the USA. Unlike any other compressor, the Keeley Compressor was given the Editor’s Pick Award from Guitar Player’s Magazine and recently awarded Reader’s Choice for Stomp Box. It is a true audiophile and studio grade compressor with an exotic rack mount quality in a stomp box form.







After a few people mentioned wanting to use resistors instead of the trimmer and so mean that it's one less "special item" you have to get in, here's a rejigged revision with the 1K resistors.  I still think I'll build it with the trimmer because I like the idea of that fine tuning ability, but you can build whichever version you prefer.


BOM:

Group Value
Tot
Qty
Resistors 1K
2
Resistors 10K
7
Resistors 15K
1
Resistors 27K
2
Resistors 56K
1
Resistors 150K
1
Resistors 220K
2
Resistors 470K
2
Resistors 1M
4
Resistors 4M7
1
Capacitors 150p
1
Capacitors 1n
1
Capacitors 2n2
1
Capacitors 10n
5
Capacitors 47n
1
Capacitors 1u
6
Capacitors 10u
2
Diodes 1N4148
2
Transistors 2N5088
5
IC CA3080
1

273 comments:

  1. Hey there! I'm really exited to start this project but this would be my first vero build and was wondering about a few things...
    1-Is the long black line that crosses the board a jumper? And what are the white dots with the blue line around them?
    2-All the pots are missing one of the cables, do they all go to ground?
    3-should wire the switch in any special way or the same as always?

    Sorry for such beginer questions... im new to this, but I really love the process of building them! thanx!

    ReplyDelete
  2. Hi Jonathan

    1 - Yes the black lines are just jumpers, and the blue and white dots are where two links are soldered in a single hole. I do that sometimes just to save space if it means I don't have to make a layout wider than it needs to be (especially when trying to get the layout to comfortably fit in a certain size box, 1590B in this case).

    2 - All the pots with the exception of the "Output" pot are simple variable resistors and so only 2 lugs were used in the original. The other lug can be ignored. For the "Output" pot the second lug is the output to the switch and so all 3 lugs are used with that one.

    3 - Same as always like this: http://tagboardeffects.blogspot.com/2012/02/offboard-wiring.html. The switching is always the same in my layouts unless noted.

    ReplyDelete
    Replies
    1. Hi. Beginner here too. Jeff. In the 'offboard' wiring pix there is a wire marked 'output' coming from the pcb -> 3pdt swtch-> output jack. Very few peals have an actual 'output' wire from the pcb while most instruct '#2 volume -> output jack. SORRY!
      Q)What is the origin of the wire from the pcb labled output?
      Is that drawn as if there is an output wire and if no output wire exists is it just #2 volume to output and that's it? That's the only thing that confuses me (other than women)is the output connections.
      Jeff

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    2. Every board has an output, the question is, what does the output go to. In something like the TS808 the volume control is earlier in the circuit and so "Output" is marked on the actual board which is then taken directly to the switch. In most effects the volume control is between the board and the switch to attenuate the final signal and so the output of the board is marked "Volume 3" and of course then goes to the Volume 3 lug, Volume 2 is then the output which goes to the switch, and Volume 1 goes to ground. I could still mark the board up as "Output" but it wouldn't make much sense because then I'd have to add an additional note saying "Output to Volume 3".

      Delete
    3. Incidentally, if your confusion is about why there is an Output 1 and Output 3 on the board, that's simply because the Keeley Compressor labels it's volume pot as "Output" so I label the layouts accordingly.

      Delete
    4. Hey there ! Im a newbee here too this is my first project and I had a couple questions concerning your plan

      1 - In your plan there are little pink/red point I was wondering what they were exactly .. ?

      2- Do you have the chart for the condensors used in the plan with the specifications and all or a reference of some sort that could help me out with the types of condensors that I should use ? Do you have the complete part listing to be able to complete this project. i know they are written but I really want to make sure that I do it right

      3- Do you have a picture or plan you could send me that I could see the finished product once completed without the back panel ?

      4- I read the part about the output1 and 3 and Im not sure I quite understood completely what you mean ... could you re-explain it to make sure that I grasp the concept please .. ?

      I would appreciate any reply on your part that could help me out to get this done ! Thanks in advance !

      Delete
    5. 1) They're track cuts, you can use a dedicated cutting tool which you'll find on eBay, or just twist an oversize drill bit in the hole to cut out the copper. Bear in mind that the layouts are all shown as component side up, and so when you turn the board round to make the track cuts, the layout will need mirroring to show exactly where the cuts will go.

      2) For picofarad values I tend to use multi layer ceramic caps, but ceramic would be fine to. For values from 1 nanofarad up to 1 microfarad I use polyester film caps. I use Panasonic ECQ* which can be found from a number of sellers on eBay, but there are plenty of other choices widely available like greenies, so just get what is more readily available to you. For values greater than 1 microfarad I use aluminium electrolytic or sometimes tantalums if I want to keep the size down to something more manageable.

      3) DrRJE, GuyC and JaviCAP posted pics here:
      http://fearedandloathed.com/Images/BYOC/k4k_front.jpg
      http://fearedandloathed.com/Images/BYOC/k4k_back.jpg
      https://sphotos-b.xx.fbcdn.net/hphotos-ash4/422207_10151131301885751_2103529966_n.jpg
      https://sphotos-b.xx.fbcdn.net/hphotos-ash4/405490_10151131302905751_1371921857_n.jpg
      http://guitarrasimportacion.foroactivo.com/t486-capinc-effects-10-crystal-glory-keeley-4-knob-compressor#6818

      4) "Output" is what Keeley called the volume pot on this effect. So Output 1 goes to lug 1 of the "Output" pot, Output 3 goes to lug 3 of the "Output" pot. Lug 2 of the "Output" pot then goes back to the switch as the true output.

      Delete
  3. heard so much good about this one, think i mightdo this instead of the ross. but as you said iv'e also heard it's veeeery close to the ross, just more options. lacking 500k rev log pots though... always something, atleast my parts stash getting better and better!

    ReplyDelete
    Replies
    1. I don't have any 500K reverse log pots either, I'll probably just use linear.

      Delete
    2. Build this keeley sound god,use pot 250k like miro say,
      i want DUMB for my bass,cant u help me iviark?thank before
      my english from google translate :)

      Delete
  4. hmm, realised i don't have the lm3080 either, bought some from the bay today. the 150k pots are harder to score. i never really understood this with modding pots, iv'e read the pot secret guide at geofx but didnt really get it. can this resistor method always be used or is it a matter of the spot it is beeing used in for every build if it will work or not?

    ReplyDelete
    Replies
    1. I'd probably just use a 100K for the clip pot, but the Attack pot is probably more important. You could try a 100K and alter the 10K Attack 1 resistor to 62K, but you'll lose some control over the attack level. Have a look at this for making your own custom pots:

      http://www.diystompboxes.com/analogalchemy/emh/emh.html

      Click on the Linear Pot link on the left.

      Delete
    2. so you actually have to use two resistors to change teh value of a linear pot? i thought that was just to make custom tapers...

      Delete
  5. This is a silly question and I should know it since I've built loads of pedals..

    How do I replace a trimmer with a resistor? I wanna put a 1k instead of the 2k trimmer.

    ReplyDelete
    Replies
    1. Two resistors. One 1K would go between where lug 1 and lug 2 connect, another 1K would go between where lug 2 and lug 3 connect. I do think the trimmer will still be useful though so you can preset the input level so there is no noise introduced by the Clip pot.

      Delete
    2. Ah I see, I might just have it as a 5-knob compressor then ;)

      Delete
    3. You could have it as an external pot, but once you set it up for your gear you'd probably never touch it again. The Clip pot ultimately sets the input level, this trimmer allows you to decide how much of that signal is allowed through to the opamp and so you can preset it so that when the Clip pot is in the maximum level position, no noise is introduced. This would then make the Clip pot potentially useful throughout its entire range rather than for instance having the first 10% of the rotation never being useed because it makes the pedal noisy.

      Basically it's just a "Fine Tune" control for the Clip pot.

      Delete
  6. I built a keeley clone a while back and it never sounded right... I did all the dynacomp mods and researched everything. I had been looking at gut shots and noticed that keeley used Tantulum caps for all the caps... This believe it or not, makes a HUGE difference in the way the pedal responds- more treble, "quicker" response. try it and see if you agree with me. I just used the little yellow "dipped" tantulums.

    you know what would be awesome... if someone added a master "Blend" control

    ReplyDelete
    Replies
    1. Yes all the electrolytics are tantalum, and the only 1u cap that isn't tantalum is the one shown between Q1 emitter and Clip 1 as per the original.

      Delete
    2. Incidentally, I would be happy to do a 5 knob version with a blend circuit but it would make the layout around 5 rows taller at the same width making it more difficult to get in a 1590B size box. If you look at the actual size of the blend circuit:

      http://tagboardeffects.blogspot.com/2012/02/split-n-blend.html

      you could easily make that up on a little daughterboard and stick it to the side of the box somewhere with velcro so it's out of the way and won't make the main board unnecessarily bigger. If you want me to do it then let me know and I'll just tack it to the bottom like with the updated Funk Machine layout, but I suspect in this instance most people would prefer to use the smaller daughterboard to make it easier to keep everything in a smaller box.

      Delete
  7. just swapped out my electros for tants...looking forward to boxing it up...daughter board?! yes please...might as well listen to this while drawing it up...i'll listen to it while adding it on :) http://grooveshark.com/s/Daughter/3oVqt2?src=5

    ReplyDelete
    Replies
    1. Yay Pearl Jam! :o) You didn't say whether it was working though, or are you waiting until it's boxed to test?

      Delete
    2. BTW, would love to know how close the BYOC 5 knob compressor is to this compressor circuit-wise...built one of those for a buddy and he swears it's the best he's heard. I only used it a few times before giving it to him, so I really don't remember how good it sounded -- ended up building a couple of rothwell love squeezes since then and that's been my go-to compressor since.

      Delete
    3. Ha. yes...haven't tested...hope to verify when I put my little guy to bed tonight ;)

      Delete
    4. Have you got a link to the BYOC scheme? It's fresh in my head so I'll probably be able to tell you straight away.

      And say goodnight to the little guy later from the IvIark family. Mine are already asleep, as I should probably be by now!

      Delete
  8. thanks :)

    I think there is a better link, but it's definitely at the bottom of this pdf

    http://buildyourownclone.com/compressorinstructions.pdf

    ReplyDelete
    Replies
    1. Very close to the Ross (and so them all really) but the tone circuit has replaced the 15K resistor at the non inverting input of the opamp, and there are a couple of buffer at the end which aren't in the original with one acting as a blend. So yes it looks like the BYOC didn't bother with the Clip pot and instead used Blend and Tone. Looking at it I reckon the BYOC version looks much more useful to most people.

      Delete
  9. well then, i guess it makes sense that A)people like BYOC stuff, and B)BYOC is keeping that circuit bundled in with the kit...which I'm sure is much more profitable for them. That said, I love byoc too...but your site will always be on my daily visits.

    ReplyDelete
    Replies
    1. BYOC is cool, I always check the site out too. The more the merrier with DIY, it gives us more places to get some inspiration and ideas from.

      Delete
  10. i've always wondered how that tone control would sound on those comps. would it be more of a tone cut? or does it add brightness? seems like it would have to be somewhat artificial due to the nature of the circuit

    however, what do i know

    ReplyDelete
    Replies
    1. It's a high pass filter so it will just cut some low end.

      Delete
  11. boxed it up in a test case and it's not working for me yet...gunna go over it tonight. Is this verified already tho?

    ReplyDelete
    Replies
    1. No it's not verified, I'll go over the layout in the meantime, but if you can get the IC and transistor voltages that may give us some clues.

      Delete
  12. Alrighty, here are my voltages :)

    IC
    1. 8.45
    2. 8.80
    3. 8.75
    4. 0.4
    5. 8.25
    6. 8.45
    7. 9.29
    8. 8.99

    Q1
    E. 2.44
    B. 2.82
    C. 6.84

    Q2
    E. 7.72
    B. 8.41
    C. 7.75

    Q3
    E. 0.4
    B. 8.41
    C. 3.18

    Q4
    E. 0.7
    B. 0.7
    C. 3.18

    Q5
    E. 8.77
    B. 9.23
    C. 9.30

    2 things I did that are not exactly like the layout:

    1. used a 25 turn trimpot for more accuracy. set it so 1&2 = 2&3. on the board, the pins are inline, not offset, but they i think it should be fine?
    2. had to chain together a few ceramics to add upto the 150pF

    Pics:
    http://fearedandloathed.com/Images/BYOC/k4k_front.jpg
    http://fearedandloathed.com/Images/BYOC/k4k_back.jpg

    (in the back pic, the IC is notch up on the upper left side)

    fingers crossed!

    ReplyDelete
    Replies
    1. Hee hee, you keep coming up with these mysteries! :o) Well Q1 looks good but that's about it! A couple of weird things straight away, pin 4 of the IC is directly connected to ground (well via the link but still solid copper) and yet it is showing 0.4V instead of 0V. But even more surprisingly than that, the collectors of Q3 and Q4 and the base of Q5 are all directly connected on the same row, and yet the collectors have a reading of 3.18V, the base has a reading of 9.23V?! Your cuts and links all look good and I can't see any break in that track which may be causing the problem but there is something very weird going on there!

      It's like the OD820 all over again :o)

      Have you checked for unwanted continuity across consecutive rows? The anomolies really remind me of the Maxon so this is crying out "Microscopic bridge"!

      Delete
  13. thinking its that pin 4...looking at that area now...

    ReplyDelete
  14. does the 9v trace across the 220k then down the next 220k to the trimmer, where it splits onto tracks 3 and 5. On track 3, it cruises down the 1M to track 6...pin 4 is next to the ground bar.

    i have almost 9v at the top of that 1M by the trimpot and 0.something on the bottom of it...does that make sense? was thinking it was a bad resistor, but didnt notice the ground jumper pin there...and really have no idea if thats how power flows through anyway :)

    ReplyDelete
    Replies
    1. 9V through the 220K > 1u to ground > 220K to trimmer wiper

      That spilts off then to pins 2 (via the small link) and 3 and both 2 and 3 then have a 1M going to ground. Check the voltage on row 2 below where 9V wire connects. That is a ground row and so should be 0V.

      Delete
    2. yep, row 2 is 0v. And sorry, Q3 and Q4 collectors are also around 9v...i really gotta get a new DMM.

      gunna examine the back under a magnifying glass...

      Delete
    3. That's a high voltage to be seen there. Between that point and the 9V supply is the 10K resistor at Attack 1 and then the Attack pot. But even if you had the Attack pot rotated so mazimum voltage was getting through, the 10K should have dropped it down well below 9V. Put the Attack pot in the centre position and see if the measurement changes.

      Delete
    4. adjusting the attack pot gives me levels between 9.23 and 9.30

      the bottom of the 10k at attack 1 is 9.28 (the top is 9.29)...should I try swapping it out?

      Delete
    5. Measured where does it give you between 9.23 and 9.3? At Q5 base, Q3 & Q4 collectors? The pot with the 10K resistor could potentially put 160K between the supply and Q5 base (etc) and you shouldn't be getting anything like that much voltage throughout the range. But that makes me think there could be some sort of bridge somewhere unrelated to the Attack pot. Q5 collector is directly connected to 9V via the link and so I'm wondering if there could be a bridge somewhere round there with Q5 base and collector being on consecutive rows?

      Delete
    6. yeah, Q3 & Q4 collectors AND Q5 base and collector are all around 9.3v...

      9.23 to 9.3 is when attack pot is min and max

      I dont see any bridges...will keep looking.

      I also swapped out Q5 for a new one and get the same readings...

      Delete
    7. They're all supplied voltage from the Attack pot, so if the voltage stays that high there must be a bridge somewhere or the pot is more knackered than any I've come across. I've been over the layout several times and I can't see anything wrong, but those issues like the small voltage on pin 4 strongly suggest a bridge somewhere or maybe it's worth reflowing the solder in a few suspect places. At the end of the day, if pin 4 was connected to ground then 0.4V couldn't exist there because it would be immediately grounded. What about the IC, have you tried a different one?

      Delete
    8. alrighty, we're verified.

      Must have been a bad IC. I didn't think I had another so I didn't try that first. I think I am still getting those high voltages at Q3/4/5 though...will play around with it and check it again later.

      also swapped the 10k for a 68k like you suggested (I'm using 100k pots, not 150k) at attack 1. Actually, now I see you said 62k...i have 56k or 68k...should I go with 56k?

      thanks for your help!

      Delete
    9. Excellent, nice one. Yes go with 56K, the original resistor in the Dyna Comp which the Attack pot (+10K) replaced was 150K so that'll get you closer. The voltages still seem weirdly high to me but if it works it works I suppose. :o)

      Delete
  15. wanted to say this thing sounds really good.

    thanks man.

    ReplyDelete
    Replies
    1. Excellent, glad it's been a worthwhile build for you. Have you taken any pics yet for my collection? :o) I loved your OD820, it looked brilliant and I'm sure you've done just as good a job with this.

      Delete
  16. :) was going to wait to see if the blend option was coming up before I finish it. Will post some pics when it's all boxed up for good.

    It definitely has more squish than the Love Squeeze, and is just as transparent as far as overall tone. This is a tad noiser than the Love Squeeze though...gunna have to recalibrate the Decimator...or build another one! Muahahahaha :)

    ReplyDelete
  17. Hello, so if I wanted to ditch the trimmer where would I put the 2 1K's?

    Also dumb question, but i am new to your layouts, the polarity of the caps, is the tiny box on one side representing the negative? I am assuming but better ask before I solder anything.

    And dang on 150K B pots!!! never seen em

    ReplyDelete
    Replies
    1. The 1K's are already in the second layout, and yes the marked side of the cap is negative.

      Delete
  18. Wow I i\did not even see that second layout. If you got the subscription widget I would totally subscribe to your site here!

    ReplyDelete
    Replies
    1. There's a Follow By Email subscription box over there ►
      Or you can subscribe to the feed at the bottom of the page ▼

      Delete
  19. She works! Will post pix after I box it

    https://www.facebook.com/ajax/messaging/attachment.php?attach_id=dc7598687f4eaa83dd38b94a21b08920&mid=id.266246443489595&ext=1343974500&hash=AQC2rOJtbFE-Fro3

    ReplyDelete
    Replies
    1. Nice one Guy, look forward to the pics

      Delete
  20. I've read somewhere that supposedly, the key to this circuit is matching the 2n5088's... or having a specific gain or soemthing... i believe its matching that matters. 2n5088's are not jfets, they are just amplifiers, correct?

    so... would the hFE thing on my DMM work to get my 2n5088's matched up?

    Does anyone have a measurement that I should aim for? I've built a couple 2 knob keeleys and while they are very close with the right component materials- they have never been quite right there... just lacking that natural attack and sparkle that my real keeley commands.

    also, anyone ever try a vintage RCA CA3080 metal can package? they can still be had, wondering if it would be worth a try?

    ReplyDelete
  21. I have never heard a real Keeley, but this build sounds fantastic!

    https://sphotos-b.xx.fbcdn.net/hphotos-ash4/422207_10151131301885751_2103529966_n.jpg

    https://sphotos-b.xx.fbcdn.net/hphotos-ash4/405490_10151131302905751_1371921857_n.jpg

    ReplyDelete
    Replies
    1. Sorry Guy I missed these. Great pics and a nice addition to my collection! Thanks

      Delete
  22. So, which cap should be an electo and not a tant? The 1u in column 1?

    thanks!

    Here's mine boxed, not labelled yet tho...

    http://fearedandloathed.com/Images/BYOC/keeley1.jpg
    http://fearedandloathed.com/Images/BYOC/keeley2.jpg

    ReplyDelete
    Replies
    1. Very nice job, thanks for the pics. Not electro, it's poly and you've already included it, it's the 1u from Q1 emitter to Clip 1.

      Oh and by the way, I tried to PM you through FSB but it's not been delivered yet. Your email address has been hacked and spam is being sent from it to all your contacts. I've had a couple from you now. I'd download and run combofix to get rid of whatever dodgy malware you've got and change your passwords.

      Delete
    2. no shit? thanks for the heads up.

      Delete
  23. Hello Mark,

    Pedal done. Really sounds great, best compressor I've ever tried before. More pics por your colection (now I'm using 125B, i feel more confortable with these ones than with the 1590B's):

    http://guitarrasimportacion.foroactivo.com/t486-capinc-effects-10-crystal-glory-keeley-4-knob-compressor#6818

    Best regards and thank you once again!

    ReplyDelete
    Replies
    1. Excellent job, glad you're liking it

      Delete
  24. Know of anywhere to find 150k lin's cheap? Or perhaps a substitute? I can't seem to find them anywhere for less than $2-3 apiece and usually i pay $50c for pots...hah

    ReplyDelete
    Replies
    1. Use 500K linear pot and solder 220K resistor to lugs 1 and 3. That'll give you 152K pot.

      Other option would be 250K pot with 330K resistor. That equals 142.24K

      I think either of those should be close enough.
      +m

      Delete
    2. hey, i know this is an old comment but when you say solder 220k resistor to lugs 1 and 3, do you mean a single 220k resistor wired across the pot from lug 1 to lug 3, then solder up the pot in the usual manner?

      Delete
    3. I just did this and when turned fully down it reads exactly 150k between lugs 2 and 3. however I think the taper may be weird. In the first 1/3 of the turn it climbs fast enough to about 180k, then descends down to 0 the remaining 2/3. not sure if this will make it behave strangely?

      Delete
    4. Eric, having built this a few months ago, have you had any issues running it with the 220k across lugs 1 and 3? I'm about to do this build and have B500Ks on hand, while trying to find 150K seems to be next to impossible in the US.

      Delete
  25. Thanks Miro, saved me yet again!!

    ReplyDelete
  26. I have built this one , but it seems that clipping has no function. It also works , when clipping pot is not
    wired. In the videos of original keeley 4 knob i can see that clipping has influence on the volume of the pedal.
    Is it right or clipping is only for little nuances?

    ReplyDelete
    Replies
    1. What guitar are you using it with? The Clip pot is used to control the input level if you're getting some distortion, which is more likely with high output singles or humbuckers. It's not a very useful external control IMO, better to be on an internal trimmer because it is more of a "set and forget" thing.

      Personally I'd probably make this with 3 knobs or add a blend circuit for the 4th control which would be much more useful.

      Delete
    2. I just finished mine. I notice the clip pot has an subtle tone effect on my tonezone bridge pickup (a relatively hot humbucker) But not so much from my other guitar with PAF Fred and PAF Joe pickups.

      So I like the nob on the outside. I will need it when I switch guitars.

      Also, all 5 of my transistors were matched. Q1 and Q2 at Hfe 368. Q3 and Q4 at Hfe 354. and Q5 was at 372.

      KUDOS to you guys, Mark, John, and Marosol. This website is awesome!

      Delete
  27. Thanks for your very fast reaction. I also tryed to connect 2.2M resistor instead of pot ,but it seems to have no
    action. I tryed it also with humbucker with the same result. It probably has no big importance.
    Another thing i would like to ask you is a spittitng pots.I have built several builts , but sometimes i have
    problems with spiting pots . They are spits at the end of their lines. Is it possible to remove this spitting?
    Best Regards

    ReplyDelete
  28. i just finished this one today. it works perfectly and performs exactly like the youtube videos of it (it sounds awesome too!). i'm using matched MPSa18's for Q1 & Q2 (1100hfe each). matched 2n3904's for Q3 & Q4 (335hfe) and a 2n5089 for Q5. the only thing that i had to do to make it operate like the original is to change the 'attack 1' lead to attack 3 and change the 'clip 1' to clip 3. it also sounds great on 18 volts, but its not a huge difference so i'm going to run mine at 9V.

    BTW, Robert Keeley stated that they discontinued using the 2K trimmer long ago( but i do have one in mine set at dead center).

    ReplyDelete
    Replies
    1. Thanks for the feedback about the lugs John, I'll update it now

      Delete
  29. hey mark, love your blog. im excited to try this one.
    have you thought about doing a layout of a boss cs2?
    this thread had a pcb layout with mods for a ba6110 and true bypass switch but i cant easily translate it to stripboard.
    http://freestompboxes.org/viewtopic.php?f=1&t=4405

    ReplyDelete
  30. Just completed this. It definitely has a great sound, used tants as recommended above. Was going to use 200k for attack and sustain and attach 680k's to them which my multimeter measured at 148k but I left them as is to test before completing the pedal and it sounds good to me with 200k' s in fact I like the sound with all knobs full tilt, maybe roll off the clip a bit but works for me.

    ReplyDelete
  31. If one does use the trimmer version...what are we setting it to and component to monitor??

    ReplyDelete
  32. Hey, could you point me towards the schematic you used please? trying to troubleshoot my build..

    G

    ReplyDelete
  33. This comment has been removed by the author.

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  34. Hi Ivlark,

    Thanks for your fantastic website!
    I'm trying to finish this pedal, but it still gives me no sound... So I have few questions :

    1) On the shematic you show, attack and clip pots use pin 1 and 2, whereas on the veroboard is shows pin 2 and 3. Which one should I follow ?

    2) Still on the shematics, Q3 and Q4 seems to be opposite, whereas on the vero they are in the same direction. Is that OK ?

    3) I used one tantale capacitor instead of the ceramic one until I get one. Could the no-sounding problem come from that ?

    Sorry for my english...

    ReplyDelete
    Replies
    1. 1) They use 2 and 3 via the link, 1 has no connection

      2) The schematic is representative and lays out the components in the way which makes the finished scheme most legible, so it doesn't mean the transistor should actually be turned round. In the layout the correct connections are made to each of the transistor pins.

      3) No that wouldn't cause a problem unless the cap was faulty. I'd suggest building an audio probe and going through it until you can see where the problem comes in. IC and transistor pin voltages may give a good clue though.

      Delete
    2. Thanks a lot, I didn't know this tool,

      But I'm still stuck with this non-sounding build....
      So I made an audio probe, and I can follow the input signal up to pins 2 and 3 of the IC. Then, I have nothing on the pin 6. I thought it was the IC and I have another one so I replaced it but the problem is still the same... (unless I have the same problem with both!)...
      When I use the audio probe like an input signal on the pin 6, i get a very low signal in the output.

      I measured the voltage in case, and I get :

      IC :
      1 = 55mV, 2 = 4,2V, 3 = 4,2V, 4 = 0V
      5 = 60mV, 6 = 6V, 7 = 8,1V, 8 = 7,3V

      Q1 : C = 2V, B = 2,4V, E = 6,1V
      Q2 : C = 5,3V, B = 6V, E = 5,3V
      Q3 : C = 8,1V, B = 0V, E = 0V
      Q4 : C = 8,1V, B = 0V, E = 0V
      Q5 : C = 8,1V, B = 8,1V, E = 7,5V

      Hope you find out something...

      Delete
    3. It looks like you have a short between the base and collector of Q5. Check your soldering and for any unwanted bridge around there.

      Delete
    4. Checked this area and found nothing. In fact there is few millivolts between the base and the collector of Q5 and.
      Is the pins 5 voltage of the IC OK? I really don't understand why I don't get any signal at pin 6.

      Delete
  35. Should the IC be CA3080 or LM3080 - are they the same thing? Does anyone have a cheap link for these? Cheers!

    ReplyDelete
  36. Should the IC be CA3080 or LM3080 - are they the same thing? Does anyone have a cheap link for these? Cheers!

    ReplyDelete
    Replies
    1. They are both the same, just from different manufacturers

      Delete
  37. Weird I built this once and it was great, I just built it again and the attack and clip knobs are not quit right. I am using B100k's, I can remember what I used the first time around............ I am pretty sure not 150ks lol, any how, the clip knob seems to add alot to the volume, and the attack knob, when turned off, almost entirely kills all volume level, besides that and at about noon the effect seems to be functioning properly. I am using a RCA CA3080, which is much nicer than the LM3080 I used the first time around I think

    ReplyDelete
  38. vladimir did you solved the problem with no sound on pin 6?

    ReplyDelete
    Replies
    1. This comment has been removed by the author.

      Delete
    2. No, I left out this project since I had this problem.
      I think I'll desolder evrything and check separately evry components... or burn the circuit

      Delete
  39. now im working on it ,for now i find a bad transistor ,just finished schematic,
    in the upper midlle is IC schematic
    maybe helps to someone

    http://www.speedyshare.com/nrGNB/Image.png
    tomorow i will put some voltages readings

    ReplyDelete
  40. This comment has been removed by the author.

    ReplyDelete
    Replies
    1. Hi,

      Pot's values are clearly stated on the pic, don't know what more explanation you need :P. They come identified by the name (Attack, Sustain, Output, Clip), the taper kind (lin, rev log......) and the value (150, 500.....).

      The switch should be a 3PDT stompswitch.

      By the way, and just a suggestion, this may not be a good first diy project (more than 50 components, multiple links, 4 pots, messin' wiring....).

      BR

      Delete
    2. Yeah I'm so sorry it was very clear, I just didn't see it...

      You may be right about the beginning but I already ordered what I needed for that (except the pots).
      Plus it will actually be my second or third DIY project because I'm first going to build a reamp box (in a full kit) and a passive microphone splitter which both should be a lot easier.

      Thank's for the answer though. I will post here if I'm having trouble.
      If I succeed, I will get this pedal for 77% cheaper than the original ! DIY is awesome :D

      Delete
    3. You're welcome :) For any doubt we're here, so, go ahead if you're decided :)

      BR

      Delete
  41. So, put this one together and having no luck. No sound at all. Had a round of probing with the DMM and here are the readings...

    IC
    1-0.12
    2-0.14
    3-3.86
    4-0.00
    5-0.12
    6-6.89
    7-9.02 (same as provided by the psu)
    8-8.29 (does this voltage come from the IC? the pin itself is NC..?)

    TRANSISTORS
    Q1 Q2 Q3 Q4 Q5
    E 6.61 6.20 0 0 8.44
    B 1.50 6.90 0 0 7.90
    C 2.33 6.20 8 8 9

    So, yeah... looks pretty weird to me, but not 100% what voltages I should be expecting. Does anyone have the desired voltages for comparison? That would help me hugely to understand what might be wrong/where to look for cold joints/micro bridges/faulty components/general faults and mistakes.

    Any input is much appreciated, so a big thank in advance to any of you who might be of help! :)

    Alex

    ReplyDelete
    Replies
    1. Oh, and I replaced the trim pot with two 1k resistors, going from where lug 1-2 and 2-3 of the preset would have been (realised I didn't have the right value and opted for the two standing resistors)

      Delete
  42. Hi, yeah you must have a component in the wrong place, did you get all the double links? I have built this a few times and everytime a component ends up in the wrong spot!

    ReplyDelete
    Replies
    1. Hey Guy, thanks for the reply!

      Gone through it another time and all seems fine. Also, the double links were successfully probed for continuity.

      Here are a couple photos... Joints look a bit dodgy because I didn't have the good side cutting pliers (hence a bit of the legs are popping out..!) and had to use lesser gauge solder than usual, which I don't particularly favour/am not too used to.

      http://dl.dropbox.com/u/65506935/k4kc_up.JPG

      http://dl.dropbox.com/u/65506935/k4kc_down.JPG

      Delete
    2. Hey Alex,

      At first sight, it seems that you have a solder bridge between rows 3 and 4 (Clip 2 and nex dow row, at about 2nd hole.

      Can you check it?

      BR

      Delete
    3. And another one between rows 5 and 6, that would mean put to ground IC's pin 3.
      Let us know

      Delete
    4. This comment has been removed by the author.

      Delete
    5. Hi Javi thanks a lot for chipping in!

      Checked and neither is bridged. What makes it look that way are long protruding components legs seen at an angle.

      I got hold of some voltages to be expected on a Ross compressor thanks to a contribution from the DIYSB forum, here they are:

      IC1

      1. NC
      2. 4.6
      3. 4.6
      4. 0.0
      5. 0.7
      6. 2.7
      7. 9.0
      8. NC

      Q1

      C 6.6
      B 2.8
      E 2.2

      Q2

      C 6.9
      B 2.7 (connected directly to pin 6 of IC1)
      E 2.1

      Q3

      C 8.9
      B 0.0
      E 0.0

      Q4 same as Q3. They are not conducting at the moment, as there's no input signal, so these figures are to be expected.

      Q5

      C 9.0
      B 8.9
      E 8.4

      Quite a lot or me to look at right now..!

      Delete
    6. D'oh! I completely missed up until now the link between rows 3 and 4 (under the horizontal 22k resistor). Heating the iron up, fingers crossed that's all that was wrong with it!
      That would explain why I'm not getting anything on pin 2 of the IC. Don't have its pinout at hand, but hopefully explains the other anomalies too..!

      Delete
    7. Still no joy... Trying to figure out why I'm getting such high voltage on pin 6 and Q2 B, as well as lower voltages on Q5... Doing my head in!

      Delete
  43. Hi guys,

    Thanks for the great content you are bringing here. This website is on my daily routine of things to check out :)
    Now down to business. I have an original Keeley C4 but I'm building one for a friend.
    I got it finished but it's not working. Nothing comes out of it.
    It working mentioning that I built the version with the trimmer only to realize that I only had a 1K trimmer.
    So I ended up using 2 1k resistor instead.

    Here are my readings:
    Q1 C=7.10 B=2.269 E=1.841
    Q2 C=6.87 B=2.648 E=2.117
    Q3 E=8.84 B=0 C=0
    Q4 E=8.84 B=0 C=0
    Q5 C=8.98 B=8.83 E=8.46

    IC Pin 1=Variable Pin 2=4.63 Pin 3=4.63 Pin 4=0 Pin 5=0.56 Pin 6=2.670 Pin 7=8.98 Pin 8=Variable

    These look comparable to the values Alex S posted above.

    I triple checked for bridges, unwanted continuity. I'm positive that my CA3080 works as I tested it on the original Keeley.

    I have an test box with an audio probe and weird thing is, I'm loosing the signal right at the start.
    Another weird thing is, I'm getting 2.1V on at Input lead when not connected to the input jack. I'm guessing something's wrong here. I thought that the purpose of the input capacitor C1 was to block the circuit DC, am I wrong ?
    I'm running out of ideas...

    Any help guys ?

    Cheers

    ReplyDelete
  44. Well, I found my problem. Microscopic bridge that was letting current go through the input.
    My build sounds pretty my as good as the original. I got a lot of radio frequency interference though but I'm hoping to cut them out when I box the thing.
    Thanks to Alex S for posting the expected voltages, that was a great help.

    Cheers

    ReplyDelete
    Replies
    1. No problem, only wish I got my blooming build to work! :)

      Actually tried to start from scratch and still getting thos 6 pdd volts at pin 6 and Q3 base, not sure what I've done wrong both times...! Will have a probe around a few resistors to make sure I haven't labelled values wrong in the parts bin, being colour blind doen't help spotting values!

      Delete
  45. I built this and it worked great. But now it seems the attack and clip pots don't do much at now. I used b200k pots for those with no resistors in between the lugs. Could this be the problem? Any suggestions?

    ReplyDelete
    Replies
    1. IDK what your problem is, but those values should work fine

      Delete
  46. I have built this one and am getting a lot of rf interference even when boxed. Any ideas?

    ReplyDelete
    Replies
    1. Are you sure it's RF interference? It could be a dodgy solder joint somewhere. Check stable continuity between all points of ground. If it is RF, then a low value resistor like 100 ohms in series with the input and supply should help. Plus a low value cap like 10pf between input and ground.

      Delete
    2. Hi Ivlark,

      mine does recieve radio frequency too when I turn it on at certain outdoor stages.I would like to make sure is it to connect the input jack and the positive of 9v supply jack with a 100ohm? Thank you ~

      Delete
  47. Its definitely rf. I am getting the local radio station around 96.5 in the background when the pedal is connected and on. I thought it might be an amp ground issue but it isn't.

    ReplyDelete
  48. This comment has been removed by the author.

    ReplyDelete
  49. hello,
    i build this but the volume is extreem low
    need to put evry knob on max , dist, amp , boost

    ps great site

    ReplyDelete
    Replies
    1. this pedal has a TON of gain. if your volume is low, then you have made an error somewhere.

      Delete
    2. how do you spot an error on a built ?
      this is my 5th pedal lol

      Delete
    3. Measure all transistor and IC voltages, that will probably give a good clue

      Delete
  50. This comment has been removed by the author.

    ReplyDelete
  51. I don't like it...the output seems to be too low. I mean, i was expecting more of a volume boost when volume is at 3 o clock

    Could the fact that i used BC550 (obviously at 180 degrees), instead of 2n5088, have anything to do with it?

    ReplyDelete
  52. well i guess unity is normal for this one, if i read the reports of the original here http://www.thegearpage.net/board/archive/index.php/t-1015768.html

    ReplyDelete
  53. maybe because i am used to insane big crush rocktron like compressors haha

    ReplyDelete
  54. if you're not getting a big gain boost at 3:00 then, IMO something is wrong. this pedal can add a TON of boost.

    ReplyDelete
  55. Sure, at 3 o'clock this pedal can blow any speaker. Check your board / wiring.

    ReplyDelete
  56. This comment has been removed by the author.

    ReplyDelete
  57. Some quotes about the original by a number of people:

    "The only way I could fix it was by keeping the sustain at 12:00 and up. Even then, it seemed like it still cut the volume just a tad. The noise is probably normal past 3:00."

    "when they engage the compressor, not only it will not lose the signal level, instead it has a little bit of boost, while their level just set past 12 o'clock..This really confuses me if I got the defective unit?"


    "exactly!! I noticed that too, if the sustain turn past 12 o'clock the volume and with level turned all way up to eleven then the bypass and engaged signal level are close but not exactly the same"

    "It is a great comp and I love the tone and smoothness, I am just deciding if I can deal with the volume drop or if I prefer more volume at the cost of headroom."

    "I've heard this many-a-time about the Keeley comp."

    "I'm curious if it really is a volume drop you're experiencing or just the way the Keeley compresses the highs."

    "it does compress the highs A LOT.
    but it's definitely whole spectrum amplitude dropped.
    I analysed with frequency meter. it's as like 6db peak reduction, which is normal
    the problem is the level (make up gain) doesn't work..doesn't really make up the gain loss.,"


    "Try turning the attack up. That may give you a bit more highs and attack. As for the level, the Keeley is unity gain at best, and that's with single coils, or regular output pickups. Basically, what you are experiencing is normal with high output humbuckers. Your best bet is to turn the volume, attack and clipping all the way up, and turn the sustain all the way down. With high output pickups, this should still give you a good amount of compression. Unfortunately, it will still be less than unity when spicing or strumming hard."

    ReplyDelete
  58. yeah i have bilt a few of these, unity is around 3 o clock on my norm settings

    ReplyDelete
  59. Hey Mark,
    Any chance you'd be willing to look over my attempt at the compressor? It's my second build of the same layout..First one worked like a charm! so well in fact, a buddy wants one. Thus the issue- No sound. I'v looked into everything...rewired all my offboard components three times to make sure i got it right...I do. It's isolated to the board..but i can't figure it out. Here's a couple photos:
    Front
    http://img24.imageshack.us/img24/3016/img1434ag.jpg
    Back
    http://img189.imageshack.us/img189/1173/img1435n.jpg

    Re-flowed all solder connections, i think i'm just not seeing the incorrect component!
    Thanks in advance!
    Eric

    ReplyDelete
  60. is there a chance you could rework this design to use 4 100k lin pots... the boxes im building use all through hole style pots and cant find rev audio/log 5k through hole 25mm shaft any where. unless u know a place... I purchased DIGI blank boxes, and the all came with mounted pots and stuff....

    ReplyDelete
    Replies
    1. in a word -NO. get the correct pots for it if you want it to work properly.

      Delete
  61. I've just built this, it works perfectly!
    I've ordered two 150k pots in ebay, all the rest in tayda. The pots came from Macau and they are huge, but fitted alright. It sounds amazing.

    the board: http://tinypic.com/r/qqrbzb/5
    the finished pedal: http://tinypic.com/r/2elqu4x/5

    ReplyDelete
    Replies
    1. Nice one, thanks for the pics

      Delete
    2. I've printed the schematic and glued on the board. I'm thinking of preparing a video tutorial on how to build pedals from your designs. The hard part is to print the drawing with the right proportion.

      Delete
  62. Hi all - I built the pedal but i get no sound at all when it is on, the LED comes on but that is it. I have double checked the layout and it seems right, I have also double checked for solder bridges. My IC i am using is a CA3080E - not sure if this is the problem as the layout states CA3080, but according to the spec CA3080E is the same just not rated as highly for operating temperatures.

    My Readings:
    IC
    1 - 0
    2 - 4.7
    3 - 4.9
    4 - 0
    5 - 0.4
    6 - 9.4
    7 - 0.7
    8 - 0


    Q1 C - 7.8, B - 2.13, E - 1.7
    Q2 C - 0.7, B - 1.39, E - 0.69
    Q3 C - 0, B - 0.69, E - 0
    Q4 C - 0, B - 0, E - 0
    Q5 C - 9.5, B - 0, E - 0.3

    This is just my second build so any help would be awesome

    Thanks
    Warren

    ReplyDelete
    Replies
    1. I think you've got the IC pin numbering a bit wrong, it should be:

      1---8
      2---7
      3---6
      4---5

      Pin 6 is the output and seems low to me so you should check around that, maybe even swap for another IC if you socketed and have a spare.

      Q1 looks ok, but the collector voltages on Q2 to Q4 all look well off, so again check round there and look for anything misplaced, components, cuts or links, and check for unwanted bridges.

      We know the layout works so something must be physically amiss with your build.

      Delete
  63. I just built this, it works great but not right away. I stayed up until about 130 last making it, and this morning when i finished the case wiring i was disappointed when it didn't fire up right away... i was extra cautious making the cuts and putting the components in the right spot.

    Just after dinner I was looking at the underside of the circuit board, I noticed one component hadn't been soldered on both sides. Doh... fixed it. Fired up, nothing still. Looked under there again, found another 1/2 soldered component. Fixed it and fired it up again, nothing! So I looked, AGAIN, and found a third 1/2 soldered component... What the hell. So I fixed that, fired it up and nothing! Instead of getting angry I replaced the CA3080 with a new one and it worked perfectly.

    I have never missed a solder on the under side let alone 3 and I rarely have a bad IC but I got one here. At least 3 of my issues were from lack of sleep...

    This is a great sounding compressor.

    ReplyDelete
  64. I found my stupidity... Q2 Transistor is out by 1 row, it is 1 row too close to the bottom edge - i will move it tonight, hopefully I have not damaged anything and it solves my issues. I have to stop building pedals at 12:00 am ;-)

    ReplyDelete
  65. Fixed, voltages all right and the pedal is working great - thanks Mark

    ReplyDelete
  66. Sooo I'm having a bit of trouble with this one. Built the version without a trimmer, won't get any sound with the pedal engaged. Already triple and quadruple checked the component placement, resoldered them all.
    The gaps are knifed, the cuts are all 100% cut, no continuity.

    My voltages are:

    Q1 CBE 6,70 / 2,68 / 2,32

    Q2 CBE 6,25 / 6,91 / 6,24

    Q3 CBE 8,90 / 0,00 / 0,00

    Q4 CBE 8,91 / 0,00 / 0,00

    Q5 CBE 9,01 / 8,39 / 8,30

    IC Pins:

    1) 0,11

    2) 4,67

    3) 4,67

    4) 0,00

    5) 0,13

    6) 6,91

    7) 9,01

    8) 8,29

    I hope one of you guys can help or post his measurements.
    Thanks a lot in advance

    Chris

    ReplyDelete
  67. Hey Guys,]


    Finished this today, one issue though- My attack pot does absolutely nothing. any ideas?

    ReplyDelete
  68. Hi, I am completely new. I built a pedal from Anderton's book back in the 90's. After finding this site, the bug got me again.

    So I am starting with this one.

    NOOB MISTAKES I HAVE MADE:

    1. Mistake: Substituting a Log Pot for the Reverse Log Pot listed for the sustain. Just because the word "Log" is in it doesn't make it a good replacement. A Linear Pot is closer to a reverse log than a Log Pot is. Duh. So time to order more linear pots.

    2. The capacitors are all shown with a negative terminal, but symbolically, they aren't show as tantaliums. But I read in the comments that the sound is better with Tantaliums. So I ordered as many of the capacitors in tantalium that I could find. It turns out, that the parts list shows 6 capacitors of 1u. I got all of my 1u's in Tantalium, which are polarized. But there is 1 of them not shown as polarized. I figured I would just use the tantalium one I ordered, but I am scared because I don't know which way to put it in. So I just ordered a bag of metal film 1u's. The pics some people posted show these HUGE things for that one.

    3. Mistake: Not ordering enough Transistors to find some good Hfe matches. I did get a cheapie meter on ebay that has Hfe measuring. But I only ordered 20 transistors. For as cheap as they are, I should have ordered 100 in several types to make matching easier.

    4. Mistake: Buying a small box like the veterans around here do. There is no shame in using a larger enclosure when you are just starting out. I ordered a 1590BB box which is bigger. All is well. But I can't IMAGINE how these guys manage to do this in those tiny 1590A or 1590B boxes.

    I'm not done building, but I am getting close. Just waiting on my second order to fix my mistakes. Also, my OPAMPS are coming from hong kong, so it'll be another week or so.

    ReplyDelete
    Replies
    1. Mistake: spelling tantalum wrong

      LOL

      Delete
  69. By the way, my new meter arrived that measures Hfe, and finding several good pairs in the bag of 20 resistors wasn't as hard as I thought it would be. Now, had they been germanium, maybe it would have been harder. From what I understand, they tend to range around a little less predictably than the silicon specified for this Keeley.

    ReplyDelete
  70. Help me. Please. I got it all wired up last night. The only thing that works is the true bypass and the LED. ha ha....(sob)

    To verify that it wasn't the IC, I swapped out the LM3080N for a LM386N that I know is functional. The voltages changed a LOT from that, but still dead when switched to circuit. So here are my voltages with the LM3080N with all knobs dead center:

    IC:
    1=0 (I just realized I might have needed to switch my meter to mV, so there may have been a small mV on pin 1)
    2=3.52
    3=3.52
    4=0
    5=0.64
    6=0.64
    7=8.32
    8=0

    .......Q1...........Q2.........Q3..........Q4...........Q5
    C_____ 8.23 _______ 8.09 ______7.34 _______7.34 ________8.30
    B_____ 0.0 ________ 0.64 ______0.0 _______0.0 ________7.34
    E_____ 0.0 ________ 0.14 ______0.0 _______0.0 ________7.75

    I would really appreciate any ideas. Does it look like something is grounding out? I have examined the board thoroughly. The only thing that is bothering me now is my off-board wiring at the input jack. I'll give a rundown on how I did my wiring later. Although the bypass works fine. In the meantime, anyone have any ideas?



    ReplyDelete
  71. OK here is the wiring that I did. See anything wrong here?

    http://i42.tinypic.com/14j6l9h.jpg

    Is it OK that I put the LED power on the top rail to the left of that resistor?

    By the way, my top rail shows less than 9v. Something around 8.2V. But when I disconnect the battery, the battery shows 9.06V. Is this more evidence of grounding out somewhere?

    ReplyDelete
  72. I have no idea why you'd try an LM386 in there since that's a power amp chip which is COMPLETELY different than a 3080. if built properly, this vero works perfectly (exactly like the original) so you must have and error like a solder bridge, a bad cut or a misplaced component somewhere.

    ReplyDelete
  73. I didn't really know that. The specifics of IC's is outside my level, without a doubt.

    I will go back over it all. After looking at the vero, I'm thinking I have a short somewhere in the power jumpers. More troubleshooting tonight.

    But one quick question: If a battery is sending 9V to a circuit, will the circuit itself pull the power rail down to 8.3V just due to load? Or is that a clear symptom of grounding the lead?

    ReplyDelete
  74. It depends on the condition of the battery, but this circuit doesn't draw that much power so I don't think that it should sag it down that much with a new battery.

    ReplyDelete
  75. Thanks John. I looked it over at lunch. I found one Tantalum in backwards. Excited, I de-soldiered it and put a brand new one in the right way. Still nothing. Did you have a chance to look at my wiring diagram? checked for continuity between the ground rails and the power rails. No bridges. I'll keep at it.

    ReplyDelete
  76. I checked everything I could think of. I used a microscope attachment on my Iphone to look for bridges. (highly recommended, by the way. I got mine for $5.00 on ebay. WAY better than a magnifying glass!)

    I poured over my wiring 3 times. Nothing was wrong. I checked the location of every component 3 times. Nothing was wrong. Why wasn't it working?

    I tried to "figure out" with my multimeter where the voltgage was getting stuck. Switching from checking continuity to checking the voltages.

    Finally, I put the meter on each individual resistor and checked it.

    R18 and R15 are shown as 27K Ohms. My noob mistake: 27 Ohms. DOH!

    I didn't have any 27K so I put two 56k's together for 28K. Bingo! It works! This thing really does sound fantastic. I don't hear any hum or hiss at all. And the sustain is awesome.

    Quick question: My resistors have these long legs. I just stuck them into the sockets for testing. But now I want to screw the back of the box on. So I am going to trim them down, but that means I am going to have to bend the legs in 90 degree angles to get it lined up with the sockets. My question is, will I damage the resistor by bending against it, or do I need to use the tiny needle nose pliers to place the first bend 1mm below the transistor? I seem to remember a caution about this issue somewhere, but I don't remember which components were the most delicate.

    ReplyDelete
  77. OK-I just finished my second one. I built the boards simultaneously and then finished out the first one, troubleshot it, and then finished out the second one, and troubleshot it. They both work pretty much the same. There are a few differences:

    Pedal #1: Attack and Clip pots are 500k with added resistors to bring them down to 152k.

    Pedal #2: Attack and Clip pots are 250k with added resistors to bring them down to 147k.

    Pedal #1: has a few carbon resistors
    Pedal #2: has ALL metal film resistors.

    Other than that, they are identical. But one of them is definitely "harsher" or "sharper on the twang" than the other. (sorry I don't remember which one). So I will be swapping the IC's to make sure one of them isn't bad, and swapping the transistors around to see if I can find the culprit. More to come.

    ReplyDelete
  78. So, it turns out it was the IC. Swapping the IC's moved the twang to the other compressor. I guess I'll order another one. I've been ordering just enough parts to build what I want. Then I order more parts. The shipping is killing me. I guess I'll just have to give in to the dark side and commit to buying a whole stock of stuff so I can stop playing this game of "just one more project".

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  79. This comment has been removed by the author.

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  80. anyone got a recommendation for a blend circuit to use on this guy?

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  81. i just finished this as my 3rd dynacomp variation and i have to say there is something about those tantalum caps and matching transistors. my last build i just built it up (a guitarpcb compressor board) and subbing standard can type lytics with tants made a huge difference (without matching transistors). this build i went all the way and even bought a nos ca3080 and it sounds phenomenal... though i dont have a regular ca3080 to compare it to. thanks for the layout!

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  82. Hello.

    I am very much interested in this build and I have one question. Is there any way to turn the trimmer on the first version into an actual pot. If so, can you please explain how.

    Much thanks

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    Replies
    1. If I'm not mistaken, you could run a wire from each lug of a 2K pot to the corresponding lugs of the trimmer (since I believe the top connection of the trimmer acts as the equivalent of lug 1 and the middle acts as lug 2, etc.).

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  83. Why are they 2 outputs? I keep seeing schematics with output 1 and output 3.

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    1. Output 1 is the lug number 1 of the pot called output. Output 3 is the lug number 3 of the pot called output. You take the only output from that pot's lug number 2.
      +m

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  84. Hello, thank you all for your advices, was very helpfull.

    I just wired my board and pots and the voltage between the terminals of the source is is 0 when connected instead when disconnected source gives 9.06v, there isn't a short when unplugged, not even the LED works. Any idea where to start checking? could the IC3080 make this fail?

    Sorry for my English, One more time, Thanks!

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  85. Quick question about the 1u capacitor shown with no polarity markings (top left). I ordered 6 polarised electrolytic caps, can I use one of them in that position? and if so which way should it go in? :/

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    Replies
    1. Yes you can use it and I would assume that the negative leg will go to the emitter. If you're going to build up a stock of components though I'd really recommend getting some of these:

      http://www.ebay.com/itm/250879684670

      Dirt cheap and small so they come in very handy sometimes when space is running out.

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    2. Cool cheers Mark, I'll certainly stock up on those caps for the future. Just to confirm, is the emitter the row with Clip 3 on it? (so negative would go to the 2nd row from the top?)

      Thanks again

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    3. It's the leg soldered next to the emitter of Q1

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    4. oh sorry yeah I get you now. still learning! thanks a lot Mark.

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  86. Just finished this build, absolutely LOVE the sound!! Great work Mark!

    Thought I'd upload a few pics of the finished build :)
    Front- http://i58.tinypic.com/29qjt4g.jpg
    Back- http://i60.tinypic.com/2b441y.jpg

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    Replies
    1. Great job, thanks for the pics, and of the EP

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  87. I am about to build this one and do not want to order 150k pots from Macau. Can someone please tell me what has worked for them for the Clipping and Attack controls. If using different value pots, can you tell me what resistors to solder where? Thank you

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    Replies
    1. I've built couple of these circuits with 100K pots. Works just fine.
      +m

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    2. I DID buy the pots from Macau.. they are military grade pots.. and military SIZE.. the pots were so big, in fact, that i had to put the board into a "BB" to get it to fit, putting the 150's at the outer edges of the top, the two 16mm alphas in the center and squeezing the board between the 150's. fits, but barely

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  88. Hi all.
    Can I sub a pot for the trimmer and top mount it using trimmer 1,2,3 = pot 1,2,3??

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  89. just finished the board, but I'm getting a very fast ticking sound. it gets louder when i turn up the output or sustain, and quieter in the other direction, but is always there. It is only hooked to a breadboard, so I'm hoping maybe it goes away once I box it up, but just throwing this out there to check with you all before I do that just in case anyone else might know if I have a problem elsewhere.

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  90. The capacitor that goes Q1 to Clip3 is electrolytic or polyester?
    thanks

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  91. I used a Panasonic film cap for that 1u, but could even use a multil-layered ceramic

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  92. Hey,excellent blog, it provide the information about Compressors thanks for posting.

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  93. I'm gonna use five 2N5088 transistors.
    Should I select five that deliver the same gain or what is the best matching?

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  94. Where do you find 150k linear pots these days?

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    Replies
    1. Try 100K for both. I've built a few with them and they have worked fine.
      +m

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    2. I'll go ahead and do that. Thanks!

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  95. Has anyone successfully replaced the clip pot with a blend daughterboard, or added a blend as a 5-knob configuration? I build the split n' blend in to this, but with the inverting I get cancelation when the blend is set to 12:00. Would love to see this worked with a blend!

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  96. hello, excuse my ignorance. how it works if I use two for mastering music?
    make two circuits, put it on a rack and cables out of the sound card.
    It is possible with this or other effect?

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  97. Hi.
    I build this pedal, but it sounds distorted and very bad sounding. I tried to change the ic, but it sill not working.
    Can you help me?

    Q1 C=8.1 B=1.84 E=1.37
    Q2 C=0.22 B=0.78 E=0.21
    Q3 C=9.48 B=0.05 E=0
    Q4 C=9.48 B=0.49 E=0
    Q5 C=9.50 B=5.47 E=8.71

    IC Pin 1=0.25 2=4.36 Pin 3=4.33 Pin 4=0 Pin 5=0.70 Pin 6=0.8 Pin 7=9.50 Pin 8=0.8 (variable)

    Please this is a birthday gift!

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    Replies
    1. There's something peculiar in your measurements. Q3 & Q4 collectors and Q5 base are all on the same row, but the measurements are different? Check that out, and also does the voltage there change as you rotate the Attack pot?

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    2. Yes it change. From 9.50v to 9.00v... it isn't a very big difference. Look at Q2, its voltages are right?

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    3. Q2 voltages should all be higher, pin 6 of the IC is also maybe 2V lower than I would expect. So you need to check for misplaced components, bad soldering or bridges etc around the IC and Q2 connections.

      Typical voltages for a Ross Compressor are:

      IC1

      1. NC
      2. 4.6
      3. 4.6
      4. 0.0
      5. 0.7
      6. 2.7
      7. 9.0
      8. NC

      Q1

      C 6.6
      B 2.8
      E 2.2

      Q2

      C 6.9
      B 2.7 (connected directly to pin 6 of IC1)
      E 2.1

      Q3

      C 8.9
      B 0.0
      E 0.0

      Q4

      C 8.9
      B 0.0
      E 0.0

      Q5

      C 9.0
      B 8.9
      E 8.4

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    4. If everything suggested looks ok, do you have another IC to try it with?

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    5. Yes i've already tried another ic. I'll try to make this effect to another board.
      Finger cossed

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  98. Hi.
    I rebuilt my pedal and it works! The voltages are perfect.
    But, meanwhile I played this pedal the attack knob doesn't work properly. When is totally "closed" there isn't any sound, but when is at half value sounds. Do you know why ?

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  99. I am having problems finding a reverse log C500K pot. I have a A500K as well as a B500K. Can I replace te C500K with a A500K. From what I understand, they have the same curve only in reverse. I am hesitant because I can only find a B200K instead of a B150K. I do have the B50K so no problem there. Can I use what I have without changing the tonal qualities or should I keep searching? I know that I am asking total newbie questions but your help would be greatly appreciated. Thank you in advance.

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    Replies
    1. The taper defines how the resistance of the pot changes in relationship to turning the shaft, so the tone will be the same, but the way it comes on will be different. as long as the value is the same they will affect the circuit the same amount, and do the same job, way you hear it will be different. check this out from beavisaudio about pots and resistors.

      http://www.beavisaudio.com/techpages/Pots/

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  100. My pedal works fine. However after a while playing the sound becomes more and more distorted. This can be fixed by shorting the circuit. When I hold the outer tip of the power supply against the case (ground) and plug it back in, it works again for a while.

    Do you have any idea/suggestions what this might be?

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    Replies
    1. Sounds like at least one of the caps is either in reverse or shorting. Symptoms point to ground/cap problems. You could start by triple checking all the electrolytics.
      +m

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  101. Hi guys, what do we need to change to make this pedal work properly on bass?
    Twitter: Mr @robertkeeley is your four knob compressor fully recomended for bass guitar?
    Answer: 8 - 30 de abr. de 2014
    - Not really. new bass comp is going to be out Soon! Chris Fleming, Fender Masterbuilder has the 4 knob installed in his bass!

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  102. Hi! I built this pedal today! The sound comes through, but I have no compression. The comprewssion pot acts as volume. increasing the volume when i turn it to the max.No one have any ideas...??? Thanks
    D.

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  103. Hey there...I built this pedal and it works great but i put in series two 1m res. as a substitute for the 4m7. I was curious what that would do to the tone? I am going to put a 4m7 when i get ahold of one. Just wanted to understand the circuit more...thnx!!!

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