Thursday, 8 March 2012

Paul Cochrane Timmy

This has been requested by a few people and although I was in two minds about posting this, it's pretty well documented that the Lovepedal Amp11 is a blatant rip off and as the layout for that one is on this site (and I strongly encourage anyone considering buying the original of that pedal to build one instead), it seems pointless to hide the Timmy layout away, especially seeing as there are other layouts available out there for it.

This is very much an effect that I would encourage people to buy though, as I have.  Paul is a good guy and the original is very reasonably priced.  It's also one of the best overdrives out there at the moment IMO, and the best stacking overdrive I've used (Zendrive into Timmy is an excellent combo).

This one is verified:




Gearmandude demo:








More compact layout:




Updated 5th September 2014 - Even more compact layout






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241 comments:

  1. Thanks for this one! Are the pots the same values as the lovepedal?

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  2. Replies
    1. I see this post is mighty old but I just put this together and have an issue. As Paul C. is such a cool guy, getting advice from the other forums I belong to is not really feasible. My issue is this; as I follow the signal through the circuit with an audio probe everything is as it should until I get to pin 6 and 7 of the op amp. The signal I get at this point has a little more volume and some motor boating happening at fairly low frequencies. It seems to be happening somewhere between leaving the op amp and the 3k3 resistor. Any help isuch appreciated. Thanks!

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  3. Thanks! I appreciate this! I'm study the heck out of this thing this weekend!

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  4. Can I get some more info on the clipping of this pedal? What would be a stock setup? no switches? is that symmetric clipping stock?

    can you use the 3 switches (2 sets) together or are they to be used seperately?

    Thanks!

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  5. The Timmy as standard has the 4 board mounted diodes in circuit, it then uses (in my older version on protoboard) a 2 pole board mounted dip switch to allow you to select symmetrical compressed clipping (with both additional diodes in circuit) or asymmetrical clipping using half of the waveform with one switch on, one switch off, or asymmetrical clipping using the other half of the waveform with the switches vice versa.

    You wouldn't use all 3 switches, just choose the method that you prefer. The option with the 2 switches allows you to switch the additional diodes individually and so you can replicate exactly what you can do with the original version Timmy. The single on/off/on will give you the standard mode, compressed symmetrical and one asymmetrical option. You can definitely get the most useful clipping with the single switch, but you can always use the two switch option if you must have it as per the original and you want the complete clipping options.

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  6. So need to give this bad boy a going over tonight. Can I use a LM1458 as a work alike until I get hold of the right IC?

    Hope you've got ya royal blue jersey ready for tonight mate! COYB!

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    1. Yes, in fact I've heard some people say the LM1458 sounds really good in there. And yes, I'm wearing my blues with pride tonight, COYB! Jags will score for us! :o)

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  7. Aces thanks mate! Hope hope, love smashing the gobshites! ;0)

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  8. Replies
    1. No way! I'm Mancunian, United all the way. But Milkit supports Everton and so do I when they play Liverpool :o)

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    2. Ah I see. I'm a spurs fan. Because football over here in the states is a joke. Not happy about our loss to everton the other week but as long as we keep Chelsea out of the champions league. Redknap hasn't decided on the English manager position yet has he. I would be heartbroken if he wasn't the spurs coach anymore. He's done great things with the team.

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  9. Is the 3 way dpdt the on/off/on variety?

    Great work on this btw & thanks!

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    Replies
    1. Yes, on/off/on. Then the centre position adds no additional diodes and just leaves the ones on the board in circuit.

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  10. Hey IvIark,

    I've built this tonight and I noticed something is not right with the bass pot wiring.
    I'm 100% positive that the Bass 1 lug goes to the 39nF cap
    Bass 2 and 3 together goes to the 1uF cap

    According to this numbering scheme: http://i76.photobucket.com/albums/j6/IvIark_2006/DIY/Pot20numbering.jpg

    Just like in this schematic over FSB:
    http://freestompboxes.org/download/file.php?id=13394&mode=view

    So in comparison to your layout Bass pot wires should be the other way around and 2-3 tied together not 1-2.

    BTW thank you for your work. Layouts are professionally beautiful and tight. I love the way you try not to use standing resistors.

    Oh, and Timmy is awesome! This vero is VERIFIED :)

    Cheers,
    rizibiz

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    1. Thanks rizibiz, I've built this and although I haven't still got the pedal I can't remember it working backwards. Does your bass control act as a bass cut, and so fully counter clockwise gives the most bass?

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    2. Yes fully CCW is the most bass heavy setting and towards CW is less bassy.
      I think this is the desired behavior. Every way I tried where bass lug 1-2 were tied together gave messed up taper where only the last quarter of the turn had effect on tone.

      All the other pots are fine wired as they can be seen in your layout.

      Just take a look at the linked schem. in my previous comment. It has markings for pot rotation. Bass pot is different but all the others are overlapping with your layout.

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    3. Cheers for that, I'll update the layout

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  11. so those are two different sized 47uf blue electrolytics? not one 4.7uf and the larger one 47uf?

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    1. Yes. They're the same size as caps I have in stock so I used the bigger one basically because there was enough space for it. But you can use any size caps.

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    2. word. so both 47uf? sorry "size" disceprancies... I have some of the big blue bc 47uf lytics. are they in the original... like part of the Timmy mojo sound? is the big axial 47n in the original as well... or just used to cover the space? I am a believer in the mojo of those old big components... i just had 10 of those big blue bc lytics test 47uf +/- 1uf and some axial xicons range from 37-57uf haha! ridiculous

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  12. No there's no mojo in the original. I've got a Timmy and this is the gutshot.

    http://i76.photobucket.com/albums/j6/IvIark_2006/DIY/Gutshots/10112010415_2.jpg

    I like big old mojo components too, but something like the Timmy proves you don't need them to make great sounding effects. Although as you point out, you DO often need to pay a bit more if you want better tolerances. I love the blue electros, but the best ones I've bought for accuracy were Siemens/Matsushita which were all pretty much bang on the money.

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  13. just built this with the old pot wiring...and it still sounds really, really good ;)

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  14. I just built this... and it sounds excellent... pretty dead on IIRC, its been a while since I've played a real timmy though.

    the treble cut works as you turn the knob clockwise... ie: there is more treble content when turning the treble knob counter clockwise. should I just reverse the wires?

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    1. The treble and bass pots are supposed to cut and so there should be more treble and bass content in the far counter clockwise position. The idea is that as you increase gain the treble and bass pots are rotated to the same position as the gain pot to keep a flat response.

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  15. I just realised i have a 5k pot for bass instead of 50k. I wired everything up and its all working fine except that it's super bassy and it cant be dialed out.

    Is that because of the pot?

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    1. Yes, definitely. With a 5K pot it's like having a 50K pot that can only move from the 7 o'clock starting position (fully counter clockwise) to the 8 o'clock position.

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  16. Why oh why did I not make this one earlier! I just finished one and it sounds seriously good! Here's a photo of it: http://instagram.com/p/Ma6TqPy98h/

    Thanks Mark!

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    1. Cheers for the photo, looks cool

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  17. Thanks man! I didn't have a 3 position DPDT switch, only a 2 position one so I used it anyways. In the middle position, wouldn't that just be like having no switch (which should be about the same as the position where you have the two diodes wired together)? Sorry for the silly question =p

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  18. Will this work with a 4558 Opamp.... And what´s The differentse between a 4558 and a 4559 opamp

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    1. Yes it will work fine with a 4558, I've made one using it and it sounded great. The specs are very close but the 4559 has a higher slew rate and greater gain bandwidth product.

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    2. Thanx for your Online Support ... I Made one earlyer today ( with a 4558 Opamp ) and it sounds and works great ... I think the Tone controls are very good... ( and the Diode Switch )
      Have a good summer and keep on rocking ....Cheers

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  19. This may be a dumb question, but I'm new at this, so bear with me:

    I have an On-On-On DPDT switch. Will that work for this build, or will I have to buy an On-Off-On toggle switch (as suggested above) for the extra clipping options?

    By the way, this is a fantastic resource, and, as a DIY noob, I greatly appreciate the effort you've put into this website.

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    1. That would be a bit difficult to use for clipping, as it's connections go like this: http://i207.photobucket.com/albums/bb89/SomeoneYouKnew/fixes/on-on-on.gif

      While on-off-on connects upper and middle lugs on down, no connection on center and lower and middle lugs on up position.

      I haven't seen any effect circuit that uses on-on-on (those are used on 2 humb guitars though), but on-off-on are very common. You should get these quite cheap form almost any shop. Tayda has them, but they are relatively pricey. Banzai and Musikding has them for less..
      +m

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  20. Just want to thank you, Ivlark for all these great layouts. I've been building a few pedals up, used to get kits, but this is way more fun. The timmy was my latest build (well actually boxing, as I had it populated quite a while ago). It sounds great. I have mine set for a fairly low gain sound that tightens up the bass a hair and adds a touch of treble. Still sounds like my amp though which is awesome!

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  21. Built this last night, Very nice & goes great with the Zendrive & Purple Plexi. Done my first swirl paint job on the enclosure & worked out nicely, I'll post a pic later.
    One question, on the 3 position dpdt does it matter which way D5 is facing ?
    Thanks again for all your hard work!
    Rob.

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    Replies
    1. Yeah the Timmy and Zendrive are one of my favourite stacked combinations. It doesn't really matter which way the diode goes. One way will clip the top of the waveform, the other way will clip the bottom and it's unlikely anyone would notice which was which.

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  22. Heres a pic of the Timmy & Zendrive i finished last week
    Thanks again !

    http://farm9.staticflickr.com/8353/8263604627_6539fb1cb3.jpg

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  23. I think I saw a comment from Paul C about modifications to the Timmy that would change it into more of a clean boost. I had something to do with removing the tone controls and clipping diodes. I can't seem to find the forum where he posted that, but if you could shed any light on that, I'd appreciate it.

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    1. I don't know what Paul's suggestion was, but if I wanted to reduce the gain I'd lower the gain pot, and maybe instead of the diode clipping options just include a 3 series pair like the Xotic RC Booster. I probably wouldn't remove the diodes completely though because if the opamp starts clipping it's not particularly pleasant compared to diodes.

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  24. Built it; sounds wonderful. I feel with this and zendrive you don't need anything else on your board. 2 of the best ODs. Thanks again Mark.

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    1. Have you built the gainster yet? :)
      +m

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  25. Anyone compared the sound from one of these builds side by side with a real one? - how close is it?

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    1. Yes I've got an original Timmy and compared them. I preferred mine, but then I may be biased :o)

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  26. haha - how close are they though? - are the changes subtle? or obvious?

    Why the difference? - is the schematic you built from likely to not be exact? components different from those used in the real thing? or is it purely just component tolerances?

    Thanks,

    Ian

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    1. They're essentially identical and the scheme I did the layout from is definitely right, Paul Cochrane confirmed it. The thing is with any bought pedal though is that you get what you're given, whereas with any DIY build you can tweak here and there to get it to sound exactly as you like with your gear. So you may change a couple of cap values to change filter frequency, or you may use your favourite diode clipping combinations, but the point is you can fine tune it to exactly how you want it.

      Paul used polyester box caps, carbon film resistors, 20% radial electrolytics and a silver mica for the 100p cap on protoboard in my original. In the one I built I used Panasonic film caps, Dale metal film resistors, 20% Panasonic axial electrolytics and also a silver mica for the 100p.

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  27. Very interesting!! - can you recommend any good guides/descriptions of what's changeable, what the options are and generically what kind of difference it makes? - has anyone documented that kind of stuff?

    Thanks,

    Ian

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  28. I'm working on building this one right now. I only have radial electrolytic caps in the 1uF value. Could anyone tell me how to arrange the polarities on the cap to put them in place of the two non polar 1uF's in the layout? Thanks!

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    Replies
    1. Minus to Volume 3 and minus to Bass 2&3. Or that's how i percieve it :) (Volume 3 is at output cap, so dc stays on the circuit side, Bass 2&3 connects to vref through that 1µ, so vref must be the plus side...)
      +m

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    2. Thanks for the fast reply! Hopefully I'll be comparing this to my Timmy V2 before the end of the day.

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    3. Hmmm all wired up and no sound. I put the polar caps in place the way you suggested. Double checked the cuts and jumpers, checked rows for bridges, tried different chips, reflowed all the solder. Bypass and led wired to the board work but no sound. The fun continues...

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    4. I believe this layout has been built over and over, so it should be ok. Do you have a probe? (http://www.diystompboxes.com/pedals/debug.html)
      You could try to trace where the signal dies with one of those (it's just a guitar cable with ~100n cap).
      Also, you could measure the voltages on the IC pins, so if there's something wrong with those...
      +m

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  29. When connecting the clipping switch, which way should the wires go on the two pads? (obviously it won't matter when it's off or with D6/D7 active, but with D5 on the direction presumably matters?)

    Which way is asymmetric and which is compressed? - what do they actually mean? - what difference should I hear? - to me, it sounds louder in the middle position but I can't really hear any other discernable difference in the other modes - is that normal?

    I connected the LED up as per the wiring on the offboard page before realising that there was a resistor and LED output on the board - is that any different?

    Thanks,

    Ian

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    1. It doesn't matter which way D5 goes. All that does is clip one side of the waveform slightly more than the other. The middle position should be louder because the other positions add the diodes which compresses the signal more. The differences will be there but they can be quite subtle. If you've done an offboard LED and resistor you can ignore the LED+ connection on the board

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  30. I only have 1 axial 47u (25 v, alum.) cap and a bunch of radials (16 v). Where should I put the axial one, or does it really make a difference?

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    1. Use the axial in the spot up to 9V. It makes much more sense to use it in the spot with the largest span

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  31. So no other tonal or noise consideration? Is it strictly a size/spacing issue?

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  32. Another question: I ordered a bunch of supplies from tayda, and I chose Polyester Film Box Type caps (http://www.taydaelectronics.com/capacitors/polyester-film-box-type-capacitors.html) Are these suitable for projects like this? Would the greenies be preferred? It seems to me that I see layouts with the red ones (Polyfilm? as seen on Mammoth Electronics); are they better?

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    Replies

    1. FWIW, those are pretty much all I ever use...

      You've probably seen this
      http://tagboardeffects.blogspot.com/p/components.html

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  33. I had read that, but it still seems like the majority of te gut shots I see have either the red or green poly caps. Looking back through the comments above, I see that someone posted a gut shot of the actual timmy, and it looks like Paul C used box-type caps. Go figure.

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    Replies
    1. Paul used box caps but I wouldn't worry too much about the actual cap form, it's more important to select a cap that is appropriate for the span. Box caps are great but unless you find some with long leads you're restricted where you could use them, basically the pitch is 5mm and you may get away with 7.5mm, but you're not going to be able to use them, for instance for the 10n cap in this layout. I use box caps all the time, but also use Panasonic ECQ series caps (the maroon ones shown in the layouts) and greenies which are much better for these builds because the long leads mean you don't have the span restrictions. A set of greenies like this would be perfect:

      http://www.ebay.co.uk/itm/260840976632

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  34. For some reason when I measure the resistance across my 2M2 resistor Im getting around 550k.. which is really weird...off the board it reads at 2.2M but once on it gets 550k? Also my IC pin 5 is reading at 0.8V, any thoughts on where I may be going wrong? What are the correct IC pin voltages?

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    Replies
    1. That's perfectly normal. Once the resistor is part of the board, it is sure to be a part of a a resistor network and you are reading a resistance of the entire resistive network at these two points. Most of the resistors (and capacitors as well) will measure funky once soldered alongside other components.

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  35. I've built this unit before and had no issues... the build I'm working on now squeals to high heaven when I turn up the volume or gain any substantial amount. Any thoughts on what my issue might be?

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  36. Son of a gun, I'm new to the vero/strip board layout, but I'm really digging it! Great job! I did check out the off board wiring diagram that you have available, so in regards to the Timmy, where does the output come from on the veroboard, to go to the stomp switch?

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    Replies
    1. Ahhh, lets see if I can answer my own question. Lug 2 from volume pot goes to the top right lug on the stomp?

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  37. Bonjour
    Excusez moi d’écrire en français mais je suis nul en anglais.
    Je vient de construire le kit paul cochrane timmy acheter sur le site bitsbox et je ne comprend pas pourquoi sur le plan il y a 2 condensateur de 1 uf alors que dans les composant fournit avec le kit il n’y en a qu’un. J’ai mis ce condensateur en bas à gauche , à coté du cut et remplacer celui qui est indiquer en haut à droite (à coté des fils « volume3 », « treble 1 », » 9v ») par un cavalier. Cela marche mais je me demande si c’est bien correct .
    Merci à la bonne âme qui me répondra.
    vincent

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  38. traduction reverso ...
    Hello
    Excuse I for writing in French but I am hopeless in English.
    I have just built the kit cochrane paul timmy to buy on the bitsbox site and I does not understand why on the plan there is 2 condenser of 1 uf while in composing them supplies with the kit there is only one. I put this lower left condenser, in quoted(esteemed) by the cut and to replace the one who is to indicate above on the right (in quoted(esteemed) by the sons(threads) "volume3", " treble 1 ", "9v) by a rider. It walks(works) but I wonder if it is very correct.
    Thanks to the kind soul which will answer me.
    Vincent

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  39. This is my first build and I had a quick question.

    Would all of this fit fine in a 1690b?

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    Replies
    1. This will fit easily in a 1590B. Generally, you can fit up to 21 wide in a 1590B.

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    2. Awesome awesome! I love this place!

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  40. I built this thing and checked and double checked everything. First time I ran it the sound coming through was REALLY quite and only two of the pots half worked. I investigated and it seemed the ground on the output jack wasn't soldered well at all. After fixing that my bypass volume seemed perfect but the effect didn't work. Guessing it may be a ground issue.

    This is how it's currently wired: http://www.tylorjreimer.com/wiring-2.jpg and this is how my other pedals have been wired http://www.tylorjreimer.com/wiring-1.jpg. I am still learning a lot about how these pedals work so would that make a difference?

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  41. Both those wiring diagrams are acceptable and are actually the same.

    Make sure the IC JRC4549 is in correctly with the cut out notch to the top.

    Check that you have no shorts at the back of the vero (Use a Magnifying Glass) Builders run knife, hacksaw blade or hot soldering iron down the rails to fix.

    Check Components, links, cuts are in correct positions and that you have them all.

    Don't Panic or Stress. You will eventually fix it.

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    Replies
    1. So I managed to get this pedal working (kind of). The volume and treble work but the drive and bass knobs don't. I don't have the DPDT switch hooked up which I assume should still work? Also for the top left wire in the diagram it says "Drive 1 / Treble 2 & 3". Does it matter what order you chain these in to the board? I'm assuming if my Treble control works then that part must be right.

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    2. There's no order to chain these things. They're all connected together so it's neither in series or parallel. You can have it any way you want, as long as the right bits are connected together.

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    3. I had this thing running and it sounds great! I let my friend try it out and he hooked it up with a 12v adapter instead of a 9v and now it doesn't work. My guess is something fried but is it safe to say what would fry? Would it be the chip?

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    4. 12VDC? If so that should work fine. If it was 12VAC then you could have potentially blown something, but I would expect the main filter cap to take the supply straight to ground and unless you used a very low voltage rated 47u cap then that should be able to take 12VAC without blowing anyway. The IC does need a DC supply though so I suppose that could have failed and would be the first thing I would swap.

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    5. Upon inspection I have run the pedal off a 12V I believe with a 0.4A output. The adapter he used on it was center positve and 2.5A. So you would try swapping out the IC?

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    6. If it was centre positive DC then the polarities have been reversed and you could have damaged any of the polarised components. Swap the 47u, or just snip them out and see if it works. The pedal will work without both caps and it'll let you see if that is the issue. The IC could have been damaged too so those are the first things I'd check

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    7. Hey Mark, first off thanks for all the help and time you put into helping us new hobbiest learn the craft. I tried snipping the 47u caps out with no luck but I'm going to look in to the chip. One weird anomaly I noticed was sound only comes through the pedal (after the incident) when the output cable is half way in to the jack (the point where the tip hits the ridge that the ring should sit on. Leads me to think I have some grounding issue. Thoughts

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  42. Hey guys just built i

    It lights up and the pots affect the sound....

    But there is no guitar going through at all. Nada.
    It's a static/hiss and that's it.

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    1. It doesn't give me my guitar sound in bypass either

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    2. Haha! Works now! Double check that your input tip isn't against the enclosure ;)

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  43. I just built this but used LM1458 instead since I didn't have the other. Also used linear pots instead except for the drive because that's all I had. Really great sounding OD!

    One question-what is the purpose of the 100pf cap? I forgot to put it in there on accident, but I don't know, it still sounds good to me.

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    1. The 100p is a filter to cut some high end, it isn't going to absolutely change the character of the pedal but can deal with any high frequency unpleasantness you might get. I'd definitely add it when you get one so you know it is as per the original.

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  44. This may be a strange question, but this is my first Timmy so I'm not sure whether it's normal - turning the treble knob clockwise causes an apparent drop in volume. I can turn up the Level knob to compensate, so it's not all bad.

    I've gone through the usual troubleshooting steps, looking for solder bridges or components in the wrong spot, but before I dig into troubleshooting some more I'd like to know whether it's actually a problem :)

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    1. Mine doesn't do that so it suggests a problem somewhere

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    2. Although the pots are wired "in reverse" so they should take a lot away from the treble and bass when turned all the way clockwise. Wouldn't call that a volume drop though.
      +m

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    3. Hmm, I'll have to keep troubleshooting, then. At least I can compensate with the Level knob in the meantime...

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    4. Post the IC voltages and we'll see if that gives any clues, but I suspect it will probably look ok with the pedal mostly working correctly which will point to maybe a temperamental components or a unwanted micro bridge somewhere

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  45. Just finished one...
    It's a phone camera so colors are a bit off.

    https://lh3.googleusercontent.com/-TqAYDsTEpMI/UcH-W89D8HI/AAAAAAAAA5s/Nj8MZBfdliw/w1029-h772-no/IMG_2560.JPG
    https://lh4.googleusercontent.com/-g5NzALSGydE/UcH-etZuf0I/AAAAAAAAA6Q/LLfZtMoh1TE/w579-h772-no/IMG_2561.JPG
    https://lh3.googleusercontent.com/-THlKxwf_PwI/UcH-e-kgwzI/AAAAAAAAA6c/k9modcO_3LQ/w579-h772-no/IMG_2564.JPG

    Trying to think outside the box with the led placement and installation method....worked out pretty well.

    https://lh6.googleusercontent.com/-t1-9BvAqCko/UcH-e2v_SpI/AAAAAAAAA6Y/27CS_bwocCU/w579-h772-no/IMG_2568.JPG

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    1. Ha ha, nice job Goran, thanks for the pics

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    2. Goran, I love how you pulled the wires through the board...great idea! I'm going to have to start doing that where I can. I feel like that will take some of the strain off of the wire, since I use solid core at the moment. And it looks nicer...I'm always looking for ways to make a cleaner build.

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  46. Here are the IC voltages from my build with the volume drop as the treble pot is turned clockwise:

    1: 5.23V
    2: 6.43V
    3: 2.54V
    4: 0.01V
    5: 5.19V
    6: 5.23V
    7: 5.20V
    8: 9.58V

    If they should all be around 5V then the voltage at pin 3 looks a little low. Also, when I turn the Treble pot fully clockwise, the voltage at pin 5 drops to 4.88V (and all other voltages stay the same). Thanks so much for the help!

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    1. Fixed!
      It turns out I'd accidentally put a 100nF cap in place of the 10nF. Once I put the correct component in, it works as it should. The voltage at pin 3 of the IC is still around 2.5V but there's no longer a voltage drop at pin 5 when the "Treble" pot is turned fully clockwise.
      How I missed the wrong cap in my previous half dozen inspections I don't know, but it's working now at least :)

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  47. is there anything i can sub dx (1n5817) for? i don't have any of those laying around.

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    1. 1N4001 will do. In fact pretty much any diode would do, you could put a 1N4148 in there if you want.

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  48. Hey Mark - just wanted to thank you for this awesome site. Built my first DIY pedal from this layout (Finished at 11:30pm last night:)and it sounds really good. Buying boutique pedals here in SA is really expensive and I have always wanted to get into building my own. This site gave me the confidence to give it a go, still heaps to learn but what an awesome hobby.
    Anyway thanks again to you and the rest that post here for the great information.

    Cheers
    Warren

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  49. Hi Mark - just one question...I apologize ahead as I am sure this has been asked multiple times .If you have multiple pot lugs going to the same place on the board is it ok to jumper the lugs together and then take one wire to the board? For example if you have treble 2&3 as well as gain1 going to the same place on the board...
    Thanks
    Warren

    ReplyDelete
    Replies
    1. Sure. It's all the same potential and that's the sort of thing that you are doing with say offboard wiring ground anyways.

      Delete
  50. Thanks Goran - that's what I thought and what I did but I'm a newb so I just wanted to be sure - thanks
    Warren

    ReplyDelete
  51. My Timmy isn't working, I get no output signal. Some help troubleshooting would be appreciated, since this is my first "from scratch"-pedalbuild.

    Not sure what information is relevant, but here are some voltages:
    V+ = 9V
    Vref = 6.31V
    pin4 =~ 1mV
    pin8 = 8.98V

    Which seems okay to me.

    With the pedal engaged and a 0.26V sine wave @700Hz in the input, I read the signal at 0.03V at pin 3, but not in pins 1, 2, 5, 6 and 7 (only the 50Hz signal at 0.016V).

    Audioprobing confirms that a signal enters the first OP, but none leaves.

    I have tested the OP-amp in another circuit, and confirmed that it is indeed working.

    Any suggestions on what might have gone wrong?

    Cheers
    /Johannes

    ReplyDelete
  52. are D6 and D7 wired in the same direction as one another?
    also - are they wired in the same direction as D5?

    ReplyDelete
    Replies
    1. D6 stripe (negative) faces to the right, D7 stripe (negative) faces to the left. D5 stripe also faces to the left.

      You can see it quite clearly if you zoom in the picture a bit.

      Delete
  53. i built the pedal, and there is no sound coimng out unless i short out the 9V+ and the one above it, or other shorts (not really sure when it happens exactly)

    i get these voltages at the IC pins:
    1 - 0
    2 - 2.42
    3 - 2.62
    4 - 0
    5 - 4.6
    6 - 5.22
    7 - 5.23
    8 - 9.44

    ReplyDelete
    Replies
    1. OK, wrong voltages for some reason:
      1 - 5.22
      2 - 6.08
      3 - 2.62
      4 - 0
      5 - 4.78
      6 - 5.22
      7 - 2.01
      8 - 9.44

      Delete
    2. even more clear:
      no sound comes out->i short the *entire circuit* with my palm - > when i lift it up, the pedal works.
      then if i close it up or move i too much - it stops.
      very weird.

      Delete
  54. My build of the Timmy, metallic purple with added sparkle flakes.
    http://instagram.com/p/cz7mbOxWE6/

    ReplyDelete
  55. I've built a few of these for some friends and they're awesome. This one is sans switch.

    http://instagram.com/p/cIaQr5nXWi/

    ReplyDelete
  56. my build of the timmy: http://imageshack.us/a/img543/8942/drva.jpg

    it really sounds awesome... i liked it a lot when playing solo at home, but i realized when i used it in my band, i couldn't believe how both full and articulate my guitar sounded...

    ReplyDelete
    Replies
    1. Dude that is gorgeous. What kind of paint did you use and where did you get those knobs?! This is my first proper build, any advice on this would be great :)

      Delete
    2. the enclosure comes from mammoth, I ordered a 125B blemished enclosure and got this! (seems like the corresponding finish is "Seafoam Green". THe knobs are from mammoth too. don't remember the reference but browse their aluminium knobs and you'll find them.

      Delete
  57. finished like this sound,, :D
    thank Ivlark

    ReplyDelete
  58. going to embark on this to hook to my Zendrive, read somewhere its what Mark uses? out of curiousity, does anyody know his gear? More importantly...

    Of the 2 additonal clipping examples, which one is the one that comes with the original Timmy? is the output sound exactly the same or will it be different? (need to decide which route to go)

    ReplyDelete
    Replies
    1. Will this work for the 3 way switch?
      http://www.taydaelectronics.com/slide-switch-2p3t-solder-lug-5-5a-250vac-1827.html

      Delete
    2. Mark's 5th comment explains everything about clipping. Don't know about the switch, I don't think it would work the same (the DPDT is on/off/on)

      Delete
  59. This is my first more advanced build. Can i just confirm, for example "Bass 1" just goes to lug 1 on the bass pot, "Drive 2" goes to lug 2 on the drive pot etc etc?

    what is the protocol if it says "Drive 1 / Treble 1 & 2"......and also "Bass 1 & 2".

    And i assume i can just google a standard offboard wiring schematic for the switch, LED, DC socket etc.

    would really appreciate help, eager to get into building pedals. thank you! :)

    ReplyDelete
    Replies
    1. lvlark has some great info on the Offboard tab on the top of the page, as far as wiring up a pedal (i.e. lug order). But yes "Bass 1" would go to lug 1 on the bass pot. As far as the "Drive 1 / Treble 1 & 2" what I did was solder two wires together and run them out of the same hole on the board to the appropriate pot. Then you would just connect lug one and two with a short wire.

      Delete
    2. Could anyone tell us if, in the case of "Drive 1 / Treble 1 & 2", could we just run one wire off the board and then just run wires from Drive 1 to Treble 1 an two, or do we need to split the signal before the pots?

      Delete
  60. By the way, I just finished this build, and it sounds sweet.

    ReplyDelete
  61. Always wanted to try one, couldn't believe all the hype. Well, just finished this with one on/off/on switch and Jesus christ this thing sounds phenomenal. I love it. Will probably get a spot on my board. Very versatile and transparent, even when in the compressed mode. Tried a JRC4558D for fun but it didn't work quite well. Turned this thing into a more sterile, compressed generic OD.

    ReplyDelete
  62. Noticed one annoying thing. On high treble settings I get a slight high pitch oscillation-like sound. Now I never use those sounds but it's still annoying. How would I go about fixing that? An additional filter cap somewhere? It's only when I crank the treble to maybe 70% and up. Still absolutely loving this thing. Beats my DIY TS9 which I modded to my tastes hands down as a JCM800 booster, which is a lot. It's the only one I prefer to the TS. Also amazing at boosting fuzz pedals to get a tight chug out of a fuzz. All in all it stacks very nicely with other pedals. AND a great clean booster for spanky cleans. Just amazing.

    ReplyDelete
    Replies
    1. Up the 100p for 150p or 220p. That should cure it.
      +m

      Delete
  63. Thanks again mate! I'll be doing just that as soon as I have time to heat the iron somewhere along the week.

    ReplyDelete
  64. Just built this tonight and it sounds great. Like others have said, the "backwards" treble and bass controls are a bit counter intuitive but I am sure that I will get used to it.

    ReplyDelete
  65. I dont really understand the Volume wiring, could someone possibly help me out and explain it? Just not sure what Volume 1 to ground, Volume 2 to output, and the Volume 3 mean and where there'll all supposed to be wired.

    Also can I use a standard wiring diagram such as this one from Beavis Audio:
    http://www.beavisaudio.com/techpages/StompboxWiring/
    Or does it have to be wired in a specific way?

    I'm pretty new to this so any help would be great

    ReplyDelete
    Replies
    1. Eric, you can use that wiring diagram, but read on....
      The wiring instructions on this site are very simple when you get used to them. Volume 1 to ground simply means, lug 1 of your volume potentiometer has to be connected to ground, equally, volume 2 to output means that lug 2 has to be connected to the lug on your footswitch for output. In the wiring diagram you linked to, volume 2 would connect to the footswitch lug in the bottom right corner of the switch.
      Hope that clarifies it.
      Cheers
      Dave

      Delete
    2. Thanks a lot for that Dave, really helpful. Is there any particular place lug 1 has to connect to ground? would it be at the ground output on the board or to the sleeve of one of the jacks etc?

      So that means both volume lug 2, and the circuit output go to the bottom right on the switch?

      Thanks again Dave, think I have my head around it now!

      Delete
    3. It doesn't matter, as long as everything that has to connect to ground ultimately connects to the negative pole of the power supply (or battery clip, or both), it doesn't matter where they connect, as long as they do.
      Sort of but not quite. Vol 2 is essentially your circuit out, You'll notice somewhere on the board it has to connect to vol 3, this is the signal leaving the circuit board to your volume control. It then leaves your volume control via lug 2, so in effect, lug 2 of the volume pot is your circuit out. So to be specific, your circuit connects to the footswitch, only via the volume pot, not directly.
      Cheers
      Dave

      Delete
    4. Oh I get you know, so the signal leaves the circuit at Volume 3 and connects to lug 3 the pot, then leaves the Pot via lug 2 which connects to the switch. So all the pot is doing is controlling the output level from the board. (haha it is a VOLUME pot I guess).

      Thanks for clarifying everything Dave, sorry for the novice questions, I'm sure everyone else on here knows this stuff pretty well. looking forward to putting this together, just wanted to have it all worked out before I start.

      Cheers! :)

      Delete
  66. I built the none compact layout. The only changes I made was I used a 511k instead of a 510k resistor and I used a JRC4558D IC. It sounds like the distortion isn't fully mixing with the clean sound. When I switch to one of the extra diode settings there is a little bit of a volume drop. Any ideas of what is going on?

    ReplyDelete
  67. I'm having the exact same problem as Steve ^^^^. I built the non-compact layout, and all the knobs seem to do what they are supposed to (volume works, gain works, bass and treble are cut knobs). It just seems like the clean volume and overdrive signals aren't mixed together. Any thoughts? I'm pretty new to pedal building, so I could have easily made a silly mistake somewhere.

    ReplyDelete
  68. Could anyone tell us if, in the case of "Drive 1 / Treble 1 & 2", could we just run one wire off the board and then just run wires from Drive 1 to Treble 1 an two, or do we need to split the signal before the pots?

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

    ReplyDelete
  70. Still having this issue if any one could help that would be awesome. The clean and overdrive signals aren't mixed together fully. It's more noticeable when using a single coil Strat. If I use a guitar with a humbucker the clean and overdrive signals mix better but not totally.

    ReplyDelete
  71. I just put this together and am having a small issue. As I follow the signal with an audio probe it is as it should be until it gets to pin 6 of the op amp. Pin 5 is good and somewhere after that it picks up a little volume and unpleasant distortion and kind of a phasey wavey kind of sound. It seems to be somewhere between the output of the op amp and the subsequent 3k3 resistor. Any thoughts?

    ReplyDelete
  72. I don't know about what's mixing with what but I also get the volume drop in one of the clipping modes, compact layout here. Other than that. This thing sounds pretty much perfect.. I never touch the switch, just keep in the middle where I like it.

    ReplyDelete
  73. Alright... I've build this one before for a friend and don't have it with me to compare.
    Everything works as far as knobs and switches and knobs but I'm not sure it's supposed to sound like this. With everything at 12, when you step on it it's like someone threw a blanket over the amp. Everything is muffled. Tweaking the pots (treble in particular) somewhat brings it back to life but it's not at all how the clips I've seen sound (and I can't for the life of me remember how my first one sounded). Any ideas?

    ReplyDelete
  74. I am a little unsure how the clipping switch is being wired. It says you can take a feed from Drive 1 and Drive 3. Here's how it is wired right now and I'm finding it hard to hear much difference between the 3 switch positions. https://www.dropbox.com/s/ptl5lsf2vg5ppnc/Timmy-Wiring.jpg

    Do the wires off the board need to go to switch and THEN head to the potentiometer?

    ReplyDelete
    Replies
    1. Yes that's right. As long as all the points connect up it doesn't matter which one you go to first. The difference isn't night and day, some people will find it quite subtle.

      Delete
  75. Hi Guys,
    Managed to start it working last night.
    i am a bit confused... it seems a quite "high-gain" pedal to me, did not expect it.
    Even more confused when I checked some pictures of the Timmy "interior" in the net.
    Here goes one:
    http://www.auctiva.com/hostedimages/showimage.aspx?gid=1421791&image=721750804&images=721750763,721750768,721750776,721750785,721750792,721750798,721750804,721750809,721750816,721750825&formats=0,0,0,0,0,0,0,0,0,0&format=0
    As you can see, couple of capacitors more, some are with different values from the schematic.
    Any chance there is a new version (this pedal is produced in 2012), and , also, do you think
    these changes might seriously affect the tone?
    Cheers,
    Yavor

    ReplyDelete
    Replies
    1. It looks to me like he's made a couple of changes.

      1) The input cap now seems to be 39n instead of 47n in the older one (I'd probably prefer to stick to the 47n here because I don't think the Timmy will benefit to being slightly brighter)

      2) He appears to have included a low value cap from the first non inverting input to ground. This can help with RF noise and I've seen values from 10p to 100p used in that position.

      3) The 2n2 seems to be a new addition. I would guess that it is in parallel with the 3K3 between the inverting input and output of the second opamp channel and this will act as a filter which would make an audible difference I would say. It would tame some high end (which may be why the input cap was reduced). It could also be a second filter cap from supply (pin 8 of the IC) to ground, but I think that is less likely because I doubt Paul would put it in that position and would be more likely to put it in the space at the top right hand side near that bigger 47u filter cap.

      Those would be my educated guesses but we'd need to see a modern version to confirm. I have a Timmy myself but it won't help us because it's one of the older ones on proto board. The main change from what I mentioned that will cause an audible change would be the 2n2 if it is used as I suggested in parallel with the 3K3. If you want to see how it would affect the pedal, just tack solder a 2n2 cap to the resistor leads of the 3K3 directly to the right hand side of the IC.

      The Timmy does go pretty high gain so what you say is expected. If you don't want it that high and would prefer a better resolution of control at lower gain settings, then change the Drive pot to a 500K.

      Delete
    2. IvIark, you are great, fast and competent. As usual !
      Thank you!
      I will try modding it a bit. And I believe I found some clue to what the 2n2 and also the yellow "thingie" on the left of the opamp for:
      http://3.bp.blogspot.com/-0znV3OdEOIE/T1neO5y5ZjI/AAAAAAAABDU/rvvxgPJnv_k/s1600/Timmy+%253D+Feedback+C.JPG
      Cheers and thanks again!
      Great pedal, great build.
      For the benefit of supporting the producer I have just ordered an original one, as you advise as well.

      Delete
    3. I don't think Paul has done that, that was just a suggestion someone made on FSB to add feedback to the Timmy, but it would require a second switch.

      Delete
    4. I have actually done the mod and I really recommend it.
      It gives the pedal a very "bluesy" feeling and sound, cuts the gain down.
      I am curious to compare with the original pedal, when it arrives.
      Thanks again for the advises.

      Delete
    5. Excellent. When you get the original, if you send me a pic of the front and back of the board I'll post a Timmy 2014 layout

      Delete
    6. It is a second hand one. If it is not the old model, will send pics asap :)))

      Delete
  76. I just built this guy and it seems to be working properly, but at low gain settings and with soft picking dynamics, there is a weird buzzy overtone to the notes. the circuit seems fine...could this be a faulty diode or a grounding issue maybe? any help would be greatly appreciated. thanks so much for the blog!

    ReplyDelete
  77. what other IC could i use instead of the 4559?
    would 4558 work the same here?

    ReplyDelete
    Replies
    1. Any Dual opamp should be fine 4558, 4580, TL072, NE5532 and so on.
      I believe new Timmys are equipped with LM1458.
      +m

      Delete
  78. These are the voltages I'm getting:

    1 - 5V
    2 - 5.45V
    3 - 2.24V
    4 - 0V
    5 - 4.91V
    6 - 4.95V
    7 - 5V
    8 - 9.09V

    Looks like pin 3 might be the issue?

    ReplyDelete
    Replies
    1. I actually think pins 1, 2, 5, 6 & 7 all look a bit high actually, and so it doesn't help to tie down which are the problem may have started. So all I can advise is going over the layout very closely making sure your values are correct, knife between all the rows to make sure there are no unwanted bridges, redo the cuts to make sure there are no burrs which may be making unwanted connections and if all that fails then you may have to start swapping components to see if one is faulty.

      Delete
  79. Hello there, unfortunately i haven't any 1M pot at this time just 470K, is there anyway that i can make it work or make the pot in bigger resistance? Also the led light stays allways on either when bypassed or engaged!!!

    Thanks in advance!!!

    ReplyDelete
    Replies
    1. You can make a pot smaller but not bigger. A 470K will work fine in there, you just won't get quite as much gain out of it.

      You could mimic the higher gain settings though if you prefer a bit more dirt. If you imagine the gain settings in the standard pedal being between 0 and 100%, you could add a 470K minimum resistor which would then give you 1M total resistance in series with the pot, but then you would only get 50% to 100% drive settings and so no option for anything lower.

      Basically if you're more interested in the lower gain settings then use a 470K pot, if you want the higher gain option then personally I'd order the correct pot and wait.

      Delete
  80. U are gr8 Ivlark i try it out with the 470 and it is fine i dont need any more gain ar all... The led is ok now it was my stupidness to connect the (-) with ground... I connect it now with the footswitch lug and it is perfect!!!

    ReplyDelete
  81. Here's my build, just for personal use. It really is a great pedal, very versatile. in retrospect i should have used axial caps... it was a little tight fitting everything in with the switch, but in the end it was fine.

    http://i.imgur.com/Oo1OvbI.jpg

    http://i.imgur.com/MfMTeTn.jpg

    It is my first reverse etch.. messed up the first sanding so had to put an extra coat of paint, so there isn't as much depth as before. So much to learn with this hobby!

    ReplyDelete
    Replies
    1. Dig that reverse etch, Adam.

      As an aside, I used to lay radial caps sideways like you are doing. But I have found that i can actually lay it down sideways in the direction of one of the leads ( the cap will sit on top of one of the leads while the other comes almost straight down from the bottom of the cap ) . Helps in some of those tight places. Not always workable but it usually is. You can insulate that lead that the cap is sitting on, but I've never had an issue since the cap itself is covered in an insulated wrap.

      Nice build!

      Delete
  82. I tried browsing the comments for this question but didn't see it.

    Why does the compact layout have a 1n5817 diode up by the 9v input while the other layout doesn't ?

    ReplyDelete
    Replies
    1. The compact layout is more recent and was done when I was going through a phase of adding series reverse polarity protection to everything. It's not nexessary though, include it or remove it, the main effect won't change

      Delete
  83. Built it this afternoon. Sounds really nice. The only problem I'm having is the Drive pot, which doesn't appear to be working right. It's wired up correctly, but it seems to be working more like a volume control. If I turn the Drive knob below about ten o'clock, there's no output from the pedal. From 10 o'clock up, the control seems to work as expected. As a result, I don't think I'm ever getting to the max possible gain.

    Wondering if anyone has any ideas? Thanks.

    ReplyDelete
    Replies
    1. Definitely something wrong there. All the gain control does is vary the resistance between pins 1 and 2 but even in the far CCW position there is still an increase in gain. Check your pin voltage and also check them at both rotations of the gain pot and see what measurements you get.

      Delete
    2. Thanks Mark. When you put it that way the control seems a bit simpler. at Pin 1 I get 4.55v when fully CCW and 3.98v at Pin 2.

      Fully CW, I get 4.03v at Pin 1 and 4.45v at Pin 2. Using a 4558 if that affects "normal" at all.

      I don't know what those numbers *should be* so I don't know what would indicate a problem ... the variation doesn't seem huge, but I'm guessing it doesn't take much voltage to change the gain. I'm also trying to figure out how the Treble control works exactly, since that's connected to Pin 1 of the Drive pot as well. Though, that seems to be working as expected as a treble cut.

      Delete
    3. The numbers look ok, I was just making sure that when it went silent you weren't getting 0V somewhere which could indicate one side of the pot was being grounded somewhere or something like that. Check your soldering on both ends of the 3K3 resistor going to drive 2. The control is really simple so it going silent on one side suggests something really amiss somewhere around the gain control. What are your other pin voltages? And knife all the gaps around there to make sure there are no unwanted bridges.

      And of course it could be a faulty pot.

      Delete
    4. Thanks for the help, as always, Mark. No idea what was happening. I had cut the hell out of the gaps before, but I re-soldered the 3k3, and cut all the gaps even more, and viola! A working Timmy!

      Delete
    5. Just one more little question. I prefer the standard sound with the switch in the middle position, so I'm not too worried about it, but if I do switch to one of the sides, I have a slight volume drop. Just wondering if that's normal. I read the Ben Adrian Audio explanation of diode clipping but I'd be lying if I said I understood it all. Though it seems like the added clipping could just be letting less highs/lows through, equating to less overall volume.

      Delete
    6. And by highs/lows I meant that with regards to voltage. See, told you I barely understood it.

      Delete
    7. This may not cover all the bases for the electronics experts out there but is meant to be easy to understand and relate to people building these effects. We always talk about DC voltages when we're trying to debug pedals because that's what is used to provide the transistors and opamps with their supply, but the signal from your guitar is AC which these things are designed to amplify. This is why capacitors are used in between stages because they block DC used for the supply of the active components, and only allow the AC signal from your guitar to pass to the next stage for further amplification or filtering etc.

      So in this pedal the AC voltage that comes into the circuit from your pickups is amplified by the opamp and clipped by the diodes in the feedback loop which distorts the signal. The default Timmy setting has parallel pairs of diodes and so the clipping threshold is the forward voltage of the diode type x 2 because you have two of them in each direction in series. If we assume that the 1N4149 diodes each have a forward voltage of 0.7V that just means that the diodes will start their work when the signal exceeds 1.4V (0.7V x 2). So say the signal was 2V as an example, the diodes would limit and clip the signal to 1.4V and this clipping and compression of the waveform is what makes the signal distort (or overdrive in this case :o).

      The switch is connected to pins 1 and 2 of the opamp and so will put the diodes soldered on the switch in parallel with the diodes soldered on the board, and because there is only 1 diode in each direction that means the signal will now be limited to 0.7V (or 0.7V on one side of the waveform and 1.4V on the other if you have selected the asymmetrical position of the switch). The diodes on the board are essentially bypassed because the diodes on the switch means the signal level can't reach the point when the board diodes start to limit the signal. So the output level is reduced because it is being more limited by the single back to back pair that you switched into the circuit.

      Does that make sense or am I waffling? :o) But basically yes, that is exactly what you should expect.

      Delete
    8. Mark, you are brilliant. That actually makes perfect sense, and is easy to understand. Thank you for taking the time. If there's a job out there writing textbooks on pedal-building, you'd be perfect for it. Clear and concise! Thanks again.

      Delete
  84. I am a little confused. I have one lead coming from the board and I split it and one is Drive 1 the other to Treble 2 & 3. And then for the clipping switch, i take one the drive 1 lead combine it with the lead for drive 3, take them to the switch, and then after the switch one to drive 1 one to drive 3??

    ReplyDelete
    Replies
    1. No need to split the wire.
      Treble 2&3 to the board.
      Drive 1 wire goes to the treble pot on 2 or 3.
      For the switch, take a lead from each side of the drive pot and go to the clipping switch as shown in the small diagram.

      Delete
    2. well i cant for the life of me figure out what i did wrong. is there a link to the schematic so i can trace the audio path? thanks.

      Delete
    3. found my problem. are you ready for this?? it was the op-amp. i used a socket and when i swapped the chip 4559 for a 4558 it worked. AMAZING!!! Special thank you to Lazy Swamis for the wiring tip!

      Delete
  85. /V\ark I've wired up the compact layout Timmy but I'm getting no voltage anywhere, even at the DC Jack. Does that mean I've got a short somewhere? I get 9.3V on the multimeter when I test the PS directly, but 0V once plugged in... :/

    ReplyDelete
    Replies
    1. Could be a short with the supply being immediately dumped to ground. Does anything get hot? Or it could be a mechanical fault with the DC socket so a contact isn't being made. At the end of the day there isn't too many things it could be if you're getting 9V out of the power supply but it isn't reaching the circuit, so just check each in turn.

      Delete
  86. Just built one of these (on a PCB) and since I did not have a 4559 I've tried 4558, 072, and 1458 and liked the 1458 the best. Seemed to be the loudest of the bunch without adding too much noise.

    ReplyDelete
    Replies
    1. I think Cochrane is using 1458s for some revision of the original...
      +m

      Delete
  87. How on earth do I connect the LED. All it says on the thing is LED+ and on the offboard wiring there is nothing. So what do I connect it to? Please help I've looked everywhere and haven't found any useful information

    ReplyDelete
    Replies
    1. Have you looked at the switch wiring diagram on the Offboard page in the menu above?

      Delete
    2. Yes I've looked at everything on that page but I haven't seen anything about LEDs but maybe I'm blind if so can you tell me the link. Also another thing I have found is the pots have a sticky up bit so you can't

      Delete
  88. Does it matter which way round the op amp is and if so which way and how can you tell?

    ReplyDelete
  89. I see the pots have changed in the last layout.. should these all be LOG?

    ReplyDelete
    Replies
    1. Yes use log. I didn't refer to my older layouts with this, I did it straight from the schematic so I wasn't influenced where to put things from my old layout, I find I can often save space doing that because I'm better now at using the available space than I was when I did the original layout. And that scheme only has the volume pot as log and must have been done before Paul corrected us on the pot tapers. Thanks for the heads up

      Delete
  90. (And thanks! I was just looking for parts to build this, when you posted an even more compact layout..)

    ReplyDelete
  91. Just built this. Some really great sounds but is it me or is the gain pot pretty much useless below 50% on a clean amp?

    ReplyDelete
    Replies
    1. It's fine as a booster on 25% or something but I wasn't expecting it to be so clean on the lower settings. Used the mojo layout and it was perfect. Thanks!

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

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  93. This comment has been removed by the author.

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

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  94. I'm getting a huge volume drop when the volume is at 12:00, but when I turn up the volume and gain I'm getting a lot of squeal and the signal cutting out like it's hitting a limiter. I've checked for bridges and cold solder joints, ran a knife across the board, verified all components and positions, and tried another 4558 and 1458 in this. Voltages seem low on the IC, but are 7+ elsewhere on the board (at the switch, diodes, caps). Here's the voltages I'm getting at the IC, all knobs at noon and the switch in the middle:

    1 - 1.68
    2 - 1.75
    3 - 1.57
    4 - 0
    5 - 1.71
    6 - 1.73
    7 - 1.73
    8 - 9.02

    Any ideas on other places to look at this one?

    Thanks!

    ReplyDelete