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Thursday, 21 February 2008

Clock of Tone 50 - Modifed Lovepedal COT50

[Image of an Original COT 50 Pedal]

The COT50 has been a boutique favourite for a while now, it's basic and effective and does produce some really nice tones. Here's the description from the Lovepedal Site:

"Church of tone 50. The 50 is an ultra simple pedal, more like a tool in the guitarist's tool box.

I use to go to these blues jams in Detroit MI. They always had some junky amp for jammers to play through. So I came up with this box that would simulate tube amp break up, give me enough of a boost to get above the band for solos and clean up very well with the volume knob on the guitar.

It has a very vintage plexi sound. It was designed to sound like a late 60s plexi loaded with 6550s. Through any amplifier, even a Solid State amp. It cleans up very well, when you roll back the volume knob on your guitar. This works like a pre gain adjustment.

The uniqueness of this unit is in the dynamics. A world of different subtle break up is available at the guitar volume knob. It cleans up so fast at the guitar most people leave it on all the time and work the guitar volume for everything they need. The knob is there for a bias adjustment. Hot biased or trimmed to original signal strength. If your the type of player that digs rolling off at the guitar. This is the pedal you want. Very crystal clear and raw uncompressed tone. This is the Billy Gibbons tone or early Hendrix sound. Depending on how you set the unit and the controls at your guitar.

The 50 has one knob that adjusts the bias of the transistor. This knob will make some noise when you adjust, the old Dallas Rangemasters did the same thing. Set the bias knob for the sweet spot, adjust volume knob on guitar to clean or dirty your signal. The 50 will push your amp! The switch for the 9 volt power supply is located on the input jack. So make sure you unplug the unit at the input jack to turn unit off. Carbon Batteries sound best to me (dollar store 2 for a buck). But try alkaline to see which you like best.

"Some of the best tones in this box come by simply adjusting your volume and tone at the guitar."
There is a lot of different shades of gain in this box and it sounds great with any guitar/amp combination."

Along with a demo video of the original in action;

But the original isn't why we're here - it's the Clock of Tone :-)

EDIT - Demo video (Not me playing!) of the Clock of Tone 50 circuit ; http://www.youtube.com/watch?v=PFBIZkjEw34 :

EDIT 2 - Here is another sound sample, it's got a master volume (470k pot at the end of the circuit) and a pot controlling the clipping threshold of the diodes (if I remember correctly a 10k pot worked pretty well..). It's the "Electric Church Pedal". http://skipregan.com/archives/535/electric-church-pedal/

I tried a COT50 booster the other day - nice tone, I thought, but it could be better! So I got my breadboard out and modified away until I was happy! More bass response was a must so I changed th input and output caps from 47nF and 100nF to 56n and 120nF, only a slight difference but it's enough to give your tone an extra thickness. Also I wanted to alter the clipping response slightly, it seemed a little harsh to me. I swapped out the 1N60 diodes used originally and went for some 1N270 Ge diodes, this softened up the top end a little. You can also see the 47nF cap in parallel to the diodes, this acts as a highpass filter and removes unwanted sizzle - no more "Icepick". If you want those extra highs reduce the value of the 47nF cap :-)

Finally, as always, I wanted more versatility. This is where I came up with the "Nature" control to accompany the already present "Structure" control. The Nature control allows you to blend between a full on thick boost and a rangemaster style treble boost, a nice feature to add I thought. The Nature knob is fairly interactive with the Structure knob, for example with the Structure knob at min and the Nature towards treble boost you get a pretty high treble boost but with the Structure at min (and Nature still towards treble) the treble boost is much less pronounced and it just takes away a little bottom end from you tone and prevents a muddy bottom end.

Well with those mods the COT50 became a useful little pedal... Just got to send the finished article back to my buddy now, see if he likes it ;-)

Here is a great vero layout for the Clock of Tone 50 from Torchy :-)

Here's a mojotastic tagboard layout by IVIark of http://tagboardeffects.blogspot.com:

EDIT - Here's a sound sample provided by AndreGarcia57 and it shows the differences in tone between transistor types BC108 and 2N5088, on low, medium and full gain settings:

"COT50 BC108 - 0 - 0s
COT50 BC108 - 5 - 21s
COT50 BC108 - 10 - 30s

COT50 2N5088 - 0 - 56s
COT50 2N5088 - 5 - 1:10s
COT50 2N5088 - 10 - 1:29s"

Here's the sample:  http://www.4shared.com/audio/XB5sVR9Y/DRIVE50.html


  1. Hi
    good job
    I'll try it asap

  2. Just built it last night, works great! I'm suprised at how quiet it is, (background hiss). It seems a little less gainy at full than the clips of the COT 50 I've heard, which is nice. Thanks for posting this circuit, I've wanted to get one, but didn't have the coin.

  3. Howdy just finished a proper COT with better parts. Love it, I could see this as something that gets left on all the time.

  4. Hi, great circuit and mods!
    I don't have 1N270 but 1N276, what you estimate the difference will be?
    From specs, the only diff. is fwd current (1N270 200mA vs 1N276 40mA. The 1N60 has a few more diff.)
    I didn't expect it to sound different with 1N270 instead of 1N60, so I ask...

  5. I built the COT yesterday, and it sounds pretty good. I didnt have the 1N270s but still thought it was a sure fit in my lineup. I should be getting the diodes today so I will put them in. I am considering putting them on a switch bc I really like how the pedal sounds now. Thanks for the circuit and mods.

  6. I just built one of these and like it very much. Both the structure and nature knobs work nicely, but are very subtle (almost too subtle, sorry). One question / issue I have is that it does not seem to have a good volume range. I think it blends well in my pedal chain and does give me a boost, but shouldnt there be a volume control? Thanks.

  7. Try all sorts of diodes they will alter the sound a lot with different clipping thresholds and speeds - I settled with BAT46 in mine.

    The original COT50 has no "volume" control - but you can add one by placing a 500ka pot on the end of the circuit wired as standard.

    1. So "wired as standard" meaning take the output wire into lug1, then out of lug 2 or 3? to be the actual output wire?


    2. Lug 1 will be the output from the circuit, lug 2 (the middle one) will be the new output and lug 3 goes to ground :)

    3. Hi, built my own as well with volume knob last WE and it's sounding great. good subtle variations. Would have expected a bit more crunch and crisp but I've got home made disto+ like boxes for this... A big Thank you !

  8. I built the pedal, I love the sound, but I have one question. One of the comments (complaints?) I have heard about the original COT50 is that there is a significant volume boost when the pedal is engaged. My pedal is barely louder than the bypassed sound, which works for me, I just wondered if that might be a sign that something is wrong or if that is how it is supposed to work. Thanks.

  9. I can't seem to find the 2N5088 where
    I'm living. Can I use a BC550C instead?
    And, if so, will I be able to use it as a direct replacement or should I change any of the other components' values?

  10. Any high gain NPN transistor will work, make sure you check the pin out though!

  11. http://www.youtube.com/watch?v=PFBIZkjEw34

    Here is a Demo video of the Clock of Tone in action :-)

  12. what should the bias on the emitter be with the gain/bias knob all the way up?

  13. sorry i meant to say the collector!!

    1. I'm sorry, I never checked that value and I don't have one around to test it for you at the moment :-(

  14. Hey, I"m new to pedal building, and I just built this circuit. I love it. Only thing is it's got a higher noise floor than I would like. It's a hiss, that is constant, and doesn't change with turing the knobs. It's only when effect is engaged. Is there anything that would cause this, being that it's my "novice" work, or is this the nature of the circuit?


  15. I built and boxed one this week. Sounds great for such a little circuit! I used some tiny si signal diodes in mine with a DP3T switch for 1 or none or two diodes. Also BC108 and PIO caps in the signal path. It interacts with my volume knob very nicely.I really like the Fred style "structure-nature" adjustments, very subtle, nature is scratchy though. Perhaps a detent pot would cure that. I am considering a rotary switch instead of the structure pot that also changes cap values for the nature pot too. I think the Nature pot is backwards in the turret drawing. Thanks for posting this, What a little wonder it is!

  16. hello and nice greetings to all....i m a real beginner in fx building....but i d like to do a cot 50....can anybody tell where i have to wire a switch in this cot 50 project?
    best regards gerd

  17. Can anyone point me to a switch/jack/led/dc diagram that will work with this one. I have tried a number of them and no effect. I used the R.G. Keen audio probe and the circuit is good. Thanks in advance.

  18. On strip board are red dots breaks in copper track thanks.

  19. Torchy's layout is definitely incorrect. Rather -- either it is incorrect or the schematic is incorrect. The layout structure 3 and and Nature 2 need to be swapped, and R4 needs to go up to ROW 2 (the other end of R5).

    Trust me. Look at the position of C4 to guide --- the layout is wrong. Sorry folks. Or - is the schematic wrong? It looks right to me anyway. Nature 2 goes from the juntion of R5 and R4 (BUT) it should NOT be touching C4 at all... that must go twixt structure 3, Nature 3 and R5 .. which it will do after you make the mods I just pointed out.

    1. I _think_ alternatively, C4 (-) can be moved from row 3 to row2... but that's a tight fit. Looks like that would make the layout correct as well.

      As is, the 47uF (C4) is straddling Nature 3 and Nature 2.

      The Schematic shows it (C4) should be running serially between Nature 3 and the junction of Structure 3 and R5.

      Love the site. Appreciate all of it. No negativity intended here. Just - a correction to a killer layout.

    2. I agree. I was trying to figure this out and I finally got through all of the comments to find yours. C4 SHOULD go to Nature 3 and Structure 3 per the scheme, but in the vero it goes from Nature 2 to Nature 3. In other words, the negative side of C4 is on the wrong side of R5.

  20. Hi, As said previously I've built this pedal and it sounds great. I've also built a kind of clone between an electra and the cot50. I confirm the output has to go through a volume pot but in both cases the level of crunch is a bit too low, so I have a question: how can we raise the distortion level without touching the diodes ? by saturating the transistor ? changing the resistor between its 2 legs ?
    Many thanks

  21. Would anyone be willing to build one of these for me and modding it to utilize a Zener diode?
    Basically merging this schematic with the super hard on schematic?



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