Clock of Tone 50 - Modified COT50

briggs · Post by **briggs** » 26 Feb 2008, 10:18

Thanks for that MC. Yeah, 47n is correct. I would strongly recommend you socket that cap though - it needs to be tweaked for different amps. The amp I was testing through was quite poor and pretty bright.

Is it OK if I post your layout on my blog, of course, full credit will be given?

MoreCowbell · Post by **MoreCowbell** » 26 Feb 2008, 17:14

briggs wrote:Thanks for that MC. Yeah, 47n is correct. I would strongly recommend you socket that cap though - it needs to be tweaked for different amps. The amp I was testing through was quite poor and pretty bright.

Good to know. It seems like a "large" cap...thats why I asked.

Is it OK if I post your layout on my blog, of course, full credit will be given?

Sure, no problem !

briggs · Post by **briggs** » 26 Feb 2008, 22:15

Thanks Andy. I'll put it up, I just tried this thing with mosfets. It's a more "modern" sound, much more headroom and even greater dynamic range! I added a blend pot to got between the two and it was pretty usefull. It's just a 10kB pot blending between the two diode sets - 1n270 and BS170 mosfets, it allows you to dial in a bit of both, an interesting and very usable sound.

Blues Lyne · Post by **Blues Lyne** » 27 Feb 2008, 04:59

briggs wrote:Thanks Andy. I'll put it up, I just tried this thing with mosfets. It's a more "modern" sound, much more headroom and even greater dynamic range! I added a blend pot to got between the two and it was pretty usefull. It's just a 10kB pot blending between the two diode sets - 1n270 and BS170 mosfets, it allows you to dial in a bit of both, an interesting and very usable sound.

Great idea, more versitile than the switch I used. I really like to sound of the mosfets (I think mine are 2N7000's) but sometimes wish I had a little more break up.

briggs · Post by **briggs** » 28 Feb 2008, 14:08

Yup, you can use the blend control to dial in just a little more fizz than the mosfets provide. I imagine it would be a good control to have as an internal trimmer. No need for it to be external really. Unless you want super versatile!

erikm5150 · Post by **erikm5150** » 04 Mar 2008, 15:24

Cool looking circuit... I'm planning this for my next build...

Here's a vero layout that I'm planning to use...
I'm still new to this, so please let me know if there are any mistakes:

allmonochrome · Post by **allmonochrome** » 08 Mar 2008, 21:24

erikm5150 wrote:Cool looking circuit... I'm planning this for my next build...

Here's a vero layout that I'm planning to use...
I'm still new to this, so please let me know if there are any mistakes:

have you verified this yet? i really wanna build it

culturejam · Post by **culturejam** » 09 Mar 2008, 07:39

briggs wrote:Thanks Andy. I'll put it up, I just tried this thing with mosfets. It's a more "modern" sound, much more headroom and even greater dynamic range! I added a blend pot to got between the two and it was pretty usefull. It's just a 10kB pot blending between the two diode sets - 1n270 and BS170 mosfets, it allows you to dial in a bit of both, an interesting and very usable sound.

This sounds like a great idea, but I'm a little shaky on how to set that up. Could you give a little more detail on how to wire up the blend control with diodes?

Also, why a 10k pot?

Thanks for the help.

briggs · Post by **briggs** » 09 Mar 2008, 13:17

From Jack Ormans AMZ. There is a vero layout from Torchy on my blog

Don't bother witht he 1k resistor shown here. I used a 10kB pot bcause it worked the best

culturejam · Post by **culturejam** » 09 Mar 2008, 16:17

Thanks, briggs!

That's pretty close to what I was thinking in my head, but it's nice to see a small schematic.

Deaj · Post by **Deaj** » 15 Mar 2008, 21:53

I've had some time to play with this circuit since building it and I have some observations to share. It's very similar to the COT-50 blue. With 1N270 Ge diodes its a little closer to unity gain when compared to the COT-50 and has a bit more low end / more balanced EQ. It also clips the signal a bit more along the entire sweep of the Structure (bias) control as compared to a COT-50. The Nature (tone) control is very useful. The first 20% of its sweep allows one to adjust the bass response effectively. The rest of the sweep mostly affects the top and upper midrange. The Structure control does more than just add grit. As it's turned up it gradually introduces a 'sag' like effect to the attack when the strings are struck hard, much like a low wattage tweed or early tube rectified Marshall. Cool circuit! Thanks Briggs!

Blues Lyne · Post by **Blues Lyne** » 16 Mar 2008, 22:58

Anyone else notice that when the "bias" knob is turned to 3:00 or beyond, the tone gets thinner? It's either losing bass or gaining high end. Mine sounds nice and full up until just before 3:00. Just curious if it's just a fluke with mine, or normal for the circuit.

Torchy · Post by **Torchy** » 16 Mar 2008, 23:43

What "bias" knob ???

briggs · Post by **briggs** » 17 Mar 2008, 01:06

Why thank you deaj!

The gain control; on an actual COT50 it's called bias. The structure (bias) and nature controls are very interactive - they do affect the effect of one another depending on how they are set. I think it's an interesting and useful interaction though, it allows for many more tones to be created

Blues Lyne · Post by **Blues Lyne** » 17 Mar 2008, 22:31

I wan't thinkin'. I should have posted that in the COT 50 thread, since I haven't tried the nature control yet.

premiumplus · Post by **premiumplus** » 04 Apr 2008, 21:29

Thanks briggs, great circuit. I built mine a couple of weeks ago but just got it boxed up today. I've been playing it and it's going on my board for the weekend at least.
I'm going to build all these...

briggs · Post by **briggs** » 04 Apr 2008, 23:34

Glad you like it. I've not had chance to test one with my new "suprono" yet! Can't wait to though!

culturejam · Post by **culturejam** » 29 Apr 2008, 15:09

Has anyone verified the pcb layout by Mr. Cowbell?

I figured I'd go ahead and make the pcb and give it a try. I don't mind being the first to test it, but if someone else has built the COT50 from this layout, I'm interested to know how it went.

Thanks.

jzilla · Post by **jzilla** » 06 May 2008, 01:56

briggs wrote:Thanks for that MC. Yeah, 47n is correct. I would strongly recommend you socket that cap though - it needs to be tweaked for different amps. The amp I was testing through was quite poor and pretty bright.

what range of values would you suggest to experiment with? thanks!
-j

briggs · Post by **briggs** » 06 May 2008, 11:47

Any range from 1n to 100n, just keep playing with it until your happy...