Danelectro - CO-1 - Cool Cat Drive  [schematic]

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
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Pedalpusher
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Post by Pedalpusher »

By His definition 90% of OD pedals out there are TS circuits. I think His improvements are largely in the minds of His customers. The Drive sounds pretty darn good as is. I was amazed where He said He couldn't remeber which opamp was in there.

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Post by Greg »

Pedalpusher wrote:By His definition 90% of OD pedals out there are TS circuits. I think His improvements are largely in the minds of His customers. The Drive sounds pretty darn good as is. I was amazed where He said He couldn't remeber which opamp was in there.
Yep.
He doesn't know how a filter works.
He doesn't understand the difference between clipping to ground or in a feedback loop...
But he'll modify a pedal for ya..

Brain Wampler.. you have a lot to answer for :mrgreen:
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Post by soulsonic »

That schematic is worse than worthless; it hurts more than helps. Any poor fool tries to build something from that mess....
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Post by analogguru »

Greg_G wrote: Whether the guy's a beginner or not, the similarities are much to close to be coincidence... essentially it's an OCD with an output buffer and silicon diodes instead of Mosfet diodes.
THE OCD V1 DOESN`T USE "MOSFET DIODES" SIMPLY BECAUSE THEY DON´T EXISTS !!!

Even when there are soldered Mosfets in the pcb the (used protection) diodes in the Mosfet´s are simple silicon diodes and the mosfet part is not used.

So there is no difference in the clipping section.

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Post by Greg »

analogguru wrote:
Greg_G wrote: Whether the guy's a beginner or not, the similarities are much to close to be coincidence... essentially it's an OCD with an output buffer and silicon diodes instead of Mosfet diodes.
THE OCD V1 DOESN`T USE "MOSFET DIODES" SIMPLY BECAUSE THEY DON´T EXISTS !!!

Even when there are soldered Mosfets in the pcb the (used protection) diodes in the Mosfet´s are simple silicon diodes and the mosfet part is not used.

So there is no difference in the clipping section.

analogguru
I understand and agree AG.. I stated it like that as a way of differentiating between a standard silicon diode and a mosfet internal diode.
By Mosfet diodes I just meant diodes inside a mosfet..
It's a point of difference between the circuits.. whether it actually makes a difference or not :scratch:
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Post by ShortScaleMike »

soulsonic wrote:That schematic is worse than worthless; it hurts more than helps. Any poor fool tries to build something from that mess....
My exact point. It is Garbage and should be disregarded until someone with some experience does the job properly

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Post by mfgobbi »

Guys, just a note. That schematics was posted by this "boutique mod guy" originaly at TGP. When I put a link to it here my intention was NOT to post the definitive CC-Drive schematics. It was to inform about what was going on there. A verified CC-Drive schematics is still needed, of course.
ShortScaleMike wrote:
soulsonic wrote:That schematic is worse than worthless; it hurts more than helps. Any poor fool tries to build something from that mess....
My exact point. It is Garbage and should be disregarded until someone with some experience does the job properly

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Post by RnFR »

It's impossible to get the blanket on the amp now.
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Post by JHS »

The forward voltage of a diode used as a clipper does not tell anything about the clipping or the sound.
Diodes with a forward voltages of app. 0,6V can produce really different distortion.
The protection diode in a BS170 for ex. produce a harder/rougher sound when used as a clipping diode compared to a 1N914.

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Post by DougH »

The forward voltage of a diode used as a clipper does not tell anything about the clipping or the sound.
It tells you some things but it doesn't tell you everything.

The I-V curve is the key.
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Post by ShortScaleMike »

mfgobbi wrote:Guys, just a note. That schematics was posted by this "boutique mod guy" originaly at TGP. When I put a link to it here my intention was NOT to post the definitive CC-Drive schematics. It was to inform about what was going on there. A verified CC-Drive schematics is still needed, of course.
ShortScaleMike wrote:
soulsonic wrote:That schematic is worse than worthless; it hurts more than helps. Any poor fool tries to build something from that mess....
My exact point. It is Garbage and should be disregarded until someone with some experience does the job properly
The guy annoys me. He's a hack and he doesn't know what he's talking about, yet postures as if he does. I just caught him saying a test for true bypass is to pull the power supply and check if the pedal passes sound in bypass mode. I mean really?

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Post by Fuzzer »

DougH wrote:It tells you some things but it doesn't tell you everything.

The I-V curve is the key.
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Post by george giblet »

I wouldn't bag-out the schematic too much - you don't need to have a "status" to do a PCB trace! With the corrections already posted above, it looks pretty good. There's no doubt it's a VLOD type circuit. I can't vouch for the cap values because I can't see them. The diodes are marked A6 which are common BAS16's (similar to 1N4148's).

--------
By the way, not all diodes are alike. There's a parameter "n" in the diode model which affects the hardness of the clipping (irrespective of the nominal voltage), see the last equation in.

http://www.ece.umd.edu/class/enee480.F2 ... eality.pdf

Normal silicon diodes tend to be in the 1.5 to 2 region whereas transistors and the *body* diodes from MOSFETS tend to be around 1.0 (harder clipping). There is some credibility to using MOSFET body diodes for a different sound. The other MOSFET clipper configurations shouldn't be confuse with MOSFET body diode clipping - they produce higher clipping voltage and are often also "hard" in there clipping characteristic.

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Post by Greg »

george giblet wrote:I wouldn't bag-out the schematic too much - you don't need to have a "status" to do a PCB trace! With the corrections already posted above, it looks pretty good. There's no doubt it's a VLOD type circuit. I can't vouch for the cap values because I can't see them. The diodes are marked A6 which are common BAS16's (similar to 1N4148's).

--------
By the way, not all diodes are alike. There's a parameter "n" in the diode model which affects the hardness of the clipping (irrespective of the nominal voltage), see the last equation in.

http://www.ece.umd.edu/class/enee480.F2 ... eality.pdf

Normal silicon diodes tend to be in the 1.5 to 2 region whereas transistors and the *body* diodes from MOSFETS tend to be around 1.0 (harder clipping). There is some credibility to using MOSFET body diodes for a different sound. The other MOSFET clipper configurations shouldn't be confuse with MOSFET body diode clipping - they produce higher clipping voltage and are often also "hard" in there clipping characteristic.
I agree about the schematic... I also thought it was good enough to see what the circuit was.. and any mistakes were pretty self evident.

I'd love to hear more about the diode 'n' factor, but the linked article was a little too "engineer speak" for me to follow.
Is there anywhere else I could read about it, or could you explain it a little more.
The difference between diode types is really interesting.
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Post by ShortScaleMike »

I made a demo of the stock pedal by the way, you'll be able to see what I mean about the brightness of the tone control



George - you're right of course that you don't need "status" to do it, but it's also not wise to post it if it is inaccurate, and this coupled with his Tubescreamer and bypass comments just show him up as the chancer he is.

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Post by nooneknows »

I saw your demo and I think the pedal sounds very close to my first ocd build, mine had that sudden "dark to brittle" bump in a short excurtion too. The problem was cured enlarging the cap in parallel to the diode couple and changing the tone control to ocd V4.
The CC Drive however sounds really cool.

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Post by george giblet »

Here's an example of how diode ideality affects the V-I curve,

https://i476.photobucket.com/albums/rr1 ... eality.png

The diodes all pass through 0.65V at 1mA and n is varied over it's typical range.

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Post by nooneknows »

george giblet wrote:Here's an example of how diode ideality affects the V-I curve
I bet a BJT base-emitter junction curve could be similiar to mosfet knee, some investigation might be interesting.
Does anyone has an oscilloscope (and a lot of time...) to trace out various type of diode/junction? (schottky, LED, germanium, signal and rectifying silicon diode, bjt, mosfet...)

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Post by george giblet »

> I bet a BJT base-emitter junction curve could be similiar to mosfet knee, so

It is, the 'n' value is very close. Types of devices determine the 'n'. Large devices require larger I's to get the same V.

I've measured many types and sizes of device over the years.

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Post by DougH »

Yeah, but "MOSFET" sounds kooler and more tooby, doodz... :mrgreen:
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