Boss CS-2, CS-3, Dynacomp, Keeley, Wampler, how are the circuits different?

[nashville]

Hello! I'm not very knowledgable about circuits, so when I look at schematics or PCBs I can't tell what's going on. But I'm curious about the circuit differences between the main compressor pedals I've seen people use over the years.

Is the Keeley 2-knob just a Dynacomp? Is the CS-2 just a Dynacomp with an attack knob? Is the CS-3 just a CS-2 with a tone knob? Is the Wampler just a CS-3 with a blend knob? Or is there something about the compression circuits in each that cause unique attack/release/ratio/frequency response?

Thanks!

[ElectricDruid]

Have you got links to the schematics you're talking about so we can take a look?

Thanks!

[antonis]

Is the Keeley 2-knob just a Dynacomp? Is the CS-2 just a Dynacomp with an attack knob? Is the CS-3 just a CS-2 with a tone knob? Is the Wampler just a CS-3 with a blend knob?

To summarize your querry into one row:
Wampler =>  Keeley 2-knob + Attack knob + Tone knob + Blend knob..??

[Rob Strand]

Is the CS-2 just a Dynacomp with an attack knob? Is the CS-3 just a CS-2 with a tone knob? Is the Wampler just a CS-3 with a blend knob?

The CS-2 is *very* similar to the Dynacomp. 

On a coarse scale the CS-3 does have similarities with the CS-2.   The main feature common is the rectifier circuit, and that determines a lot of the behaviour.
However, there's also some differences:
- The VCA chip on the CS-3 is not only different it works differently.  It will increase the compression ratio, but
  probably not by an extreme amount.   The CS-3 VCA chips is probably better quality.
- I seem to remember the way the sustain control worked on the CS-3 was different.   Different in how it interacted
  with the time constants.
It's probably 15+ years since I looked at the details but it is the fine details where they differ - that's why I can't remember the specifics.  You might even find some old posts of mine discussing the CS-3 - I'd trust those more than my memory.

[antonis]

I'd trust those more than my memory.

In short, nowadays you aren't able to take up the cause for older interpretations..

[Rob Strand]

In short, nowadays you aren't able to take up the cause for older interpretations..

Not really that I can't.  Some of that stuff requires a lot of time and effort to go through all the fine details (even understanding *exactly what the chips do).   You can burn up a lot of hours analyzing and simulating stuff.  I know I did it back in the day.  The old posts document some of those details (I hope  ).   To make matters worse there were hand traced CS-3 schematics on line at the time - I'm sure they had some errors, so that meant finding PCB pics and retracing PCB's.   I've archived a lot of that info and I'm using different software.

It's like when you go through 10 pages of maths to derive some result.   It's a long process, you make mistakes, so you have cross check everything and fixed stuff up.    Sometimes too painful to do again when you know have you already done it.

After doing all that work, the only conclusion is the sustain pot worked differently, and that might have been before I worked out the schematic was wrong!

[wampcat1]

Is the Keeley 2-knob just a Dynacomp? Is the CS-2 just a Dynacomp with an attack knob? Is the CS-3 just a CS-2 with a tone knob? Is the Wampler just a CS-3 with a blend knob?

To summarize your query into one row:
Wampler =>  Keeley 2-knob + Attack knob + Tone knob + Blend knob..??

kinda/sorta/not really.
Keeley 2 knob is a ross comp, which is quite close to a dynacomp.
I added the "attack" (it's actually more of a release thing but it's commonly called "attack" on this circuit), tone control (which is just changing some of the filtering on the comp circuit), and a blend knob which is sort of a panning thing.

As mentioned above, cs-2 is sort of more along the lines of dynacomp/ross, CS-3 is different.

[Rob Strand]

Something that often gets lost with these compressor threads is the knob called Attack isn't the attack time at all, it's the release time - pretty much applies to all those compressor sustainer units which use the two transistor rectifiers (on the limiter units and many other compressors the Attack control does in fact set the attack time).

I had a chance to check a few details:

As far as comparing the CS-2 and CS-3 the way the release works is different.   For the same Attack control position the CS-3 has a somewhat faster release time.  So to compare the units you probably need a to advance the control on the CS-2 (faster release) and back off the control on the CS-3 (slower release).  Both at the same pot position won't be apples to apples.

The actual attack time on the two units is similar but perhaps a tad faster on the CS-3.    This can come down to specifics of transistor gains.