Rev4 circuit
In April, 2013 we really improved the COMPROSSOR circuit. Mike had been playing in a band
for a few years, and noticed that SOME pedals on his board would not drive a load
well, they would get dark and dull, due to a bad (high) output impedance.
This is easily tested by running pedals into something like
a low impedance volume pedal, with a switchable buffer between them. The ARDX20 with the
delay level down is excellent for testing - when ON it's a great buffer, when OFF it's true bypassed.
To test a pedal, simply turn the buffer on and off and listen for a change in tone.
With most pedals, like our Chorus, Juicer, etc, there is no difference - they can drive
the signal to your amp through long cables or volume pedals no problem. But the Comprossor
sounded dull when the buffer was removed. The original Ross, Dynacomp, and all the other
Ross clones do the same exact thing- they really need a buffer after them to sound good.
Also these pedals don't have a very loud output, especially when you hit them hard, for example
with humbuckers or a boosted signal.
One other problem all these pedals have is phase reversal - they flip the phase of your
signal when you turn them ON. This may not be a problem for most people, but if you split your
signal and combine it, or run into two amps, the out of phase signals will cancel
and you will get a VERY thin sound.
Also, for use as a clean boost, there was too much compression even with the SUSTAIN pot
all the way down. So we reduced the minimum compression amount, without changing the maximum amount.
Now the pedal is more usable as a clean boost, and also sounds great left on all the time
as a tone sweetener/buffer. It's great stacked into dirt pedals, chorus, vibes, etc now.
With these problems fixed, there is no need for a blend knob, you should be able
to keep your pure tone without the need for additional circuitry. One other thing we improved was
the LED circuitry. Now, if one side of the bicomp/mini bicomp is ON, and you turn the other
side ON, the first LED does not get dimmer. A small change but something that bothered us.
The REV4 boards are usually blue as seen in this picture of the BICOMP.
All of these problems are fixed in the REV4 circuit -
- Excellent output impedance for a clearer tone with no signal loss or need for a buffer
- More available output for boosting your amp
- No phase reversal
- Less compression available
Rev5 circuit
This
is pretty much the same as REV4 with the addition of a MIX control,
which can go from full dry (no compression) to full wet (same as REV4).
Mixing in dry gives you the attack of the note, which is compressed away
normally, if you want to hear that. When set at full dry, the pedal
becomes a clean boost/buffer pedal and makes pedals after it sound
really great, with more presence. Mix is available as a trimpot on the
circuit board of the 3 knob small comprossor, or as a fourth external knob.
Ryck toggle option
The Dynacomp and Ross circuit is not very bright, to keep white noise down. But sometimes it's nice
to have a bright trebly tone, as heard on Rickenbacker guitar's built-in compressor. Looking at the Rickenbacher
schematic, it's about the same as the Dyna/Ross except it allows more treble for that jingle-jangle sound.
We decided to offer this with a three-way switch so you can get just the amount of treble you want.
One position is the normal Dynacomp/Ross value for about the same tone as OFF and low noise. The
second position adds a bit more treble and just a touch of noise - this may be great to use all the time with
a dark guitar like a Les Paul with high output pickups. The third position is twice as bright,
close to the Rickenbacker setting, for a sound that really pops, with a bit of noise that you won't notice
till you stop playing. We can put this toggle on any of our new CompROSSor or Dynacomp pedals when ordered,
or we can add it later on which costs a bit more as it's more work to add it after the pedal is built.
Here is a good article on the REV4 comp from Tone Quest Report : Tone Quest 2013 article
We also offer the USA 12V power supply for a little more headroom, good if you run a hot signal into the comp.
Here are the optional 9V power supplies for overseas:
awesome comp 
