Recording - December 2015 - 35

slower, rounder and softer. Think of FETbased designs like the Universal Audio
1176LN, or even an optocell-based compressor like the Teletronix LA-2A.
Note, though, that while this compressor offers this level of versatility, in no way
does it try to sound like any of the above
examples.
The last knob on the PWM-501 is the highpass filter knob. An HPF is a common feature
on compressors nowadays, handling the primary function of what used to require a
sidechain and external EQ. The filter cuts out
low frequences to keep the compressor from
clamping down on the low end, which tends
to affect compressors more than high frequency material. In the PWM-501 this is a
fully variable 12 dB/octave (2nd order) filter
with a throw of 20 Hz up to 600 Hz.
Further controls on the unit include a Link
button, which will link the control voltages
of two units together for stereo use if supported by your chosen rack. It worked very
well in a Radial Workhorse and the newest
8 slot API lunchbox®, both of which offer
stereo linking. Uniquely, you can set one
unit so that the other unit will act as a master control for both (setting its attack and
release times to full and turning off its ratio
control), or set the two units to the same settings for ratio and attack and release times
before adjusting the controls to taste.
There is a bypass button for the highpass filter as well as a hard bypass button
for the whole unit. The last button switches the 16-stage LED meter between input,
output, and gain reduction settings. Each
segment represents 1 dB of volume or
reduction; like the compressor, the meter's
ballistics are lightning fast.
In use
This is a unit that requires a bit of playing, pushing, and experimenting before
the engineer will become comfortable
with how it works. My early units didn't
yet come with a manual, although Great
River now provides one. I should thank
the Vintage King Audio site for acting as
my online manual as I became familiar
with the unit and wrote this review.
Once you start to master the PWM-501,
you realize just how remarkably versatile
it is. It's capable of slow thick rounded
transient reduction, but it can also do
grabby, fast pumping and/or gluing.
The biggest thing to remember when
working with this compressor is that its
magic lies in how the controls are intertwined and work together. As such it's a
unit that you set by ear and by feel. If you
like finely repeatable results, this unit may
frustrate you, but if you love to twist dials
until it sounds and feels right, then the
PWM-501 is right up your alley.
Sonically this is a very clean and neutral unit with no sound of its own, but in
feedforward mode, when shaving off 1-3
dB, it can add an edge and sparkle to a
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mix. When set slow in feedback mode it
can round the sound and roll off crisp transients. In either scenario, what you hear is
the sound of the compression process, not
the sound of the actual hardware.
I have been mixing a guitar-based classic
rock style album, and the PWM-501 and its
sibling, the Harrison 32 (one of my favorite
EQs), have seen use somewhere on every
mix, especially on vocals. My second
biggest use was on electric guitar cabinets.
I find it to be great compressor for snare
drum, bass guitar, and electric piano. It
makes one heck of a 2-bus compressor
when linked, adding a great width and
sparkle as mentioned above, a bit similar
to what I get out of my A-Designs Nail.

Conclusions
The more I use and get used to the possibilities in the PWM-501, the more I like
it. This is possibly one of the most versatile and chameleon-like compression
boxes on the market. Patience in learning
its behavior yields huge rewards, and
there really is no other compressor quite
like it. While it took years for Dan and
Great River to bring a compressor to the
recording world, I think it was well worth
the wait!
Price: $1090 ($835 street)
More from: Great River Electronics,
www.greweb.com

http://www.greweb.com http://www.dpamicrophones.com

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