M87 BASS COMPRESSOR
BY DAN BERKOWITZ
For many bassists, a compressor is a most mysterious piece of gear. Though most
can suss out that they do just what their
name implies—i.e., compress the dynamic
range of your signal—the task of adjusting
a compressor correctly can be daunting for
the uninitiated. Happily, the MXR M87
Bass Compressor gets the job done pretty
easily, while still allowing for a good range
of variation from basic settings.
Tweaking the knobs
Though pedal compressors often have too
few controls to provide the top-quality compression one gets from a pro rack unit—that
invaluable-but-hard-to-detect quality that you
don’t really notice until you A/B it with the
uneffected signal or watch a channel meter—
happily the MXR Bass Compressor has its
own version of a rack compressor’s five most
potent controls—threshold, attack, release,
ratio, and gain—plus a gain-reduction meter.
Although dealing with five knobs and a meter
may sound daunting, the basic functions of
this pedal are fairly easy to use. As the concise
owner’s manual suggests, adjusting the Input,
Output, Attack, and Release controls to noon,
with Ratio at 4: 1, is a good starting point.
To test the M87, I plugged in a P bass
loaded with a Seymour Duncan Quarter
Pound pickup and strung up with fresh
roundwound strings. With the basic settings, the MXR easily provided a natural
fingerstyle sound that revealed some compression on the meter, yet went nearly
undetected to the ear until I used the
true-bypass footswitch to A/B the sounds.
Turning up Input and tweaking Output
increased the amount of compression while
keeping the volume the same.
Essentially, the Input control on the MXR
Bass Compressor functions like a Threshold
control on a rack unit. The Output control
provides the “makeup gain” to bring back
what was lost after the compressor lowered the
volume. Through all this tweaking, I found
the gain-reduction meter to be a handy feature
that enabled my eyes to guide what my ears
were hearing. The manual suggests adjusting
10-LED gain-reduction meter
Either as a compressor or a limiter, the
M87 did its job remarkably well. It added
no noticeable noise to the signal and left
my bass lines intact.
Input until three to seven bars show on the
meter. Three bars on the peaks provides just
a little compression, while seven bars knocks
down the peaks considerably—especially on
the lower notes that pack more energy.
know Your Limits
Most adjustable compressors can also serve
as a limiter by changing the ratio to 20: 1 or
higher and dialing-in fast attack and release.
This is a useful setting for slappers who