Quite literally "out of the blue"
comes a new line of products from a company that once made 'only'
an acoustic guitar preamp. The OCL-2 is an optical compressor
/ limiter with a minimal, Class A signal path consisting of two
tubes per channel. (List Price: $2795) It is so minimal, that
there are no input or output transformers even though XLR connectors
get you the old 'in-out.'
The beauty of working with the OCL-2 as well and with its
designer, Greg Gualtieri, is that both are remarkably open and
flexible. Translation: There are a number of options, including
balanced I/O and passive side-chain EQ filters. Mastering engineers
and tweak heads take note: many of the control pots can be 'customized'
to reflect user preferences such as Attack and Release ranges.
After an extensive interview, I learned that Mr. Gualtieri's
design philosophy is derived from his need to capture acoustic
guitar in the most transparent way possible. He is, however,
not so much of a purist as to scoff at compression. Classic vintage
signal processors are not always clean enough - nor are they
in such great condition after time and abuse to justify current
market prices. Greg originally created both the OCL-2 as well
as the 6386 Compressor / Limiter for his own personal studio.
WEIRD (but cool) SCIENCE
The Pendulum OCL-2 is not a clone of
the Teletronics LA-2A. As a former physicist for Bell Labs, Mr.
Gualtieri knows how a photo resistor works at the molecular level
having devised a proprietary method of taming the unruly optical
beasts to a previously unattainable level of consistency. As
such, the OCL-2 inspires confidence
as a stereo unit that no other optical unit can match and then
It is hard to make traditional optical limiters sound bad.
Without Attack and Release controls, users are limited to the
natural characteristics of the optical parts, which just happen
to be perfect for voice, guitars and bass - gentle enough to
massage a stereo mix but not damage it. Other modern optical
boxes like the Joemeek have added Attack and Release controls
that go beyond normal to create interesting near-backwards effects.
The controls on the OCL-2 are more effective (without the effect),
in part because of the proprietary tweak that only Pendulum has.
A LA MODE
Science aside, the OCL-2 has a three-position MODE switch
- labeled FAST, PRESETS and MANUAL. The first two preset disable
the Attack and Release controls. FAST is
as FAST does. In this mode, the OCL-2 gets about the most sonic
agility possible from an optical device.
Four of the Six PRESETS were originally modeled from the popular
Fairchild Limiter. The last two presets are 'Program Dependent',
which is to say that their response is more akin to a human 'riding
the gain' and so less obviously processed. MANUAL mode turns
on the Attack (1mS to 40mS) and Release (.1S to 2S) controls.
HOW FAST DO YOU WANT IT?
A VU Meter can indicate apparent 'loudness' better than a
bargraph-style Peak Meter (unless the latter can simultaneously
indicate peak and average levels). Instruments such as voice
and bass have a nearly identical peak-to-average ratio, a perfect
match for accurate display via VU meter. (The exceptions would
be 'P-popping' consonants and 'snap happy' electric bass strings!)
Conversely, transient-intense instruments such as drums and tambourine
might deflect a VU meter only as high as ~5dB, but the peaks
can be 10-dB to 15-dB higher. Analog tape machine users learn
this lesson very quickly!
ON THE ROAD
The OCL-2 was evaluated at the same time as the Pendulum 6386
Tube Limiter even though the two reviews appear in separate issues.
(See the 6386 review in the December 1999 issue). The units were
daisy-chained along with a Great River transformer-less mic preamp
and the TASCAM DA-45HR 24-bit DAT recorder. I was completely
comfortable using them together with no fear of signal degradation
and so thankful for the BYPASS switches, which are not common
on vintage products (and even some modern units). Having both
units in the signal path made the comparison of identical settings
quite easy. With slow attack and fast release the two models
behaved as twins, but in FAST mode, the 6386 is more responsive.
GETTING WITH THE PROGRAM
Stereo program was the first signal passed through the OCL-2
because that is my acid test. Pass the test and you know the
unit can handle individual tracks with ease. The
LA-2A and the LA-3A were most notable for their transparent approach
to dynamics processing. The OCL-2 goes two steps further by being
more sonically transparent (no input or output transformers on
a 'stock' unit) and far more versatile in terms of Attack and
Release parameters. This will be of particular interest to those
who wish to capture vocals, or any acoustic instrument, with
the least amount of added color while still having equally transparent
control over dynamics variations.
With the luxury of having the two models at the same time,
I set the OCL-2 for a Slow Attack and Fast Release (my personal
default) followed by the 6386 in FAST mode (as a peak limiter).
My heavy-handed visuaî setting for the 6386 had lots of
meter movement in Gain Reduction mode. To fully appreciate the
FAST mode, however, more conservative settings of less than 1-dB
of meter movement (2dB for the OCL-2) yielded such a profound
sonic improvement that the 6386 review served as my VU meter
refresher course. The combination of both
units on a stereo mix was killer. (And this is as close
to 'born again' as I will ever be!)
NOTE: Mention of the meter's response time appears on page
four of the manual. It also deserves ìhonorable mention
on the first page, where front and rear panel layouts, plus a
quick summary of each control (a simple yet brilliant move) serve
as a convenient and quick reminder.
FLAT, COOL HEAD
Unlike the LA-2A (and especially the ADL clones), the OCL-2
has a very flat detector circuit, which means the unit equally
processes ALL frequencies. One approach is not better than the
other although I personally prefer a weighted detector circuit,
one that 'hears' in a similar non-linear way to the human ear.
(Through experimentation with side-chain equalization, I have
found that a broad 6-dB boost centered at 2.5kHz works well for
many applications.) Pendulum sells a TRS side-chain insert plugs
with a passive RC network customizable to a user's needs. Very
Though not as quiet as the 6386, the
OCL-2 has gobs of headroom. (Maximum out is +35 dBu into a hi-Z
load, +24dBm into a 600-ohm load.) Maximum gain reduction is
27 dB. The OCL-2 is always open and airy, never harsh or muddy.
This was made even more apparent on the very last test narration
clearly showing that the OCL-2 has feet planted in two worlds,
satisfying the passions of the sonic purist along with the needs
of audio control freaks.
For the audiophile / minimalist, the
plain and simple signal path, using high quality components (gold
switches, polypropylene caps) is most reassuring. For the knob
needy, no optical signal processor can match its control range.
The Pendulum OCL-2 is not 'Rehashed Retro', but Enhanced Vintage
EQ Lab Report
MANUFACTURER: Pendulum Audio, Inc.; PO Box 339, Gillette,
NJ 07933; Vox: 908-665-9333 Web: http://www.pendulumaudio.com
e-mail: info@ pendulumaudio.com
APPLICATION: Audio Dynamics Processing
SUMMARY: Stereo (or Dual-Mono) Optical compressor /
limiter with three Response modes: FAST, Preset (4 'normal' plus
2 'program dependent') and Manual (front panel Attack / Release).
STRENGTHS: Minimal Class A signal path maintains sonic
purity. In addition to a BYPASS switch, the output is normally
bypassed until the unit warms up and voltages are stabilized.
WEAKNESS: The Gain Reduction Meter needs (and may get)
expanded range to more accurately reflect the amount of processing
when in FAST mode.