Aphex Systems Compellor 320D User Manual

320D Compellor

Dual Mono/Stereo Automatic Level Controller
with Digital and Analog I/O

®

The World Standard

Since the introduction of the original
Compellor in 1983, no other audio level
controller has met with such success.
Around the world, in broadcasting, record­ing or sound reinforcement, the Compellor
is specified more than any other level
controller.

Leading Aphex Technology

The Compellor circuits are totally unique.
By throwing away all conventional design
ideas, we created audio processing with
unprecedented sound transparency, yet is
exceedingly effective at controlling levels.
Because our designs are patented, no
other company has been able to match the
performance. Algorithms like our exclusive
“DVG”, “DRC”, and “FDL” have yet to find
any rivals.

Unmatched Reliability

Aphex engineering and manufacturing
produces products that last and last with­out need for repairs or calibration. Some
Compellors have literally been in 24-hour
use in the same rack for a decade or
longer! When you specify a Compellor, you
know it will do its job flawlessly and give
you peace of mind.

Digital Advancements

The first Compellor was introduced in 1983
as an analog product. Because of their
advanced technology, most of those older
units are still in regular use. Since that time,
newer models have been produced, still in
analog form. Digital technology of today
promises many improvements in user
interfaces, and sometimes in sound qual­ity, but not in audio processing algorithms.
No digital processor can match an analog
Compellor for sound quality and effecive­ness. Nevertheless, many of today’s sys-

Improving The Way The World Sounds

S Y S T E M S

Aphex Systems Ltd. • 11068 Randall St., Sun Valley, CA 91352. Tel: [phone] Fax: [phone] Email: [e-mail] . Aphex
and Compellor are registered trademarks.

tems need a Compellor that can interface to digital
audio. With the model 320D, Aphex brings you just
that. You get all the advantages of the analog proces­sor with AES3 connectivity.

Compression - Leveling - Limiting:
A Very Brief Tutorial

Two properties of audio that can cause problems are
the average level (the “loudness”), and unpredict­able peaks that can clip. The Compellor handles
both problems for you, fitting the sound into an ideal
sound envelope package.

The Compellor’s “Frequency Discriminate Leveler
(FDL)” section with the “Dynamic Verification Gate
(DVG)” and the “Silence Gate (SG)” slowly corrects
the volume level of an audio stream with very com­plex algorithms that hide it’s work. It works differently
at different frequencies, for example. It locks up when
the sound stops, and resumes instantly when sound
reappears. When you listen, you know the levels are
made more even, but you don’t perceive the levels
are shifting.

The Compellor’s Variable Slope Compressor with
the “Dynamic Recovery Computer” and the “DVG”
work on top of the leveling platform to add adaptable
compression that helps match the texture of chang­ing audio sources. Again, you don’t hear “pumping”
or other compressor artifacts. Just very natural sound
that is evenly consistent in loudness.

The Compellor’s limiter acts on peaks that shoot
beyond typical audio crest factors. Extremely peaky
sounds will be brought into an envelope that is easy
to handle by any analog or digital recording or trans­portation medium including digital codecs.

Typical Uses

Broadcast pre-processing, MP3 encoding, Record­ing, Installed and Mobile Sound, DAW Input, Mas­tering, Satellite Uplinks, Home Stereo, Ham Radio,
Background Music, Tape Duplication, Cable TV.

w w w . a p h e x . c o m

Features

• Frequency Discriminate Leveler

No bass pull-back in music

• Dynamic Release Computer

Adds compression intelligently
smoothing out transitions.

• Dynamic Verification Gate

adds greater transparency

• Silence Gate

Locks gain when audio stops

• Process Balance

Lets you have any combination
of leveling and compression

• True Bypass

No electronics in bypass

• AES3 I/O

up to 96kHz

• Analog I/O

Fully professional balanced

• High Reliability

Famous Aphex engineering

• Stereo & Dual Mono

Use as two separate channels
or linked for stereo

• Source Select

Chose digital or analog input

• Dual Outputs

Use both digital and analog
outputs at the same time with
either input selected

®

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C US

59887

DRIVE

METER SELECT

PROCESS

INPUT

OUT IN

OUTPUT

UNLIN

K

LEVELING &
COMPRESSION

STERE

O

ENHANC

E

LEVELING

LINK

G.R. DVG

S

0dB

F

RATE

OUT IN

LIMITER

PROCESS BALANCE OUTPUT THRESHOLD

SILENCE GATE

2

-154-126-98-610-312014+316+618+920+12
GR(dB)

PGM(dB)

-

CO

MPRESSLEVEL +10dB-10dB 0dB-40dB

DRIVE

PROCESS

OUT IN

DV

G

S

0dB

F

RATE

OUT IN

LIMITER

PROCESS BALANCE OUTPUT THRESHOLD

SILENCE GATE

COMPELLOR

®

MODEL 320D

ANALOG & DIGITAL I/O

POWER

2

-154-1

2

6-98-610-312

014+316+618+920+12

GR(dB)

PGM(dB)

-

COMPRESSLEVEL +10dB-10dB 0dB-40dB

AC LINE 30 WATTS

FUSE: 100-120V (3/8ASB) 200-240V (1/4ASB)

PROTECTED BY ONE OR MORE OF

THE FOLLOW

ING PATENTS:

41

55047 4578648 5422602

COMPELLOR

®

MODEL 320D

S Y S T E M S

|

COMMERCIAL

AU

DIO

EQUIPMENT

59887

ANALOG

CH2

DIGITAL

AES3 INPUT

AUDIO
SOURCE
SELECT

ANALOG

CH1

IN

32-96kHz

OUT

IN

OP

LEVE

L

-10
+4

OUT IN OUT

ANALOG
DIGITAL

OP

LEVE

L

-10
+4

MADE

IN

U.S.A.

320D Compellor

Get the Best of Both Worlds

DUAL MONO or STEREO

The 320D converts between acting as two independent mono processors and
one linked stereo processor by front panel selection. This is true with both analog
and digital I/O.

ANALOG or DIGITAL IN, ANALOG and DIGITAL OUT!

The 320D serves as a fine A to D converter with processing. When you use the
analog input, the digital output contains the Compellor’s processing and is there­fore ready for use in almost any application. Conversely, the 320D serves as a fine
D to A converter. When you use the digital input, the analog output contains the
Compellor’s processing, and is properly leveled and packaged.

ANALOG and DIGITAL AUDIO INTERFACES

The professional analog audio inputs and outputs are fully balanced and adapt
to consumer or professional operating levels at the touch of a button. Analog or
digital source selection is made at the rear panel.

For digital interfacing, the 320D contains a high quality 24-bit low noise codec
to receive digital audio and to transmit digital audio. Once the incoming digital
audio is converted by the DAC section, it passes through the Compellor as normal
audio. The audio output is then converted back into digital by the ADC section of
the codec.

The rear panel AES3 jacks are standard professional XLR 110 ohm interfaces.
There is no word clock input or output. Synchronizing is accomplished from the
AES3 input signal or an internal clock. When a digital input is present, the output is
synchronized to the input sample rate. If no digital input is present, the digital out­put automatically locks to the internal default sample clock. The user can specify
the default sample rate by changing the internal crystal. Spare crystals for 32kHz,

44.1kHz, 48kHz, and 96kHz are supplied with the unit free of charge.

The Model 320D codec translates the -20dBFS level of the digital audio source to
the 0dB reference within the Compellor circuits. The average output levels will tar­get around -20dBFS. The selectable peak limiter’s threshold translates to -6dBFS.
Thus, no digital audio output peaks will rise above -6dBFS when the limiter is on.
The combination of averaging the level around -20dBFS and holding peaks below

-6dBFS packages the audio perfectly for natural sound quality and for most trans­fer or transmission purposes. For example, the digital audio would be ready for
direct input to an MP3 coder, HD recorder, broadcast digital STL, .wav file, etc.

ARCHITECT’S SPECIFICATIONS

A single rack space electronic audio level controlling device with both analog and
AES3 digital audio I/O combining leveling, compression, and limiting for automati­cally and continuously correcting audio levels. The level controller shall be of such
design as to reduce the audible artifacts of compression. It shall also be of such
design as to prevent the rising of background noises when the audio source stops
producing sound. The leveling function shall adapt discriminately to frequencies
in a manner to reduce the impression of bass sounds losing impact in music. The
compression function shall contain a means to adapt itself to the peak factor of
sound so as to improve the consistency of volume levels. The limiter shall operate
at a threshold 14dB above the 0VU reference level. Digital and analog audio out­puts shall be simultaneously available. The input shall be switchable between the
analog and digital sources. The AES3 I/O shall operate normally at sample rates
from 32kHz to 96kHz.

SPECIFICATIONS

5.1A ANALOG INPUTS

Connector: 3 pin XLR female
Type: transformerless, servo balanced, RFI fIltered
Impedance: 22K-ohms balanced, 11K-ohms unbalanced
Operating Level: user selectable +4dBu or -10dBV
Max input level: +27dBu(ref = +8), +25dBu(ref = +4), +10.8dBV(ref = -10)
CMRR: >90dB/100Hz, >70dB, 1KHz, >50dB, 20KHz

5.1B DIGITAL INPUT

Connector: 3 pin XLR female
Type: transformer balamced
Impedance: 110 ohms

5.2A ANALOG OUTPUTS

Connector: 3 pin XLR male
Type: electronic servo balanced (unbalanced without 6dB loss)
Impedance: 65 ohms bal or unbal (nominal load 600 ohms or greater)
Max level out (bal): +25dBu(ref = +4), +10.8dBV(ref = -10)
Max level out (unbal): +20dBu(ref = +4), +10.8dBV(ref = -10)

5.2B DIGITAL OUTPUTS

Connector: 3 pin XLR male
Type: transformer balanced
Impedance: 110 ohms

5.3 AUDIO

Frequency response: +/- 1dB 10Hz to 65KHz
Hum & noise: measured for a 1KHz tone at unity gain
No gain reduction: -67dBu(ref = +4), -86dBV(ref = -10)
10dB gain reduction: -74dBu(ref = +4), -89dBV(ref = -10)
Crosstalk @ 20KHz: -65dBu(ref = +4), -78dBV(ref = -10)
Dynamic THD typically .05% for 1KHz at 20dB gain reduction
Static THD: .025% at maximum output level
IMD, max output: .13%(ref = +4), .4%(ref = -10)

5.4 SYSTEM FUNCTIONS

Compression
Frequency Discriminate Leveling
Peak Limiter
Dynamic Verification Gate (DVG)
Dynamic Recovery Computer (DRC)
Silence Gate
Stereo Enhance

5.5 THRESHOLD

Compressor: 30dB below nominal level
Leveler: 30dB below nominal level
Limiter: 14dB above nominal level

5.6 RATIO

Compressor: 1.1:1 to 3:1 program dependent
Leveler: 20:1
Limiter: >30:1

5.7 ATTACK TIMES

Compressor: 5 to 50mSec program dependent
Leveler, fast: 20Hz = 1.5 Sec > 1KHz Frequency Discriminate Leveler
Leveler, slow: 20Hz = 5 Sec > 1KHz Frequency Discriminate Leveler
Limiter: 1 uSec

5.8 RELEASE TIMES

Compressor: 200 mSec to 1 Sec program dependent
Leveler, fast: 3 Sec
Leveler, slow: 10 Sec
Limiter: 200 mSec

5.9 DIGITAL AUDIO

Input SR: Locks to 44.1, 48, 88.2, 96kHz +/- 3%
I/O Type: AES/EBU 110 ohms XLR
Default Output SR: User definable by replacing crystal; 48kHz standard
Word Clock: Not Supported

5.10 OTHER SPECIFICATIONS

AC input: IEC standard receptacle with voltage selector, fuse, & filter
Power requirements: 100-120-220-240VAC, 50-60Hz
Power input (max): 20 watts
Dimensions: 19”W x 1.75” H x 10.125” overall depth
depth behind front panel = 9.25”
Net weight: 8 lbs.
Shipping weight: 9 lbs.