Aphex Systems 661 User Manual

11068 Randall Street • Sun Valley, CA91352 • [phone] • [phone]

Aphex is proudly American... 100% owned, engineered and manufactured in the U.S.A. Aphex is a registered trademark of Aphex Systems Ltd.
Aphex is constantly striving to maintain the highest professional standards. As a result of these efforts, modification may be made from time to time to existing

products without prior notice. Specifications and apperance may differ from those listed or shown. This product is protected by U.S. patents 5115471,
5450034, 5483600.

Expressor

TM

with

Tubessence

®

Model 661

SPECIFICATIONS

NOMINAL OPERATING LEVEL
(user selectable on back) +4dBu -10dBV

INPUT

Connector: 3-pin XLR female and

TRS 1/4” phone jack same

Type: Transformerless, servo-

balanced, RFI filtered same

Impedance: Balanced 20KΩ 20KΩ

Unbalanced 10KΩ 10KΩ
Nominal Level: +4dBu -10dBV (-7.8dBu)
Maximum Level: +25dBu +13dBV (+15.2dBu)
CMRR (typical): >90dB/100Hz; >70dB/1kHz;

>50dB/20kHz same

OUTPUT

Connector: 3-pin XLR male and

TRS 1/4” phone jack same

Type: Transformerless, differential

servo- balanced
(may be used unbalanced) same

Impedance: Balanced 65Ω same

Unbalanced 65Ω same
Nominal Level: +4dBu -10dBV (-7.8dBu)
Maximum Level: Balanced +22dBu +8dBV (+10.2dBu)

Unbalanced +20dBu +8dBV (+10.2dBu)

AUDIO

Frequency Response: ± 0.5dB 2Hz- 110kHz same
Dynamic Range 94dB same
Hum and Noise (No G.R.): -83dBu -95dBV
(unweighted 10Hz-22kHz)
Crosstalk (10Hz-22kHz @ max output) -80dB same
THD @ maximum output .6% same
THD @ nominal output +6dB .15% same
IMD @ maximum output .5% same
IMD @ nominal output +6dB .25% same

COMPRESSION PARAMETERS

Threshold: Auto Variable: -30dB to +20dB

Manual same
Ratio: Auto The Easyrider No-Knee™ Compression Curve

starts at 1.1:1 and ends at 6:1

Manual Starts at 1:1 and ends at 30:1
Attack Time: Auto Program (Waveform) Dependent

Manual .05 to 100ms
Release Time: Auto Program (Waveform) Dependent

Manual .04 to 4s
Input Control Range: 40dB
Output Control Range: 30dB

CONTROLS, FUNCTION SWITCHES AND METERING

Controls: Input; Threshold, Output, Ratio, Attack, Release, HFX Ratio, Frequency (HFX)
Switches: Process In/Bypass; SPR; Slow/Fast; Auto/Manual, Soft Knee,

Low Cut, Input/Output (meter select), Unlink, Link, Slave, Power

Meters: Audio Level (Input and Output), Gain Reduction

OTHER SPECIFICATIONS

AC Input: IEC standard receptacle with voltage selector, fuse and filter.
Power Requirements: 100-120-220-240 VAC, 50-60 Hz
Power Input (maximum): 20 watts
Dimensions: 19” W x 1.75“ H x 10.125” overall depth, depth behind front panel: 9.25”

Unit mounts in standard 19” rack, using 1 RU of vertical space.
Net Weights: 5.5 lbs.
Shipping Weight: 9 lbs.

Tube Compressor/Limiter

Expressor®/Easyrider®withTubessence

®

Model 661

The Model 661 is a totally new type of compressor incorporating vacuum tube technology with the latest innovations
in audio compression. This single channel compressor/limiter is loaded with features, consolidating for the first time
in one rack space, three Aphex patented circuits; Tubessence

®

, Easyrider®and High Frequency Expander®.

Tubessence is a true tube circuit which provides that “vintage” tube sound without, high heat, bulk, short life, fragility
and sonic variability found in traditional tube designs.

Easyrider is an Auto mode that actually works, consisting of the Wave Dependent Compressor™ (WDC) circuit
which takes the guess work out of compressing individual instruments and vocals especially in live mixes. WDC
automatically adjusts attack and release times according to the complexity of the program material. It’s No-Knee™
compression curve makes the transition into compression virtually invisible.

In the Manual mode, the Model 661 provides the full compliment of compressor adjustments, such as Ratio, Attack
and Release, for maximum flexibility. Express yourself and get those “punch”, “slap”, “fat”, “pump”, and “squeeze”
sounds fast and clean.

The 661 includes the patented High Frequency Expander®(HFX) which decompresses high frequencies, with user­adjustable ratio and corner frequency. Add “life” and “air” to your compressed signals without fear of background
noise pumping.

The Spectral Phase Refractor™ (SPR) restores clarity and punch to your tracks. Bass frequencies are more defined
with more apparent power. Higher frequencies also seem to gain more detail and presence.

Use the Model 661 to control dynamics for mixdowns, protect your sound system’s loudspeakers from transients
and distortion or shape the sound of individual instruments and vocals. Compress dynamic levels without fear of
reducing frequency response. What ever type of dynamics control you’re looking for, it can be done with the Model
661 Tube Compressor/Limiter Expressor

®

.

FEATURES

• Auto or full Manual operation. In Auto mode, compression parameters constantly change for best sound.

• Atrue tube circuit (Tubessence) in the output stage for a “warm”, “live” and “full” sound.

• HFX allows the use of high compression ratios without the loss of high frequencies.

• SPR increases apparent bass energy level, without amplitude equalization or bass boost.

• Use Sidechain Access jacks for creative processing (de-essing and ducking).

• Stereo, dual mono or master/slave operation for total flexiblity.

APPLICATIONS

Music Production - Improve the sound on individual instruments, vocals and mixes.
Sound Reinforcement - Aroadable tube compressor/limiter in only one rack space.
Broadcast & Post Production - Agreat vocal processor and a powerful studio tool.
Project Studios - Improve the sound of digital recorders and workstations.
Musicians - The ultimate compressor for the professional guitar, bass, keyboard instrument rig.

Tube Compressor/Limiter
Expressor

®

/Easyrider®withTubessence

®

Model 661

FRONT PANEL

(1-14 Active in Auto and Manual Modes)

1. The PROCESS IN / BYPASS Switch operates a
bypass relay (indicated by a yellow LED) that connects
the Main Audio input directly to the Output, completely
bypassing the 661. PROCESS IN (indicated by a red
LED) engages the 661 circuitry.

2. The SPR Switch controls the Spectral Phase
Refractor circuit. SPR can reverse the effect of accu­mulated low frequency time delays caused by audio
passing through too many electronic stages.

3. The INPUT Control sets the amount of gain in the
661’s input stage.

4. The THRESHOLD Control sets the level above
which input signals will be processed by the 661’s gain
control circuitry in a manner defined by the settings of
the various AUTO or MANUALcontrols.

5. The OUTPUT Control sets the amount of gain in the
661’s output stage, restoring level lost by compression
(make-up gain).

6. The LOW CUT Switch inserts a 6dB per octave low
cut filter with an 80Hz corner frequency into the
sidechain. This is most useful when using the 661 (two
in stereo link mode) to process a stereo mix-down of
base predominate material.

7. HIGH FREQUENCY EXPANDER (HFX) is a form of
dynamic equalization that boosts high frequencies
when gain reduction occurs. The HFX RATIO Control
sets the amount of equalization (6 dB per octave shelv­ing) for the amount of Gain Reduction. At 1:1 there is 1
dB of High Frequency Expansion (or boost) for every
1dB of Gain Reduction.

8. The FREQUENCY Control lets you set the (HFX)
corner frequency of the shelving EQ anywhere between
2 kHz to 20 kHz.

9. The AUDIO LEVEL Meter monitors the Input and
Output level depending on the position of the switch
below the meters. Ared CLIP LED at the right of the
meter indicates clipping.

10. The GAIN REDUCTION Meter shows the amount
of compression in 2dB steps with a maximum of 30dB.

11. UNLINK must be engaged for normal operation of
one 661. Depressing LINK or SLAVE when using only
one 661 will cause the unit to malfunction.

12. LINK is engaged when two 661’s are used in
stereo. Both 661’s must have the LINK switch engaged.

13. SLAVE is used when two 661’s are being config­ured for a master/slave operation. Only the unit acting
as a SLAVE should have the SLAVE switch engaged.
The master unit needs to be in LINK.

14. The LED at the top of the POWER SWITCH illumi­nates when the unit is powered.

The AUTO / MANUAL Mode switch determines if
the 661’s primary control parameters will be manually
adjusted by the user or automatically adjusted by the

661. In the AUTO (Easyrider) Mode the Fast / Slow
switch is active while Soft Knee, Ratio, Attack and
Release are defeated. In the MANUAL Mode, Soft
Knee, Ratio, Attack and Release are active, while the
Fast / Slow switch is defeated

AUTO MODE

When in the AUTO Mode the attack and release

characteristics of the Easyrider circuit are auto­matically adjusted based upon the waveform of the
input. The SLOW/ FAST switch selects between two
ranges of the automatic release circuit.

MANUAL MODE

The SOFT KNEE Switch in the OFF position

results in a transition at threshold that is of the
abrupt Hard Knee type. In the ON position (indicated by
red LED), signals are processed more gradually and
the transition is less noticeable

The RATIO Control determines the amount of

change in output level for a given change in input
level above threshold. This is expressed as a ratio: rel­ative input versus output. The range of this control is
1:1 to 30:1.

The ATTACK Control adjusts the time in which

the 661 will reduce the gain after an increase in
input over threshold. The range of the control is .05 to
100 ms.

The RELEASE Control adjusts how long it takes

the 661 to release gain reduction after a decrease
in input level. The range of this control is .04 to 4 sec­onds.

BACK PANEL

1. VOLTAGE SELECTION AND FUSE

AC line power is supplied to the unit via an integral
receptacle/fuse holder on the rear panel which meets
all of the international safety certification requirements
and also doubles as a radio frequency line filter.

2. LINK provides two different methods of linking the
VCA control between two 661’s: Stereo Link and
Master/Slave. To link two 661’s, insert a 1/4” TS cable
into the LINK jack on both units.

3. SIDECHAIN ACCESS provides a 1/4” TS jack to
send the output of the 661 into an external processing
device and a return 1/4” TS jack for returning the out­put of an external processing device into the 661.

4. The OPERATING LEVEL Switch on the rear panel
selects the nominal operating level to either +4dBu or ­10dBV. This switch sets the dynamic range of the 661’s
circuitry to best match you standard operating level,
and also sets the 0dB calibration of the front panel
AUDIO LEVEL Meter to equal the reference level
selected.

5. Two servo balanced INPUT Connectors are provid­ed, choose either a 3-pin XLR female connector or a
1/4” TRS phone jack.

6. Two servo balanced OUTPUT Connectors are pro­vided, choose either a 3-pin XLR male connector or a
1/4” TRS phone jack.

7. A WIRING TABLE is printed on the back panel for
assistance in the proper wiring of connectors.

PROCESS
IN

BYPASS

SPR

0

-2

-4

-6

-8

-1

0

+2

+4

+6

+8

+1

0

INPUT

dB

-7

-9

-12

-17

-25

-3

0

-5
0

+3

+9

+2

0

THRESHOLD

dB

0

-3

-6

-10

-11

-1

2

+3

+6

+10

+14

+1

8

OUTPUT

dB

Easyrider

TM

AUTO
SLOW

FAST

MANUAL
SOFT

KNEE

4

3

2.5
2

1.3

1.0

5

6

7

10

3

0

RATIO

20

1

0

5

1

.5

.05

3

0

4

0
6

0

80

1

00

ATTAC K

mSEC

.22

.16

.1

.

0

6

.

0

5

.

0

4

.4

1

2

3

4

RELEASE

SEC

SIDECHAIN

LOW
CUT

.5

.4

.3

.2

.1

OFF

.6

.7

.8

.9

1.

0

HFX RATIO

HIGH FREQUENCY EXPANDER

FREQUENCY(kHz)

-30 -24 -18 -12 -6 0 +3 +6 +9 +12 CLIP

30 24 20 16 13 10 8 6 4 2

AUDIO LEVEL

GAIN REDUCTION

INPUT

OUTPUT UNLINK LINK SLAVE POWER

8

6.4

4.6

3.2

2.4
2

10

14

16

18

20

EXPRESSOR

TM

with

Tubessence

®

RETURN

SEND

OUTPUT

INPUT

MODEL 661

EXPRESSOR

MADE IN USA

APHEX SYSTEMS LTD.

SUN VALLEY, CA

U.S. PATENT NO. 5115471

OTHER PATENTS

ISSUED OR PENDING

AC 100/120/220/240V 50/60HZ 20 WATTS

FUSE: 100/120V=0.375A 220/240V=0.25A (250V SLOW BLOW)

TM

SERIAL #
CHASSIS

GROUND

59887

COMMERCIAL

AUDIO EQUIPMENT

®

SIDECHAIN ACCESS

TIP/SLEEVE - UNBALANCED

MAIN AUDIO

1/4"

SLEEVE

TIP

RING

GROUND

POS
NEG

XLR
PIN 1
PIN 2
PIN 3

OP

LEVEL

+4

-10

LINK

TIP/SLEEVE

UNBALANCED

CAUTION

RISK OF ELECTRIC SHOCK

DO NOT OPEN

TO PREVENT FIRE OR SHOCK HAZARD, DO NOT EXPOSE
THIS DEVICE TO RAIN OR MOISTURE. DO NOT REMOVE
THE COVER. NO USER SERVICABLE PARTS INSIDE.
REFER SERVICING TO QUALIFIED PERSONNELONLY.

ATTENTION: AFIN D'EVITER DES CHOCS ELECTRIQUES,
N'ENLEVEZ PAS LE COUVERCLE. IL N'Y A AUCUNE
PIECES D'ENTRETIEN A L'INTERIEUR. REFEREZ LES
REPARATIONS A UNE PERSONNE QUALIFIEE.

ATTENTION: RISQUE DE CHOC ELECTRIQUE

NE PAS OUVRIR

L

I

S

T

E

D

1 23 76 4 5

1 2 3 4 5 6 7 8 9 11 12 13 10 14

BACK PANEL

FRONT PANEL

A/M

A1

M1

M2

M3

M4

A/M M1 M2 M3 M4A1