DigiTech VCS1 User Manual

WARNING

FOR YOUR PROTECTION, PLEASE READ THE
FOLLOWING:

Water and Moisture: Appliance should not be used near water (e.g. near a
bathtub, washbowl, kitchen sink, laundry tub, in a wet basement, or near a
swimming pool, etc). Care should be taken so that objects do not fall and liq­uids are not spilled into the enclosure through openings.

POWER SOURCES: The appliance should be connected to a power supply
only of the type described in the operating instructions or as marked on the
appliance.

GROUNDING OR POLARIZATION: Precautions should be taken so that the
grounding or polarization means of an appliance is not defeated.

POWER CORD PROTECTION: Power supply cords should be routed so that
they are not likely to be walked on or pinched by items placed upon or against
them, paying particular attention to cords at plugs, convenience receptacles,
and the point where they exit from the appliance.

SERVICING: To reduce the risk of fire or electric shock, the user should not
attempt to service the appliance beyond that described in the operating instruc­tions. All other servicing should be referred to qualified service personnel.

CAUTION: To reduce the risk of fire replace only with same type fuse.
ATTENTION: Utiliser un fusible de recharge de même type.

CAUTION: To reduce the risk of fire replace LAMPwith manufacturers rec­ommended part ( Refer to service literature)

U.K. MAINS PLUG WARNING

A moulded mains plug that has been cut off from the cord is unsafe. Discard
the mains plug at a suitable disposal facility. NEVER UNDER ANY CIR­CUMSTANCES SHOULD YOU INSERTA DAMAGED OR CUT MAINS
PLUG INTO A13 AMP POWER SOCKET. Do not use the mains plug with­out the fuse cover in place. Replacement fuse covers can be obtained from
your local retailer. Replacement fuses are 13 amps and MUST be ASTA
approved to BS1362.

The symbols shown above are internationally accepted symbols that warn of
potential hazards with electrical products. The lightning flash with arrowpoint
in an equilateral triangle means that there are dangerous voltages present with­in the unit. The exclamation point in an equilateral triangle indicates that it is
necessary for the user to refer to the owner’s manual.

These symbols warn that there are no user serviceable parts inside the unit.
Do not open the unit. Do not attempt to service the unit yourself. Refer all
servicing to qualified personnel. Opening the chassis for any reason will void
the manufacturer’s warranty. Do not get the unit wet. If liquid is spilled on
the unit, shut it off immediately and take it to a dealer for service. Disconnect
the unit during storms to prevent damage.

ELECTROMAGNETIC
COMPATIBILITY

This unit conforms to the Product Specifications noted on the Declaration of
Conformity. Operation is subject to the following two conditions:

• this device may not cause harmful interference, and

• this device must accept any interference received, including
interference that may cause undesired operation. Operation of
this unit within significant electromagnetic fields should be
avoided.

• use only shielded interconnecting cables.

FCC COMPLIANCE

This equipment has been tested and found to comply with the limits for a Class
B digital device, pursuant to Part 15 of the FCC Rules. These limits are
designed to provide reasonable protection against harmful interference in a res­idential installation. This equipment generates, uses and can radiate radio fre­quency energy and, if not installed and used in accordance with the instruc­tions, may cause harmful interference to radio communications. However, there
is no guarantee that interference will not occur in a particular installation. If
this equipment does cause harmful interference to radio or television reception,
which can be determined by turning the equipment off and on, the user is
encouraged to try to correct the interference by one or more of the following
measures:

• Reorient or relocate the receiving antenna

• Increase the separation between the equipment and receiver that may cause
undesired operation.

• Connect the equipment into an outlet on a circuit different from that to which
the receiver is connected

• Consult the dealer or an experienced radio/TV technician for help.

SAFETY INSTRUCTIONS

Notice For Customers If Your Unit Is Equipped With A Power Cord.
WARNING:THISAPPLIANCEMUSTBEEARTHED.
The cores in the mains lead are coloured in accordance with the following
code:
GREEN and YELLOW - Earth BLUE - Neutral BROWN - Live
As colours of the cores in the mains lead of this appliance may not correspond
with the coloured markings identifying the terminals in your plug, proceed as
follows:

• The core which is coloured green and yellow must be con­nected to the terminal in the plug marked with the letter E, or
with the earth symbol, or coloured green, or green and yellow.

• The core which is coloured blue must be connected to the ter­minal marked N or coloured black.

• The core which is coloured brown must be connected to the
terminal marked L or coloured red.

This equipment may require the use of a different line cord, attachment plug,
or both, depending on the available power source at installation. Connect this
equipment only to the power source indicated on the equipment rear panel. If
the attachment plug needs to be changed, refer servicing to qualified service
personnel who should refer to the table below. The green/yellow wire shall be
connected directly to the unit's chassis.

WARNING: If the ground is defeated, certain fault conditions in the unit or in
the system to which it is connected can result in full line voltage between
chassis and earth ground. Severe injury or death can then result if the chassis
and earth ground are touched simultaneously.

Line

Neutral

Earth Grnd.

CONDUCTOR

L

N

Brown

Blue

Green/Yel.

Black

WIRE COLOR

White

Green

DECLARATION OF CONFORMITY

Manufacturer’s Name: IVL Technologies Ltd.

per DigiTech specifications

Manufacturer’s Address: 6710 Bertram Place

Victoria, B.C.
Canada V8M 1Z6

declares that the products:

DigiTech VCS-1 Dynamics Processor

conform to the following product specifications:

EMC: EN 55022 (1987):

CISPR 22 (1993) Class B
EN 50082-1 (1992)

Supplementary Information:
The product herewith complies with the requirements of the Low Voltage Directive
73/23/EEC and the EMC Directive 89/336/EEC (1989) as amended by the CE
Marking Directive 93/68/EEC (1993).

IVL Technologies Ltd.
6710 Bertram Place
Victoria, B.C.
Canada V8M 1Z6
December 12, 1996

Peter George, Vice President of Engineering

European Contact: Your local DigiTech Sales and Service Office or
International Sales Office
3 Overlook Drive Unit #4
Amherst, New Hampshire 03031, USA Tel [phone] Fax [phone]

Safety: EN 60065

IEC 65 (1993)
Amendment 1 (1987)
Amendment 2 (1989)
Amendment 3 (1992)

Digitech VCS-1 Owner’s Manual
Table of Contents

Introduction ..........................................................................1

Connection Examples..........................................................2

Rear Panel............................................................................3

Wiring Scheme.....................................................................3

Line Input.............................................................................3

Level Switch........................................................................3

Sidechain Send & Return ....................................................3

Line Output..........................................................................4

Front Panel...........................................................................5

Output Control.....................................................................5

Clip LED ..............................................................................5

Tube Gain Control...............................................................5

VU Meter.............................................................................5

Trim Adjustment..................................................................6

Gate Threshold & Attenuation.............................................6

De-ess Control .....................................................................6

Peak Limiter.........................................................................7

Compressor Controls ...........................................................7

Meter Function Switch ........................................................8

Auto Switch .........................................................................8

Knee Switch.........................................................................8

Process Switch.....................................................................8

Stereo Link Switch ..............................................................8

Application Notes................................................................9

Specifications.....................................................................13

Signal Flow Diagram.........................................................15

DigiTech VCS-1 Owners Manual version 1.01 rev. 12/16/96

Introduction

Thank you and congratulations on your purchase of the Digitech VCS-1. This product was devel­oped to give you precise control over dynamics in digital recording, analog recording and live per­formance. The VCS-1 also has an adjustable-gain vacuum tube stage with analog VU metering and
LED peak indication.

The compression circuit is comprised of the latest solid state VCA components available. This
ensures that even under considerable compression, the VCS-1 will not contribute significant
amounts of noise or colouration to an audio signal. The attack and release timing is based on the
“True Logarithmic Compression” design that sounds most natural to human hearing and is an emu­lation of “vintage” compressor sound.

The vacuum tube amplification stage in the VCS-1 is a classic, high plate-voltage design utilizing a
pure class Atopology. A parallel-triode arrangement is employed, in addition to a fully-regulated
235V plate supply to maximize signal-to-noise performance and transient response. The premium­grade 12AX7A vacuum tubes used in the VTP-1 are manufactured in Russia, and hand tested and
graded specifically for the VCS-1 by Audio Glassic in the USA.

Precision 1% metal-film resistors are used throughout the audio path to ensure performance stability
and low noise. In addition to precision resistors, all filter circuits utilize high quality plastic-film
capacitors to maintain spectral accuracy and minimize the long-term effects of component drift. To
ensure years of trouble-free operation, each VCS-1 must pass a rigorous set of performance tests and
a 24-hour burn-in period before it is shipped from the factory.

Features

• Fast, quiet industry standard VCA circuitry with “True Logarithmic Compression” timing

• Dual Class Avacuum tube stages

• Convenient single knob De-ess control

• Input, Output and Gain Reduction VU metering with LED peak indication

• Peak limiter circuit for transient peak protection

• Gate feature with variable attenuation level

• XLR and TRS 1/4” balanced inputs and outputs

• Sidechain loop for frequency-sensitive compression and gating

•••

1 •••

Connection Examples

The following diagrams show a few ways in which the VCS-1 can be used.

••• 2 •••

REAR PANEL

WIRING SCHEME

All of the XLR input and output connectors are pin 2 hot, meaning that pin 2 carries the positive
side of the balanced signal. Pin 3 is cold, carrying the negative polarity and pin 1 is the shield.

The 1/4” TRS jacks are wired so that when you use 3 conductor cables and balanced signals, the tip
is hot, the ring is cold and the sleeve is the shield. The 1/4” jacks can also be used with 2 conductor
unbalanced cables. In this case, the tip is hot and the ring and sleeve are grounded.

LINE INPUT

The XLR connector for the line input is electronically balanced and will accept +4 dBu or -10 dBV
signals. The 1/4” phone connector is also a balanced input using TRS (Tip Ring Sleeve) connectors.
TRS jacks require a cable with stereo phone jacks to be used if balancing is desired. The 1/4” TRS
inputs can also be used with an unbalanced source using a standard two conductor cable. Plugging a
1/4” connector into the phone jack input will override signal coming into the XLR input.

LEVEL SWITCH

This switch sets the nominal operating level for the line input only. When the switch is in the -10
dBV position a small amount of gain is added to the input signal to match the internal level of the
VCS-1. Consult your manual on any device connected here if you are unsure of which setting is
best.

SIDECHAIN SEND AND RETURN

These connectors allow you to insert an external processor or audio signal into the detector signal
path which is known as a “Sidechain”. Sidechain processing is used to accomplish frequency-sensi­tive compression, keyed gating and ducking. The Sidechain Send output level is +4 dBu and the
connector is 1/4” TRS impedance balanced. The Sidechain Return is +4 dBu unbalanced.

••• 3 •••