Crest Audio XR-20 Owners manual

owner’s manual

X-Rackrack mount mixers

XR-20
XR-24

Important precautions

XR-20 / XR-24 owner’s manual

Save the carton and packing materials!

1

Should you ever need to ship the unit,
use only the original factory packing.

For replacement packaging, call Crest Audio’s
Customer Service Department directly.

Read all documentation before

2

operating your equipment.Retain all
documentation for future reference.

Follow all instructions printed on

3

unit chassis for proper operation.

Do not use the unit if the electrical

4

power cord is frayed or broken.

The power supply cord should be rout­ed so that it is not likely to be walked on
or pinched by items placed upon or
against it.

Always operate the unit with the

5

AC ground wire connected to the
electrical system ground.Precautions

should be taken so that the means of
grounding of a piece of equipment is not
defeated.

Service Information

Do not open unit!

Opening the unit will expose you to
potentially dangerous voltages. There are
no user serviceable parts inside.

Equipment should be serviced by
qualified service personnel when:

A.The equipment has been exposed to rain.
B.The equipment does not appear to oper-

ate normally, or exhibits a marked change in
performance.

C.The equipment has been dropped, or the

enclosure damaged.

To obtain service:

contact your nearest Crest Audio
Service Center, Distributor, Dealer,
or Crest Audio at 201.909.8700
or visit www.crestaudio.com for addi­tional information.

email techserve

@crestaudio.com

USA

This symbol is used to alert
the operator to follow important
procedures and precautions
detailed in documentation.

This symbol is used to warn opera­tors that uninsulated “dangerous
voltages” are present within the
equipment enclosure that may

pose a risk of electrical shock.

Damage caused by connection to

6

improper AC voltage is not covered
by any warranty.

Do not spill water or other liquids

7

into or on the unit, or operate the
unit while standing in liquid.

The power cord of equipment

8

should be unplugged from the out­let when left unused for a long peri­od of time.

IIMMPPOORRTTAANNTT SSAAFFEETTYY IINNSSTTRRUUCCTTIIOONNSS

WWAARRNNIINNGG::

When using electrical products, basic cautions should always be followed, including the following:

1. Read these instructions.

2. Keep these instructions.

3. Heed all warnings.

4. Follow all instructions.

5. Do not use this apparatus near water.

6. Clean only with a dry cloth.

7. Do not block any of the ventilation openings. Install in accordance with manufacturer’s instructions.

8. Do not install near any heat sources such as radiators, heat registers, stoves or other apparatus (including
amplifiers) that produce heat.

9. Do not defeat the safety purpose of the polarized or grounding-type plug. A polarized plug has two blades with one
wider than the other. A grounding type plug has two blades and a third grounding plug. The wide blade or third
prong is provided for your safety. If the provided plug does not fit into your outlet, consult an electrician for
replacement of the obsolete outlet.

10. Protect the power cord from being walked on or pinched, particularly at plugs, convenience receptacles, and the
point they exit from the apparatus.

11. Only use attachments/accessories provided by the manufacturer.

12. Use only with a cart, stand, tripod, bracket, or table specified by the manufacturer or sold with the apparatus. When
a cart is used, use caution when moving the cart/apparatus combination to avoid injury from tip-over.

13. Unplug this apparatus during lightning storms or when unused for long periods of time.

14. Refer all servicing to qualified service personnel. Servicing is required when the apparatus has been damaged in

any way, such as power-supply cord or plug is damaged, liquid has been spilled or objects have fallen into the
apparatus, the apparatus has been exposed to rain or moisture, does not operate normally, or has been dropped.

15. Never break off the ground pin. Write for our free booklet “Shock Hazard and Grounding.” Connect only to a power
supply of the type marked on the unit adjacent to the power supply cord.

16. If this product is to be mounted in an equipment rack, rear support should be provided.

17. Exposure to extremely high noise levels may cause a permanent hearing loss. Individuals vary considerably in
susceptibility to noise-induced hearing loss, but nearly everyone will lose some hearing if exposed to sufficiently
intense noise for a sufficient time. The U.S. Government’s Occupational and Health Administration (OSHA) has
specified the following permissible noise level exposures:

Duration Per Day In Hours Sound Level dBA, Slow Response

890
692
495
397
2 100

1 1/2 102

1 105

1/2 110

1/4 or less 115

According to OSHA, any exposure in excess of the above permissible limits could result in some hearing loss. Ear plugs or protectors to the
ear canals or over the ears must be worn when operating this amplification system in order to prevent a permanent hearing loss, if exposure
is in excess of the limits as set forth above. To ensure against potentially dangerous exposure to high sound pressure levels, it is
recommended that all persons exposed to equipment capable of producing high sound pressure levels such as this amplification system be
protected by hearing protectors while this unit is in operation.

SSAAVVEE TTHHEESSEE IINNSSTTRRUUCCTTIIOONNSS!!

4

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table of contents

Introduction

Thank you and congratulations on your purchase of your new
Crest Audio X-Rack mixer. We’re confident that you will enjoy
many years of trouble-free service from it. You will quickly find
that it fits into a wide variety of mixing applications with ease.
Due to well thought out sets of features, coupled with intelli­gent circuit design and the highest standards in construction &
workmanship, all Crest Audio console products excel above and
beyond the competitor’s products, in every area.

This owner’s manual covers both the XR-20 and the XR-24 X­Rack mixers. Features are identical for both models, the only dif­ference is the amount of Mono Inputs versus Stereo Inputs. The
XR-20 has 12 Mono inputs and 4 Stereo inputs, adding up to a
total of 20 microphone inputs. The XR-24 has 8 Mono inputs
and 8 Stereo inputs, adding up to a total of 24 microphone
Inputs.

Please read this manual thoroughly and keep it handy for future
reference. If you have any operating concerns that are not cov­ered in this manual, or have application questions of any type,
don’t hesitate to contact Crest Audio directly either by phone,
fax, or email. Here is our technical support contact information:
Phone: [phone]
Fax: [phone]
Email: [e-mail]

Mono Input channels p. 7

Front panel controls and rear panel connections

Stereo Input channels p.17

Front panel controls and rear panel connections

Master section P .27

Aux masters, groups, main outs, monitor section.
Front panel controls and rear panel connectors.

Specifications P. 47

XR-20 / XR-24 owner’s manual

p.4

XR-20/24 block diagram

JIMI

how to use this manual

format

This manual uses a format that is intended to be easy to read, yet technical for those
who need to know all the details. For feature descriptions, this is done by devoting the
left side of each page to 1) an overall module picture, 2) a block diagram, and 3) a con­trol closeup. These images all pertain to the features and control descriptions on the
right side of the page. The intention is to make the manual easy to read while including
all the technical details needed for getting the most out of the X-Rack - a compact, flexi­ble, feature-rich addition to Crest Audio's growing line of audio mixing console products.

conventions

Control Icons

This manual uses symbols to illustrate what the control descriptions are referring to. This
makes it possible to avoid redundant wording and makes the control descriptions clear.

Switch in the UP, non-activated position
Switch in DOWN, activated position

Switch that illuminates when in the DOWN position

Momentary switch that illuminates when activated

LEDthat is on, indicating that it's associated feature is activated

Potentiometer

Standard 1/4" TRSjack (used for line level inputs and insert sends)

1/4" TRSjack with normal switching (used on insert returns)

Female XLRinput jack

Male XLRoutput jack

p.5

Mono input channel

1

XR-20 / XR-24 owner’s manual

Module

Block diagram

+48V ON

BAL MIC IN

+48V

LINE

GAIN

12 - 70 dB

Controls

HPF

70Hz

-18dB/Oct

p.6

BAL LINE IN

27dB

PAD

HPF

INPUT

PREAMP

Mono Input channel

Front panel features

Mono Input channel features are identical for both the XR-20 and the XR-24. The XR-20
has 12 Mono inputs and the XR-24 has 8 Mono inputs.

Line Input (mic pad)

The input preamp circuit is set up to accept a mic-level signal. This signal is
brought in via the XLR mic-input connector located on the rear panel. The 1/4"
TRS input jack is disabled.

The input preamp circuit is set up to accept a line-level signal from either
the XLR mic-input connector or the 1/4" TRS input jack, both located on the rear
panel. Since the sensitivity of the input preamp is reduced, this control can also act
as a PAD for bringing a very hot microphone feed down to a controllable level,
avoiding overload. When a plug is inserted into the 1/4" TRS input jack, the XLR
mic-input connector is disabled.

Gain

The Input gain control is used to establish proper gain structure in the chan­nel. For best results, use the Solo system to monitor the channel while you set
the gain. The goal is maximum gain without distortion. Both the main LED meters
(during Solo) and the channel’s Level/Peak indicator can be used for adjusting gain.

1

70 Hz high-pass filter

The high-pass filter reduces or eliminates unwanted low frequencies without sub­stantially affecting the program material. Quite often such unwanted low frequen­cies are included with mic- or line-input signals. For example, stage rumble or
wind can be picked up through vocal mics. The cut-off frequency of the high-pass
filter is 70 Hz and the slope is -18dB per octave.

HPF

High-pass filter is on.

p.7

Mono input channel

1

XR-20 / XR-24 owner’s manual

Module

Controls

p.8

Block diagram

LEVEL

LF LOW MID HI MID HF

FREQ LEVEL LEVELFREQ LEVEL

EQ ON

12 KHZ400 - 8 KHZ80 - 2 KHZ80 HZ

FOUR BAND EQ

Front panel features
EQ

Many audio signals coming into the console require some degree of corrective eq
in order to be part of a good sounding mix. XR-20 & XR-24 offer a very useful
and great sounding eq section on each channel. The input EQ consists of four
bands: High, High-mid, Low-mid and Low. The High and Low frequency bands each
have a boost/cut control and their frequencies are fixed. The High-mid and Low­mid bands each have variable boost/cut and variable frequency.

high frequency—HF

Boost / Cut15dB boost and cut. Shelving @ 12 kHz

high mid—HM

FrequencyContinuously sweepable between 400 Hz and 8 kHz.
Boost / Cut15dB boost and cut. Bell curve with a Q of 1

Mono Input channel

1

Low mid—LM

FrequencyContinuously sweepable between 100 Hz and 2 kHz.

Boost / Cut15dB boost and cut. Bell curve with a Q of 1

Low frequency—LF

Boost / Cut15dB boost and cut. Shelving @ 80 Hz.

EQ on

Equalizer is on. This switch is used to activate the EQ section and can be

used to make A/B comparisons between "flat" and eq'd signals.

p.9

Mono input channel

MUT

E

1

XR-20 / XR-24 owner’s manual

Module

Controls

Block diagram

PRE

INSERT

PRE

EQ

EQ ON

FADER

PRE-SOURCE

SELECT

HF

12 KHZ

CHAN

FADER

100MM

PRE

FADER AMP

+10

YES

PRE

SOURCE

MUTE ?

NO

PRE-SOURCE

BUFFER

PAN

A1-2
PRE

A3-4
PRE

A5-6
PRE

MONO L-R G1-2

BUS ASSIGN

SWITCHES

PAN

1-2

AUX SENDS

1 THRU 6

LEVEL

1-2

LEV 3

LEV 4

LEV 5

LEV 6

G3-4

A1

A2

A3

A4

A5

A6

p.10

AUX send features

Six auxiliary sends are available for creating individual output mixes. These can be
used to drive effects processors, provide monitor mixes, create broadcast or
alternate sound reinforcement mixes, or for other special requirements.
Note: The default PRE setting for the Auxes is pre-fader, but post-mute,
post-insert, and post eq. Internal settings can be changed so that PREis also pre­eq and pre mute

Aux 1 - 2 PRE

AUX 1/2 stereo pair is post fader
AUX1/2 stereo pair is pre-fader

Aux sends 1 & 2

Auxes 1 and 2 are configured as a stereo pair. The top knob controls the level
and the bottom knob acts as a PANcontrol. This stereo aux send can be used for
any type of stereo feed from the console, such as live two-track recording, stereo
in-ear monitors, alternate stereo feed for broadcast, and stereo signal processors.
Also, by properly using the pan control Auxes 1 and 2 can be used as discrete
mono Aux buses

Mono Input channel

1

Aux 1/2 level Send level for the Aux 1/2 stereo pair
Aux 1/2 PAN Stereo placement for the Aux 1/2 stereo pair

AUX 3-4 PRE

AUX 3 and AUX 4 are post fader
AUX3 and AUX 4 are pre-fader

Aux sends 3, 4, 5 & 6

Auxes 3, 4, 5, & 6 are configured as descrete mono aux sends. They are typically
used to feed signal processors and for on-stage monitors.

Auxes 3, 4, 5, &6 level Set levels Auxes 3, 4, 5, & 6.

AUX 5-6 PRE

AUX 5 and AUX 6 are post fader.
AUX5 and AUX 6 are pre-fader.

p.11

Mono input channel

1

XR-20 / XR-24 owner’s manual

Module

Block diagram

MUTE

TO

PEAK

CIRCUIT

PFL

Controls

SOLO LEFT

SOLO RIGHT

SOLO DC

p.12

EQ ON

RE

Q

PRE-SOURCE

CHAN

FADER

100MM

PRE

FADER

SELECT

FADER AMP

+10

YES

PRE

SOURCE

MUTE ?

NO

PRE-SOURCE

BUFFER

PAN

A1-2
PRE

A3-4
PRE

A5-6
PRE

MONO L-R G1-2

BUS ASSIGN

SWITCHES

PAN

1-2

AUX SENDS

1 THRU 6

LEVEL

1-2

LEV 3

LEV 4

LEV 5

LEV 6

G3-4

A1

A2

A3

A4

A5

A6

Bus assignment features

The bus assignment section offers considerable flexibility for creating what even­tually becomes the main output mix. Two stereo subgroups are available for creat­ing submixes or separate stereo mixes. All assignments are derived post-fader,
post-eq, and post-mute.

PAN control

The pan control positions the signal within the stereo left/right (or
odd/even) field. PAN affects signals that are assigned directly to Left-Right, Groups
1-2 and Groups 3-4

Mono bus assign

The channel is assigned to the MONOmix bus. PANhas no affect on

MONO

L-R bus assign

The channel is assigned to the Left and Right mix buses.

G 1-2 bus assign

The channel is assigned to Groups 1 and 2. Groups 1 and 2 are configured
as a stereo pair. They can also be treated as two discrete mono groups by using
the PAN control.

Mono Input channel

1

G 3-4 bus assign

The channel is assigned Groups 3 and 4. Groups 4 and 4 are configured as a
stereo pair. They can also be treated as two discrete mono groups by using the
PAN control.

Input fader (100mm)

The fader is the primary level control for signals being sent to any of the consoles
post fader mix buses,

MUTE

The input channel is muted and the MUTELEDis alluminated. All AUX
feeds and bus assignments are shut off. Insert send and SOLO signals are still
active.

PK / SIG LED indicator

This two-color(green & red) LED is used to monitor the channel’s signal
level. Signal present (green) is monitored pre-fader. Peak (red) is monitored at the
preamp and before & after the fader.

PFL

PFL -Pre fader listen. This button routes the channel’s signal to the Solo bus
for monitoring through headphones or in the control room. The Peak (red) LED
is illuminated to show PFLstatus.

p.13