Manley Labs Manley Core Reference Channel Strip Microphone Preamplifier Manley Core Owner's Manual

0

ACK

ATT

MAX

RELEASE

SLOW F

BYP

SLOW

MIC IN

INSTRUMENT

IN

LINE IN

LINE

STAGE

IN

ASS

DI

STAGE

AST

FAST

PHASE

LOW

dB

-10 +10

0

1kHz-10kHz

dB

c o r e

c o r e

c o r e

RE FE RE NC E C HA NN EL ST RI P

c o r e

ESSO

PR

M

O

C

-12 +12

R

100Hz-1kHz

FREQUENCY

MIN

E

-12 +12

MAX

Q

OPERATIONAL BLOCK DIAGRAM

HP

FILTER

ATTENUATOR

COMPRESSOR

®

TUBE STAGE

HI

0

dB

INSERT

JACK

DIRECT

OUT 1

M

I

L

EQ

LIMITING

-6

OUTPUT

GAIN

0

dB

MIN

R

RELEASE

SLOW

R

TE

I

MAIN

OUT 2

F

LIMIT

AST

MAX

OUTPUT

GAIN

FET

BRICKWALL

LIMITER

MANLEY LABORATORIES INC.

13880 MAGNOLIA AVE. CHINO, CA 91710

PHONE [phone]

[e-mail]

www.manley.com

HAND CRAFTED IN USA

MAIN OUTPUT (2)

TIP: SEND

RING: RETURN

SLEEVE: GROUND

INSERT

DIRECT OUTPUT (1)

OWNER’S MANUAL

LINE INPUT

Contents

PAGECHAPTER

I) Introduction 2

ii) Manual Conventions 2

iii) Copyright Notice 2

1. Important Safety Instructions 3

2. Getting Started 3

3. Front Panel 4

4. Input Section 4

5. Optical Compressor 5

6. Equalizer 5

7. Limiter 6

8. VU Meter 6

9. Rear Panel 7-8

10. Rear Panel Connections 9

11. Operational Notes 9

12. Questions 10

13. Reading a VU Meter 10

14. Servicing 11

15. Core Calibration Procedure 11-12

16. Curves & Specifications 13

17. Recall Sheet 14

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.
* 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.

c o r e

1

i) An Introduction To The Manley CORE Reference Channel Strip

®

Thank you for selecting the Manley CORE® Reference Channel Strip. This unit combines a high quality vacuum
tube microphone preamplifier, an ELOP®Compressor, an EQ section and a fast FET Brickwall Limiter.

Musical. Flexible. Forgiving.

These three concepts were our main goals in designing the CORE® channel strip. To give the musician tools he or
she really needs, without needless complication.

Why is this important?

Because recording has become more complicated than ever!

Computers, plug-ins, and software can easily distract from creating your music. By designing a dedicated
recording channel with very high quality stages – but without extra functions you will rarely use – you can
concentrate on your art, not worry about the technology.

The elements that make up the CORE® are the result of decades of design, listening and experience of working
with engineers and musicians. The CORE® may have fewer knobs than other units, but we think they are the

right knobs!

ii) Manual Conventions

Please take a few moments to read through this manual carefully. It contains essential information for the
proper operation of your Manley CORE Reference Channel Strip.

Also in the following pages you will find useful hints and tips, allowing us to help you achieve the utmost
performance from your equipment.

Below are the following conventions, used to pick out particularly important parts of the manual. The
symbols are found in the margin next to the body of text of interest.

Especially Useful Tip

Caution! Pay Attention!

!

iii) Notice

This manual provides general and technical information for use, installation, and operating instructions for the
Manley CORE Reference Channel Strip. Manley Laboratories, Inc. reserves the right to make changes in

specifications and other information contained in this publication without prior notice. Manley Laboratories,
Inc. shall not be liable for errors contained herein or direct, indirect, incidental or consequential damages in
connection with the furnishing, performance, or use of this material. No statement contained in this
publication, including statements regarding suitability or performance of products shall be considered a
warranty by Manley Laboratories, Inc. for any purpose or give rise to any liability of Manley Laboratories, Inc.

© 2014 COPYRIGHT Manley Laboratories, Inc. All rights reserved.

This manual and any associated artwork, product designs, and design concepts are subject to copyright
protection. No part of this document may be produced, in any form, without prior written permission of

Manley Laboratories, Inc. CORE , ELOP , VOXBOX , MANLEY and the Manley Laboratories, Inc. logo are
trademarks of Manley Laboratories, Inc.

®

® ® ® ®

Important Information. Read Carefully

Refer to another section in this Manual

c o r e

2

1. Important Safety Instructions

1. Water and Moisture – Do not use The CORE near any source of water or in excessively moist

environments.

2. Object and Liquid Entry – Care should be taken so that objects do not fall, and liquids are not

spilled, into the enclosure through the openings.

3. Heat & Ventilation – When installing The CORE in a rack or any other location, be sure there is

adequate ventilation. Improper ventilation will cause overheating, and can damage the unit.
The unit should be situated away from heat sources, or other equipment that produce heat.

4. Power Sources – The CORE has a universal power supply which can operate in any country. It

has an input voltage range of 90-260 VAC at 50/60 Hz.

5. Cleaning - The CORE can be cleaned with just a damp cloth, or alcohol/methylated spirits for

more stubborn marks.

6. Damage - If after unpacking your CORE there are signs of shipping damage, contact your

dealer.

7. Servicing - Do not attempt any servicing without consulting your dealer or Manley

Laboratories, Inc. The user should not attempt to service the unit beyond that described in the
operating instructions. All other servicing should be referred to qualified service personnel.
This unit has high voltages present, even after the power has been switched off.

8. DO NOT connect the AC supply cord until all other connections have been made. Afer initial

power up the VU Meter back light will “blink” for thirty seconds. The unit remains in MUTE
until this warm up period has elapsed.

2. Getting Started

Unpacking your

CORE

The is secured in its packing carton by two end-caps.

Hold the unit by the middle and simply lift the unit vertically straight out of the box.

After it has been unpacked, check that nothing is loose inside when handling the unit. The unit is
shipped with the vacuum tubes installed. Make sure they are not loose by looking through the vent
holes on the top cover. Ensure they are standing upright in their sockets.

It is advisable to keep the original packaging. In the event of servicing or relocating, the original
packaging ensures that the unit will always be shipped safely.

This package contains the following;

CORE:

1 x Manley Reference Channel Strip
1 x Manley Owner’s Manual

CORE

CORE
1 x IEC Power Cable
1 x Warranty Registration Card
1 x Warranty Statement

c

o r e

3

3. Front Panel

MIC

120Hz

HI

4

LINE

FLAT

LOW

H

A

N

DC

PHANTOM

RAF

TED I

N CA

L

IFO

DIRECT IN

0

INPUT
LEVEL

8V

180

MIC

0

RNI

A

U

SA

COMPRESSION

MIN

ATTACK

MAX

RELEASE

SLOW

BYPASS

SLOW

LOW

dB

-10

COMPRESSOR

0

1kHz-10kHz

100Hz-1kHz

dB

-12

+12

FREQUENCY

MIN

FAST

IN

F

AST

HI

+10

0

dB

-12

+12

L

I

M

I

T

MAX

E

Q

E

LIMITING

MIN

MAX

UNITY

LIMIT

RELEASE

SLOW

R

dB

-6

+4

OUTPUT

GAIN

F

AST

REFERENCE

c

o

r

e

CHANNEL S

TRIP

O/P

2

O/P 1

GR

PREAMPLIFIER

Input Attenuator
Mic/Line
Source Select
High Pass Filter
High/Low Gain
Mic 48V Phantom
Mic Phase Invert
Instrument
Direct Input

As the signal flow in the CORE is from right to left, we'll describe the functions in that order as well:

4. Input Section

COMPRESSOR

Attack
Release
Bypass
Compression
(Threshold)

INPUT
LEVEL

EQ

High & Low Shelf
Sweepable Mid
Frequency
Low/High Range
Select
Continuously
Variable Frequency
Selection

LIMITER

Fast Attack FET
Brickwall Limiter
Limiting/Threshold
Release
Limit LED
Indicator
Output Gain
Control

VU METER

Meter Source
Select Switch

Displays Audio;
Compressor
Gain Reduction
Tube Preamp Out
Final Output

The INPUT LEVEL control is an input attenuator. It functions like a
variable pad. It acts on the Direct In (DI), Mic and Line inputs. Fully
counter-clockwise is off, and clockwise rotation increases the level.
For the Mic input, fully clockwise represents about 40dB of gain.

With the gain switch set to LOW and the input level set fully clockwise
the MIC input will yield about 40dB of gain and the LINE input will
produce 20dB of gain.

The top label of the selector switches show operational status when
the button is pushed in and illuminated.

MIC/LINE selects either the MIC XLR input or it selects the LINE XLR or
DI 1/4 “ inputs.

c o r e

MIC

120Hz

HI

4

8

V

180

The 120Hz high pass filter position is useful for reducing breath
“pops,” or any time a reduction of LOW frequencies such as train or

MIC

LINE

FLA

T

LOW

PHAN

TOM

0

H

AN

DC

R

A

FTE

D

IN C A

LI

FO

RN

I

A US A

traffic rumble or air conditioning rumble.

The HI/LOW gain switch adds 10dB of gain (or when the internal
jumper is set, 20dB of gain) to the circuit when engaged. For most
applications, this switch can be in the LOW position, but for low output
microphones or quiet sources, extra gain may be needed. (Note: If the
internal 20dB jumper is used, noise floor will also increase.)

DIRECT IN

48 Volt “PHANTOM” power is applied to the Mic input XLR when this

!

switch is engaged. This should only be used for microphones that
require phantom power.

Diagram 2

0 0

0 / 180 - The Mic phase switch inverts the signal by 180 degrees when
engaged.

DIRECT IN, Instrument input. This 1/4 inch input jack is for use with
guitars, keyboards, or any other instrument. When a plug is inserted
the CORE will automatically switch to the DI input. The Mic/Line
switch must be set to the Line position to activate the DI. This is an
unbalanced 10 MegOhm input that will not load down Hi Z instruments
such as a guitar. The connections on this TS Jack are TIP-HOT, SLEEVE­GROUND.

4

®

ELOP

5. Compressor

ATTACK

The Compressor utilizes our famous circuit topology as
found in the VOXBOX , and is also similar to the ELOP and SLAM

® ®

®

ELOP

limiters.

The COMPRESSION (Threshold) control determines at what level
the compressor begins to act. Clockwise rotation makes the
compressor reduce the signal.

COMPRESSION

MIN

MAX

RELEASE

SLOW

BYP

IN

ASS

FAST

With the meter in the “GR” position, the amount of gain reduction
can be displayed. (Refer to Diagram 6, pg.6)

The ATTACK control determines how long the compressor takes to
respond to signals above the threshold.

The RELEASE control determines how long the compressor takes to
recover after the signal falls below the threshold level.

SLOW

F

AST

C

OMP

R

ESSOR

The BYPASS switch can be used to bypass the compressor section.
It may be used during recording as the switching process is silent.

Diagram 3

The output after this stage is available on XLR O/P 1 and also at
the INSERT SEND. (Refer to Diagram 7, pg.8) This audio level can
be monitored on the VU Meter.

While compression is one of the most powerful tools
in recording, it is possible to overdo it. And, unlike
EQ, it's not reversible. Although there are really no
rules when it comes to creativity and the recording
process, a few guidelines can be helpful. When it
comes to vocals, you might not need more than a
couple dB of gain-reduction. It's better to adjust the
singing style or distance from the mic than to rely on
compression to get a totally even performance.
That said, there is no harm in really burying the GR
needle if that's the sound you're going for.

Try starting with the attack and release knobs in
the 12 O'clock position and go for a dB or three of
gain reduction. If there are still peaks that are
sounding too loud, move the attack more clockwise
to the faster settings. For percussive sounds,
starting with a faster attack can also be good.
Putting the attack and release fully clockwise and
really getting a lot of gain reduction can also
produce an interesting sound. Consider combining
a track processed this way with one done at
minimal compression.

6. Equalizer

c o r e

-12

LOW

0

dB

+12

0

dB

-10

1kHz-10kHz

100Hz-1kHz

FREQUENCY

MIN

E

Q

Diagram 4

+10

MAX

-12

The LOW and HI Shelf controls are Baxandall curves centered
around 90 Hz and 12kHz respectively. At 12 O’clock no
equalization is occurring. Fully CCW will reduce levels below the
center frequency to a maximum of 12dB. Fully CW will increase
levels above the center frequency to a maximum of 12dB.

The Mid Frequency EQ is a bell shaped curve, with a range

HI

0

control in the low position of 100Hz to 1kHz, and in the high
position, between 1kHz and 10kHz. The desired range is selected
using the toggle switch. One can then boost or cut at the
selected frequency by approximately 10dB.

dB

+12

The FREQUENCY control allows continuous sweepable frequency
of the selected range so that you can TUNE IN the desired
frequency.

The controls that run vertically through the middle of the EQ
section are: MID FREQUENCY EQ, TOGGLE RANGE SWITCH, and
FREQUENCY SWEEP. These all operate together. There is
substantial overlap available between the shelf and peaking
controls, allowing a large amount of EQ control.

The EQ response curves can be seen on page 13.

5

7. Limiter

LIMITING

The FET output limiter is a powerful, high-ratio, peak limiter. It can be
used for many creative effects, as well as for setting a maximum
output ceiling to avoid overloading the next piece of gear in the chain.

The LIMITING knob controls the amount of limiting. The LIMIT LED lights
when the signal crosses the threshold, and goes off when the signal is
both below the threshold and the release time is completed.

MIN

RELEASE

SLOW

LI M

IT

ER

Diagram 5

8. VU Meter

F

AST

MAX

LIMIT

-6

OUTPUT

UNITY

dB

GAIN

The RELEASE controls how FAST or SLOW the limiter returns to full
volume. The

The RELEASE time control has purposely been made with a very wide

+4

control range. Very fast release times can create a distortion effect,
this area of the RELEASE control is highlighted with a zig-zag on the
dial.

The Final OUTPUT GAIN control has a range of 10dB. This is an active
gain stage following the FET limiter that can both attenuate and
amplify the Main Output. This output is available from XLR O/P 2.
(Refer to Diagram 7, pg.7) The UNITY gain position will be within the
hash marks around the 12 o’clock area. Due to component tolerances
there may be slight variations from unit to unit.

When Limiting is set to “Minimum” the LIMIT light acts as a general
overload indicator at +20 dBu.

Three positions are selectable on the analog VU meter selector switch.

O/P 1- shows the audio level of the DIRECT OUTPUT of the preamplifier
and compressor section.

c o r e

c

o

O/P

r

2

GR

REFERENCE CHANNEL S

O/P 1

Diagram 6

O/P 2 - shows the MAIN OUTPUT audio level of the CORE.

GR - indicates the amount of COMPRESSOR gain reduction in decibels.
This position stays at “0 VU” when there is no gain reduction and
moves to the left to show the amount of compression.

Because the VU meter is mechanical and really just shows the average
level, it can't follow every signal exactly. In fact, things like snare
drums are not displayed very accurately at all. The VU meter might
only be ticking over at -10, but the actual peak level may be 20dB

e

TRIP

higher. This is OK, as every workstation has a digital peak meter. And
it's a good idea to keep all of your peak levels in the DAW to around ­6dBFS anyway. There is no reason to go to 0dBFS on the individual
tracks, and the final result will sound better and actually combine
better if the tracks are recorded with some headroom below zero.

Also, it's a good general practice to look at the VU meter occasionally
when recording and try to keep the majority of the track on the scale
of the meter – not a hard and fast rule – but if you are pinning it all the
time (unless for an intentional effect) or the needle isn't moving at all,
you might need to adjust the input gain of the CORE.

6

9. Rear Panel

H

H

MIC

MIC

LINE

LINE

ANDC

ANDC

R

R

120Hz

120Hz

FLAT

FLAT

A

A

F

F

INPUT

INPUT
LEVEL

LEVEL

HI

HI

48

48

V

V

180

180

MIC

MIC

LOW

LOW

PHANTOM

PHANTOM

0

T

T

ED I

ED I

N C

N C

A

A

0

LIF

LIF

ORN

ORN

I

I

A

A

U

U

S

S

A

A

MAINS VOLTAGE SHOWN ON SERIAL TAG

ELECTRIC SHOCK, DO NOT EXPOSE THIS UNIT TO RAIN OR MOISTURE CAUTION: RISK OF

ELECTRIC SHOCK. DO NOT OPEN. REFER SERVICING TO QUALIFIED PERSONNEL ONLY.

WARNING: TO REDUCE THE RISK OF FIRE OR

Serial Number

MIC IN

MIC IN

PHASE

PHASE

INSTRUMENT

INSTRUMENT

IN

IN

DI

DI

STAGE

LINE

LINE

STAGE

STAGE

STAGE

LINE IN

LINE IN

MANLEY LABORATORIES INC.

MANLEY LABORATORIES INC.

13880 MAGNOLIA AVE. CHINO, CA 91710

13880 MAGNOLIA AVE. CHINO, CA 91710

PHONE [phone]

PHONE [phone]

[e-mail]

[e-mail]

www.manley.com

www.manley.com

HANDCRAFTED IN USA

HANDCRAFTED IN USA

OPERATIONAL BLOCK DIAGRAM

OPERATIONAL BLOCK DIAGRAM

OPERATIONAL BLOCK DIAGRAM

OPERATIONAL BLOCK DIAGRAM

FILTER

FILTER

FILTER

FILTER

DIRECT IN

DIRECT IN

HP

HP

HP

HP

ATTENUATOR

ATTENUATOR

ATTENUATOR

ATTENUATOR

MAIN OUTPUT (2)

MAIN OUTPUT (2)

MAIN OUTPUT (2)

MAIN OUTPUT (2)

DIRECT INPUT (FRONT PANEL)

®

®

®

®

COMPRESSOR

COMPRESSOR

COMPRESSOR

COMPRESSOR

TUBE STAGE

c o r e

OPTIONAL OUTBOARD
ANALOG TO DIGITAL CONVERTER

SIGNAL PROCESSOR
EQ OR COMPRESSOR OR EFFECTS

Diagram 7

TUBE STAGE

TIP: SEND

RING: RETURN

SLEEVE: GROUND

INSERT

INSERT

JACK

DIRECT

OUT 1

EQ

MAIN
OUT 2

OUTPUT

GAIN

FET

BRICKWALL

LIMITER

DIRECT OUTPUT (1)

LINE INPUT

c o r e

REFERENCE CHANNEL STRIP

MIC INPUT

XLR PINOUT

PIN1: SHIELD/GROUND
PIN2: HOT/POSITIVE PHASE
PIN3: LOW/NEGATIVE PHASE

MIXER

DIGITAL AUDIO
WORKSTATION

DIGITAL TO ANALOG CONVERTER

8

10. Rear Panel Connections

From Right to Left:

MIC INPUT: This is a transformer balanced, microphone input to the preamplifier.
The pinout is PIN 1: Ground, PIN 2: HOT (+), PIN 3: COLD(-).

!

All pins must be driven. DO NOT “float” PIN 2 or PIN 3.

LINE INPUT: An electronically-balanced, line-level input.
The pinout is PIN 1: Ground, PIN 2: HOT (+), PIN 3: COLD(-). An unbalanced source can be connected with
PIN2 or 3 grounded. Unused pins can be grounded.

DIRECT OUT (1): Gives an pseudo or impedance balanced output directly after the tube preamp and ELOP
compressor stage. The pinout is PIN 1:Ground, PIN 2: HOT (+), PIN 3: COLD(-). An unbalanced source can be
connected with PIN3 grounded.

INSERT: This TRS 1/4” jack interrupts the connection between the PREAMP/COMPRESSOR and EQ/FET
LIMITER sections, allowing external gear to be inserted into the signal path. Alternately, it provides an input
to the CORE that is after the tube preamp, to the input of the EQ stage. The interface is unbalanced in and
out. The pinout is TIP: SEND, RING: RETURN, SLEEVE: GROUND.

OUTPUT (2): This is the main output from the CORE which is an electronically-balanced output. It is after
the EQ/Limiter section. The pinout is PIN 1: GROUND, PIN 2: HOT (+), PIN 3: COLD(-). An unbalanced source
can be connected with PIN2 or 3 floated but DO NOT ground pin 2 or 3.

®

11. Operational Notes

Unbalanced Operation

All of the XLR inputs of the CORE can be used with either balanced or unbalanced sources. However, the Main
(2) XLR output should only be connected to balanced inputs. If it's necessary to connect to a unbalanced
input, a cable must be used that has NO connection on XLR pin 3. This is important in order to prevent
damage to the CORE, as well as distortion to the signal. DO NOT GROUND PINS 2 OR 3 on the MAIN O/P 2.

!

Getting the most from your CORE

Earlier, in the Introduction we mentioned one of the three design principles was “Forgiving”. We want the
CORE to be easy to use and difficult to make a bad sound! An example of this is the placement of the
compressor before the amplifier stages. This allows the signal to be reduced by the compressor first which
prevents the preamp from being overloaded. Setting the COMPRESSION level just at the start of gain­reduction will allow you to get the full dynamic range of the source, but if the musician suddenly plays louder
the compressor will gracefully ride the level down.

Another forgiving element of the CORE is the FET output limiter which can be set to reduce just under the
overload level of the following piece of gear. This can be especially useful to protect an A/D converter from
overload.

There is no rule that says you can't put a line-level signal in the Mic input. Try it! Many different transformer
or tube saturation effects can be made this way.

Just be careful not to engage the PHANTOM power 48V switch if you have anything other than a phantom-

!

powered microphone plugged into the MIC INPUT.

c o r e

9

12. Questions

Q: “Where's the -20dB pad switch?”

Because the input attenuator precedes the tube gain stage, the input level control acts as a variable pad. It
should be used to either reduce the level of a hot input signal, or to simply set the overall gain of the preamp.
For best performance keep the GAIN switch set to LOW. HIGH gain should be used only if there is not enough
gain with the INPUT LEVEL knob turned to maximum.

Q: “Sometimes I hear distortion in the peak limiter!”

To allow for maximum creativity, the release time of the limiter was intentionally allowed to operate over a
wide range. This means that with some signals, when the release time is set to the fastest setting some
audible distortion may be created. But not to worry, if this distortion is not desired, just turn the release
time knob counter-clockwise and slow down the release time. The sound of a super-fast release time can be
used as a creative effect. Try it on vocals or drums! Try it on anything. You won’t damage any circuitry!

Q: “I am having problems with troubleshooting Ground Loops?”

A Ground Loop is a low level background hum 50/60Hz in your setup, caused by more than one item grounding
creating a “loop”. Earlier CORE units have two Ground Lifts. Try and resolve any grounding issues in your setup
by using dedicated cabling etc. If you cannot remove a ground loop in your setup, you can disconnect the
Signal Ground from the Chassis Ground on the CORE by removing the Ground Lift jumper(s), as shown in
diagram 9.

Q: “Why do I hear some hiss at the higher GAIN settings?”

The input control is an ATTENUATOR, not a volume control. It is used to reduce the level of a hot signal, not
boost the level of a weak one. The default position on this control is FULL CLOCKWISE. Turning this control up
does not raise the noise level, but stepping up the gain DOES. The lowest noise performance is going to be
with the INPUT control fully CW (Clockwise), and with the GAIN switch set at the lowest setting (40db). When
set to the 60db gain setting, you might hear some hiss.

Go to www.manley.com and read our extensive FAQ for more information about the care and feeding of
vacuum tubes!

13. Reading a VU Meter

Diagram 8

dBu - Decibel Units
dBFS - Decibels Relative to Full Scale
VU - Volume Unit

VU METER

ANALOG

SCALE

(PRO REF

+4 dBu)

+20

+18
+16

+14

+12

+10

+8
+6
+4
+2

0

-2

-4

-6

-8

-10

DIGITAL

SCALE
(dBFS)

+0

-2

-4

-6

-8

-10

-12

-14

-16

-18

-20

-22

-24

-26

-28

-30

c o r e

10

14. Servicing

GROUND LIFT JUMPER

(see page 10)

Diagram 10

12AX7WA

GR-ZERO

VR11

6922

GR-METER

VR9

TUBE LOCATION

CALIBRATION TRIM POT LOCATION

LIM REF V

GR-AUDIO

VR6

LIM CV

VR15

VR12

OP1 ZERO VU

VR16

Diagram 9

2 Amp Slow-Blow (T)
20mm Ceramic FUSE

c o r e

11

TEST POINT LOCATION

15. Core Calibration Procedure

CALIBRATION / INTERNAL ADJUSTMENTS - FOR EXPERIENCED TECHNICIANS ONLY*

The CORE requires calibration for 3 sections of its circuitry:

I) VU METER- Adjust: +4dBu (1.228 Volts RMS) = “0” VU, Meter “GR” zero set
ii) ELOP COMPRESSOR - Adjust: Gain Reduction (Audio & Meter GR)
iii) FET PEAK LIMITER - Adjust: reference voltage & FET control voltage

Tools required:

- Audio Tone Generator (oscillator)

- Audio Analyzer or a voltmeter capable of reading both DC & AC voltages.

Initial settings:

- Mic/Line Input select switch: Out = LINE IN Enable

- 120Hz HP filter switch: Out = Disable

- Gain switch: Out = LOW

- 48V Phantom switch: Out = OFF

- Phase Invert switch: Out = 0

- Input Level Attenuator: Set at Minimum

- Compressor Section: Switch = Bypass; Compression = MAX, Attack & Release = FAST

- Shelving EQ section: High/Low controls set both = 12:00 o'clock.

- Mid EQ section: Boost/Cut control = 12:00 O'clock, Frequency range select switch = 100Hz-1kHz,

- Peak Limiter section: Limiting = MIN, Release = 12:00 o'clock

- Output Gain Control: 12:00 o'clock

®

Frequency sweep control = MIN

* Experienced Technicians

Only

The calibration procedures

mentioned here are to aid the

servicing of the unit. They

should only be attempted by

a skilled Technician. These

adjustments should not be

attempted by the user

without experience. Trimming

these potentiometers without

the correct understanding

will result in poor

performance of the unit.

i) CALIBRATION OF VU METER:

1- Feed a balanced sine tone @ 1 KHz, +4dBu (1.228V RMS) from an audio tone
generator/oscillator into the LINE INPUT XLR.
2- Use your audio analyzer and/or, set your voltmeter to read volts AC and put it at the output of
XLR “OP1”. Star tbringing up the Input level attenuator until you have +4dBu (1.228V
RMS) at the output XLR “OP1”. This will be the same level as the input signal from oscillator
(unity gain)
3- Use the VU meter select switch to read “OP1”. Adjust VR16 (OP1 ZERO VU) so that the meter
reads “0” VU.
4- Use the VU meter select switch to read “GR”. Adjust VR11 (GR-ZERO) so meter reads “0” VU.

ii) CALIBRATION OF ELOP COMPRESSOR:

®

1- Make sure the output level at XLR “OP1” is still set for +4dBu, and the meter reading for

“OP1” is “0” VU.

2- Move your voltmeter (Volts AC)/Audio Analyzer to read the output XLR “OP2”.
3- Use the VU meter select switch to read “OP2”.
4- Adjust the OUTPUT GAIN control for an output level of +4dBu (1.228V RMS) at “OP2”. Meter
reading for “OP2” should be “0” VU.
5- Switch IN the COMPRESSOR.
6- Adjust VR6 (GR-AUDIO) for a gain reduction of 6dB at “OP2”. (The output XLR “OP2” will read

-2 dBu).
7- Use the VU meter select switch to read “GR”.
8- The VU meter should read -6. If not, adjust VR9 (GR-METER). Verify that VU “GR” and audio
are within 0.2dB of each other.
9- Repeat steps 6 to 8.
10- Switch out the COMPRESSOR by switching it to BYPASS.

iii) CALIBRATION OF PEAK LIMITER:

1- Make sure the output level at XLR “OP2” is still reading +4dBu, and the meter reading for

“OP2” is “0” VU.

2- Turn OFF your audio generator/oscillator temporarily to complete next step.
3- Switch your voltmeter to read Volts DC. Locate test point TP13 on the front panel PCB and use
your voltmeter to check for a voltage reading of +9.0VDC (± 0.1VDC). Adjust VR15
(LIM REF V.) So that TP13 reads 9.0 VDC. Locate test point TP14 verify a voltage reading of -

9.0Vdc (± 0.1VDC).
4- Locate test point TP20. Check for a reading of -4.4VDC (± 0.3Vdc), Adjust VR12 (LIM CV) so
that TP20 = -4.4 VDC
5- Turn audio generator/oscillator back on.
6- Make sure the output level at XLR “OP2” is still +4dBu, and the meter reading for “OP2” is “0” VU.
7- Move the limiting control to “MAX”. Peak limiter red LED indicator should turn ON (± 1.0dB).
Decrease oscillator output level by 2dB. The LED indicator should turn OFF.
8- Return the limiting control back to “MIN”. Restore oscillator output level back to +4dBu.
9- Use the VU meter select switch to read “GR”.
10- Increase the oscillator output to +21dBu. The Peak limiter red LED indicator should turn ON

(±1.5db). Decrease oscillator output level by 2dB. The LED indicator should turn OFF.

c o r e

Note-1: if you do not have enough output level coming from your oscillator, then increase the signal level coming into
the CORE by adjusting the INPUT LEVEL ATTENUATOR control. Bring up the input level attenuator until you have a
reading of +21dBu at the output XLR “OP2”.

Note-2: The Manley CORE Peak limiter section was designed to automatically “kick in” according to specific output
levels at the main output “OP2”.
When the LIMITING control knob is set at MIN the LIMIT threshold will be at +20dBu (± 1dB)

When the LIMITING control knob is set at MAX the LIMIT threshold will be at +3.5dBu (± 0.5dB)

12

16. Curves & Specifications

• ALL-TUBE preamplifier audio path using 1 x 12AX7WA for gain and 1 x 6922 White Follower

• Balanced Transformer Coupled XLR Microphone Input Impedance: 1250 Ohms

• Balanced XLR Line Input Impedance: 10 kOhms

• Unbalanced 1/4" Direct Input Impedance: 10 Meg Ohm

• Hi-current drive Direct Output Impedance: 50 Ohms

• Silent conductive plastic INPUT attenuator

• Compressor Maximum GAIN REDUCTION: 16 dB

• Compressor ATTACK time: 60ms slowest CCW, 30ms at 12:00,
5ms fastest CW for 6dB compression

• Compressor RELEASE time: 1.5s slowest CCW, 1s at 12:00,
100ms fastest CW from 6dB compression

• Limiter ATTACK time: 155µs

• Limiter RELEASE time: 300 ms slowest CCW, 150 ms at 12:00,

2.3 ms fastest CW

• HPF slope is 6db per octave

• Maximum Input Mic input (Low Gain Setting): -5 dBu or 435mV RMS @ 0.5% THD

• Maximum Input Mic input (High Gain* Setting): -25 dBu or 44mV RMS @ 0.5% THD

• Maximum Input Line input (Low Gain Setting): +13 dBu or 3.5V RMS @ 0.5% THD

• Maximum Input Line input (High Gain* Setting): -8 dBu or 300mV RMS @ 0.5% THD

• Maximum Input Direct input (Low Gain Setting): +24 dBu or 12V RMS @ 0.5% THD

• Maximum Input Direct input (High Gain* Setting): +17 dBu or 5.5V RMS @ 0.5% THD

• Maximum Input Insert return: +20 dBu or 7.8V RMS @ 0.5% THD

• Maximum Preamp Output (Insert Send): +35 dBu or 43V RMS @ 0.5% THD

• Maximum Preamp Output (Insert Send): +22 dBu into 600 Ohms

• Maximum Main Output: +20 dBu

• Insert Send output impedance: 50 Ohms

• Insert Return input impedance: 13 kOhms

• Main Output Impedance: 50 Ohms

• Direct Output Headroom (referenced to +4 dBu): 31 dB

• Main Output Headroom (referenced to +4 dBu): 16 dB

• Dynamic Range: >90 dB

• Frequency Response: 10 Hz to 75 kHz -0.15dB, -0.5 dB

• Large LED illuminated VU METER

• Meters switch to read Direct Output (1) from preamp, Output (2) from Main Out,
or Compressor Gain Reduction

• THD & Noise (1kHz @ +4 dBm): 0.02% at Low Gain setting

• Noise Floor Micpre (A WGT): - 84dB @ LOW GAIN, -64dB *HI GAIN

• EIN (A WGT): -124dBu

22-22kHz BW, 40dB gain, with 150 Ohm source impedance

• Gain via Microphone Input: 40 LOW or 50/60 dB *HI GAIN

• Gain via Line Input: 20 or 30/40dB *HI GAIN

• Maximum Gain of EQ & Limiter section: 10 dB

• Noise Floor Insert Return to OP2: - 90dBu BW: 22Hz - 22kHz

• AUTOMUTE warmup delay: 30 seconds

• Power consumption: 35 Watts

• Operating mains voltage: 90 to 254 VAC (internal universal supply)

• Mains Voltage Frequency: 50~60Hz

• Dimensions: 19" x 3 ½" x 7" (occupies 2u)

• Unit weight: 8.3 lbs.

OUTPUT LEVEL dBu

• Shipping weight: 11.5 lbs.

EQ SHELF

MID EQ PLOT

LIMITER, MIN, MED, MAX

15

*HIGH GAIN when referred to is @ 60dB unless otherwise stated. This relates to
whether the internal HI GAIN jumper is either set to an extra 10dB or 20dB of gain.

c o r e

INPUT LEVEL dBu

13

17. Recall Sheet

TRIP

TRIP

e

GR

r

2

O/P

CHANNEL S

1

O/P

c o

REFERENCE

ENGINEER

DATE

+4

dB

LIMIT

OUTPUT

-6

RELEASE

+12

dB

-12

100Hz-1kHz

FREQUENCY

+12

dB

-12

BYPASS

MAX

GAIN

RELEASE

AST
F

SLOW

AST

F

SLOW

UNITY

LIMITING

MAX

TTACK
A

dB

LOW

MIN

0

HI

+10

-10

0

ER

MIT
I
L

MAX

Q
E

MIN

R
O

S
ES

R
P

COM

0

UNITY

LIMITING

MAX

MIN

0

HI

ACK

ATT

dB

LOW

+10

-10

1kHz-10kHz

0

AST
F

IN

SLOW

0

1kHz-10kHz

FAST

IN

SLOW

LIMIT

+4

dB

-6

RELEASE

+12

dB

-12

100Hz-1kHz

+12

dB

-12

BYPASS

MAX

r e

CHANNEL S

c o

REFERENCE

GAIN

OUTPUT

FREQUENCY

RELEASE

2

O/P

FAST

SLOW

AST
F

SLOW

GR

1

O/P

ENGINEER

DATE

R
E
T

LIM I

MAX

EQ

MIN

SOR
S
E

MPR
O
C

c o r e

INPUT

LEVEL

COMPRESSION

MIC

180

V
48

HI

120Hz

MIC

MIN

USA

0

A

ORNI
F

LI

PHANTOM

CA

LOW

IN
D

E

T

FT

FLA

A

CR

ND

LINE

A
H

IN

DIRECT

MIC NOTES

INSTRUMENT / TRACK

ARTIST

SONG

INPUT

LEVEL

COMPRESSION

MIC

180

V
48

HI

120Hz

MIC

MIN

A
S
U

0

IA
N
R

LIFO

PHANTOM

N CA

LOW

I
D

T

TE

FLA

DCRA F
N

LINE

A
H

MIC NOTES

INSTRUMENT / TRACK

DIRECT IN

ARTIST

SONG

14

120Hz

FLA

RAF

T

TE

D I

0

INPUT
LEVEL

ACK

ATT

HI

48V

180

COMPRESSION

SLOW F

IN

AST

LOW

0

dB

-10 +10

1kHz-10kHz

MIC

ASS

BYP

0

LOWLINE

N

HANT

P

C

A

LI

M

O

F

ORNIA U

MIN

S

A

MAX

-12

dB

+12

100Hz-1kHz

FREQUENCY

RELEASE

DIRECT

IN

Designed & Handcrafted in USA

Manley Laboratories, Inc.

13880 Magnolia Avenue

Chino, CA 91710 USA

T: [phone]

MAINS VOLTAGE SHOWN ON SERIAL TAG WARNING: TO REDUCE THE RISK OF FIRE OR

ELECTRIC SHOCK, DO NOT EXPOSE THIS UNIT TO RAIN OR MOISTURE CAUTION: RISK OF

ELECTRIC SHOCK. DO NOT OPEN. REFER SERVICING TO QUALIFIED PERSONNEL ONLY.

SERIAL No.

www.manley.com

INSTRUMENT

MANLEY LABORATORIES INC.

13880 MAGNOLIA AVE. CHINO, CA 91710

PHONE [phone]

[e-mail]

www.manley.com

MIC IN

LINE IN

SLOW

IN

LINE

STAGE

DI

STAGE

FAST

PHASE

R

PRESSO

M

O

C

OPERATIONAL BLOCK DIAGRAM

HP

FILTER

ATTENUATOR

COMPRESSOR

MAIN OUTPUT (2)

MIN

Q

E

®

TUBE STAGE

Rev. 4.7 ZF 2018

HAND CRAFTED IN USA

Z

Z