Manley Laboratories Variable MU User Manual

LEVELINPUT

+8

+1

LINK

+2

+4

+3

HP SC

IN

V A R I A B L E M U

V A R I A B L E M U

c o r e

LIMITER / COMPRESSOR

LIMITER / COMPRESSOR

OUTPUT

SLOW

ATTACK THRESHOLD

RECOVERY

LIMIT

10

R

8

6

4

2

0

IN

SLOW

FAST

MIN MAX

BYPASS

OWNER’S MANUAL

CONTENTS

SECTION PAGE

INTRODUCTION 2

MAINS CONNECTIONS 3

INSTALLATION 4

FRONT PANEL 5

REAR PANEL 6

EXAMPLE SETTINGS 7

FRONT PANEL ADJUSTMENTS 8

OPERATIONAL NOTES 9

MASTERING AND M/S MODELS 10

T-BAR MODIFICATION 11

GAIN REDUCTION CURVES 12

SPECIFICATIONS 13

TECHNICAL NOTES 14

SERVICE ADJUSTMENTS 15

BLANK RECALL SHEETS 16- 19

NOTES 20

Rev 5.2

INTRODUCTION

THANK YOU!...

for choosing the Manley Laboratories Stereo Variable Mu® Limiter Compressor. This unit has
been our best selling product for many years. It is one of the very few compressors that has be­come a real standard in Mastering studios and contributed to most hit records over the last decade
and probably the next. “Mu” is tube-speak for gain, and Variable Mu® is our registered trademark
for this limiter compressor. It works by using the “remote cut-off” or re-biasing of a vacuum tube
to achieve compression. The precious vintage Fairchild 670 also uses this technique and is one

of few all-tube compressor to do so, that we know of. Even the side-chain has glowing rectier

bottles. How’s it work? The unique 5670 dual triode is at the center of the peak-reducing and

compression action constantly being re-biased by the vacuum tube rectied side-chain control

voltages which cause this tube to smoothly change its gain. Just like that.

LOCATION & VENTILATION

The Manley Stereo Variable Mu® Limiter Compressor must be installed in a stable loca­tion with ample ventilation. It is recommended, if this unit is rack mounted, that you allow
enough clearance on the top and bottom of the unit such that constant movement of air can

ow through the ventilation holes. There are 8 tubes inside this unit so it does run quite hot.
Good ventilation is denitely encouraged.

UNPACKING: Unpack the unit carefully by removing all the custom foam packing materi­al and make sure that all supplied accessories are present. Carefully examine all items for any
possibility of shipping damage. All of the tubes are already installed and should have survived
the journey from our factory to your studio. They should be standing at attention in their sock­ets, and should show no signs of distress such as chipped glass, loose internal components or
obvious breakage. If the unit is damaged or fails to operate, notify the shipper or your dealer
or us or your local authorities immediately. Or if you suspect The Shipping People threw it off

the airplane and onto your front porch whilst ying overhead at 30,000 feet, notify the shipping

company without delay and complain to them as we only guarantee this unit to be able to survive
a drop of 23,487 feet or less.

Your Manley Variable Mu® Limiter Compressor was packed with extreme love and care, and
each box includes the following components and accessories:

a) 1 each, 6 foot IEC 3-conductor power cable
b) 1 each, Owner’s Manual (that we hope you will keep reading.)

It is prudent to retain the shipping materials for future use, as they are custom-formed for this
unit and will greatly minimize the chance of shipping-related damage should you ever need to put
your precious Variable Mu®in the careless hands of The Shipping People again. We have heard
that certain rodents might enjoy munching on the packing foam. We are sorry to report that we do
not warranty the packing foam against attack by mice, rats, or other hungry critters, hungry chil­dren, hungry neighbors, etc. Try glue traps or spring-traps loaded with peanut butter to eliminate
these unwelcome freeloaders from your property.

2

INTRODUCTION

THANK YOU!...

for choosing the Manley Laboratories Stereo Variable Mu® Limiter Compressor. This unit has
been our best selling product for many years. It is one of the very few compressors that has be­come a real standard in Mastering studios and contributed to most hit records over the last decade
and probably the next. “Mu” is tube-speak for gain, and Variable Mu® is our registered trademark
for this limiter compressor. It works by using the “remote cut-off” or re-biasing of a vacuum tube
to achieve compression. The precious vintage Fairchild 670 also uses this technique and is one

of few all-tube compressor to do so, that we know of. Even the side-chain has glowing rectier

bottles. How’s it work? The unique 5670 dual triode is at the center of the peak-reducing and

compression action constantly being re-biased by the vacuum tube rectied side-chain control

voltages which cause this tube to smoothly change its gain. Just like that.

LOCATION & VENTILATION

The Manley Stereo Variable Mu® Limiter Compressor must be installed in a stable loca­tion with ample ventilation. It is recommended, if this unit is rack mounted, that you allow
enough clearance on the top and bottom of the unit such that constant movement of air can

ow through the ventilation holes. There are 8 tubes inside this unit so it does run quite hot.
Good ventilation is denitely encouraged.

UNPACKING: Unpack the unit carefully by removing all the custom foam packing materi­al and make sure that all supplied accessories are present. Carefully examine all items for any
possibility of shipping damage. All of the tubes are already installed and should have survived
the journey from our factory to your studio. They should be standing at attention in their sock­ets, and should show no signs of distress such as chipped glass, loose internal components or
obvious breakage. If the unit is damaged or fails to operate, notify the shipper or your dealer
or us or your local authorities immediately. Or if you suspect The Shipping People threw it off

the airplane and onto your front porch whilst ying overhead at 30,000 feet, notify the shipping

company without delay and complain to them as we only guarantee this unit to be able to survive
a drop of 23,487 feet or less.

Your Manley Variable Mu® Limiter Compressor was packed with extreme love and care, and
each box includes the following components and accessories:

a) 1 each, 6 foot IEC 3-conductor power cable
b) 1 each, Owner’s Manual (that we hope you will keep reading.)

It is prudent to retain the shipping materials for future use, as they are custom-formed for this
unit and will greatly minimize the chance of shipping-related damage should you ever need to put
your precious Variable Mu®in the careless hands of The Shipping People again. We have heard
that certain rodents might enjoy munching on the packing foam. We are sorry to report that we do
not warranty the packing foam against attack by mice, rats, or other hungry critters, hungry chil­dren, hungry neighbors, etc. Try glue traps or spring-traps loaded with peanut butter to eliminate
these unwelcome freeloaders from your property.

2

MAINS CONNECTIONS

Your VARIABLE MU has been factory set to the correct mains voltage for your country. The voltage setting is
marked on the serial badge, located on the rear panel. Check that this complies with your local supply.

Export units for certain markets have a moulded mains plug tted to comply with local requirements. If your unit
does not have a plug tted the coloured wires should be connected to the appropriate plug terminals in accordance

with the following code:

GREEN/YELLOW EARTH
BLUE NEUTRAL
BROWN LIVE

As the colours of the wires in the mains lead may not correspond with the coloured marking identifying the termi­nals in your plug proceed as follows:

The wire which is coloured GREEN/YELLOW must be connected to the terminal in the plug which is
marked by the letter E or by the safety earth symbol or coloured GREEN or GREEN and YELLOW.

The wire which is coloured BLUE must be connected to the terminal in the plug which is marked by the letter
N or coloured BLACK.

The wire which is coloured BROWN must be connected to the terminal in the plug which is marked by the
letter L or coloured RED.

DO NOT CONNECT/SWITCH ON THE MAINS SUPPLY UNTIL ALL OTHER CONNECTIONS HAVE BEEN
MADE.

Waste Electrical and Electronic Equipment (WEEE)

Information for customers:
The European Parliament and the Council of the European Union have issued the Waste Electrical and Electronic Equipment Directive. The purpose of the Direc­tive is the prevention of waste of electrical and electronic equipment, and to promote the reuse and recycling and other forms of recovery of such waste. As such
the Directive concerns producers, distributors and consumers.

The WEEE directive requires that both manufacturers and end-consumers dispose of electrical and electronic equipment and parts in an environmentally safe man­ner, and that equipment and waste are reused or recovered for their materials or energy. Electrical and electronic equipment and parts must not be disposed of with
normal household wastage; all electrical and electronic equipment and parts must be collected and disposed of separately.

Products and equipment which must be collected for reuse, recycling and other forms of recovery are marked with the following pictogram:

Small products may not always be marked with this pictogram in which case this is present in the instructions for use, on the guarantee certicate and printed on

the packaging.

When disposing of electrical and electronic equipment by use of the collection systems available in your country, you protect the environment, human health and
contribute to the prudent and rational use of natural resources. Collecting electrical and electronic equipment and waste prevents the potential contamination of

nature with the hazardous substances which may be present in electrical and electronic products and equipment.

Your MANLEY retailer will assist with and advise you of the correct way of disposal in your country.

3

INSTALLATION

Please refer to the REAR PANEL section for a full layout of the rear panel of your
Manley Stereo Variable Mu® Limiter Compressor.

1. Make sure your mains voltage supply agrees with the voltage this unit is set for.

2. Be certain that the unit has the proper fuse installed.

3. Connect the input signal(s) to the 3 pin female XLR’s on the rear panel. The
input XLR’s are TRANSFORMER COUPLED balanced wired as follows:

PIN 1: GROUND
PIN 2: (+) POSITIVE GOING PHASE
PIN 3: ( - ) NEGATIVE GOING PHASE

4. Connect a 3 pin XLR cable to the male output XLR on the rear panel. The out­put XLR is balanced and the pinout is wired as follows:

PIN 1: GROUND
PIN 2: (+) POSITIVE GOING PHASE
PIN 3: ( - ) NEGATIVE GOING PHASE

The output impedance is 600 Ohms nominal.

5. Connect a standard IEC mains cable to the IEC mains socket on the rear panel.

6. Check that the power is switched off on the unit.

7. Connect the IEC mains cable to a 50/60 Hz AC source of the proper selected volt­age.

8. Power up the unit and allow it enough time to stabilize before using . it takes about
30 minutes for everything to stabilize and for it to warm up and sound its best.

Again, let us remind you: this unit runs pretty hot. We denitely encourage allowing

enough space around the chassis so that convection of air can occur and heat can be drawn
away from the unit. If the heat gets all trapped with no place to go, you’ll just bake up the
guts of the unit faster and you’ll be in for a re-cap years sooner than if you had some venti­la-tion happening. Try to give the Variable Mu® at least an inch or two on top so that air can

ow up and away from it.

If you wish to keep pizzas warm on top of the Manley Variable Mu®, please use a plate
so the cheese does not drip down through the top cover holes into the unit. Your Warranty
does not cover damage arising from foreign (or domestic) dairy substances entering the unit.

*NOTE: As of 03/2012, units are shipping with hole plugs covering the ADJUST trimmers to discourage
inadvertent un-calibrating of the triode-to-triode balance.

4

BALANCE METER METER

FRONT PANEL

C

E

G E

C

B B

H H

A D F

A. IN / BYPASS Switched in bypass mode, (down position) all effects of the limiting circuitry are bypassed and
will not affect the audio signal. In the bypass mode , the audio signal passes from the input
directly to the output (hardwire).

B. COMP / LIMIT Selects compression ( 1.5:1) or limiting (4:1) function. Compression is soft -knee, Limit is a
sharper knee. At greater than 12dB of limiting the ratio increases (up to 20:1 maximum).

C. RECOVERY Recovery times can be selected between

D. THRESHOLD Continuously variable gain reduction threshold control.

E. OUTPUT ATTENUATE Continuously variable attenuation of output signal leaving the amplier circuitry.

F. ATTACK Continuously variable sensitivity of transient detection. Determines the necessary length of
transient to initiate gain reduction. Fast =25mS, Med =50mS, Slow =70mS. Fully counter
clockwise at the slowest setting will prevent most percussive signals from causing limiting or
compression.

G. INPUT LEVEL Stepped attenuation of input signal entering the amplier limiting circuit. 12:00 is unity.

H. GR METER Measures (in decibels) amount of reduction.

I. LINK When switched to “MONO”, left side is independent from the right side. When
switched to “LINK” both channels are reduced in gain by the same number of dB. This insures

that the stereo image is unchanged. The METERs remain independent to help set THRESHOLDs.

POWER ON/OFF Power is supplied to the unit when switched UP. Meters will illuminate.

J. HP SC IN / OUT When switched to “IN”, the side chain will not respond as strongly to low frequency content. These
switches can be used with bass-heavy music where you don’t want the bass driving the WHOLE

action of the compressor. The lter is a very gentle 6dB/octave 1-pole lter, and will typically be

down 1-3dB at 100Hz and down 4-6dB at 50Hz. As you decrease the frequency, the amount of
limiting will also decrease.

K. ADJUST Trimpot #1 for tube calibration. See p.15 for instructions.

M. METER Trimpot #2 for adjusting Meter ZERO point in LIMIT mode. See p.15 for instructions.

M M

a. VERY SLOW 8 seconds
b. SLOW 4 seconds
c. MEDIUM 0.6 seconds
d. FAST 0.4 second
e. VERY FAST 0.2 second

Determines the necessary amplitude for compression or limiting to take effect. Most extreme
effect is at the MIN (fully counter clockwise) position. The lower the threshold, the more that
gets limited.

Full attenuation occurs at the full counterclockwise position.
This control is active only in IN mode.

Turning the switch clockwise will feed more signal into the amplier, increasing TH+D

and saturation; counter-clockwise rotation will feed less signal in and sound more
transparent. *Note: until late 2011 (MSLC83273), this switch was a continuously variable

potentiometer, with which it was extremely difcult to achieve proper channel-to-channel

matching. The switched input provides a far more accurate experience for the user, as well
as being far simpler from a manufacturing standpoint.

I

J J

F

D A

5