Manley Dual Mono Mic Pre 6072 Owner's Manual

MANLEY

LABORATORIES, INC.

OWNER'S MANUAL

MANLEY LABS

MONO & DUAL MONO

40 dB MICROPHONE

PREAMPLIFIERS

MANLEY LABORATORIES, INC.

13880 MAGNOLIA AVE.

CHINO, CA. USA
TEL: [phone]
FAX: [phone]

email: [e-mail]

http://www.manleylabs.com

CONTENTS

SECTION PAGE

INTRODUCTION 3

MAINS CONNECTIONS 4

BASICS 5

CONNECTING YOUR PREAMPLIFIER 6

OPERATION NOTES 8

FRONT PANEL 9

REAR PANEL 10

SPECIFICATIONS 11

TUBE AND PARTS LAYOUT 12

TROUBLESHOOTING 13

WARRANTY 15

WARRANTY REGISTRATION 16

APPENDIX 1: TEMPLATE for STORING SETTINGS (17)

APPENDIX 2: WIRING YOUR OWN CABLES (18)

2

INTRODUCTION

THANK YOU!...

for choosing the Manley Laboratories Microphone Preamplifier. We use this manual for both the
MONO and DUAL MONO versions designed by David Manley. They are identical except the
DUAL has two of everything. These Microphone Preamplifiers use the best available parts with the
shortest, cleanest, signal path possible. The Preamplifier features an all-tube circuit that has proved
to be among the finest amplification circuits for demanding audio professionals. It combines flat
frequency response, very high headroom, low noise and low distortion. The Preamplifier also has the
Input Attenuator before any tube stage so that it can easily accomodate any reasonable signal level.
There is also a rotary GAIN switch which helps to change the preamplifiers operating characteristics
to suit a wide variety of tastes and styles. There is both balanced and unbalanced inputs and outputs
so that the preamplifier can interface with virtually anything without hassle. Phantom power is
provided.

Thank you again, and please enjoy!

GENERAL NOTES

LOCATION & VENTILATION

The 40 dB Microphone Preamplifier 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 preamp such that a constant flow of air can flow through the ventilation holes.

WATER & MOISTURE

As with any electrical equipment, this preamplifier should not be used near water or moisture. If
liquid enters the preamplifier, it must be immediately returned to your dealer for servicing.

SERVICING

The user should not attempt to service the preamplifier beyond that described in the owner's manual.
Refer all servicing other than tube replacement to Manley Laboratories.

SPECIAL NOTES

Tubes may become loose during transit. Straighten and press down each tube before plugging the
preamplifier into the mains socket. Furthermore, NEVER touch the tubes after the preamplifier has
been switched on, the tubes become very hot during operation and should only be handled after the
power has been turned off and the tubes have cooled. Please note high voltages inside the chassis.

WARNING!

!

TO PREVENT THE RISK OF ELECTRIC SHOCK

DO NOT OPEN THE CABINET

REFER SERVICING TO

QUALIFIED PERSONEL

3

MAINS CONNECTIONS

Your preamplifier 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 molded mains plug fitted to comply with local
requirements. If your unit does not have a plug fitted the coloured wires should be connected
to the appropriate plug terminals in accordance with the following code.

GREEN/YELLOW EARTH terminal
BLUE NEUTRAL terminal
BROWN LIVE terminal

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.

A LITTLE NOTE FOR LIVE ENGINEERS

The biggest concern for most engineers considering using tube gear live is its reliability. This is mostly quite
unjustified. You can visit just about any studio and see 30 and 40 year old tube gear working like new in the
racks. It is unlikely you will find any early solid state gear in use. Manley uses construction methods that
combine the most reliable parts of tube and solid state techniques like high quality circuit boards, strong over­engineered chassis, transformer inputs and outputs, heavy 1/2 watt metal film resistors, and no electrolytic caps
in the signal path. This product should stand up to decades of heavy use. Unlike guitar amps that require re­tubing every 3 or 6 months - this unit has no "power tubes", "rectifier tubes" and in power amps where we do use
such "Glow Fets" we run them cool and they tend to average about 5 years. On a positive note about tube guitar
amps - who avoids them because they might not handle the road? For 50 years they have proven road-worthy,
more reliable than solid state or speakers and easy to repair and find parts. On the other hand, we know other
tube gear that is not built to our standards and that may be difficult to repair - look inside before you buy.

The only two concerns are: Tubes tend to become microphonic when subjected to lots of vibration. Typical
outboard racks have some reasonable impact protection and this will help. The best answer to your concern is:
Carry a few spare tubes! You can almost always fix a problem in a few minutes this way. Unlike solid state, most
tubes tend to die gradually (like a battery) so 90% of the time you have plenty of warning.

4

BASICS

This Microphone Preamp, like most mic preamps, is pretty easy to use. First we can discuss why
outboard mic pre's have become "a must have item" in almost every studio even though your console
probably has a bunch of them and that manufacturer claims that they are really great and you don't need
outboard mic pre's. Then, why is everybody buying them, using them, and why are most people going back
to tubes?

Good question. The signal from a typical mic is very low - anywhere from 20 to 70 dB below your
normal line level signals. 95% of the time 30 to 40 dB of gain is all that is needed to boost the signal to line
levels. Where you really need a lot of gain is with most ribbon mics and when you are recording quiet music
from a distance. What is required of a good Mic Pre? No EQ, no compression, nothing elaborate - just basic
gain. Each preamp, tube or solid state seems to impart a flavour or color (or personality) of its own. Some
of these flavours are subtle and some are not. Maybe it is the mic reacting different into different circuits.

A few engineers have an array of mic pre's and use them almost like effects - using each for a certain flavor
as needed. The rest of us only have the budget for one or two great mic pre's so we tend to choose one that
sounds "best", or is priced for us, or is used by "xxxxxx" or has cute ads. The Manley Mic Pre wins most
shoot-outs or at least ties with units twice as expensive. It is regularly used by major engineers, in "A" rooms
for famous artists and by hundreds of serious musicians in project studios. Most people choose the Manley
because it sounds "alive" and musical, warm and rich without audible distortion and the instrument sounds
like the real thing. What more is there ? You probably agree that if more color and personality is needed,
then the engineer has EQs and compressors and dozens of digital toys to squeeze that once clean signal
through. This is not the main function of a well engineered Mic Pre, however we have included the Gain
Control for some subtle differences of taste, style and so-called "tube warmth".

Some consider that the "headroom" factor is the most important issue in mic pre's. We believe that
it is just one of a number of issues. The input stage is unlikely to clip because the Attenuator (not the GAIN
switch) is before the tubes. This Preamplifier has more headroom than almost all mic pre's. The line driver
clips at between +30 and +32 dBV. This is about twice the voltage that most solid state can deliver. If
overdriven, which is not easy, it starts to clip in a gentle, smooth way, creating less nasty upper harmonics.
A more likely effect will be that the next device after the pre will be the place actually distorting. More
importantly are subtle issues of transient response. We believe this is one area where good tube circuits are
audibly superior to virtually all solid state. The transient details are important for reproducing the true
character of the instrument, the room and stereo image. Solid state often seems to smear transients, probably
due to the extreme amounts of negative feedback normally used to achieve the distortion specs. Transient
accuracy is not a "spec" and test benches don't produce hit records. You should be able to readily hear this
"effect" if your monitors are good. More than Left -Right it should also have nearness or depth.

Which brings us to the next topic - METERING - We do get questions like "How do I set up the
Mic Pre levels when there are no meters?". Answer - Look at where you are sending the signal, if it has
meters - use them. Why ? Most people are recording to digital mediums where there is no real standard. If
you use the tape machine's digital meters, you will most likely get the best recording levels using the
machine's meters. If we included a meter, it would most likely not be "calibrated" to your meters and mislead
or confuse the user. Also, if we included metering, it would be VU which is a standard of its own, appropriate
for analog tape only. Start off with the GAIN switch set to "45" which is what most people use. Turn up
the LEVEL control until the loudest peaks to tape are a few dB below maximum and not producing "Over"
Leds (for safety) and not too low (10 dB below clipping or lower). If we had a "Clipping LED" for the
preamp, it would be probably be dark when the machine's meters were pinned. Cosmetically a meter might
be nice but functionally it would be misleading or mostly useless.

5