Manley Langevin Dual Mic Pre with EQ Owner's Manual

OWNER'S MANUAL

LANGEVIN DUAL MONO

MICROPHONE PREAMPLIFIER

WITH EQ

MANLEY

LABORATORIES, INC.

MANUFACTURED BY:

MANLEY LABORATORIES, INC.

13880 MAGNOLIA AVE.

CHINO, CA. 91710 USA

TEL: [phone]
FAX: [phone]

email:[e-mail]

http://www.manleylabs.com

REV 4-3-2006

CONTENTS

SECTION PAGE

INTRODUCTION 3

MAINS CONNECTIONS 4

BASICS 5

CONNECTING YOUR PREAMPLIFIER 6

FRONT PANEL 8

REAR PANEL 9

TECH NOTES 10

SPECIFICATIONS 11

WARRANTY 12

WARRANTY REGISTRATION 13

APPENDIX A: WIRING YOUR OWN CABLES

APPENDIX B: TEMPLATE FOR STORING SETTINGS

INTRODUCTION

THANK YOU!...

for choosing the Langevin Dual Mono Microphone Preamplifier. Manley Labs bought all the rights
to the Langevin name and circuits in 1992. Manley Labs uses the Langevin name for its solid state
products including versions of an all discrete Pultec and Electro-Optical Limiter, as well as, other high
performance non-tube products. This Mic Preamplifier uses an all discrete transistor audio path that
simply sounds pretty damn good. We believe it is because the circuit has good audio performance
before any negative feedback was used to lower the gain and further improve noise and distortion.
This Microphone Preamplifier is a low cost way to enjoy good old high-end performance. It is built
to the same standards as the Manley gear and uses all of the same top quality components. It is one
of the best alternatives for those needing a superb stereo mic pre but for whatever reason cannot get
the Manley Tube Mic Preamp. The Langevin preamplifier also has useful tone shaping (EQ), (fused)
phantom power and very high reliability.

Thank you again, and please enjoy!

WATER & MOISTURE

As with any electrical equipment, this equipment 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 this unit beyond that described in the owner's manual. Refer
all servicing to Manley Laboratories.

WARNING!

TO PREVENT THE RISK OF ELECTRIC SHOCK

DO NOT OPEN THE CABINET

REFER SERVICING TO

QUALIFIED PERSONEL

!

3

MAINS CONNECTIONS

Your unit 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. The voltage changeover switch is located inside the unit in the middle of the PCB near the
power transformer. To change the voltage from 120 to 240 volts, simply remove the top cover by
unscrewing the center fixing screw and sliding the top out towards the rear of the chassis. Turn the
top of the voltage changeover switch with a firm positive action using a small flat screwdriver.

Export units for certain markets have a moulded 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.

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 or
vintage transistor based circuits?

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 chamber
music from a distance. Mic signals are fragile and raw. The fragility is apparent when one compares various
mic pre's - each preamp seems to sound different - no EQ, no compression, nothing elaborate - just basic gain.
Maybe it is the mic reacting different into different circuits. 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. 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". The Langevin Microphone Preamplifier is superb sounding ­probably because it has a simple all discrete gain stage with a minimum of components and a minumum
amount of negative feedback. Specifications, while important, will not be truly indicative of an audio
product's "sound" until methods of determining the transient accuracy are established. Transient accuracy
is not a "spec" and test benches don't produce hit records. The transient details are important for reproducing
the true character of the instrument, the room and stereo image. Most solid state circuits use a large amont
of negative feedback to lower noise and distortion at the cost of transient accuracy. This preamplifier started
out clean and quiet so minimal negative feedback was necessary.

Op-amp based designs, by comparison, have dozens of transistors in each "chip" (its easier to
fabricate a transistor than a resistor on silicon), hundreds of dB's of negative feedback and sometimes a few
discrete transistors to provide performance that an "IC" simply cannot. The result is good specs - but that
harsh, hard, cold sound that makes shakers sound like pink noise, makes vocals sibilant in an unpleasant way,
and can only render a 2 dimensional image at best. We prefer tubes or simple discrete circuits.

We mentioned mic signals are fragile and raw. 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 including the harmonic
character of the distortion. Except for the final output, all circuits are "Class A" which is usually associated
with no crossover distortion and near clipping will be even order distortion and less upper harmonics.This
Preamplifier has more headroom than most solid state mic pre's because of the 48 volt power supply used,
compared to 30 volts (+/- 15V or 24 volts) used in other designs. If overdriven, which is not easy, it starts
to clip in a gentle, smooth way.

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. 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.

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