Drawmer 1972 User manual

DRAWMER
Dual Mic, Line & Instrument
Pre-Amplier
OPERATOR’S MANUAL
CONTENTS
Warranty
Safety Consideration
Chapter 1 - Introduction
Introduction
Installation
Power Connection
Audio Connections
Chapter 2 - Control Description
Control Description
Chapter 3 - General Information
If a fault develops
Contacting Drawmer
Specication Data
Block Diagram
Recall Sheet
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2DRAWMER 1972 OPERATOR’S MANUAL
Drawmer Electronics Ltd., warrants the Drawmer 1972
Dual Mic/Line/Instrument Pre-Amplifier to conform
substantially to the specications of this manual for a period
of one year from the original date of purchase when used in
accordance with the specications detailed in this manual.
In the case of a valid warranty claim, your sole and exclusive
remedy and Drawmer’s entire liability under any theory of
liability will be to, at Drawmer’s discretion, repair or replace
the product without charge, or, if not possible, to refund the
purchase price to you. This warranty is not transferable. It
applies only to the original purchaser of the product.
For warranty service please call your local Drawmer dealer.
Alternatively call Drawmer Electronics Ltd. at +44 (0)1709
527574. Then ship the defective product, with transportation
and insurance charges prepaid, to Drawmer Electronics
Ltd., Coleman Street, Parkgate, Rotherham, S62 6EL
UK. Write the RA number in large letters in a prominent
position on the shipping box. Enclose your name, address,
telephone number, copy of the original sales invoice and a
detailed description of the problem. Drawmer will not accept
responsibility for loss or damage during transit.
This warranty is void if the product has been damaged by
misuse, modication or unauthorised repair.
THIS WARRANTY IS IN LIEU OF ALL WARRANTIES,
WHETHER ORAL OR WRITTEN, EXPRESSED,
IMPLIED OR STATUTORY. DRAWMER MAKES NO
OTHER WARRANTY EITHER EXPRESS OR IMPLIED,
INCLUDING, WITHOUT LIMITATION, ANY IMPLIED
WARRANTIES OF MERCHANTABILITY, FITNESS FOR
A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
PURCHASER’S SOLE AND EXCLUSIVE REMEDY
UNDER THIS WARRANTY SHALL BE REPAIR OR
REPLACEMENT AS SPECIFIED HEREIN.
IN NO EVENT WILL DRAWMER ELECTRONICS LTD.
BE LIABLE FOR ANY DIRECT, INDIRECT, SPECIAL,
INCIDENTAL OR CONSEQUENTIAL DAMAGES
RESULTING FROM ANY DEFECT IN THE PRODUCT,
INCLUDING LOST PROFITS, DAMAGE TO PROPERTY,
AND, TO THE EXTENT PERMITTED BY LAW, DAMAGE
FOR PERSONAL INJURY, EVEN IF DRAWMER HAS
BEEN ADVISED OF THE POSSIBILITY OF SUCH
DAMAGES.
Some states and specific countries do not allow the
exclusion of implied warranties or limitations on how long
an implied warranty may last, so the above limitations may
not apply to you. This warranty gives you specic legal
rights. You may have additional rights that vary from state
to state, and country to country.
In the interests of product development, Drawmer reserve the right to modify or
improve specications of this product at any time, without prior notice.
ONE YEAR LIMITED WARRANTY
COPYRIGHT
This manual is copyrighted © 2022 by Drawmer Electronics Ltd. With all rights reserved. Under copyright
laws, no part of this publication may be reproduced, transmitted, stored in a retrieval system or translated
into any language in any form by any means, mechanical, optical, electronic, recording, or otherwise, without
the written permission of Drawmer Electronics Ltd.
DRAWMER
1972
Dual Mic, Line &
Instrument Pre-Amplier
SAFETY CONSIDERATIONS
CAUTION - MAINS FUSE
TO REDUCE THE RISK OF FIRE
REPLACE THE MAINS FUSE ONLY WITH
A FUSE THAT CONFORMS TO IEC127-2.
250 VOLT WORKING, TIME DELAY TYPE
AND BODY SIZE OF 20mm x 5mm.
THE MAINS INPUT FUSE MUST BE
RATED AT 230V=T160mA and 115V=T315mA.
CAUTION - MAINS CABLE
DO NOT ATTEMPT TO CHANGE
OR TAMPER WITH THE
SUPPLIED MAINS CABLE.
CAUTION - SERVICING
DO NOT PERFORM ANY SERVICING.
REFER ALL SERVICING TO QUALIFIED
SERVICE PERSONNEL.
WARNING
TO REDUCE THE RISK OF FIRE OR
ELECTRIC SHOCK DO NOT EXPOSE
THIS EQUIPMENT TO RAIN OR MOISTURE.

3
DRAWMER 1972 OPERATOR’S MANUAL
DRAWMER
The 1972 Dual Mic, Line & Instrument Pre-Amplier has
been developed to make it ultra easy for you to capture
perfect recordings every time. The 1972 gives you the
ability to record pristine audio from a variety of sources and
especially makes the most of the multitude of microphones
that you nd in the studio, from budget to high-end dynamic
and also ribbon mics. Uniquely it has added features that
help out in dicult to record situations that are not found on
other preampliers.
The 1972 uses the latest THAT Corporation technology
in the two independent mic preamps to provide ultra
clean, transparent and precise recordings, that can be
processed at a later stage using your favourite methods,
be it compression, E.Q., saturation, valve, transformer or
tape. Each channel is capable of 66dB of stepped gain, with
an additional +/-12dB’s trim at the output, and incorporates
switchable mic impedance for accurate mic matching to bring
out the best from any microphone used, and also provides a
way to “sculpt” the sound of passive dynamic, and especially
low-impedance ribbon microphones.
CHAPTER 1
INTRODUCTION
Two THAT Corporation ultra clean
mic pre’s with 66dB of gain in 6dB
steps, plus +/-12dB’s trim at output.
Separate Line & Mic input XLR’s on
the rear plus a pro quality instrument
DI input on the front panel.
Can be used on a multitude of
sources including instruments and
all type of microphones in the studio
from low to high end, plus ribbon
mics.
Switchable Mic Impedance for
accurate mic matching and also mic
tone sculpting.
•
•
•
•
As well as standard features that you will nd on most
preampliers, such as phase reverse, the 1972 also has
a wealth of tools that help when recording dicult sources,
making it possible to get the best quality recording with
ease:
Fully variable LoCut and HiCut controls have been included
to allow you to tune into recordings and remove superuous
signals in the low and high frequencies, removing rumble
and hiss with ease. In addition the Shape feature allows
you to bring out the bass or treble using a subtle tilt EQ.
A unique feature that has been developed by Ivor Drawmer
and currently only available on the 1972 is the Lift control.
Lift is essentially a low level dynamic gain module which
has no eect on signals above 0dB. This makes it possible
to record very quiet signals in a transparent and natural way
without distortion and clipping taking place on the louder
passages, and is especially eective for very dynamic
signals, nding great use in recording piano, and on all
vocals including speech, and for capturing ambiance.
Two backlit Analogue V.U. Meters
with Switchable +10dB Rescale
Mode.
Time delay relays on outputs for
clean power up/down.
Internal Low Hum Toroidal Linear
Power Supply with Voltage Selector
Switch.
Classic Drawmer build quality
with rugged steel chassis and
aluminium front panel.
Designed and Handmade by
Drawmer in the UK.
•
•
•
•
•
A wealth of features not found on
other preamps make it ease to
capture dicult to record sources.
Unique Lift feature for boosting very
low signals without the loud signals
clipping.
Fully variable LoCut and HiCut lters
to tune into signals and remove
unwanted sounds.
Shape switches are included to
control bass and treble using a subtle
tilt EQ.
Phantom Power and Phase
Reverse
•
•
•
•
•

4DRAWMER 1972 OPERATOR’S MANUAL
The 1972 is designed for standard 19” rack mounting and
occupies 1U of rack space. Avoid mounting the unit directly
above power ampliers or power supplies that radiate
signicant amounts of heat and always connect the mains
earth to the unit. Fibre or plastic washers may be used to
prevent the front panel becoming marked by the mounting
bolts. It is also advisable to leave space above the unit to
allow the heat to dissipate.
INSTALLATION
The 1972 unit will be supplied with a power cable suitable for domestic power outlets in your country. For your own
safety, it is important that you use this cable to connect to the mains supply earth. The cable must not be tampered
with or modied.
The power supply socket has an integral fuse drawer containing the power fuse of the same value, to suit the mains
voltage for which the unit has been supplied. Removal of the drawer is only possible with the power cord removed.
The fuse should never blow under normal operation. If the fuse is suspected of having blown, then a fault will have
occurred and this fault condition should be inspected by a qualied service engineer. When replacing the fuse, always
comply with the Safety Instructions.
If the unit is to be used with a mains input operating voltage dierent to that for which the unit is supplied, the following
procedure must be carried out by a technically competent person, (see following diagrams)
POWER CONNECTION
1: Disconnect the unit from the mains.
2: Using a number 1 size pozidrive
screwdriver, remove the seven self
-tapping screws that retain the top
cover. Two screws are found along
each side; two along the top edge at
the rear; and the upper central screw
on the front facia panel.
3: Slide the voltage change-over switch
(S11) until the correct (or nearest)
mains input voltage is visible on the
switch actuator.
(see g.2)
For conversion to 115Volt AC (previously
set to 230Volt AC).....
4a: Exchange the 160mA fuse below
the mains socket for a similar type rated
at 315mA
For conversion to 230VoltAC (previously
set to 115Volt AC).....
4b: Exchange the 315mA fuse below
the mains socket for a similar type rated
at 160mA
In all cases:
5: Replace the top cover using the
seven screws.
6: Re-connect to mains power source.
g.2 The Voltage Selector Switch
Fuse
g.3 The Location of the Fuse
Voltage Selector
Switch located here

5
DRAWMER 1972 OPERATOR’S MANUAL
AUDIO CONNECTIONS
The inputs and outputs are electronically balanced on conventionally wired XLRs (pin 1 screen, pin 2 hot, pin 3 cold and XLR
shell is connected to chassis). The 1972 fully conforms to the EMC standards, if the unit is used where it maybe exposed
to high levels of disturbance such as found close to a TV or radio transmitter we suggest that the screen of the signal cable
is connected to the chassis connection on the XLR type connector. The operating level is nominally +4dBu.
If ground loop problems are encountered, never disconnect the mains earth, but instead, try disconnecting the signal screen
on one end of each of the cables connecting the outputs of the 1972 to the patchbay. If such measures are
necessary,
balanced operation is recommended.
In addition to the instrument input 1/4” jack connector located in the instrument section on the front panel there are
also several found on the rear panel:
Mic Input
A dedicated microphone input via balanced XLR connector per channel located on the rear panel.
Line Input
A dedicated line level input via balanced Neutrik Combo XLR / 1/4” jack connector per channel
Output
A dedicated output via balanced XLR for each channel.

6DRAWMER 1972 OPERATOR’S MANUAL
CONTROL DESCRIPTION
CHAPTER 2
The two channels of the 1972 are completely identical to each other, from the matching connectors on the rear to the
identical front panel controls. They are also entirely independent of each other and cannot be linked.
SELECT Instrument/Line/Mic 2.4 kOhm/Mic 600 Ohm/Mic 200 Ohm/Mic +48V
The source select is a six position rotary switch that, as well as setting the input source, also sets the load impedance
of the microphone.
When in the INST. position the channel takes its source from the instrument jack found on the front panel, to the
right of the switch.
In the Line position the signal comes via the dedicated input XLR on the rear panel. Note that the Line input has
an automatic level pad of 24 decibels.
The remaining four positions all take their source from the dedicated microphone input on the rear panel. The rst
three positions set the load impedance at settings of 200, 600 and 2.4k Ohms in order to aid the matching for a
dynamic microphone.
In the +48V Phantom Power switch position the red LED will illuminate to indicate that 48V of dc voltage is being
sent down the XLR cable in order to power the electronics of a condenser microphone.
NOTE: DO NOT ACTIVATE THE +48V SETTING UNLESS THE MICROPHONE REQUIRES IT.
INSTRUMENT INPUT
A 1/4” jack provides a specialised instrument input stage suitable for use with both active and passive guitar pickup
systems as well as with electronic keyboards.
PHASE REVERSE O - On
This switch reverses the signal polarity, and is often useful when recording an instrument with more than one
microphone. If, for example, you record a guitar cabinet with two mics, the two signals could be so similar that
they would cancel each other out partially, resulting in a very thin sound. Reversing the phase of one channel
would rectify this.
INPUT GAIN 0 - +66dB
A twelve position switch adds gain in 6dB steps from 0dB to +66dB, making it incredibly easy to replicate previous
settings and have total control over levels.
It is the most common practice to set the input for any given source to read 0dBs to provide the best volume, a
4 bar LED Meter above, with settings of -20, -10, 0 & +10dBs displays this input level. This can be ne tuned by
the O/P Trim later.
O - On
A variable high and low pass lter can be switched in and out of the signal path via this switch. The two lters
combine to help remove any extraneous noise and tune in to the required signal.
LoCUT 15 - 350Hz
The variable high-pass lter (also known as Low Cut) can be set between 15Hz and 350Hz at a slope of 12dB per
Octave, and is used to attenuate low frequency signals that might otherwise prove troublesome, eg. trac rumble
or stage vibration, and let the higher frequencies pass.
HiCUT 1.5 - 20kHz
The variable low-pass lter (also known as High Cut) can be set between 1.5kHz and 20kHz at a slope of 12dB
per Octave, and is used to attenuate high frequency signals that might not be required eg. sibilance and hiss, and
let the lower frequencies pass.

7
DRAWMER 1972 OPERATOR’S MANUAL
SHAPE
It is easiest to think of the Shape feature as a xed boost/cut tilt equaliser whereby the signal increases and
decreases by the same amount around a xed point on the scale, in the case of the 1972, at 500Hz.
The bass frequencies are boosted and the high frequencies cut by 2.5dB (at the extremes).
The bass frequencies are cut and the high frequencies boosted.
However, note that when both switches are active they interact with each other and provide a classic “smiley face”
EQ curve that will boost the low and high frequencies by approximately 1.5dBs, with a slight cut in the mids of 1dB.
OUTPUT TRIM -12dB - +12dB
Because the Input Gain switches the volume in 6dB steps the Output Trim, being a continuous control, is used to
nely adjust the output to the absolute desired level.
VU METER
A backlit moving coil VU meter displays the level of the output signal as found at the output XLR
+10dB Pad VU - +10dB
Adjusts the meter to show either normal output level, (and for those working at ‘hot’ output levels) VU +10dB i.e.
with the switch at VU +10dB, when the VU meter reads 0dB the actual level is +10dB.
LIFT
LIFT is a single switch solution to recording low signal levels.
Seamless in it’s operation, LIFT is, in essence, a low level dynamic
gain module which has no eect on signals above 0dB, but increases
gain dynamically on levels between 0dB and -30B, up to a maximum of
10dB, and then continues to add 10dB of gain to signals below -30dB.
You may ask yourself: why would this be necessary?
When recording very quiet passages the most common answer to
obtain a loud enough recording is to simply add more gain, however,
as this occurs throughout the entire audio level range, increasing
the loud signals also, clipping and distortion can easily occur. The
cleverness of the LIFT switch is that it dynamically increases only the
volume of the very quiet signals below the threshold of 0dB, leaving
anything above untouched, meaning that no unnecessary clipping
occurs during loud passages.
If done crudely the eect would be obvious and unnatural, however the
paramaters of the 1972 LIFT feature have been xed at settings that
provide as transparent, smooth and musical quality as possible, whilst making the operation as simple as a single
switch press. The feature will nd many uses in the studio, radio, TV sound, conferences and public address. It is
of great value on piano, drum ambience as well as other types of percussion, and on all vocals including speech.
Mic technique is used to compensate for vocal intensity and one can often see singers move closer to the mic
during quiet passages. LIFT reduces or even eliminates the need to do this.
Please note that, just like any other gain increase, the noise oor will also be increased by 10dB, and in addition,
in a live situation, acoustic feedback is more likely to occur and should be considered during sound check.

8DRAWMER 1972 OPERATOR’S MANUAL
CHAPTER 3
IF A FAULT DEVELOPS
For warranty service please call Drawmer Electronics Ltd. or
their nearest authorised service facility, giving full details of the
diculty.
A list of all main dealers can be found on the Drawmer webpages.
On receipt of this information, service or shipping instructions
will be forwarded to you.
No equipment should be returned under the warranty without
prior consent from Drawmer or their authorised representative.
For service claims under the warranty agreement a service
Returns Authorisation (RA) number will be issued.
Write this RA number in large letters in a prominent position
on the shipping box. Enclose your name, address, telephone
number, copy of the original sales invoice and a detailed
description of the problem.
Authorised returns should be prepaid and must be insured.
All Drawmer products are packaged in specially designed
containers for protection. If the unit is to be returned, the original
container must be used. If this container is not available, then
the equipment should be packaged in substantial shockproof
material, capable of withstanding the handling for the transit.
CONTACTING DRAWMER
Drawmer Electronics Ltd., will be pleased to answer all
application questions to enhance your usage of this equipment.
Please address correspondence to:
Drawmer (Technical Help line)
Coleman Street
Parkgate
Rotherham
S62 6EL
UK
Alternatively contact us by E-mail on :
for sales enquiries: sales@drawmer.com
or for technical issues: tech@drawmer.com
Further information on all Drawmer dealers, Authorised service
departments and other contact information can be obtained from
our web pages on:
http://www.drawmer.com
GENERAL INFORMATION
INPUT
Input Impedance 20k Ohms or greater
Maximum Input Level +21dBu
OUTPUT
Output Impedance 100 Ohms
Maximum Output Level +21dBu into 10k Ohms Load
FREQUENCY RESPONSE
20Hz to 20kHz +/-0.5dB
CROSSTALK < -85dB @ 1kHz
NOISE AT UNITY GAIN
20Hz - 20kHz >92dB
1972 DUAL MIC, LINE AND INSTRUMENT PRE-AMPLIER
DATA SPECIFICATION
% DISTORTION (THD & NOISE) @ 1kHz
0dB 0.07%
10dB 0.07%
MIC EIN -130dB Aweighted
POWER REQUIREMENTS
230Volt or 115V at 50-60hZ, 15VA
FUSE RATING
T160mA for 230Volt,
T315mA for 115Volt
Conforming to IEC 127-2
FUSE TYPE
20mm x 5mm, Class 3 Timed-Blo, 250Volt working
CASE SIZE
482mm (W) x 44mm (H) x 200mm (D)
WEIGHT 2.6Kgs

9
DRAWMER 1972 OPERATOR’S MANUAL
BLOCK DIAGRAM
1972 ver 01 E 22/08/22

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