Drawmer 1962 User Manual
1962
DIGITAL VACUUM TUBE PRE-AMP
OPERATORS MANUAL
i
TWELVE MONTHS LIMITED WARRANTY
DRAWMER ELECTRONICS LTD., (HEREIN AFTER KNOWN AS THE MANUFACTURER)
WARRANTS THIS AUDIO PRODUCT TO BE FREE FROM DEFECTS AND CONFORM
SUBSTANTIALLY TO THE SPECIFICATIONS OF THIS MANUAL FOR A PERIOD OF
TWELVE MONTHS FROM THE ORIGINAL DATE OF PURCHASE, WHEN USED IN
ACCORDANCE WITH THE SPECIFICATIONS DETAILED IN THIS MANUAL. THIS
WARRANTY IS NOT TRANSFERABLE. IT APPLIES ONLY TO THE ORIGINAL PURCHASER
OF THE PRODUCT. THIS GUARANTEE DOES NOT COVER ANY PRODUCT, OR PARTS,
OR FUSES THAT HAVE BEEN SUBJECTED TO MISUSE, NEGLECT, ACCIDENT OR
ABNORMAL CONDITIONS OF OPERATION. ADDITIONALLY, THIS WARRANTY IS VOID
IF THE PRODUCT HAS BEEN MODIFIED OR DAMAGED BY UNAUTHORISED REPAIR.
IN NO EVENT WILL THE MANUFACTURER 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 THE
MANUFACTURER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
THE MANUFACTURER SHALL NOT BE RESPONSIBLE FOR ANY DAMAGE OR LOSS
DURING SHIPMENT TO AND FROM THE FACTORY OR ITS DESIGNATED SERVICE
FACILITY.
THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES, WHETHER ORAL OR
WRITTEN, EXPRESSED, OR IMPLIED. THE MANUFACTURER MAKES NO OTHER
WARRANTY EITHER EXPRESS OR IMPLIED, INCLUDING, WITHOUT LIMITATION, ANY
IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
PURPOSE, OR NON-INFRINGEMENT. THE PURCHASER’S SOLE AND EXCLUSIVE
REMEDY UNDER THIS WARRANTY SHALL BE REPAIR OR REPLACEMENT AS
SPECIFIED HEREIN.
THE MANUFACTURER RESERVES THE RIGHT TO MAKE CHANGES OR
IMPROVEMENTS IN THE DESIGN AND CONSTRUCTION OF THIS UNIT WITHOUT
OBLIGATION TO MAKE CHANGES OR IMPROVEMENTS IN THE PURCHASER’S UNIT.
IN THE EVENT OF A FAILURE OF A PRODUCT COVERED BY THIS GUARANTEE, THE
MANUFACTURER OR THEIR CERTIFIED REPRESENTATIVES WILL REPAIR AND
CALIBRATE EQUIPMENT RETURNED, PRE-PAID, TO AN AUTHORISED SERVICE
FACILITY WITHIN TWELVE MONTHS OF THE ORIGINAL PURCHASE FREE OF ANY
CHARGE. ANY FAULT CAUSED BY MISUSE, NEGLECT, ACCIDENT, ACT OF GOD, WAR
OR CIVIL INSURRECTION, ALTERATION OR REPAIR BY UNAUTHORISED PERSONAL,
OPERATION FROM AN INCORRECT POWER SOURCE OR ABNORMAL CONDITIONS OF
USE WILL NOT BE COVERED BY THIS WARRANTY.
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.
ANY DISPUTE ARISING FROM THIS WARRANTY SHALL BE SUBJECT TO ENGLISH LAW.
THIS DOES NOT AFFECT YOUR STATUTORY RIGHTS.
ii
CONTENTS
SAFETY CONSIDERATIONS page 1
INTRODUCTION page 2
APPLICATIONS page 3
INSTALLATION page 4
Audio connections
"
"
Digital connections page 5
"
Power connections
CONTROL DESCRIPTIONS: page 8
"
Channel Input
"
Limit page 8
"
Microphone Pre-amplifier
"
Auxiliary Input page 9
"
Line Input page 10
"
High and Low Pass Filters
"
Fine Tune EQ page 11
"
Enhance page 12
"
Tube Drive page 13
"
Stereo Mix
"
Digital Section D62-T/-A (where fitted) page 15
"
Stereo Link operation page 19
page 4
page 7
page 8
page 9
page 11
page 14
CONFIGURATION:
"
Internal jumpers
page 19
IF A FAULT DEVELOPS page 20
CONTACTING DRAWMER page 20
TECHNICAL SPECIFICATION page 21
BLOCK DIAGRAM page 22
iii
For the USA
FEDERAL COMMUNICATIONS COMMISSION RADIO FREQUENCY INTERFERENCE
STATEMENT
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 interference to radio or television
reception, which can be determined by turning the equipment off an on, then 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 the 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.
Unauthorised changes or modification to this system can void the users’ authority to
operate this equipment.
This equipment requires shielded interface cables in order to meet FCC class B limit.
For Canada
CLASS B NOTICE
This digital apparatus does not exceed the Class B limits for radio noise emissions set
out in the Radio Interference Regulations of the Canadian Department of
Communications.
CLASSE B AVIS
Cet appareil numérique ne dépasse pas les limites de la classe B au niveau des
émissions de bruits radioélectriques fixés dans le Règlement des signaux parasites par
le ministère Canadien des Communications.
COPYRIGHT
This manual is copyrighted © 1997 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.
All brand or product names mentioned in this manual are trademarks or registered
trademarks of their respective owners.
iv
1962 OPERATORS’ MANUAL
DRAWMER 1962
Digital Vacuum Tube Pre-Amp
SAFETY CONSIDERATIONS
CAUTION - MAINS FUSE
TO REDUCE THE RISK OF FIRE REPLACE THE MAINS FUSE ONLY WITH A
FUSE THAT CONFORMS TO IEC 127-2. 250 VOLT WORKING, TIME DELAY
TYPE AND BODY SIZE OF 20mm x 5mm.
THE MAINS INPUT FUSE MUST BE RATED AT 250mA WHERE THE MAINS
INPUT VOLTAGE SWITCH IS SET TO 230 VOLTS AC. AND 500mA WHERE
THE MAINS INPUT VOLTAGE IS 115 VOLTS AC.
1
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.
2
1962 OPERATORS’ MANUAL
INTRODUCTION
The 1962 is a hybrid vacuum tube/semi-conductor, dual-channel pre-amplifier which
features extremely low noise operation and the option of a 24-bit digital output. Balanced
microphone and line inputs are included making the 1962 a powerful and versatile tool in
all areas of audio, including studio recording, live sound, location recording, postproduction, mastering and as part of a musician's rack system.
In addition to providing 'clean gain', the 1962 includes variable high and low-pass shelving
filters, a 3-band 'sweetening' EQ, high and low frequency enhancement plus a switchable
peak limiter. A variable Tube Drive system enables the user to apply a precise amount of
tube colouration while a simple mixing system provides level and pan control for each of the
two channels.
The optional D62-T or D62-A digital convertor module may be ordered with the 1962 or
retrofitted when required and provides 16, 18, 20 or 24-bit wordlength outputs in both
AES/EBU and S/PDIF formats with user selectable dither. The D62-T also includes a
Tascam™ T-DIF interface while the D62-A has an integral ADAT™ optical interface. Word
sync in and out is provided as standard and the user may select between 48kHz, 44.1kHz
and externally clocked sample rates. This manual will refer to the digital module as the D62
wherever it is applicable to both T-DIF and ADAT.
One major advantage of the hybrid approach is that it combines the dynamic range,
reliability and stability of modern solid-state designs with the warm, detailed sound of
vintage classic tube designs. The microphone input stages feature extremely low noise,
balanced input circuitry followed by true, high voltage tube amplification, enabling modern
microphones to take on the characteristics of older tube models. Phantom power is
individually switchable on the two microphone inputs and each microphone input has a
phase reverse switch.
The line/instrument pre-amplifiers are compatible with a variety of signal sources, from
electric guitars and basses to stereo electronic keyboards and synthesizer modules. By
overdriving the tube stage, tonal colouration may be added to an instrument, and with the
addition of an external speaker simulator, overdriven guitar, synth or organ sounds may be
Direct Injected into the mixing console.
There are two, dual-stage tubes in the audio signal path and, in order to maintain optimum
signal purity, the EQ, enhancement and tube drive stages may be switched out of circuit to
provide a minimum signal path between the input and output. To maintain the highest
possible signal-to-noise performance, continuously variable input gain controls are used
instead of rotary switches and high resolution, 24-element LED metering is provided along
with peak overload LEDs. Output level metering and gain control is provided and each
channel has a switchable limiter, which can be used to prevent unwanted overloading particularly important when driving digital equipment or when using the optional digital
output stage. A Gain Reduction LED monitors the limiter action. Console-style insert points
on the rear panel allow additional processing to be added to the signal path.
Up to a maximum of three additional stereo analogue signals can be mixed together with the
internally processed signal(s) by utilising the rear panel connector. Providing a facility to fit
only one 1962 with the D62 analogue to digital convertor module.
1962 OPERATORS’ MANUAL
APPLICATIONS
Standalone microphone preamplifiers are generally associated with direct-to-stereo
recording or with the purist recording approach by which the traditional console is bypassed
wherever possible. Though ideally suited to these applications, and to applications where
instrument level signals require to be DI'd, the 1962 is much more flexible than traditional
preamplifiers, because of its variable Tube Drive control and its versatile equaliser/enhancer
section. Because of its ability to modify and enhance the tonal quality of a signal, the 1962
is perfectly suited to stereo mix processing, subgroup processing, or to discerning mastering
operations where the digital output may be used directly to feed a digital tape or disk-based
editing machine. The subtle tube colourations add warmth, depth and transparency to a mix
while emphasising mid-range and high-frequency detail.
For high quality location recording, the 1962 makes the perfect partner for a DAT machine,
combining the functions of stereo mic preamp with the capability to output high resolution
digital data with up to 24-bit word length. The mic inputs provide up to +60dB of gain while
closely approaching the theoretical minimum noise level; the performance of the 1962 is
invariably determined by the quality of the microphones plugged into it rather than by any
inherent limitations.
3
As an instrument amplifier, the 1962 provides a warm-sounding tube input, making it ideal
for DI'ing guitars, basses and even keyboards. The tube gain stages are versatile enough
to provide a clean, punchy sound or the gain may be increased to provide the type of
overdrive sound associated with tube guitar amplifiers. Although the EQ facilities offered on
the 1962 are designed mainly for sweetening, they have sufficient range to be used in a
creative context when creating instrument sounds.
The limiter may be used to prevent the output level from clipping when the maximum level
of the input signal cannot be established with certainty.
4
1962 OPERATORS’ MANUAL
INSTALLATION
The 1962 is designed for standard 19" rack mounting and occupies 2U (88mm) of rack
space. Avoid mounting the unit directly above power amplifiers or power supplies that
radiate significant amounts of heat, or in poorly ventilated or unusually warm environments.
We advise that a blank space above the unit with a ventilated rack blanking panel is fitted.
Fibre or plastic washers may be used to prevent the front panel becoming marked by the
mounting bolts. In mobile systems, it is recommended that a shock resistant flight case is
used. In severe conditions where there might be excessive vibration, additional rear support
might be required.
AUDIO CONNECTIONS
CHANNEL IN/OUT
The channel inputs and outputs are electronically balanced on conventionally wired XLRs
(pin1 screen, pin 2 hot, pin 3 cold and XLR shell is connected to the chassis), with an
operating level nominally of +4dBu. If the unit is to be used where it may be 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 be connected to the chassis connection on the XLR connector as
opposed to connecting to pin1. The 1962 fully conforms to the EMC standards.
If ground loop problems are encountered,
instead, try disconnecting the signal screen on one end of each cable connecting the
outputs of the 1962 to the patchbay. If such measures are necessary, balanced operation
is recommended. Various signal cable earthing options may have to be tried to achieve the
most hum-free connection.
The intended use of the audio insert jacks would be to patch in an additional EQ (eg
Drawmer 1961), reverb or similar processing to the signal path. Insert connection is via
quarter-inch TRS jacks, the wiring convention being: ring - signal send, tip - signal return
and sleeve - ground. The insert jack may be permanently wired to a normalised patch bay
for easier connection. The signal path to and from this insert jack and enhance any external
processing can be overridden by disabling the Fine EQ section.
never
disconnect the power inlet earth, but
STEREO OUTPUTS
The Stereo Mix Output XLRs are electronically balanced and follow the usual wiring
convention of: pin 1 screen, pin 2 hot, pin 3 cold and XLR shell connected to the chassis.
If the unit is to be used where it may be exposed to high levels of disturbance (such as close
to a TV or radio transmitter), we suggest that the screen of the signal cable be connected
to the chassis connection on the XLR connector as opposed to connecting to pin1. The 1962
fully conforms to the EMC standards.
If ground loop problems are encountered,
instead, try disconnecting the signal screen on one end of each cable connecting the
never
disconnect the power inlet earth, but
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