Drawmer S3 User Manual

DRAWMER

S3

Three-Band Stereo

Vacuum Tube Compressor

OPERATOR’S MANUAL

Warranty
Safety Consideration

Chapter 1 - Introduction

Introduction
Installation
Audio Connections
Power Connection

Chapter 2 - Control Description

Control Description
Quick Setup Procedure

Chapter 3 - General Information

If a fault develops
Contacting Drawmer
Specification
Block Diagram

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CONTENTS

COPYRIGHT

This manual is copyrighted © 2006 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.

ONE YEAR LIMITED WARRANTY

Drawmer Electronics Ltd., warrants the Drawmer S3 Three­Band Stereo Vacuum Tube Compressor to conform
substantially to the specifications of this manual for a period
of one year from the original date of purchase when used
in accordance with the specifications 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.

SAFETY CONSIDERATIONS

REPLACE THE MAINS FUSE ONLY WITH

A FUSE THAT CONFORMS TO IEC127-2.

250 VOLT WORKING, TIME DELAY TYPE

RATED AT 230V=T500mA and 115V=T1Amp.

DRAWMER

S3

Three-Band Stereo

Vacuum Tube Compressor

CAUTION - MAINS FUSE

TO REDUCE THE RISK OF FIRE

AND BODY SIZE OF 20mm x 5mm.

THE MAINS INPUT FUSE MUST BE

This warranty is void if the product has been damaged by
misuse, modification 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 specific legal
rights. You may have additional rights that vary from state
to state, and country to country.

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.

In the interests of product development, Drawmer reserve the right to modify or

improve specifications of this product at any time, without prior notice.

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DRAWMER S3 OPERATOR’S MANUAL

CHAPTER 1

DRAWMER

S3

THREE-BAND STEREO VACUUM TUBE COMPRESSOR

INTRODUCTION

The new S3 Three-Band Stereo Vacuum Tube Compressor

incorporates the very latest in Ivor Drawmer designs and

the aim from the very beginning was to create a 'no

technical compromise' circuit using only the highest grade

The Key Features are as follows:

• Fully balanced signal path class A design

• Isolation transformers in and out

• 20 x active tube stages

• High power 'push/pull' output stage delivering up to +30dBu

• Variable band split points

• Switchable 'peak' or 'VU' metering to display transients, with +10dB or +20dB re-scaling

• 'Air' mode for high band

components. The S3 forms the basis of a 'Signature Series'

and offers previously unattainable control and tonality over

each of the three bands - gain control at each stage

provides precise spectral balancing.

• 'Big' mode for low band

• Switchable mute and bypass on each band

• Individual gain reduction metering on all bands

DRAWMER S3 OPERATOR’S MANUAL

3

INSTALLATION

The S3 is designed for standard 19" rack mounting and
occupies 3U of rack space. Fibre or plastic washers may
be used to prevent the front panel becoming marked by
the mounting bolts. Always connect the mains earth to
the unit.

Because the S3 contains ten valves it will generate more
heat than a simple solid state unit. Avoid mounting the
unit directly above power amplifiers or power supplies that
radiate significant amounts of heat. In addition it is advised
that you leave at least 1U of space above to allow heat to
dissipate. Alternatively, a fan should be fitted somewhere
near to the rear of the unit to circulate cooler air and help
expel any excess heat. (see fig. 1).

It is also recommended to the S3 is mounted horizontally
to allow heat to escape vertically through the vents on the
lid. To mount at an angle may cause the S3 to overheat
which will damage internal components (see fig. 2).

fig.1 RACK MOUNT POSITIONING

fig.2 MOUNT HORIZONTALLY

fig.2 TYPICAL S3 SETUP

4

DRAWMER S3 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 operating
level is nominally +4dBu. Balanced use is recommended.

fig.3 XLR WIRING

• Ground Loops:
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 S3 to the
patchbay. If such measures are necessary, balanced
operation is recommended.

POWER CONNECTION

The unit will have been 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. The unit should always be connected to the
mains supply earth using this cable, and no other.

If for some reason the unit is to be used at a mains
input operating voltage which is different to that as
supplied, the following procedure must be carried out.

1: Disconnect the unit from the mains.
2: Remove the two screws holding the voltage
selection cover-plate.
3: Remove the cover plate and slide the switch
fully to its opposite end.
4: Rotate the cover plate one half turn (180 degrees)
and refit the two screws.
5: Replace with a correctly rated fuse for the
selected operation voltage in the IEC socket:
230V-T500mA and 115V-T1Amp
6: Re-connect to mains power source.

Never disconnect the earth

from the mains supply

• Interference:
If the S3 is to be used where it maybe exposed to high
levels of disturbance such as found close to a TV or
radio transmitter, we advise that it is operated in a
balanced configuration. The screens of the signal
cables should be connected to the chassis connection
on the XLR connector as opposed to connecting to
pin1. The S3 conforms to the EMC standards.

fig.4 Altering the Voltage

DRAWMER S3 OPERATOR’S MANUAL

5

CONTROL DESCRIPTION

CHAPTER 2

BAND SPLIT

The 6dB per octave crossover frequencies
determine the points within the frequency
spectrum one band stops to process audio, and
another band takes over.

Low Split Frequency: 60Hz - 1.4kHz

1

Sets the frequency point at which the split
between low and mid bands occurs.

High Split Frequency: 1.4kHz - 14kHz

2

Sets the frequency point at which the split
between mid and high bands occurs.

The following diagram provides a good, but
general, idea of some useful frequencies:

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DRAWMER S3 OPERATOR’S MANUAL

LOW BAND, MID BAND, HIGH BAND

Threshold: infinity - -32dB all bands

3

Determines the level below which compression starts to take
place. The S3 incorporates a Soft Knee, more compression is
applied automatically as the input signal level increases, negating
the need for a Ratio control.

Gain Reduction Meter: all bands

4

Eight Leds at 0,-1,-3,-5,-7,-10,-15,-20dB

Big: Off - On low band only

5

Reduces the ducking effect caused by bass energy and effectively
boosts the bass output.

Air: Off - On high band only

6

Use to brighten and enhance the high band detail. Cymbals sound more vibrant without becoming splashy, vocals
sound more open but without becoming sibilant.

Attack: see Fig. 5 all bands

7

Controls the speed that the compressor responds to signals that exceed the level set by threshold. Six switchable
Attack settings. All times are nominal, the actual attack time is further modified by the release setting chosen.

Release: see Fig. 6 all bands

8

Sets the time taken for the signal to return to normal after the input level has fallen below threshold.
The first three switch positions are fixed and provide progressively increasing release times, while positions F(ast),
M(id) and S(low) cause the release times to vary in a manner which automatically adapts to the dynamics of the
incoming signal.

Attack Presets

Gain: -10 - +20dB all bands

9

During compression the signal is attenuated, gain may be required to produce the required output level. In addition,
as the S3 is multi-band, the three gain controls are used to adjust the levels of each band to obtain a desirable
overall signal, or to bring out the bass, treble etc.

10

Mute: Off - On all bands

In the “MUTE” position the signal for that particular band is effectively turned off. Any combination of mute is
available - to hear only the signal of the low band mute the mid and high bands etc.

Bypass: Off - On all bands

11

In the “BYPASS” position the signal for the low, mid, or high band is allowed to pass through to the summing stage
without being altered by the compressor stage (including gain).
Using a combination of mute and bypass switches for the various bands allows the operator to hear and monitor
only the frequencies that are required and so tune the low and high frequency settings.

Release Presets

DRAWMER S3 OPERATOR’S MANUAL

7

METERS

VU Meter:

12

Two moving coil VU meters monitor either the level of the input or output signal.

Pad: Vu - +10dB - +20dB

13

A three-position switch adjusts the meters to show either normal output level, (and for those working at ‘hot’ output
levels) VU +10dB or VU +20dB modes. i.e. with the switch at VU +10dB - when the VU meter reads 0dB the actual
level is +10dB.

Response: Peak VU - VU

14

On smooth, gentle pieces of music the “VU” (average level) setting would be sufficient, however, on fast dynamic
signals the “Peak VU” setting provides more accurate readings.

Select: Output - Input

15

Set to "Input" and adjust the level of the incoming signal: an optimal level of 0dB provides optimum headroom and
signal-to-noise ratio. If the input level is too low little compression will occur (and, raising the overall output level of
the signal will amplify the noise floor).
The Output setting shows the signal level after the signal has been summed and the “Gain” (17) and “Balance” (18)
have been applied.

OUTPUT

Temperature Led

16

The S3 is at optimum temperature when the front panel LED indicator is lit, i.e. after the soft start and when the
valves have reached optimum temperature - this may take a few seconds.

Gain: -11 - +12dB

The S3 provides a single control to modify the stereo output level after summing, without having to adjust the three

17

band gain controls (and thus altering the mix). Adjust so that the output signal approaches the desired level only on
signal peaks.

Balance: Left - 0 - Right

Modifies left/right balance within the stereo mix.

18

Bypass: Off - On

A fully balanced hard-wire unit bypass connects the input directly to the output.

19

Note: in bypass the VU meters display the levels as though the unit is still compressing until the Meter Select
switch is set to “Input”. This has been implemented to provide the user with optimum control of the meters.

Power: Off - On

20

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DRAWMER S3 OPERATOR’S MANUAL

QUICK SETUP PROCEDURE

Please note that the following procedure is only a guide. All audio is different, requiring numerous settings, however,
this should give a good staring point:

1) Set the compressor settings to be the same on all bands - Threshold at “infinite”, Gain at 0dB, the
Attack in a mid position (2 or 3) and Release set to F(ast). The overall Gain control should be set to 0dB,
and the Balance at 0.

2) Set the Meter Select switch to Input and adjust the incoming signal so that the meters read 0dB. Set the
switch to output.

3) With the Low Frequency Split set fully counter-clockwise, and the High Frequency Split set fully
clockwise, listen to the audio and bring in the two knobs to the positions that you think the cross-over points
should be set - generally to separate the main bass and treble sounds from the mid-range. Using a combination
of Mute and Bypass switches for the various bands allows the operator to monitor only the frequencies that are
required and so tune the low, mid and high frequencies.

4) Keeping an eye on the Gain Reduction Meters alter the Threshold level control for each band until the
desired compression level is achieved - a G.R. level up to -10dB is acceptable.

5) Adjust the Gain control of each band until 0dB is reached on the Output VU meter. To see only the band that
is being adjusted on the VU meter Mute the other two bands.

6) Set the Attack and Release settings of each band to suit the audio being compressed.

7) The Threshold and Gain of each band can be modified to achieve the desired compression, levels and tonal
balance to the overall signal.

8) At this point the Bypass switches can be toggled to listen to the affect that the S3 is having on the audio.
Adjust to suit.

9) Once each band is setup correctly modify the overall Output Gain and Balance until the VU meters read 0dB
(more if in +10dB VU or +20dB modes).

Above is an example setup that could be used for a General Pop Mix, though, of course, as all music is diverse and
varied, will not be ideal elsewhere.

DRAWMER S3 OPERATOR’S MANUAL

9

GENERAL INFORMATION

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 difficulty.

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 shock-proof
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: [e-mail]

or for technical issues: [e-mail]

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

S3 THREE-BAND STEREO VACUUM TUBE COMPRESSOR

DATA SPECIFICATION

INPUT

Input Impedance 600 Ohms or greater
Maximum Input Level +30dBu

OUTPUT

Output Impedance 600 Ohms
Maximum Output Level +30dBu @ 10k Ohms Load

+26dBu @ 600 Ohms Load

FREQUENCY RESPONSE

<24Hz to 38kHz -1dB
<10Hz to 60kHz -3dB

CROSSTALK < -80dB @ 10kHz

< -74dB @ 20kHz

NOISE AT UNITY GAIN

with flat EQ response switched in circuit

Wideband 22Hz - 22kHz

AV -79dB -84dB

-87dB -94dB

% DISTORTION (THD & NOISE) @ 1kHz

0dB (ref +4) 0.03%
10dB (ref +4) 0.1%
20dB (ref +4) 0.4%

POWER REQUIREMENTS

230Volt or 115V at 50-60hZ, 60VA

FUSE RATING

T500mA for 230Volt, T1A for 115Volt
Conforming to IEC 127-2

FUSE TYPE

20mm x 5mm, Class 3 Timed-Blo, 250Volt working

CASE SIZE

482mm (W) x 132mm (H) x 315mm (D)

WEIGHT 9.7Kgs

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DRAWMER S3 OPERATOR’S MANUAL

BLOCK DIAGRAM

DRAWMER S3 OPERATOR’S MANUAL

S3 ver 01 C 30/03/09

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