961 VACUUM TUBE EQUALISER OPERATORS MANUAL CONTENTS SAFETY CONSIDERATIONS POWER CONNECTION INSTALLATION FUSES INTRODUCTION APPLICATIONS CONTROL DESCRIPTIONS OPERATION IF A FAULT DEVELOPS CONTACTING DRAWMER TECHNICAL SPECIFICATION BLOCK DIAGRAM i page page page page page page page page page page page page 1 2 2 3 4 5 5 7 10 10 11 12
COPYRIGHT This manual is copyrighted © 1995 by Drawmer Electronics, Ltd. With all rights reserved. Under copyright laws, this manual may not be duplicated in whole or in part without the written consent of Drawmer. ONE YEAR LIMITED WARRANTY Drawmer Electronics Ltd., warrants the Drawmer 1961 audio processor 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.
1961 OPERATORS’ MANUAL 1 DRAWMER 1961 VACUUM TUBE EQUALISER 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 WITH A 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. THE REAR PANEL H.T.
2 1961 OPERATORS’ MANUAL 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. 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.
1961 OPERATORS’ MANUAL 3 FUSES The mains fuse should be a class 3, 250 Volt, Time delay type, with a body size of 20mm x 5mm, at the correct rating for the mains input voltage. It is very important that this fuse complies with IEC127-2. Remember that, in the unlikely event of the unit developing a fault, it is normal for the mains fuse to blow and the unit must be serviced by a qualified service technician. For added protection the 1961 is also fitted with silicon re-setable fuses.
4 1961 OPERATORS’ MANUAL INTRODUCTION The Drawmer 1961 is a hybrid, vacuum tube/semi-conductor, dual-channel equaliser designed to combine the tonal qualities of classic tube circuitry with the low noise and high reliability associated with contemporary circuit design.
1961 OPERATORS’ MANUAL 5 APPLICATIONS Further to its obvious applications as a general studio equaliser, the 1961 is also particularly effective as a post-production or mastering tool when used to treat complete stereo mixes, especially when used in conjunction with the 1960 tube compressor. Even before EQ is applied, the output tube circuitry may be mildly overdriven in order to add warmth and depth to the sound, while at the same time, emphasising mid-range and high-frequency detail.
6 1961 OPERATORS’ MANUAL Hz: Frequency selector switch. Available frequencies are: Frequency Switch 1st position 2nd position 3rd position 4th position 5th position 6th position Bass 20Hz 32Hz 50Hz 80Hz 125Hz 200Hz Low-Mid 100Hz 160Hz 250Hz 400Hz 650Hz 1kHz High-Mid 500Hz 800Hz 1.2kHz 2kHz 3.2Khz 5kHz Treble 2.5kHz 4kHz 6kHz 10kHz 15kHz 25kHz Octave: Filter bandwidth (or 'Q') control. Variable between 0.3 and 3 octaves.
1961 OPERATORS’ MANUAL 7 O/L (LED): This Overload red LED illuminates when the tube output stage is being driven into audible distortion. This may be used as a creative effect and will not damage the 1961. Soft (LED): This yellow LED illuminates when the tube output stage is being driven into 'soft clipping'. This is the area that produces the classic tube sound, and though a small amount of harmonic distortion is being added, the result can often sound cleaner and more detailed than before treatment.
8 1961 OPERATORS’ MANUAL Note that a small amount of deliberately added tube distortion can produce the flattering effect associated with vintage tube equipment.
1961 OPERATORS’ MANUAL Tip: ! Electric guitars often need a little EQ to add bite or presence. The High Mid equaliser is ideally suited to this purpose and, depending on the guitar sound sought, the 1.2kHz, 2kHz or 3kHz setting might be most suitable. The degree of boost should be set by ear and the starting Octave setting should be 1, though this may also be fine-tuned by ear.
10 1961 OPERATORS’ MANUAL IF A FAULT DEVELOPS For warranty service please call Drawmer Electronics Ltd. Or their nearest authorised service facility, giving full details of the difficulty. 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 given.
1961 OPERATORS’ MANUAL 11 TECHNICAL SPECIFICATIONS (All measurements taken at +4dBu operating level) INPUT IMPEDANCES XLR INSERT MAXIMUM INPUT LEVEL 20KÙ 47KÙ +17dB (+21dBu) OUTPUT IMPEDANCES XLR INSERT 50 Ù 200 Ù FREQUENCY RESPONSE <22Hz to 42KHz -1dB CROSSTALK <-80dB @ 10KHz <-75dB @ 20KHz INPUT CMR Better than 40dB (20Hz to 10KHz) OUTPUT BALANCE Better than 40dB (20Hz to 10KHz) NOISE AT UNITY GAIN with flat EQ response switched in circuit Wideband 22Hz - 22KHz CCIR ARM IEC A Q-Pk CCI
12 1961 OPERATORS’ MANUAL BLOCK DIAGRAM
