DL231 OPERATORS MANUAL CONTENTS SAFETY CONSIDERATIONS page 1 INTRODUCTION page 2 INSTALLATION page 3 CONTROL DESCRIPTIONS page 4 OPERATION page 6 TECHNICAL SPECIFICATION page 8 h DRAWMER ELECTRONICS LTD.
COPYRIGHT This manual is copyrighted © 1990 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 DL231 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.
1 DL231 OPERATORS MANUAL DRAWMER DL231 Dual Expander Compressor Limiter SAFETY CONSIDERATIONS CAUTION - MAINS FUSE TO REDUCE THE RISK OF FIRE REPLACE THE MAINS FUSE ONLY WITH THE SAME TYPE, WHICH MUST BE A CLASS 3, 230 VOLT, TIME DELAY TYPE, RATED AT 63mA WHERE THE MAINS INPUT VOLTAGE SWITCH IS SET TO 230 VOLTS AC. AND 125mA WHERE THE MAINS INPUT VOLTAGE IS 115 VOLTS AC. ALL FUSES MUST COMPLY WITH IEC127-2. THE FUSE BODY SIZE IS 20mm x 5mm.
2 DL231 OPERATORS MANUAL INTRODUCTION A compressor is a device which automatically controls the level of an incoming signal to provide a more constant output. Even in a digital system, which has a large dynamic range, compression is necessary on some instruments and even on a final mix because the environment in which most material is heard is often noisy, to say nothing of the limited dynamic range of the reproduction equipment, e.g. portable radios and cassette players.
3 DL231 OPERATORS MANUAL INSTALLATION The DL231 is designed for standard 19" rack mounting and occupies 1U of rack space. Avoid mounting the unit directly above power amplifiers or power supplies that radiate significant amounts of heat. Fibre or plastic washers may be used to prevent the front panel becoming marked by the mounting bolts.
4 DL231 OPERATORS MANUAL CONTROL DESCRIPTION Both channels of the DL231 are identical and may be used completely independently or linked for stereo operation. In the linked mode, only the left hand channel controls are functional and serve as master controls, though the channel bypass switches remain independent.
DL231 OPERATORS MANUAL 5 LED BAR DISPLAY is a dual function facility which measures output level (input level if bypass is selected) or gain-reduction, selectable by the display switch. NB i. ii. The VU meter and threshold controls are calibrated to show 0VU at +4dB In the gain reduction mode, all the red LED’s are very slightly illuminated at all times. This is quite normal and does not indicate a fault condition. EXPANDER THRESHOLD (+10 to -40 dB) sets the point at which gain reduction takes place.
6 DL231 OPERATORS MANUAL OPERATION Having connected signal inputs and outputs as required, set the unit as followsThreshold, Ratio, Attack, Release Output Gain Display Switch Output Switch Peak Limit Stereo Link Display Expander - Anti clockwise 0 dB VU Bypass Off Off VU Off 1. Adjust input signal level on preceding equipment to show 0 dB on display, peaking to +2. 2. Change output switch to ‘norm’ and display switch to GR.
DL231 OPERATORS MANUAL 7 Using the Expander alone Disable the compressor by turning either the threshold or ratio anti-clockwise. Adjust the expander as described above but use compressor release control to adjust release time. An in-built ‘hold’ facility stabilises the expander against momentary gain reduction during short duration decreases in the signal level.
8 DL231 OPERATORS MANUAL TECHNICAL SPECIFICATIONS (Measurements taken at +4dBu operating level where applicable) INPUT IMPEDANCE BANDWIDTH MAXIMUM OUTPUT LEVEL 20KOhm 20Hz - 22KHz (1dB) +24dBm (Electronic - floating) +22dBm (Unbalanced) Send/Return Unbal, in phase input pin 2. SIDE CHAIN NOISE @ UNITY GAIN (Referred to +4dBm) Expander off. Wideband !83dB 22Hz-22KHz !90dB CCIR ARM !91dB IEC A !94dB Q. Pk CCIR !80dB DISTORTION 100Hz 1KHz 10KHz Unity gain +4dBm Input 0.025% 0.025% 0.
