Behringer DSP1100 User Manual
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Behringer DSP1100 User Manual

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User´s Manual
FEEDBACK DESTROYER
DSP1100
English Version 1.1
May 1998
The information contained in this manual is subject to change without notice. No part of this manual may be reproduced or
transmitted in any form or by any means, electronic or mechanical, including photocopying and recording of any kind, for any
purpose, without the express written permission of Behringer GmbH.
ALL RIGHTS RESERVED © 1998 Behringer GmbH. BEHRINGER is a registered trademark.
BEHRINGER INTERNATIONAL GmbH, Hanns-Martin-Schleyer-Str. 36-38, D-47877 Willich-Münchheide II
Tel. +49 (0) 21 54 / 92 06-0, Fax +49 (0) 21 54 / 92 06-30.
1

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Summary of Contents for Behringer DSP1100

  • Page 1 Behringer GmbH. ALL RIGHTS RESERVED © 1998 Behringer GmbH. BEHRINGER is a registered trademark. BEHRINGER INTERNATIONAL GmbH, Hanns-Martin-Schleyer-Str. 36-38, D-47877 Willich-Münchheide II...
  • Page 2 Name and address of the manufacturer or the introducer of the product on the market who is established in the EC herewith take the sole responsibility to confirm that the product: FEEDBACK DESTROYER DSP1100 Type designation and, if applicable, Article-N...

  • Page 3: Safety Instructions

    SAFETY INSTRUCTIONS CAUTION: To reduce the risk of electrical shock, do not remove the cover (or back). No user serviceable parts in- side; refer servicing to qualified personnel. WARNING: To reduce the risk of fire or electrical shock, do not expose this appliance to rain or moisture.

  • Page 4: The Feedback Destroyer

    The FEEDBACK DESTROYER 2-channel Digital Feedback Destroyer / Parametric EQ powered by a 24-bit high-speed DSP 20-bit A/D and D/A converters with 64/128 times oversampling for ultra-high headroom and resolution of detail Automatically and “intelligently” searches out and destroys up to 12 frequencies per channel 24 fully programmable Parametric Filters that can be set manually or via MIDI “Set-and-forget”...
  • Page 5 BEHRINGER philosophy. It is our philosopy to share our joy with you, because you are the most important member of the BEHRINGER family. With your highly competent suggestions for new products you`ve greatly contributed to shaping our company and making it successful.

  • Page 6: Table Of Contents

    TABLE OF CONTENT 1. INTRODUCTION ........................7 1.1 Technical background ........................7 1.1.1 Feedback as a physical phenomenon .................. 9 1.1.2 Graphic equalizers ......................10 1.1.3 Parametric equalizers ......................10 1.2 The FEEDBACK DESTROYER ....................10 2. THE CONCEPT ........................12 2.1 The quality of components and circuit ..................12 2.2 Two independent channels ......................

  • Page 7: Introduction

    EQ’s using a trial-and-error ap- proach. To fully understand how the Behringer FEEDBACK DESTROYER works you will need to know the meaning of a few fundamental terms used in signal equalization, such as:...
  • Page 8 Jet Engine Threshold Of Pain Power Drill Machinery Hall "Loud" Office Normal Conversation Quiet Apartment Recording Studio Falling Leaves Threshold Of Audibility Fig. 1.1.: Dynamic range of human hearing As can be seen, human hearing has a very wide dynamic range of about 130 dB, which surpasses the range of a DAT or CD player with an approximate range of 96 dB.

  • Page 9: Feedback As A Physical Phenomenon

    Now the following relationship becomes clear: the higher the Q factor, the narrower the frequency band that can be cut or boosted. On the Behringer FEEDBACK DESTROYER you can adjust the relative bandwidth conveniently with the infinitely variable jog wheel. The filter bandwidth can be tuned from 2 octaves (120/60 octaves) down to 1/60 octave (for fine adjustments).

  • Page 10: Graphic Equalizers

    The microphones used are not operated in accordance with their directivity (e.g. cardioid/super-cardioid). The acoustic properties of the room are unfavorable. Tiled walls and floors heavily reflect the sound. All rooms feature a number of natural resonances sometimes with “high” quality factor. At such frequencies the potential risk of feedback is increased.
  • Page 11 For this reason, the FEEDBACK DESTROYER also uses a highly optimized version of the automated, fully parametric filters we designed for the Behringer ULTRA-CURVE. With the FEEDBACK DESTROYER your P.A. system will be under your control again!

  • Page 12: The Concept

    2. THE CONCEPT 2.1 The quality of components and circuit Behringer’s philosophy guarantees both perfect circuit design and no-compromise selection of components. A 24-bit DSP is used as the heart of the FEEDBACK DESTROYER, which is one of the best components available owing to its outstanding specifications and excellent sonic characteristics.

  • Page 13: Installation

    3.1 Rack mounting The Behringer FEEDBACK DESTROYER fits into one standard 19" rack unit of space (1 3/4"). Please allow at least an additional 4" depth for the connectors on the back panel.

  • Page 14: Selecting The Operating Level

    3.4 Selecting the operating level With the „Operating Level“ switch on the rear of the Behringer FEEDBACK DESTROYER you can adjust the internal operating level of the unit. Thus, the FEEDBACK DESTROYER can be adapted perfectly to various levels (e.g. both the typical home recording level of -10 dBV and the professional studio level of +4 dBu). The LED indicators on the front panel help you adjust the operating level as optimally as possible.

  • Page 15: Control Elements

    Fig. 4.1: Front panel controls elements The Behringer FEEDBACK DESTROYER is equipped with ten parameters keys, one jog wheel (rotary con- trol) which is used to alter the selected parameter or preset and a numeric LED display. Each of the 24 filters has one LED assigned to it, which informs you about the status of the filter.

  • Page 16: Display And Indicators

    Please, use the Total-Bypass function only with utmost caution because by deactivation, the FEEDBACK DESTROYER possibly unlocks suppressed feedbacks. Any modifications made to a preset can be stored with the help of the Store key. Ten presets are available on the FEEDBACK DESTROYER. Press and keep the In/Out and the Store keys for about two seconds, the FEEDBACK DESTROYER automatically enters MIDI mode.
  • Page 17 4.3 Rear control elements Fig. 4.4: Connectors and control elements on the rear of the FEEDBACK DESTROYER Use the Operating Level switch to adapt the FEEDBACK DESTROYER to different operating levels. You can select a -10 dBV semi-pro level used for home recording and a +4 dBu level used in profes- sional studios.

  • Page 18: Operation

    5. OPERATION The Behringer FEEDBACK DESTROYER can operate in four different modes. To meet more complex re- quirements with regard to flexible signal processing, these modes can be combined in a program. 5.1 Activating/deactivating the filters In Off mode, the corresponding filter is deactivated and can be activated by selecting one of the modes described below.

  • Page 19: Recalling Programs

    5.4.1 Recalling programs After power-up, the FEEDBACK DESTROYERs display reads the number of the preset last used. The jog wheel allows you to conveniently select the preset of your choice. Turn the rotary control to the left to step through the programs in descending order. Turn it to the right to increment the programs. The default preset is located in front of the first program.

  • Page 20: Storing Programs

    In Single-Shot and Auto mode it is not possible to change the filter parameters. In these modes you only are allowed to call up the parameters. However you can convert such a filter into a parametric one with same frequency and bandwidth, but with a gain of 0 dB. You simply have to press and keep the FILTER MODE key for about 2 seconds.

  • Page 21: The Basics Of Digital Signal Processing

    Change and MIDI Program Change commands will be transmitted when you edit or recall filter settings. Detailed information on this future software editor are available from our Behringer hotline (Germany: tel. (0)2154-920666), our international distributors and/or our Internet homepage http://www.behringer.de.
  • Page 22 sampling rate. The sampling rate determines the effective audio frequency range. The sampling rate must always be more than twice the value of the highest frequency to be reproduced. Therefore, the well known CD sampling rate of 44.1 kHz is slightly higher than twice the highest audible frequency of 20 kHz. The accuracy at which quantization takes place is primarily dependent on the quality of the ADCs and DACs being used.
  • Page 23 Take the following simple example using a sine wave. If an analog signal starts to overload, it results in the amplitude of the signal reaching a maximum level, and the peaks of the wave starting to get compressed, or flattened. The greater the porportion of the wave being flattened, the more harmonics, audible as distortion, will be heard.

  • Page 24: Applications

    6. APPLICATIONS The Behringer FEEDBACK DESTROYER features a high level of flexibility not only in the field of feedback elimination. The following chapter describes some other possible applications for your FEEDBACK DESTROYER. 6.1 Using the FEEDBACK DESTROYER in the monitor path Inserting the FEEDBACK DESTROYER into the monitor path of your mixing console gives you maximum protection against annoying feedback.

  • Page 25: Using The Feedback Destroyer In Single Channels And Sub-Groups

    the monitor path and in single channels with critical signals. If there is no other way to eliminate feedback, you can insert the FEEDBACK DESTROYER into the main mix bus. Unless your mixing console has dedicated insert points for the main mix bus, you can simply connect the FEEDBACK DESTROYER between mixing console and power amp.

  • Page 26: Using The Feedback Destroyer In A Studio Environment

    P.A. System Channel Sub-Group Insert Insert Master Out Fig. 6.2: Inserting the FEEDBACK DESTROYER in single channels and sub-groups 6.4 Using the FEEDBACK DESTROYER in a studio environment With its highly flexible configuration the FEEDBACK DESTROYER also delivers good results in a professional studio or home recording environment, as it provides a maximum of twelve fully parametric equalizers per channel in Parametric EQ mode.

  • Page 27: Digital Overflow

    6.6.2 Digital overflow When using the FEEDBACK DESTROYER as a parametric equalizer (Parametric EQ mode) and applying extreme attenuation values in the low end range of the frequency spectrum (below 50 Hz), you should perhaps set several filters to process the same frequency. Depending on the amount of attenuation applied, the use of only one filter may lead to internal memory overflow, which produces interference in the signal path.

  • Page 28: Frequency Chart

    7. FREQUENCY CHART In order to maintain a better survey only every second value is registered in the table. The adjustable values do not exactly fit into a 1/60 octave intervall, because also the ISO frequencies do not perfectly fit into a physical 1/3 octave intervall.

  • Page 29: Midi Implementation

    8. MIDI IMPLEMENTATION Function Transmitted Recognized Remark s Basic Default OFF, 1 - 16 OFF, 1 - 16 memorized Channel Changed OFF, 1 - 16 OFF, 1 - 16 Default 1,2,3,4 1,2,3,4 Mode Messages Altered Note Number True Voice Note ON Velocity Note OFF Key´s...

  • Page 30: Specifications

    3.2 kg BEHRINGER is constantly striving to maintain the highest professional standards. As a result of these efforts, modifications may be made from time to time to existing products without prior notice. Specifications and appearance may differ from those listed or shown.

  • Page 31: Warranty

    BEHRINGER INTERNATIONAL under the terms of this warranty will be repaired or replaced within 30 days of receipt of the product at BEHRINGER INTERNATIONAL. If the product needs to be modified or adapted in order to comply with applicable technical or safety standards...
  • Page 32 BEHRINGER INTERNATIONAL. § 6 CLAIM FOR DAMAGES Failure of BEHRINGER INTERNATIONAL to provide proper warranty service shall not entitle the buyer to claim (consequential) damages. In no event shall the liability of BEHRINGER INTERNATIONAL exceed the invoiced value of the product.

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