Shure DFR11EQ Version 5, DFR11EQ 5 User Manual
*
DFR11EQ
Digital Equalizer with Feedback Reducer, Limiter and Delay
Version 5
Table of Contents
TABLE OF CONTENTS
WHAT’S NEW IN THE DFR11EQ Version 5 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
INTRODUCTION 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Hardware Features 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Software Features 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
THE DFR11EQ HARDWARE 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Front and Back Panels 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DIP Switches/Shure link Device ID 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DIP Switch and Feedback Reducer Options - Definitions 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DFR11EQ THEORY 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Feedback: Cause and Reduction 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DFR Limitations 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SETUP FOR FEEDBACK CONTROL 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
AUDIO CONNECTIONS 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DFR11EQ Version 5 SOFTWARE 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation and Set Up 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MAIN CONTROL PANEL AND RESPONSE GRAPH 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
USING THE FREQUENCY RESPONSE GRAPH 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Response Curves 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Snapshots 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GRAPHIC EQUALIZER 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PARAMETRIC EQUALIZER 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
FEEDBACK REDUCER 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DELA Y 26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using Delay in Common Applications 27. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LIMITER 29. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
OUTPUT CONTROLS 30. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IN/OUT Meters and Output Control 30. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reversing the Signal Polarity 30. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SAVING AND SELECTING SCENES 31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SHURE LINK NETWORKS 33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MAINTENANCE 34. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Customizing Graph Colors 34. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Printing DFR11EQ Settings 35. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Exiting the DFR11EQ Application 35. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
APPENDIX A. SPECIFICATIONS 36. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
APPENDIX B. CABLES 39. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
APPENDIX C. RACK MOUNTING THE DFR11EQ 41. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
APPENDIX D. KEYBOARD CONTROLS 42. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Trademark Notifications: Shure is a registered trademark of Shure Brothers Inc. Windows is a
registered trademark of Microsoft Corporation. Crystal is a registered trademark of Crystal
Semiconductor Corporation. Motorola is a registered trademark of Motorola, Inc. IBM is a registered
trademark of the IBM Corporation. Acrobat is a registered trademark of Adobe, Inc.
2
WHAT’S NEW IN DFR11EQ VERSION 5
The DFR11EQ Version 5 offers several new and improved features, including:
Faster Feedback Filters
filters provides an even greater level of protection against unwanted feedback.
Selection of Onboard Scenes using DFR Front Panel
through the scene buttons on the front panel. A total of 10 scenes may be saved onboard and accessed when
using the software interface. See
Limiter
limiting the level to which the signal level can rise. See
Increased Del ay Capabilities
creased from Version 4’s 100 ms of delay. See
One-Touch Filter Conversion in the DFR
bat feedback, they are adaptive notch filters. The new TO PEQ button on the DFR control window converts these filters to parametric filters. See
Quick Switch-Over Between Graphic and Parametric Equalization
would download the new equalizer each time the equalization mode was switched. Now they are stored
on board, making the switch-over almost instantaneous.
Improved Windows Interface -
ic or Parametric Equalizer, the Limiter and the Delay give the DFR11EQ Version 5 a cleaner, less-congested look with greater ease-of-use.
Advanced Networking Features
Global Scene Control and Remote Modem Access.
– The DFR11EQ Version 5’s new limiter prov ides a higher level of speak er and system pr otection by
– When feedback is detected, the DFR11EQ’ s faster reaction time in placing
– Up to three saved scenes can be accessed
Saving and Select ing Scenes
Limiter
– DFR11EQ Version 5 now features up to 1.3 seconds of digital delay, in-
Delay
.
- When the Digital Feedback Reducer creates filters to com-
Feedback Reducer Controls
Separate control windows for the Digital Feedback Reducer, the Graph-
– DFR11EQ Version 5 offers special advanced features, including
.
.
OTHER SYSTEM FEATURES
The DF R11EQ Version 5 also featu res these upgrades origin al ly intro d uced in Version 4
Switchable Graphic or Parametric Equalization:
izer or as a parametric equalizer. This flexibility can help meet your needs as dif ferent situations arise.
Use the graphic equalizer to equalize overall room sound; or use the parametric equalizer to control the
major feedback frequencies covered by the feedback filters, so you can free up all the feedback filters to
act as dynamic filters for stray feedback.
Editable Digital Feedback Filters:
filters, to give added control.
Digital Delay:
speakers. The audio signal to the remote loudspeaker is delayed until it is in alignment with the sound
waves coming from other loudspeakers in front. Phase cancellation and sound localization problems
are minimized. See
Scenes:
scenes) appears in the Recall Scene function, so you can find the desired scene before loading.
Hold Mode Automatically Restores the Basic Feedback Filter Setup:
DFR1 1EQ may change dynamic filters or deepen fixed filters, but the original settings will be restored the
next time you power up the unit. This is useful for storing the best filter settings for a given system.
Reverse the Output Signal Polarity:
the polarity of the audio signal, the DFR1 1EQ can reverse and correct the signal polarity. See
the Signal Polarity.
DFR11EQ Se tting Pr intouts:
for a select ed DFR11EQ, to document a sound installation. See Printing DF R11EQ Settings.
Input and Output Level Meters and Output Control:
fect of the signal processing on the audio signal. You can check these meters to see if the equalized
output sound levels are getting too low compared to the unaffected input levels. Y ou can use the output
control to raise the output level to an acceptable level. The frequency response curve graph will adjust
with the output level slider, showing you the current operating level. See
trol.
Undo:
Response Graph Snapshots:
curve. As you make changes in the filters or equalization, you can show the snapshot to see the difference between the old response and the new. See
This makes it possible to undo the most recent filter deletion.
The delay can improve the audio quality of a large sound system with widely spaced
Delay
.
Any number of scenes can be stored in separate files. A field (for entering descriptions of
With this option, you can print out a hardcopy which shows all of the settings
Y ou can edit the frequency, depth and width of individual feedback
If there is a piece of equipment in the sound system which inverts
When you take a snapshot, the computer stores the frequency response
The equalizer may be set to work as a graphic equal-
The input and output meters let you see the ef-
IN/OUT Meters and Output Con-
Snapshots
.
.
– Previously, the DFR11EQ
:
Table of Contents
When in Hold mode, a
Reversing
3
INTRODUCTION
The Shure Model DFR11EQ Version 5 is a single channel signal processor that combines an equalizer,
feedback reducer, limiter and delay in a single, half-rack enclosure. The DF R11EQ is designed to be placed in
a sound reinforc ement signal path to allow equalization of the overall sound system response and automati cally detect and control acoustical feedback. The DFR11EQ is designed for installed sound reinforcement
applications, such as theater s, conference rooms, meet ing halls or houses of wors hip. The DFR11EQ Version
5 is also an effective setup tool for controlling major feedback modes in live music applic at ions .
The equalizer of the DFR1 1EQ can be set to act as a 30–band graphic or a 10–band parametric equalizer.
The 1/ 3-oct ave graphic equalizer can boost up to 6 dB or cut 12 dB for each band. The paramet ric equalizer
offers adjust able frequency, up to 6 dB of boos t or 18 dB of cut, and up to a two octav e bandwidth.
The feedback reducer of the DFR11EQ Version 5 automatically inserts narrow notch filters at detected feedback frequencies. These notch filters stop a sound system from feeding back, but are narrow
enough so their effect on audio quality is minimized. The feedback detection algorithm constantly
searches for feedback, with or without the presence of program audio.
Hardware Features
S
Crystal* 20-bit A/D and D/A converters (Analog-to-Digital, Digital-to-Analog) allows 104 dB of dynamic range.
S
48 kHz sampling rate provides flat response to 20 kHz.
S
Onboard Scenes can be selected via front panel buttons.
1
S
/2 rack space chassis allows rack mounting of one or two units in a single rack space with no sagging or bending.
S
Shure Link Interface allows multiple Shure Link devices to be controlled with a single computer.
S
There are no internal batteries. Settings and DSP program are stored in internal EEPROM.
S
Electronically balanced input features combination 1/4-in. and XLR connector and can be used with balanced or
unbalanced outputs.
S
Independently driven, cross-coupled, balanced 1/4-in. and XLR outputs can be used with balanced or unbalanced
inputs, without signal loss.
S
Input and output levels are +4 dBu/–10 dBV DIP-switch-selectable.
S
88 MHz Motorola* DSP56009 processor engine features full 24-bit internal processing.
S
RS-232 interface allows external computer control and firmware updates.
S
Internal linear power supply is switchable between 120 and 230 Vac, eliminating the need for a cumbersome external power supply.
S
Solid state bypass eliminates unreliable mechanical relays.
Table of Contents
Software Features
S
Adaptive Notch Filter algorithm (patent pending) automatically detects feedback and deploys up to 10 narrow band
notch filters.
S
A tamper-proof equalizer can be switched between 30-band graphic or 10-band parametric equalizer.
S
The graphic equalizer is a constant-Q , 30-band, 1/3-octave graphic equalizer. It can boost up to 6 dB or cut 12 dB for
each band.
S
The parametric equalizer offers 10 filters with adjustable frequency, up to 6 dB of boost or 18 dB of cut, and up to a
two octave bandwidth.
S
Up to 1.3 seconds of Digital Delay.
S
Front and back panels both feature lockout control.
S
The Response Curve Viewer displays frequency response of the feedback reducer, equalizer, or both.
S
10 scenes can be stored on board. Multiple scenes can be stored to floppy or hard disk.
S
The Limiter provides added protection to external speakers and amplifiers.
4
DFR11EQ VERSION 5 HARDW ARE
Overview
Front Panel
DIGITAL EQ + FEEDBACK REDUCER
BYPASS
DFR FILTERS
Ê
SIGNAL CLIP
Ë
Ì
2
1
3
SCENES
Í
Ê BYPASS DFR FILTERS Button and LED. Press
this button to suspend feedback reduc er operat ion
and remove feedback filters from the audio path.
The bypass does not aff ect the equalizer, delay or
limiter. When the LED illuminates, the feedback
reducer is bypassed.
Ë SIGNAL LED. Illuminates when input signal is
present. Intensity varies with input signal level.
Ì CLIP LED. Illuminates when the input signal is
within 6 dB of clipping.
Í SCENE Selection Buttons and LEDs. Press
one of these three buttons to select a pre-set
scene. When a scene is selected, the
corresponding LED will light.
Back Panel
PRESS
TO LOCK
HOLD TO
CLEAR
Î
DFR FILTERS
Ï
DATA POWER
ÐÑ
Î LOCK/CLEAR Filters Button and LED. Press
and release this button to lock the filters you have
set. Hold down the button for three seconds, and
the filters will clear. The LED indicates that the
filters are locked.
Ï DFR FILTER LEDs (10). Indicate when individual
feedback filters are active. When a filter changes
or is added, the LED flashes, then stays on.
Ð DATA LED. Flashes in unison with the feedback
filter LEDs when the detector is deploying a new
feedback filter or changing an existing one, and
also blinks whenever the unit is communicating
with a connected computer.
Ñ POWER LED. LED illuminates when unit is
attached to a power supply.
Ê Power Connector with Integral Fuse. Connects
to AC power. The fuse is located in the drawer
below the connector.
Ë 9-Pin RS-232 Port. Connects the unit to a
computer. For use with DFR11EQ software and
for DSP firmware upgrades. (Compatible with
AMX and Crestron systems.
Ì Shure Link Interface. Allows linking of up to 16
Shure Link devices (DFR11EQs, DP11EQs, and
UA888s), which may be accessed by computer.
Í DIP Swi tches. Swit c hes 1 through 4 are used to
select the device ID. Switches 5 through 10 change
ÎÏÌËÊÍ
other available options. See
Î Output Connector—
cross-coupled, balanced outputs can be used with
balanced or unbalanced inputs. Can be switched
between +4 dBu/–10 dBV line-level operation by
DIP switch.
independently and either can be balanced or
unbalanced without affecting the other.
1
/4-Inch and XLR are driven
DIP Switches
1
/4-Inch & XLR. Active,
.
Ï Input Connector—Combined XLR and
1
/4-Inch. Active balanced input can be used with
balanced or unbalanced outputs. It can be
switched between +4 dBu/–10 dBV line-level
operation by DIP switch.
5
Table of Contents
DIP Switches
S
The DIP switches located on the rear panel are used for adapting the unit to the sound system
requirements. Switches 1 through 4 select the device ID number. Switches 5 through 10 change other
available options (see the table below).
DIP
WITCH
1–4 Device ID see below see below
5* Feedback Filter Bandwidth Select
6* Feedback Filter Memory Mode Update
7* Front Panel Lockout
8 unused — —
9 Output Sensitivity +4 dBu –10 dBV
10 Input Sensitivity +4 dBu –10 dBV
* DIP switches 5, 6, and 7 may be o ver-ridden in the Hardware Options window of the DFR11EQ software. See
Determines the Q of the feedback filter.
Disables the front panel controls, prote cts curr en t settings from tampering.
Shure Link Device ID
When your DFR11EQ is linked to other Shure Link devices, each one must be assigned a unique
Device ID, 0 through 15*. DIP switches 1 through 4 on the rear panel are used to set the Device ID. T o
change the Device ID, align the switches according to the illustrations below. The unit comes factory
preset to Device ID 15.
FUNCTION POSITION
UP DOWN
High Q
1/10-octave
Feedback Filters remain narrow as they
deepen.
Stores changed
feedback filter settings
on power down
Unlock
Front panel buttons
operational
widen as they deepen
Discards changed
feedback filter settings
on power down, but
holds original settings
Front panel buttons
Hardware Options
Low Q
1/10-octave
Feedback Filters
Hold
Lock
inactive
for details.
DEVICE ID 0
SWITCH UP
SWITCH DOWN
*UA888s may use Device IDs 0 through 3 only.
123
DEVICE ID 4
123
DEVICE ID 8
123
DEVICE ID 12
123
4
4
4
4
DEVICE ID 1
123
DEVICE ID 5
123
DEVICE ID 9
123
DEVICE ID 13
123
DEVICE ID 2
4
4
4
4
123
DEVICE ID 6
123
DEVICE ID 10
123
DEVICE ID 14
123
4
4
4
4
DEVICE ID 3
123
DEVICE ID 7
123
DEVICE ID 11
123
DEVICE ID 15
123
Table of Contents
4
4
4
4
6
DIP Switch/Hardware Options - Definitions
High Q Filters vs. Low Q Filters
The DFR1 1EQ offers two selections for the shape of the 1/10-octave notch filters: the High Q filter
(default) and the Low Q filter. A High Q filter’s width stays very narrow as the filter depth is increased.
This attenuates the minimum amount of signal possible to ensure system stability, while maintaining
excellent sound quality. This setting is appropriate for most applications.
The Low Q filter setting maintains the filter’s shape as it is deepened, so the width of the filter
effectively widens as the depth increases. Using this setting attenuates the signal more, producing a
greater system stability than the High Q setting, but with slightly diminished sound quality. This
setting is appropriate for systems such as a speech-only PA where stability is an absolute must, but
the sound quality can be compromised a bit.
The DFR1 1EQ High Q/Low Q setting may be switched at either DIP switch number 5 (see
Switch
section) or in the software’s Hardware Options window (see
HIGH Q
LOW Q
Hardware Options
DIP
section).
Front Panel Locking
The front panel of the DFR1 1EQ can be locked at either DIP Switch 6 (see
through the software’s Hardware Options window (see
tampering after the audio signal has been processed to meet the room’s requirements. In the
Hardware Options window, there is also an option to lock only the DFR controls. This allows users to
switch between scenes while maintaining protection of the filters within the scenes.
Hold/Update
The Hold/Update option is accessible using either DIP switch 6 (see
Hardware Options window (see
UPDA TE position:
the UPDA TE option is selected in the Hardware Options window, the DFR1 1EQ saves the feedback
filters every time the unit is powered off. When the DFR11EQ is powered on again, the feedback
filters will be at exactly the same settings as when the unit was powered down.
HOLD position:
option is selected in the Hardware Options window, the DFR1 1EQ immediately saves the feedback
filters at the current settings. When the DFR11EQ is powered off, any changes made to the feedback
filters after the switch was set will be forgotten. When powered on again, the feedback filter settings
will be exactly the same as when the HOLD/UPDA TE DIP switch was changed to the HOLD position.
This feature is useful for storing the best filter settings for a sound system.
DIP switch
Hardware Options
Hardware Options
When the HOLD/UPDATE DIP switch is in the UPDA TE position (default), or
When the HOLD/UPDATE DIP switch is in the HOLD position, or the HOLD
section). They operate in the following ways:
section). This prevents
DIP switch
section) or
section) or the
Table of Contents
7
Fixed and Dynamic Notch Filters
The DFR1 1EQ can control the notch filters as either
filter may change after it is created. The position of a dynamic filter may change if there is a need
detected for a new filter , such as when a hand-held microphone moves to a “hot spot” (a spot on stage
prone to feedback).
The DFR1 1EQ’s10 notch filters are factory preset as 5 fixed and 5 dynamic filters. The first filters
to be set are fixed, then the remaining filters are set as dynamic. After all 10 notch filters are set and a
new feedback frequency is detected, the DFR11EQ will remove the oldest set dynamic filter and
re-deploy it at the new feedback frequency . The fixed filters remain unchanged. However, if feedback
occurs at the same frequency as an existing dynamic or fixed filter, the existing filter will deepen.
An example of a system that would benefit from more fixed filters and fewer dynamic filters is one
that has fixed microphone and loudspeaker locations. In this type of system, the most dominant
frequencies of feedback are defined by the room dimensions and the microphone and loudspeaker
placement, and will not change appreciably. However, feedback can still occur, for instance, when
someone’s hand or head approaches a microphone. A good setting for this type of system would be 7
fixed filters for the non-changing feedback frequencies, and 3 dynamic filters to catch the feedback
frequencies caused by the talker.
On the other hand, more dynamic than fixed filters would be appropriate in a system that has
several non-stationary wireless microphones. Eight or even all 10 filters could be set to dynamic in
this type of system to obtain maximum feedback protection. As every application is different, some
experimentation is recommended to get the best results from a given sound system.
The ratio of fixed to dynamic filters can only be changed in the Hardware Options window . See the
Hardware Options
section for details.
dynamic
or
fixed.
Only the depth of a fixed
DFR11EQ Theory
Feedback: Cause and Reduction
When acoustical feedback occurs in a sound system, it is because the gain of the system is too
high. Since no sound system (microphones, loudspeakers, room acoustics, etc.) has an absolutely
flat frequency response, feedback will occur at specific frequencies before others; these are the
frequencies with the most gain. The operating principal of the DFR11EQ feedback reduction
feature is to lower the gain of these specific frequencies; then the system can operate with more
overall gain before it feeds back, without a perceptible difference in tonal quality.
At the heart of the DFR11EQ’s microprocessor is a very powerful algorithm that can accurately
and quickly discriminate between feedback and non-feedback sounds (such as speech and music).
When this algorithm detects feedback, it smoothly inserts a –3 dB, 1/10-octave filter into the audio
path to reduce the gain at the frequency which is feeding back. This filter is called a notch filter due to
the narrow section of frequency it affects. If the feedback does not stop, the filter depth is increased in
3 dB increments (to –18 dB) until the feedback stops.
Table of Contents
Frequency with excessive gain
Frequency after notch filter has been added
8
The illustrations below demonstrate how the DFR1 1EQ works in a sound system. The system on
the left shows a feedback loop, where the microphone picks up sound from the loudspeaker and
sends it back into the sound system. The system on the right shows how an installed DFR11EQ
reduces the gain on the worst case frequencies.
DFR11EQ
AMPLIFIER
AMPLIFIER
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After the DFR11EQ stops the feedback at the dominant frequency, the sound system may start
feeding back at the next dominant frequency . In this case, the DFR11EQ inserts another notch filter
into the audio path at the new frequency. The DFR1 1EQ can insert a total of 10 notch filters to reduce
feedback.
DFR1 1EQ Limitations
The DFR11EQ (or any other notch filter system) cannot entirely eliminate feedback in a sound
system, it can only help to reduce it. In a typical system, a point of diminishing returns is reached after
4 to 8 notch filters are set. This is because generally there are only a few dominant frequency
response peaks above the response of the entire system (figure 4A). The DFR1 1EQ works very well
controlling these peaks. The user can expect a 6 to 9 dB improvement of gain-before-feedback in a
typical system. However, if the system has too much overall gain, then all of the frequencies have too
much gain; instead of trying to notch out all of the frequencies, better results will be obtained by
lowering the gain of the system (Figure 4B). If the system still has insufficient gain, then other
changes must be made to the sound system such as different microphone or loudspeaker placement.
MICROPHONE
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MICROPHONE
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Figure 4A
Use notch filters to lower peaks
FREQUENCY RESPONSE OF AN UNEQUALIZED SOUND SYSTEM
Figure 4B
Lower overall gain of system
Feedback Threshold
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Setup for Feedback Control
The DFR11EQ hardware is designed to work in conjunction with the supplied software and a
personal computer to offer a wide range of digital sound processing options, including feedback
reduction, equalization, delay and limiting. However, the DFR1 1EQ may be used very effectively as a
stand-alone feedback reducer without the benefit of the software or a computer.
There are two basic ways in which to set-up the DFR11EQ as a stand alone feedback reducer:
the “Ring Out” method and the “Insurance Policy” method. Each is valid for different situations.
The “Ring Out” method is a preemptive measure in which the system gain is raised beyond the
normal setting to deliberately make the system feed back. The DFR11EQ will then set the proper
filters. The system gain is then reduced slightly, and the system is stable and useable. This set-up
method is primarily used for systems which are operated near the feedback point and need an extra
margin of stability.
For the “Insurance Policy” method, the DFR11EQ is simply installed in the sound system, but
filters are not set prior to use. The DFR11EQ adds extra insurance against feedback: the system is
not expected to feed back, but if it does, the DFR1 1EQ is there to catch it. This method is used for
systems which already have sufficient gain-before-feedback, but need protection from occasional
feedback occurrences due to non-stationary microphones or user-adjustable gain controls.
Setup
1. Connect the DFR11EQ in the desired signal path location. See
2. Set the input and output level DIP switches to the appropriate settings for the sensitivities
of the connected equipment.
WARNING: Other equipment may potentially be damaged aft er the DFR11EQ is
powered down if the DF R11EQ input is set to +4 and the output is set to –10. It is
recommended that you avoid using this setting.
Audio Connections.
3. Set the system gain to minimum, and power up all of the equipment.
4. Slowly raise the gain of the system, and set the gain of each microphone to achieve the
desired level.
5. The red CLIP LED should illuminate only on the highest signal peaks. If it illuminates
more frequently, check to see that the input level switch is set properly. If it is, lower the
level of the signal going into the DFR11EQ.
6. At this point it is highly recommended to equalize the sound system with the DFR11EQ’s
built–in equalizer (see
reducer is more effective on a well–equalized sound system.
Equalizer
) or an external equalizer. The DFR11EQ’s feedback
Ringing Out the System (“Ring Out” method only)
1. If necessary, clear any notch filters in the DFR11EQ by pressing and holding the CLEAR
button. Turn off the BYPASS and LOCK LEDs if they are not already off.
2. Slowly raise the gain of the signal going through the DFR11EQ. When feedback occurs,
the DFR11EQ will insert a filter deep enough to stop the feedback.
3. Repeat step 2 until all fixed filters are set. (There are 5 fixed filters, unless changed by
the user via the computer interface.)
4. Lower the gain by 3 to 6 dB to stabilize the sound system.
To store filter settings in the HOLD memory
1. Set the Hold/Update DIP switch to the Update position.
2. Ring out the room until all fixed filters are set.
3. Set the Hold/Update DIP switch to the Hold position.
4. During the performance, the DFR11EQ will change dynamic filters and deepen fixed
ones.
5. After the performance, turn the power off and back on; the DFR filters are restored to the
state they were in before the performance.
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Audio Connections
The DFR11EQ should be placed where an equalizer would be in a signal path.
The following four diagrams show typical connections. Because of its utility and flexibility, the
DFR11EQ can be connected in a large variety of different setups to benefit a sound system.
NOTE: All cables must be shielded. See Appendix B. for descriptions of all
cable and connection wiring.
Between the Mixer Main Output and the Power Amplifier
The DFR1 1EQ is most commonly placed between the main output of a mixer and the input of a
power amplifier . At the main output, the unit will af fect all input channels. This setup is ideal for using
the DFR11EQ as an equalizer and as a feedback reducer.
LINE IN
LINE OUT
MIXER
At a Subgroup Insert
When using a multiple bus mixer , the DFR11EQ can be connected to a single subgroup insert.
The unit will affect only the channels associated with that subgroup: the other channels will remain
unaffected.
SUB SEND
SUB RETURN
LINE
OUT
MAIN
DFR11EQ
LINE OUT
DFR11EQ
LINE IN
LINE IN
POWER AMPLIFIER
LOUDSPEAKER
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LINE IN
POWER AMPLIFIER
MIXER
LINE OUT
LOUDSPEAKER
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Inserted in an Input Channel
If only a single microphone is creating feedback problems, the DFR11EQ can be inserted on that
channel alone. This is especially useful for wireless microphones, because the constant movement
of a performer may bring the microphone too close to the sound reinforcement loudspeakers.
CHANNEL 1 IN
CHANNEL 1
INSERT
LINE
OUT
MAIN
LINE OUT
DFR11EQ
LINE IN
LINE IN
POWER AMPLIFIER
MIXER
LINE OUT
WIRELESS RECEIVER
Inserted Between Mixer and Monitor
Since monitor loudspeakers and microphones are usually in close proximity , the DFR11EQ can
be connected to stabilize a monitor system. Place a DFR1 1EQ on the mixer output which goes to the
monitor loudspeaker. For multiple monitor mixes, a DFR11EQ should be placed at the output of each
monitor send.
AUX 2
AUX 1
OUT
OUT
DFR11EQ
LINE OUT
LINE IN
DFR11EQ
LINE OUT
LINE IN
LINE IN
LINE IN
LOUDSPEAKER
MONITOR
POWER AMPLIFIER
MONITOR
LOUDSPEAKERS
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VERSION 5 SOFTWARE
Introduction
This section desc ribes the Version 5 Windows-based computer interface software which allows you
to utilize the full features of the Shure DFR1 1EQ. By connecting the DFR1 1EQ to your computer, you can
access the built-in digital equalizer, which can be configured in one of two ways: as a 30-band,
constant-Q, graphic equalizer, or as a 10-band parametric equalizer. The computer interface also allows
access to additional DFR control features to customize the operating characteristics of the feedback
filters. After the signal has been equalized and feedback filters have been created, the resulting res pons e
curve can be displayed in the frequency response graph as either a feedback filter response, EQ
response, or both combined. There is also a limiter to prot ect against potent ially damaging increases in
the output signal, and a digital delay which can add up to 1.3 seconds of delay from input to output.
Minimum Computer Requirements
The following are the minimum requirem ents to install and run the DFR11EQ Version 5 software.
S One 486DX 50 MHz IBM*-compatible computer (math coprocessor required)
S 2 MB hard drive space
S 4 MB RAM
S CD–ROM drive
S Windows version 3.1x, 95, 98 or NT
S 1 available RS-232 serial (COM) port
1
/3-octave,
S One RS-232 cable (9-pin to 9-pin or 9-pin to 25-pin)
Connecting the DFR11EQ to a Computer via the RS-232 (COM) Port
TO COMPUTER
RS-232 CONNECTOR
TO DFR11EQ RS-232
CONNECTOR (9-PIN MALE)
1. Examine the computer’s RS-232 (COM) port to determine whether it is a 9-pin or 25-pin
port. You will need either a 9-pin to 9-pin or a 9-pin to 25-pin RS-232 cable. For RS-232
cable diagrams, see
2. Connect a 9-pin plug (male) of the cable to the RS-232 port of the DFR11EQ.
3. Connect the other end of the cable to the RS-232 port of the computer.
Appendix B: Cables.
Software Installation
1. Insert the supplied CD-ROM into the CD-ROM drive of your computer. (After initial
installation, the CD-ROM is not necessary to run the software.)
2. The installation menu will appear. If you are using Windows 95 or greater or Windows
NT4 or greater, select DFR11EQ software by clicking on it. You will then be led through
the installation process. If you are using Windows 3.1X, go to File/Run and run
d:\SETUP16.EXE
3. Shure Setup will suggest a destination on your hard disk for the DFR11EQ files and will
check the computer hardware to ensure that a coprocessor is present. It will also prompt
you for your name and organizational information.
NOTE: Remember to register your software by filling out and mailing the
enclosed registration card, or online via the Shure World Wide Web site
(“http://www.shure.com”). This will ensure that you receive information about
software updates with additional features as they become available.
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