Symetrix 551E User manual

551E and 552E
Parametric Equalizers
User’s Guide
551E 552E
/

i
Table of Contents
Chapter 1 Introduction 1
Chapter 2 Operator Safety Summary 2
Chapter 3 Fast Set-Up 3
Chapter 4 Front Panel Controls 4
Chapter 5 Rear Panel Connections 7
Chapter 6 Operating Tips 9
Chapter 7 Applications 11
Chapter 8 Troubleshooting 13
Chapter 9 Specifications for the 551E 14
Chapter 10 Specifications for the 552E 15
Chapter 11 Warranty 16
Chapter 12 Service 17
Appendix A Adapter Wiring Examples 18
Appendix B Declaration of Conformity 19
Rev A.02, 1 January, 1998
Symetrix part number 53551E0A02
Subject to change at our whim and fancy without notice.
©1998, Symetrix, Inc. All right reserved.
Symetrix is a registered trademark of Symetrix, Inc.
Mention of third-party products is for informational
purposes only and constitutes neither an endorsement nor
a recommendation. Symetrix assumes no responsibility
with regard to the performance or use of these products.
Under copyright laws, no part of this manual may be
reproduced or transmitted in any form or by any means,
electronic or mechanical, including photocopying,
scanning, recording or by any information storage and
retrieval system, without permission, in writing, from
Symetrix, Inc.
Symetrix Inc.
14926 35th Ave. West
Lynnwood, WA 98037 USA
Tel [phone]
Fax [phone]
Email [e-mail]
Website www.symetrixaudio.com
551E 552E
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1
551E 552E
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IntroductionChapter 1
551E Front and Rear panels
BAND 5
BANDWIDTH CUT/BOOSTCUT/BOOST
BAND 4
FREQUENCY BANDWIDTHCUT/BOOSTFREQUENCY BANDWIDTH
BAND 3
FREQUENCY
0
850350 1.0
1.5K
2K100 .05 2.0 -20 +12
0
350 850 1.0
140
X1
X10
1.5K140
0
1.0
850350
X1
X10
1.5K
X1 140
X10 X0.1X0.1X0.1 2K100 .05 2.0 -20 +12 2K100 .05 2.0 -20 +12
(OCT)(OCT)(Hz) (dB) (dB)(OCT)(Hz) (Hz) (dB)
BAND 2
BANDWIDTH
FREQUENCY
BAND 1
BANDWIDTHFREQUENCYHIGH CUT CUT/BOOSTLOW CUTINPUT
SYSTEM CUT BANDS
850 0
1.0
350
0
1.5K140
X1
X10
350 850 1.0
18K
1.5K
42K X1 5K
115 X10 140
X0.1X0.1
65K3K 100 2K .05 +122.0 -20 2K100 .05 2.0 -20
5022
U
ACTIVE
E
8
BYPASS
551
EQUALIZER
PARAMETRIC
FIVE BAND
POWER CLIP -15 260+15 6
LEVEL (dB) (OCT)(Hz) (dB) (OCT) (Hz) (dB)
+12
CUT/BOOST
E
LYNNWOOD, WA, USA
MANUFACTURED IN
FIVE BAND PARAMETRIC EQUALIZER
INPUTOUTPUT
BALANCED/
UNBALANCED
BALANCEDBALANCED
12 3
INPUT
BALANCED/
UNBALANCED
551
TIP = HIGH(+) = PIN 2
21 3
OUTPUT
RING = LOW(-) = PIN 3
SLEEVE = GND = PIN 1
RING
TIP
SLEEVE
PERSONNEL.
TO QUALIFIED SERVICE
PARTS. REFER SERVICING
NO USER SERVICEABLE
THIS UNIT CONTAINS
15 WATTS
MAXIMUM
AC INPUT
FABRIQUÉ AUX E.-U. PAR SYMETRIX INC., LYNNWOOD, WASHINGTON.
RÉFÉREZ TOUTE RÉPARATION À UN TECHNICIEN QUALIFIÉ.
TYPICAL BALANCED CONNECTIONS
Thank you for choosing the 551E Five Band
ParametricEqualizerorthe552EDualFiveBand
ParametricEqualizer. [Withtheexceptionof
Chapters 9 and 10, all text in this User's Guide is
applicabletoboththe551Eand552E. Forbrevity
wewillusethename“551E/552E” torefertoboth
units.] Both models deliver superior fidelity,
flexibility, power, and precision through an
unbeatable combination of wide dynamic range,
ultra-lowdistortion,minimalphaseshiftand
ringing, easy to use controls and rock-solid
construction.The 551E/552Eisa leapforwardin
affordable equalizer technology.
Thefive,fullyparametricEQ bands are identical
in function. Each delivers up to 12 dB of boost
and 20 dB of cut, has an adjustable bandwidth
control (from .05 octaves to 2 octaves), and a
frequencycontrolrangefrom10Hzto20kHz.
Use each band anywhere in the audio spectrum,
not just the pre-selected ranges you find on most
equalizers. This can be very useful in sound
system work, among other things. For instance,
you can use three bands to correct low frequency
problems and still have two bands left for
midrange and high frequency work.
Youwillfind the 551E/552Eisjustasuseful for
recording and broadcast applications. The
wide control range allows you to perform
creative as well as corrective equalization.
Sweetening vocal tracks, getting that huge drum
sound, disk mastering, or perfecting your radio
station’s signature sound are the kinds of tasks
thatarewellwithinthe551E/552E’scapability.
As for sonic quality... Our proprietary topology
deliversextremelylow-noiseaudioperformance
- the kind you would normally expect only from
a much more expensive unit. We have also
included a servo balanced output that com-
pletely removes all DC offset, and direct-
coupled input and output stages that maximize
the551E/552E’slow-frequencyresponsewhile
minimizingnoiseanddistortion.
Inside and out, the 551E/552E is designed to
stand up to the worst abuse your roadies can
dish out. The tour-worthy all steel chassis
houses a double-sided fiberglass circuit board -
a significant advantage over the more common
phenolic PCBs. Gold-plated XLR connectors, a
bypass relay, and high precision components
ensure accuracy and reliability. Last, but not
least, the 551E/552E has an internal power
supply with a detachable cord.
Feel free to contact us if you have questions,
comments or suggestions at:
Phone [phone]
Fax [phone]
Email [email protected]
Website www.symetrixaudio.com
Officehours-8:00am-4:30pm PacificTime
(dB)
BAND 5
(OCT)(Hz) BANDWIDTH CUT/BOOST
0
1.0
350 850
1.5K
(dB)
CUT/BOOST
BAND 4
(OCT)(Hz)
FREQUENCY BANDWIDTH
0
140
X1
X10
1.0
350 850
1.5K140
(dB)(OCT) CUT/BOOSTFREQUENCY (Hz) BANDWIDTH
BAND 3
0
1.0
X1
X10
350 850
1.5K
X1
X10 140
FREQUENCY
+122.0
100 2K .05
BAND 5
-20
(dB)
0
(OCT)(Hz)
1.0
350 850
CUT/BOOSTBANDWIDTH
+12
1.5K
100 2K .05 2.0 -20
X0.1
-20 +12.05
100 2K
BAND 4
2.0
(dB)
0
(OCT)(Hz)
1.0
350 850
BANDWIDTHFREQUENCY CUT/BOOST
X0.1
+12.05 2.0 -20
2K100
X0.1
BAND 3
(dB)(OCT)
0
1.0
(Hz)
850350
FREQUENCY BANDWIDTH CUT/BOOST
140
X1
X10
X0.1
-20 +12
1.5K
140
2K100 .05 2.0
X1
X10
.05 2.0 +12-20 X0.1
1.5K
X1
X10 140
100
X0.1 2K
FREQUENCY
BAND 2
(dB)
(OCT)
BANDWIDTH
(dB) (Hz)
FREQUENCY
0
1.0
850
1.5K
350
0
140
X1
X10
BAND 1
BANDWIDTH
(OCT)
FREQUENCY
(Hz)
HIGH CUT
1.0
350 850
1.5K
18K
X1
X10
115 5K 42K 140
CUT/BOOSTLOW CUTINPUT
LEVEL (dB)
CHANNEL 1
22 50
U
8
ACTIVE
BYPASS
CUT BANDS
-20.05
2K 2.0
BAND 2
100
-20 +12 X0.1
(dB)
(OCT)
0
1.0
850
(dB)
350
0
(Hz)
FREQUENCY BANDWIDTH
2.0.05
2K100
BAND 1
X0.1
3K 65K
(OCT)(Hz)
1.0
850350
42K
18K
5K
HIGH CUT FREQUENCY BANDWIDTH CUT/BOOST
1.5K
-20
2K .05 2.0
140
X10
X1
-20 +12 X0.1 100
1.5K
100 2K 2.0.05
X1
X10
115
3K 65K X0.1
140
2606+15-15
CLIP
CHANNEL 2
LEVEL (dB)
5022
U
ACTIVE
BYPASS
LOW CUTINPUT
PARAMETRIC
EQUALIZER
DUAL
FIVE BAND
8
-15 +15 6 260
POWER CLIP
CUT BANDS
552 E
+12
CUT/BOOST
+12
CUT/BOOST
1
3
221 3
OUTPUT INPUT
CH1 INPUT
BALANCED
CH1 OUTPUT
UNBALANCED
UNBALANCED
BALANCED
BALANCED/ BALANCED/
SLEEVE = GND = PIN 1
RING = LOW(-) = PIN 3
TIP = HIGH(+) = PIN 2
SLEEVE
RING
BALANCED TIP
BALANCED/
UNBALANCED
BALANCED/
UNBALANCED
BALANCED
CH2 OUTPUT CH2 INPUT TYPICAL BALANCED CONNECTIONS
ELECTRIC SHOCK DO NOT EXPOSE
TO REDUCE THE RISK OF FIRE OR
CAUTION
WARNING:
NE PAS OUVRIR
RISQUE DE CHOC ELECTRIQUE
No user serviceable parts inside. Refer servicing to qualified service personnel.
S’adresser a un reparateur compétent.
SEE OWNERS MANUAL. VOIR CAHIER D’INSTRUCTIONS.
Il ne se trouve a l’interieur aucune piece pourvant entre reparée l’usager.
AVIS:
THIS EQUIPMENT TO RAIN OR MOISTURE
552E
AC INPUT
20 WATTS
MAXIMUM
RÉFÉREZ TOUTE RÉPARATION À UN TECHNICIEN QUALIFIÉ.
FABRIQUÉ AUX E.-U. PAR SYMETRIX INC., LYNNWOOD, WASHINGTON.
LYNNWOOD, WA, USA
MANUFACTURED IN
PARAMETRIC EQUALIZER
DUAL FIVE BAND
DO NOT OPEN
RISK OF ELECTRIC SHOCK
552E Front and Rear panels

2
551E 552E
/
The information in this summary is intended
for persons who operate the equipment as well
as repair personnel. Specific warnings and
cautions are found throughout this manual
wherever they may apply; they do not appear
in this summary.
The notational conventions used in this manual
and on the equipment itself are described in the
following paragraphs.
CAUTION
WARNING:
ATTENTION:
RISQUE DE CHOC ELECTRIQUE
NE PAS OUVRIR
S’adresser a un reparateur compétent.
THIS EQUIPMENT TO RAIN OR MOISTURE
ELECTRIC SHOCK DO NOT EXPOSE
TO REDUCE THE RISK OF FIRE OR
No user serviceable parts inside. Refer servicing to qualified service personnel.
Il ne se trouve a l’interieur aucune piece pourvant entre reparée l’usager.
DO NOT OPEN
RISK OF ELECTRIC SHOCK
The lightning flash with arrowhead symbol
within an equilateral triangle is intended to alert
the user of the presence of uninsulated
"dangerous voltage" within the product's
enclosure that may be of sufficient magnitude
to constitute a risk of electric shock to persons.
The exclamation point within an equilateral
triangle is intended to alert the user of the
presence of important operating and mainte-
nance (servicing) instructions in the literature
accompanyingthe551E/552E(i.e.thisguide).
Caution To prevent electric shock, do not
use the polarized plug supplied
with the 551E/552E with any
extension cord, receptacle, or
other outlet unless the blades can
be fully inserted.
Terms
Several notational conventions are used in this
manual. Some paragraphs may use Note,
Caution, or Warning as a heading or certain
typefaces and capitalization are used to
identify certain words. These are:
Note Identifies information that needs
extra emphasis. A Note generally
supplies extra information to help
you to better use the 551E/552E.
Equipment Markings
Operator Safety Summary Chapter 2
Caution Identifies information that, if not
heeded, may cause damage to the
551E/552E or other equipment in
your system.
Warning Identifiesinformationthat,if
ignored,maybehazardousto
yourhealthorthatofothers.
CAPITALS Controls, switches or other
markingsonthe551E/552E's
chassis.
Boldface Strong emphasis.
Power source - This product is intended to
operate from a power source that does not
apply more than 255Vrms between the power
supply conductors or between either power
supply conductor and ground. A protective
ground connection, by way of the grounding
conductor in the power cord, is essential for
safe operation.
Dangerfrom loss ofground- If the protective
ground connection is lost, all accessible
conductive parts, including knobs and
controls that may appear to be insulated, can
render an electric shock.
Properpowercord-Useonlythe powercord
specified for the product. Use only a power
cord that is in good condition.
Operating location - Do not operate this
equipment under any of the following condi-
tions: explosive atmospheres, in wet locations,
in inclement weather, improper or unknown AC
mains voltage, or if improperly fused.
Stayoutofthebox-Toavoidpersonal injury
or injury to others, do not remove the product
covers or panels. Do not operate the product
without the covers and panels properly
installed.

3
551E 552E
/
Plugthe551E/552E into anACoutlet
using the IEC-type detachable power
cord.
Connect audio inputs and outputs. If
you do not know how to do this, forget
Fast Set-Up and read Chapter 5.
Push the Active/Bypass button IN.
Set the Input Gain control to 12:00 (unity
gain).
Turn the Low Cut control fully counter-
clockwise and the High Cut control fully
clockwise.
Set all five Cut/Boost controls to 12:00
(zero detent).
You are ready to start.
Now read the manual.





















Fast Set-Up
This is the section for those of you who are really in a hurry and cannot take a moment to wade
through another owner’s manual. Just follow these steps:
Chapter 3




4
551E 552E
/
Front Panel Controls Chapter 4
Input Level
Use this control to adjust the input sensitivity
by±15dB. Since the551E/552E’sinputhas 18
dB of headroom above +4dBm, the unity gain
position(12:00)shouldworkfornormal
operating conditions. However, if you apply
extreme amounts of EQ boost or find that the
input signal level is too high (the clip LED will
illuminate), you may need to increase your
input headroom. Do this by turning the knob
counterclockwise to attenuate the input signal.
If you find that the input signal is very low (the
output of a -10 device is a good example), turn
the input level control clockwise to boost the
level of the signal going through the 551E/552E.
Thiswill optimize the signal-to-noise ratio.
Figure 1 - Partial view of front panel controls.
Diagram 2 - Low cut filter with
12 dB per octave.
AUDIO PRECISION 551E vs 23 MAY 96 10:49:15
-20.00
-15.00
-10.00
-5.000
0.0
5.0000
10.000
15.000
20.000
AMPL(dBu)
20 100 1k 10k 20k
FREQ(Hz)
Bypass Button
Push this button into the ACTIVE position to
engagethe551E/552E’scircuitry.TheBY-
PASS (out) position shunts the input signal
directly from the input jacks to the output
jacks via a relay. There are no passive or
active components in the signal path in this
mode.
Note: The relay mechanism is also engaged
when the AC power is disconnected,
enabling the unit to pass signal even
when the power is off.
HIGH CUT
42K
115 5K
18K
3K 65K
SYSTEM
LOW CUTINPUT
LEVEL (dB)
8
U5022
E
ACTIVE
BYPASS
2606+15-15
POWER CLIP
551
EQUALIZER
PARAMETRIC
FIVE BAND
CUT BANDS
[Withthe exceptionof Chapters 9 and 10,all textin thisUser's Guideis applicableto boththe
551E and the 552E. For brevity we will use the name “551E/552E” to refer to both units.]
Low Cut Filter
Diagram2illustrates a12dB
per octave low frequency
roll-off filter. Use this to
protect subwoofers in
sound systems, clean-up
muddy recordings, or
increase speech intelligibil-
ity in announce systems.
The frequency range is 6Hz
(essentially this is bypass)
to260Hz.
SystemControls
CutBandControls

5
551E 552E
/
Cut/Boost Knob
This control delivers up to 12 dB
of boost or 20 dB of cut at the
frequency selected by the
frequency control and range
switch. SeeDiagram5.
Note: We’ve provided a wide
range on this knob to
help you take care of the
occasional drasticprob-
lem, but you’ll get better
results from this (or any)
EQ if you use this control
inmoderation.
Diagram 3 - High cut filter
with 12 dB
per octave.
Figure 4 - Front panel view of one EQ band.
AUDIO PRECISION 551E vs 23 MAY 96 10:54:00
-20.00
-15.00
-10.00
-5.000
0.0
5.0000
10.000
15.000
20.000
AMPL(dBu)
20 100 1k 10k 20k
FREQ(Hz)
BAND 1
(Hz) (OCT)
BANDWIDTHFREQUENCY CUT/BOOST
(dB)
+12
850
1.5K
-202.0.05
2K
140
X1
X0.1
X10 100
350 1.0 0
Bandwidth
This knob determines how wide an area the
band will affect, hence the term bandwidth.
The knob is calibrated in terms of octaves. The
range is .05 (1/20th) to 2 octaves. Use the .05
setting for notch filter applications and the 1.0-
2.0 range for “tone control” type sweetening.
Diagram 5 -Typical Cut/Boost curve.
AUDIO PRECISION 551E vs 23 MAY 96 10:01:21
-20.00
-15.00
-10.00
-5.000
0.0
5.0000
10.000
15.000
20.000
AMPL(dBu)
20 100 1k 10k 20k
FREQ(Hz)
High Cut Filter
Diagram3illustratesa12dB
per octave high frequency
roll-offfilter.Therangeof
this control is 3kHz to
65kHz.
EQControls

6
551E 552E
/
Diagram 6 - Frequency graph.
Diagram 7 - Range switch action.
AUDIO PRECISION 551E vs 23 MAY 96 10:02:53
-20.00
-15.00
-10.00
-5.000
0.0
5.0000
10.000
15.000
20.000
AMPL(dBu)
20 100 1k 10k 20k
FREQ(Hz)
Frequency
knob range
AUDIO PRECISION 551E vs 23 MAY 96 10:09:46
-20.00
-15.00
-10.00
-5.000
0.0
5.0000
10.000
15.000
20.000
AMPL(dBu)
20 100 1k 10k 20k
FREQ(Hz)
1kHz
X0.1 1kHz X 1 1kHz X 10
FrequencyKnob
Use this knob, in conjunction with
the Frequency Switch, to adjust
the center frequency of the area
affected by the filter band. See
Diagram6.
FrequencySwitch
Think of this as a Frequency knob
multiplier. When you put the
toggle in the X1 position the
range of the Frequency control
corresponds to the numbers
printed around the knob - 100 Hz
to 2kHz. Use this position when
you want to work in the midrange.
The X10 position shifts the
Frequency knob’s range upward
by a factor of 10. The range
becomes1kHzto 20 kHz;suitable
for high-frequency adjustments.
The X0.1 position moves the
rangedownwards (10 Hz to 200
Hz), for fine resolution in the low-
frequency area. See Diagram 7.
Before you ask, we want you to
know that we know it seems to
makes no sense that X1 is the top
switchposition,X10 is middle,
and X0.1 is bottom. Our resident
circuit guru informs us that there
is no way to wire this toggle
switch so that it works in the
logical order. If you need proof
just look at someone else’s
parametricEQtoggleswitch.

7
551E 552E
/
Rear Panel ConnectionsChapter 5
Input Jacks
The551E/552EisequippedwithanXLRanda
¼" jack. Both will work either balanced or
unbalanced and will generally accommodate
just about any standard +4dBu nominal line
level audio source. If you plan on plugging a
micdirectlyintothe551E/552E’sXLRinput...
don’t bother. It will not hurt anything, but it
just will not work. The input jacks are config-
ured as follows:
XLR
pin 1=ground
pin2=+/high
pin3=-/low
¼"Balanced
tip = +/high
ring=-/low
sleeve=ground
See Appendix A for adapter wiring examples.
Figure 8 - View of rear panel connectors.
INPUT
BALANCED/
UNBALANCED
BALANCED/
OUTPUT
BALANCED
3
INPUT
221
3
RING
TIP
SLEEVE
1
OUTPUT
TYPICAL BALANCED CONNECTIONS
UNBALANCED
BALANCED
RING = LOW(-) = PIN 3
SLEEVE = GND = PIN 1
TIP = HIGH(+) = PIN 2
Output Jacks
There are two output jacks wired parallel to
each other - a balanced XLR, and a balanced
¼" TRS. These can drive balanced or unbal-
anced inputs but you should check Appendix
A for wiring examples. The outputs are
configured as follows:
XLR
pin 1 = ground
pin 2 = +/high
pin3 = -/low
¼"Balanced
tip = +/high
ring=-/low
sleeve = ground

8
551E 552E
/