Orban 622B User manual

622 Parametric Equalizer
OPERATING MANUAL

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Performance Specifications
Specifications apply to each channel
except as noted. All specifications apply
when equalizer drives 600 ohm or higher
impedances. All noise specifications
assume a20-20,000 Hz bandpass filter
with 18 dB/octave Butterworth skirts.
Operating Controls: EQUALIZATION,
EQUALIZATION IN/OUT, BAND
WIDTH, and TUNING for each of four
bands. MASTER EQUALIZATION
IN/OUT, GAIN, POWER ON/OFF.
Frequency Response: (EQ controls set
mechanically flat) ±0.25 dB, 20-20,000 Hz.
Available Gain: +12 dB, adjustable to -oo
by means of front-panel GAIN control.
Input: (RF suppressed)
Impedance: (each leg) 100K in parallel
with lOOOpF, electronically balanced.
Driving impedance should be 600
ohms or less.
Absolute Overload Point: +26dBm.
Output: (RF suppressed)
Level: greater than +19 dBm into 600
ohms, 20-20,000 Hz
Impedance: 47 ohms in parallel with
lOOOpF, unbalanced. (Option 01
provides atransformer-balanced
output for both channels)
Equalizer is unconditionally stable and
will not ring with any captive load.
Risetime: less than 4microseconds.
Slew Rate: greater than 6V/microsecond.
Internal bandlimiting assures that slew
rate limiting will not occur with even the
most severe equalization and program
material.
Square Wave Response: Square wave
exhibits no spurious ringing at any output
level. The only ringing observable is that
theoretically associated with any given
equalization curve.
Circuitry: active RC, utilizing FET-input
IC opamps. The output line driver utilizes a
discrete transistor current booster.
Total Harmonic Distortion (+ 18 dBm
output): less than 0.025%, 20-20,000 Hz.
Typically less than 0.002% at 1kHz, +18
dBm.
SMPTE Intermodulation Distortion:
Typically 0.008% at +18 dBm equivalent
peak output, using 60 Hz/7 kHz; 4:1.
Noise: At Output, GAIN control adjusted
for unity gain, all EQ switches IN, all EQ
controls FLAT: Less than -84 dBm;
-87 dBm typical.
Overload-to-noise Ratio of Single
Parametric Bandpass Filter: greater
than 102 dB for any combination of
TUNING and BANDWIDTH settings.
Interchannel Crosstalk, 622B dual-
channel equalizer: less than -90 dB,
20-20,000 Hz.
Equalization Characteristics: Figure 1
shows curves corresponding to the
maximum and minimum bandwidths for
each band. DB equalization contributions
of the individual bands add without inter-
action. BANDWIDTH, TUNING, and
EQUALIZATION controls are all contin-
uously variable.
Range of Adjustment of “Q”: 0.29 to 3.2.
Range of Adjustment of Peak Equal-
ization: +16 dB to -oo .Typical notch
depth obtainable is 40 dB.
Tuning Range (per band): 20-500 Hz,
68-1700 Hz, 240-5850 Hz, 800-20,000 Hz.
Tuning dials are calibrated at ISO preferred
frequencies.
Power Requirements: 115/230 volt 50-60
Hz AC, approximately 4watts (622A), 7
watts (622B). Captive “U-Ground” power
cord. Option 02 eliminates the AC power
supply. Power requirements for the Option
02 version are ±18 to 28 volts DC at
60 ma per equalizer channel. Option 02 is
supplied on special order only, and is
recommended only for users planning to
install alarge number of 622 channels
in agiven installation.
Overload Lamp: will light for approxi-
mately 200 mS if the instantaneous peak
output of any amplifier in the equalizer
is driven within 1dB of its clipping point.
Size: 19" (48.3 cm) wide x3.5" (8.9 cm)
high x 5.2" (13.3 cm) deep.
Shipping Weight: 10 lbs. (4.5 kg).
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1525 Alvarado Street. San Leandro, CA 94577 USA
Phone: [phone]; Fax: [phone]; E-Mail: [email protected]; Site: www.orban.com
P/N: 95013.000.10

Table of Contents
Specifications
Registration Card ^
Warranty 13
Is
IPart A: Installation and Operation
IIntroduction
1Performance Highlights
2Front Panel Description '
°
2Rear Panel Description
3AC Power
3Mechanical Installation
Balanced Output Tranformer Installation
4Electrical Installation
Input
Output ^
Wiring With Two-Conductor Shielded Cable
Grounding Diagram
Typical Input/Output Connection Rules
6OPERATING INSTRUCTIONS
Using the EQ Section
Boost/Cut Curve Familes
Headroom
Part C: Maintenance
Introduction
Performance Evaluation and Alignment
General
Power Supply
Signal Processing Circuitry
Maintenance and Service
Preventive Maintenance
Control Replacement
Replacement of Components on Printed Circuit Boards
Troubleshooting 1C Opamps
Factory Service
Shipping Instructions
Circuit Description
General
Input Buffer
Equalizer Sections
EQ IN/OUT Switch
Overload Indicator
Output Buffer
Power Supply
8Part B: Specific Applications 24 Appendix: Interconnections And Grounding
8Stereo
9Sound Reinforcement
House Tuning
Notch Filtering
Stage Monitors
Individual Driver Equalizer
10 Dance Bars
IIRecording Studios
I I Motion Picture Sound
12 Broadcasting
12 Electronic Music
24 Driving the Input From High-Impedance And/Or High-
Level Sources
24 Grounding
26 PARTS LIST
30 PARTS LOCATOR
31 SCHEMATIC

REGISTRATION The original purchaser should have received apostpaid Registration Card packed
CARD with this manual.
Registration is of benefit to you because it enables us to tell you of new
applications, possible performance improvements, service aids, etc., which may be
developed over the life of the product. It also provides us with the date of sale so
that we may more promptly respond to possible claims under Warranty in the
future (without having to request acopy of your Bill of Sale or other proof of
purchase).
Please fill in the Registration Card and return it to us.
If the Registration Card has become lost or you have purchased the unit used,
please photocopy the image of the card reproduced below and send it to us in an
envelope. Use the address shown on the title page.
Model #Serial #
Name or Title
Organization
Street
City/State/Country
Zip or Mail Code .
Purchased from City Date of Purchase
Nature of your application
How did you hear about it?
Comments:
Fig. I: REGISTRATION CARD
WARRANTY The Warranty, which applies only to the first end-user of record, is stated on the
Warranty Certificate on aseparate sheet packed with this manual. Save it for
future reference.
Details on obtaining factory service are provided in Part C.

Part A: Installation and Operation
INTRODUCTION The Orban 622A/B are parametric equalizers of high professional quality. The
622A is asingle-channel equalizer; the 622B is adual-channel equalizer. Each
channel contains four parametric equalization bands.
Isolation of the two channels in the 622B is extremely high (greater than -90dB,
20-20, 000Hz). Therefore, each channel may be used independently without danger of
audible crosstalk.
The 622 is equipped with rotary-type EQ controls providing up to lodB of boost
and better than 40dB of cut. The controls are non-reciprocal, providing musically
useful "constant-Q" characteristics, and permitting the equalizer to be used as a
notch filter. The center frequency and bandwidth of each band are continuously
variable to enable precise control of the audio spectrum.
Each channel of the 622 has an electronically-balanced bridging input and an
unbalanced output which can be balanced by the addition of an optional output
transformer. Input, output, and power line connections all contain effective RF
filtering. l2dB of gain is available. Aj| potential overload points in the equalizer
are monitored by an extremely fast "peak -stretching" overload detector, so that
peak clipping can be detected and corrected before it becomes audible.
The flexibility offered by the 622 makes it aparticularly powerful tool in nearly
all areas of audio: sound reinforcement, public address, recording studio,
broadcasting, motion picture sound, dance bars (discos), theater...
The 622 easily meets the quality, performance, and reliability requirements of the
demanding professional, and is also well-suited for use in semi-pro or audiophile
applications.
The controls and features of the 622 are fully described in this manual. It will
familiarize you with the unit's potential and enable you to imaginatively use the
622 for your specific installation and application.
PERFORMANCE
HIGHLIGHTS EQ Section
Four bands, each with TUNING and BANDWIDTH control
True parametric operation: non-interacting control over all three equalization
parameters
+l6dB, -infinity equalization range
"Constant-Q" curves
Each band tunes over 25: 1frequency range
"Q" is variable between 0.29 and 3.2
Bands are totally non-interacting
In/out switches for each equalizer band

Circuitry highly resistant to performance deterioration caused by control wear
FRONT PANEL
DESCRIPTION
REAR PANEL
DESCRIPTION
General
l2dB available gain
Very low noise and distortion
High slew rate for minimum TIM (SID)
"Peak-stretching” overload lamp warns of clipping anywhere in equalizer before
distortion is audible
Industrial-grade parts and construction
Extremely easy service access
RFI suppression on input, output, and power leads
Balanced output optional (order retrofit kit as required)
The INPUT control adjusts the drive level to the equalizers.
The OVERLOAD indicator monitors all critical points to warn of excessive signal
amplitude due to excessive input amplitude or to large amounts of peak boost
equalization. It indicates peak clipping substantially before any audible effects are
perceived. Overloads are eliminated by turning down the INPUT control.
The CHANNEL EQ IN/OUT switch defeats the entire EQ section, but retains the
input buffer and output amplifier so that no gain changes (other than those
associated with large amounts of equalization) occur. In the OUT position, the
OVERLOAD LAMP will still operate as if full equalization were occurring.
Input/output polarity is constant regardless of the position of this switch.
The BAND EQ IN/OUT switches defeat the equalization action of agiven
equalizer band by disconnecting the output of the bandpass resonator from its
summing amplifier. Putting unused bands in the OUT position will eliminate any
noise contribution from the resonators and will assure accurate flat response.
The EQ controls adjust the maximum peak or dip in each band over arange of
+!6dB, -infinity dB.
The TUNING controls adjust the center frequency of each of the four bands, and
have atypical calibration accuracy of +1/3 octave.
The BANDWIDTH controls adjust the "Q" (sharpness) of each band. The "Q"
becomes broader when turned clockwise; sharper when turned counterclockwise.
Calibration tolerance is typically +10% of the nominal "Q" value.
The FUSE used in the 622 is a3AG slo-blo type: 1/8 amp for either I15V or
230V operation. Replace with the same type only.
The INPUT and OUTPUT connectors provided allow connection via barrier strip (//5
screw).
2

AC POWER The power transformer can be strapped for I15 volt or 230 volt 50 or 60Hz AC
operation. If the unit was ordered for 230 volts, a tag on the power cord warns of
the modification.
The two primary windings of the power transformer are connected in paral lei for
115 volt operation, and in series for 230 volt operation. (See the Schematic
Diagram at the back of this manual.)
To strap the power transformer for adifferent voltage, remove the top cover of
the 622. Strapping instructions are found on the insulating fishpaper around the
power tranformer. It is not necessary to rearrange the heavy insulated wiring; all
strapping can be performed with bare jumper wire. Take care not to burn the
insulation.
The power cord is terminated in a"U-Ground" plug to USA standards. The green
(or green/yellow) wire (which is connected to the long prong) is connected directly
to the 622 chassis. If it becomes necessary to lift this ground to suppress ground
loops, this should be done with athree-prong to two-prong adapter plug, rather
than by damaging the power plug. It is not recommended that this ground be
defeated unless absolutely necessary because it eliminates the intrinsic safety
feature of the three-wire system.
WARNING!
IF THE GROUND IS DEFEATED, CERTAIN FAULT CONDITIONS IN
THE UNIT OR THE SYSTEM TO WHICH IT IS CONNECTED CAN
RESULT IN APPEARANCE OF FULL LINE VOLTAGE BETWEEN
CHASSIS AND EARTH GROUND. SUCH VOLTAGE IS CAPABLE OF
CAUSING SEVERE INJURY OR DEATH!
MECHANICAL Vertical space of two standard rack units (3 l/2"/8.9cm) is required.
INSTALLATION Mounting the unit directly over large heat-producing devices like avacuum-tube
power amplifier may shorten component life and is not recommended. Ambient
temperature should not exceed 113 degrees F(45 degrees C) when equipment is
powered.
Balanced Output Transformer Installation: If transformers were not installed at
the factory, refer to the installation instructions furnished with the transformer
retrofit kit, available directly from Orban. The transformers supplied with this kit
have been designed to have anegligible effect on published specifications. Should
you wish to use some other transformers, it would be wise to make careful
performance measurements with special attention to LF distortion and HF response
at high output levels, thus determining the output level achievable with
performance acceptable for your application. Atransformer meeting Orban
standards should produce approximately +20dBm (limited by clipping in the output
amplifier) without significantly compromising performance.
The Electrical Installation section describes grounding procedures in the event
transformers are used.
3

ELECTRICAL Connecting the 622 Equalizer to other equipment is quite straightforward.
INSTALLATION Relatively uncomplicated systems (such as home playback systems, "semi-pro"
recording studios, electronic music studios, dance bars, etc.) tend to come together
without serious grounding problems even if the wiring practices are somewhat
casual, provided that high RF fields are not present. Unusual situations can be
analyzed if you are familiar with the standard rules governing grounding and
interfacing between balanced and unbalanced systems.
The instructions below will apply to the majority of cases. Acomprehensive
discussion of interconnections and grounding can be found in the Appendix.
Input
The electronically-balanced input of each channel of the 622 equalizer is
compatible with most professional and semi-professional sound equipment, balanced
or unbalanced, whose source impedance is 600 ohms or less. If it is greater (as in
some vacuum-tube audiophile preamps), aminor modification may be made to the
input to accomodate the situation. Please refer to the Appendix for further details.
Nominal input level is between -10 and +4dBm. The absolute overload point is
+26dBm.
Output
The two outputs of each channel of the 622 are unbalanced (unless fitted with the
optional transformers), and the source impedance is 47 ohms in parallel with lOOOpF
to the chassis (for RFI suppression).
Wiring the 622 With Two-Conductor Shielded Cable
We recommend wiring with two-conductor shielded cable (such as Belden 8451 or
equivalent) because signal current flows through the two conductors only. The shield
does not carry signal, is used only for shielding, and is ordinarily connected to
ground at one end only. The following table and diagram are applicable to agreat
majority of installations.
4

TABLE I:
TYPICAL INPUT/OUTPUT CONNECTION RULES
INPUT
Always use "+" and as the two input terminals to the 622.
When the 622 is driven from an unbalanced source, connect shield both to
circuit ground of source, and to chassis ground of 622.
When the 622 is driven from abalanced source, connect shield at source end
to chassis ground. Do not connect shield at 622 end.
OUTPUT
On the 622 output, connect shield at 622 end to chassis ground (whether
driving balanced or unbalanced). Do not connect shield at other end.
When driving abalanced load, jumper circuit ground to chassis ground on 622
(on rear panel). When driving an unbalanced load, do not attach jumper.
622 chassis should always be earth-grounded (i.e. through third wire in power
cord or through rack.) For maximum protection from shock, float this ground
only as last resort.
If optional output transformer(s) are installed on 622, jumper the circuit
ground to chassis ground on the 622.
Because it is not always possible to determine if the pieces of equipment driving
or being driven by the 622 have their circuit grounds internally connected to their
chassis grounds (which are always connected to the ground prong of the AC line
cord), and because the use of the AC power line ground often introduces problems
because it can be noisy or otherwise imperfect, the wiring techniques in the
diagram are not universally applicable.
If you follow the diagram and hum or noise appears, don't be afraid to
experiment. If the noise sounds like alow-level crackling buzz, then probably there
isn't enough grounding. Try connecting the input of the 622 to achassis ground
terminal on the 622's barrier strip and see if the buzz goes away. You can also try
strapping the 622's chassis and circuit grounds together, and see if this helps.
Aground loop usually sounds like asmooth, steady hum rather than acrackly
buzz. If you have aground loop, you can often break it by disconnecting the
jumper between circuit and chassis grounds on the 622's rear-panel barrier strip. In
either case, think carefully about what is going on, and keep in mind the general
principle: one and only one circuit ground path should exist between each piece of
equipment! (Bear in mind that the circuit grounds of the two channels of a622B
are connected together internally, and could conceivably introduce aground loop if
you do not take this connection into account in planning your wiring.)
5

OPERATING The operating controls of the 622 have been configured to permit easy, intuitive
adjustment. The EQ and BANDWIDTH controls are concentric; the EQ control
protrudes further from the front panel. The TUNING control for each band is
located below its associated EQ and BANDWIDTH controls.
To provide best value, the 622 uses controls of high reliability but modest
calibration accuracy. Calibrations are approximate, and are intended primarily as
reference guides. Accurately defeating the equalization in agiven band is best done
with the BAND IN/OUT switch. When operating with narrow bandwidths, accurate
stereophonic matching of several 622 channels on the basis on panel calibrations
alone is impractical. However, if the BANDWIDTH controls are set on, or more
clockwise than, "5", then no problems will occur. (See the subsection on Stereo
Matching in Part Bfor matching instructions.)
Using the EQ Sections
To use the EQ section, switch the CHANNEL EQ section switch IN, and switch IN
the BAND EQ switch for each band you wish to use.
For those who have never used aParametric Equalizer before, the easiest way to
become familiar with the 622 is to center the TUNING controls, and adjust the
BANDWIDTH controls to "6". The 622 will now behave like an ordinary "four-knob"
console channel equalizer. Once you have gotten the "feel" of the 622 in this mode,
try experimenting with the TUNING and BANDWIDTH controls to see how they
affect the sound.
When you boost the EQ, discover the subtle shelving effects available from
broadband peaking (BANDWIDTH control close to full clockwise; EQ control
clockwise of "0"). Contrast this with the "ringy", colored quality of setting the
BANDWIDTH control toward narrow (ccw).
When you cut the EQ observe the effects you now achieve. Narrowband dips are
essentially inaudible, but permit suppressing sounds of fixed frequency (like hum),
typically better than 40dB in each band. (If the sound to be suppressed is rich in
harmonics, use one band per dominant harmonic.)
The EQ curves are not reciprocal: boost provides awider bandwidth than cut
because of the "Constant-Q" configuration of the equalizer. Experience has shown
this curve family to be more musically useful than the more common "reciprocal"
curves. The "Constant-Q" family also permits infinite-depth (in practice, greater
than 40dB) notches to be created which are highly useful for eliminating hum or
other interference of fixed pitch.
Specified "Q" range for any setting of the TUNING control is 0.29 to 3.2. When
varying the BANDWIDTH control, the peak gain remains constant while the skirts
of the curve vary.
Despite the non-reciprocal nature of the "Constant-Q" curves, agiven amount of
EQ (in recording atrack, for example) can be precisely cancelled later by passing
the track through the equalizer with all TUNING controls set as they were during
the original recording, with all EQ controls set equal but opposite to their original
settings, and with the BANDWIDTH controls readjusted (by ear) to provide acurve
which is reciprocal to the one used to make the recording. If aboost is to be
cancelled, use abroader "Q" setting (more clockwise); if acut is to be cancelled,
the converse is true. When the BANDWIDTH control is correctly adjusted, such a
curve will be precisely reciprocal to the original.
6