Zahl EQ1 User manual

ZÄHL EQ1
The legendary Zähl EQ from the
state-of-the-art mixing console AM1
in the API 500 format

SCOPE OF DELIVERY
• EQ1 stereo equalizer unit
in the 500 series format
• this User Manual
• (spare) countersunk screws (4 pcs.) for rack
mounting UNC 4-40 3/8, silver
• knurled head screw with M3 thread
(tool for extracting the unit, see below)
• (spare) countersunk screw for front panel M3,
black, see below
Warning: Never insert a EQ1 unit while your rack is powered.
It may cause damage to the unit as well as the rack.
EQ1 must not be operated at ambient temperatures above 40°C and below 5°C.
As API series racks are equipped individually and the cabinets they are mounted in differ a lot in the way they are
ventilated, there is no rule other than keeping an eye on the temperature inside the rack while in operation.
Operating a unit beyond the limits can lead to severe damage.
In case you need to remove EQ1 from an API 500 series rack, you may use a gadget on the front panel: Remove the
M3 countersunk screw in the LO MID section. In place of this screw, screw in the enclosed knurled head screw with
M3 thread, gently without using any force. Then seize the tool and draw out the unit from the rack. Just draw on the
tool, do not apply any force to the sides! Do not forget to unscrew the bolt and remount the M3 countersunk screw.
SETTING-UP OPERATION
EQ1 is designed to be operated in a API 500 series rack or compatible, occupying two slots.
Switch off power and remove the mains
cable from your API 500 series rack
1. Carefully insert EQ1 into two free slots, keeping
the unit well aligned until the card edge
connectors meet their counterparts
2.
Firmly push the unit in place
– do not use excessive force
3. Fix the EQ1 front panel with 4 screws
supplied by your rack manufacturer
(in case they are not available you
may use our enclosed spare screws)
4.
Connect your audio I/Os to the rack
and re-install power
5.

DESIGN FEATURES
• stereo design for mix & mastering
as well as voices & instruments
• highly musical design
• intuitive, user-friendly, self-explaining layout
• lowest noise and distortion signal paths built with
highest quality components
• audio switching on EQ gain potentiometer zero
position for bypassing unused stages
For Sensitive Use
Global EQ GAIN setting 5 dB or 15 dB
• GAIN resolution enhancement
• easier restoration of GAIN setting
• direct comparison of different GAIN settings
Single Band Switching
Individual ON/OFF switching
• direct comparison each band ON/OFF while
leaving GAIN pot in position
• minimizing noise/preserving signal integrity
by switching OFF unused bands
Twin Contest
HI with BELL/SHELF and MID with fully parametric BELL
– same quality standard, but different circuit technologies
and sound character. For optimum versatility MID
frequency range switchable to HI range, HI frequency
applicable at HI MID band. Similar: LO and LO MID.
• no microprocessor, no clock pulses,
sequential logic only
• individual power stabilization on each module,
no switched power circuitry
• fully compatible with API 500 module series
speciƙcations, occupying two slots

OPERATION
I/O Stage
• true overall hard bypass (relais),
disconnecting I/Os
• gain stage switchable to input or output, thus
optimizing headroom vs. noise
• gain range +/- 15 dB or +/- 5dB, trimmed zero
gain at mid position
• SIGNAL LED (green) level present
• O/L LED (red) overload warning driven by 10
checkpoints throughout signal chain
HI EQ
• gain range +/- 15 dB or +/- 5 dB, bypass in mid
position (potentiometer center sense logic)
• individual ON/OFF switch
• frequency 2 kHz to 20 kHz
• BELL/SHELF characteristic switchable for
effective treatment or sensitive adjustment
with very soft slope and ‘airy’ character
HI MID EQ
• gain range +/- 15 dB or +/-5 dB, bypass in mid
position (potentiometer center sense logic)
• individual ON/OFF switch
• frequency 600 Hz to 6 kHz
• frequency range switchable to
1.8 kHz to 18 kHz (x3)
• adjustable Q-factor

LO MID EQ
• gain range +/- 15 dB or +/- 5dB, bypass in mid
position (potentiometer center sense logic)
• individual ON/OFF switch
• frequency 200 Hz to 2 kHz
• frequency range switchable to
40 Hz to 400 Hz (/5)
• adjustable Q-factor
LO EQ
• gain range +/- 15 dB or +/-5 dB, bypass in mid
position (potentiometer center sense logic)
• individual ON/OFF switch
• frequency 30 Hz to 300 Hz
• BELL/SHELF characteristic switchable with
slight sub frequency roll-off at high gain shelf
LO CUT
• frequency adjustable 25 Hz to 250 Hz
• individual ON/OFF switch

I/O DATA
Inputs
technology
impedance
max. level
reference level
Outputs
technology
impedance
max. level
reference level
electronically balanced,
transformer-like behavior
(either hot or cold may be
connected to ground)
> 30 kOhm
> +26 dBu
+6 dBu/+4 dBu
+/- 15…17V (from stablilized, noisefree DC Supply)
< 250mA (i.e. 125mA max. per slot)
electronically balanced,
transformer-like behavior
(either hot or cold may be
connected to ground)
50 ohms
> +26 dBu
+6 dBu/+4 dBu
Power
DC Voltage
DC Current
Connector Pin-Out
Card Edge 15 pin 0.156“ space - compatible to EDAC type 306-015-520-102
(Contact no. 01 is located at top)
01 Ground/Case
02 Bal. Audio Output +
03 n.c.
04 Bal. Audio Output -
05 Shield
06 n.c.
07 n.c.
08 Bal. Audio Input -
09 n.c.
10 Bal. Audio Input +
11 n.c.
12 +15…+17VDC
13 0V / Common
14 -15…-17VDC
15 n.c.
EQ1 occupies two slots in the API rack.
The left card edge connector – seen from the front –
comprehends left channel connections.
The right connector serves for the right channel.
Supply Inputs incl. Ground/Case always have to be
fed to both connectors even if only one channel
is used!
!

The equipment must only be used for the purpose
described in this manual.
1. Keep the manual for further reference. When passing
the equipment on, enclose the manual.
2. Do not operate the equipment at
- very high air humidity (>85% relative humidity)
- high ambient temperature (>40°C) or in the vicinity
of heat radiating equipment or objects
- places which are exposed to solar radiation
- at very low temperatures (<5°C)
3. Ensure appropriate air ventilation.
4. Do not store the equipment at temperatures below
-20°C or above +50°C.
5. Do never expose the equipment to environmental
conditions which can lead to the incidence of con-
densation water.
6. Do not expose the equipment to mechanical stress
or shock.
7. Ensure that liquids cannot get into the equipment.
8. Ensure that foreign objects cannot get into the
equipment.
9. Only operate the equipment on a safe, legally appro-
ved, mains power supply
10. Only clean the equipment with smooth cleaning
tissues and soft detergents.
11. Never open the equipment.
12. In case the equipment has been dropped or there is
any external or functional damage, do not continue
to operate the equipment. Have the equipment
checked at your dealer’s workshop or a person who is
qualiƙed to do such checks.
13. When shipping, use a package which protects the
equipment from environmental impact such as
mechanical shock or humidity.
14. The equipment applies to EU directives RoHS and
WEEE. Dispose separately according to WEEE. Manu-
facturer WEEE register number: DE 90586269
15. Manufacturer’s warranty covers the equipment to be
free from defects of quality at the time of delivery for
a period of 24 month presumed that
- the equipment was treated properly according to its
intended use
- all information and safety instructions given in this
manual have been followed
- the equipment shows no external damage
- the equipment is shipped to the manufacturer or to
an authorised repairshop free of charge
- a proof of purchase is supplied
- a detailed failure description is supplied
The manufacturer takes over cost of parts and labour
incurred by repair. Any other costs including shipping
and packaging will be charged.
16. We expressly exclude any liability for incidental or
consequential damages which might arise from
operating the equipment, including failure of the
equipment.
17. All information in this manual has been carefully re-
viewed. It has been updated at the time of passing for
press. Nevertheless we do not take over any liability
for sufƙciency or errors.
18. EEC Declaration of Conformity: The equipment
applies to applicable EMC rules 2004/108/EEC.
)
NOTES, SAFETY INSTRUCTIONS, WARRANTY

Zähl Elektronik-Tontechnik |D-51465 Bergisch Gladbach Germany
phone [phone] |inf[email protected] |www.zaehl.com
For further information scan the qr-code to visit www.zaehl-eq1.com >>>
HI - parametric
gain range selectable +/-5 dB or +/-15 dB
bypass in mid position, individual bypass switch
frequency 2 kHz to 20 kHz
characteristic switchable bell or shelf with
very soft slope - ‚airy‘ character
HI MID - fully parametric
gain range selectable +/-5 dB or +/-15 dB
bypass in mid position, individual bypass switch
frequency 600 Hz to 6 kHz
freq. range switchable to 1.8 kHz to 18 kHz (x3)
adjustable Q-factor
LO MID - fully parametric
gain range selectable +/-5 dB or +/-15 dB
bypass in mid position, individual bypass switch
frequency 200 Hz to 2 kHz
freq. range switchable to 40 Hz to 400 Hz (/5)
adjustable Q-factor
LO - parametric
gain range selectable +/-5 dB or +/-15 dB
bypass in mid position, individual bypass switch
frequency 30 Hz to 300 Hz
characteristic switchable bell or shelf with slight
sub frequency roll-off at high gain shelf
LO CUT
frequency adjustable 25 Hz to 250 Hz
individual ON/OFF switch
INPUT/OUTPUT
assignable gain stage INPUT or OUTPUT
gain range selectable +/-5 dB or +/-15 dB
BYPASS
switchable overall hard bypass, disconnecting I/Os
SIGNAL LED
at input
OVERLOAD LED
driven by 10 checkpoints throughout signal chain
ZÄHL EQ1
Stereo Equalizer in the API 500 format