api select SR24 Dual Channel Equalizer User Manual
- June 6, 2024
- API Select
Table of Contents
2 CHANNEL
4 BAND EQUALIZER
MODEL SR24
INTRODUCTION
Thank you for choosing this API Select SR24 Equalizer. The SR24 is a two-
channel four-band equalizer in a two-rack-space chassis. With a dedicated knob
and/or switch for each control function, the SR24 is both easy to use and easy
to re-set. By using continuously-variable controls for both frequency and
boost/cut, the SR24 can be very precise in applying equalization to the
selected audio material.
HISTORY
The design of the SR24 circuitry is not entirely new. For a brief period in
the late 1970s and early 1980’s an audio company called APSI manufactured
consoles and equalizers. The APSI 562 was a 4-band Parametric equalizer that
was made by APSI, but sold through API. A variety of APSI modules were
included in the sales brochures and literature produced by API. The 562 has
over the years remained on the ‘favorites’ list of a number of studio
engineers. The original APSI 562’s, however, have become more difficult to
find and nearly impossible to find in good working conditions. The SR24 is a
faithfully updated re-engineered version of the original APSI 562.
LAYOUT
The API SR24 contains two identical equalizer channels in one chassis, sharing
only a common ON/OFF switch.
The equalizer covers the range from 20Hz to 20kHz in four EQ bands of
overlapping frequencies – 20Hz to 200Hz, 100Hz to 1000Hz, 500Hz to 5000Hz, and
2000Hz to 20kHz.
Each band has a boost/cut control with a range of +/- 12dB.
There is a separate IN/OUT switch for each equalizer channel.
Rear panel connections include both balanced XLR connectors as well as
balanced 1/4″ jacks.
FRONT PANEL CONTROLS
POWER SWITCH
The front panel power switch turns power to the SR24 on and off.
The indicator immediately above the switch will glow RED when the SR24 is
powered on.
IN/OUT SWITCH
When in the active (illuminated) state, the IN switch for each EQ channel will
place the SR24 into the active audio path via a silent relay.
In the deactivated position, there is no active circuitry between the IN and
OUT rear panel connectors.
CENTER FREQUENCY POT
This pot selects the center frequency of the chosen EQ band. The pot is
continuously variable. allowing very precise selection of the desired
frequency.
BOOST/CUT POT
The larger knob controls Boost or Cut within the chosen frequency range. With
the pot in the straight-up (12 o’clock) position, no change in the tonal
balance of the selected range will be applied.
REAR PANEL
INPUT CONNECTORS
The inputs to the SR24 can be either the 3 pin XLR-type balanced connector or
the 1/4″ balanced (tip, ring, sleeve) jack. Note that if you were to connect
to both connectors, the signal from the 1/4″ jack takes priority. The input
XLR connector is wired pin 2 hot (or +).
OUTPUT CONNECTORS
The outputs of the SR24 can be taken from either the 3 pin XLR-type connector
or via the 1/4″ balanced TRS (tip, ring, sleeve) connector on the rear panel.
Like the input, the output XLR connector is wired pin 2 hot (or +), and the
1/4″ TRS connector is wired tip hot (or +). These two connectors are wired in
parallel, so output audio will appear on both connectors.
AC MAINS CONNECTOR
The mains AC connector is the standard IEC-type 3 pin connector. The ground of
this AC connector is permanently internally connected to the chassis of the
SR24 for safety. Be sure the Voltage Select switch is in the correct position
for your country and the appropriate value fuse is in the holder before
applying AC voltage to the SR24.
AC FUSE HOLDER
When set to the 115V position use a 500mA GMA fuse with Slo-Blo
characteristics. At the 230V setting use a 250mA Slo-Blo fuse. It is important
to change the fuse when changing the supply voltage.
AC VOLTAGE SELECT SLIDING SWITCH
For line voltages from 100V to 120V, set the switch to 115V. The 230V position
is good for all line voltages from 200-240 Volts.
TECHNICAL SPECIFICATIONS – SR24
Inputs: Balanced XLR and 1/4″ parallel jacks
Outputs: Transformer Balanced XLR and 1/4″ parallel jacks (All measurements
with 600 Ohm output load)
Bandwidth: +/- 0.5db, 20Hz – 20kHz THD+N @ 1kHz, +4dbu: 0.01%
Maximum Level: +23dbu Signal-to-Noise Ratio: -100db
EQ Bands: 4 bands, all +/-12db Peak/Dip type
Lo: 20Hz – 200Hz
Lo-Mid: 100Hz – 1kHz
Hi-Mid: 500Hz – 5kHz
Hi: 2kHz – 20kHz
Power Consumption: 10 Watts
Dimensions: 2U EIA 19″ Rack
Height: 3.5 Inches
Width: 19 Inches
Depth: 10 Inches
Weight: 13 lbs
Input Impedance: 12k Ohms
Output Impedance: 300 Ohms Transformer Balanced
API Limited Warranty and Service Information
a) Warranty Information : API products carry a one-year factory
service and five-year pads warranty from the date of purchase. API (Automated
Processes, Incorporated) does not cover claims for damage due to alteration
and/or abuse. This warranty is limited to failures during normal use, which is
due to defects in material or workmanship. If any defects are found in the
materials or workmanship, or if the product fails to function properly during
the applicable warranty period, API, at its option, will repair or replace the
product.
b) PLEASE NOTE: The design or quality of any non-authorized third-party
service or vendor is beyond the control of API. Therefore, the use of NON-API
VPR Alliance modules in any API product including consoles may VOID this
warranty. Also, service or modification of any API unit except by an
authorized API representative may VOID this warranty.
c) API reserves the right to inspect any products that may be the subject of
any warranty claims before repair or replacement is carried out. The final
determination of warranty coverage lies solely with API.
d) This warranty is extended to the original purchaser and to anyone who may
subsequently purchase this product within the applicable warranty period.
Proof of purchase may be required.
e) For questions regarding the operation, interfacing, or service of your API
product, please contact your API dealer from whom you purchased the unit. Many
times, your authorized API dealer is the fastest and most cost-effective way
to maintain and service your product.
f) The below steps are the best way to initiate the repair process or to
submit a parts order request:
Repair procedure:
- Fill out a Return Authorization(RA) form at service.apiaudio.com.
- Wait to receive an e-mail from API Audio with an RA#.
- Use the API original box to package the unit. Write the RA# large and legibly on the box (if the RA# is not clearly visible on the box, the unit may be rejected by our receiving department)
- Include a copy of the RA form with the unit.
- Ship the product freight prepaid to:
API SERVICE DEPARTMENT 8301 Patuxent Range Road Ste Al Jessup, MD 20794
Parts Order procedure:
- Fill out the online PO form (for parts and parts numbers not listed online please fill out the PO form with your name, e-mail, contact phone, and shipping address and describe the part you need).
- Submit an online PO form.
- API will e-mail you back with part numbers and procedures on how to order/pay.
g) This is your sole warranty. API does not authorize any third party,
including any dealer or sales representative, to assume liability on behalf of
API or to make any warranty for API.
h) THE WARRANTY GIVEN ON THIS PAGE IS THE SOLE WARRANTY GIVEN BY API AND IS IN
LIEU OF ALL OTHER WARRANTIES, EXPRESS AND IMPLIED, INCLUDING THE WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE WARRANTY GIVEN ON
THIS PAGE SHALL BE STRICTLY LIMITED IN DURATION TO FIVE (5) YEARS FROM THE
DATE OF THE ORIGINAL PURCHASE FROM API OR AN AUTHORIZED API DEALER. UPON
EXPIRATION OF THE APPLICABLE WARRANTY PERIOD API SHALL HAVE NO FURTHER
WARRANTY OBLIGATION OF ANY KIND. API SHALL NOT BE LIABLE FOR ANY INCIDENTAL,
SPECIAL, OR CONSEQUENTIAL DAMAGES THAT MAY RESULT FROM ANY DEFECT IN THE API
PRODUCT OR ANY WARRANTY CLAIM.
i) This warranty provides specific legal rights and you may have other rights,
which vary from state to state.
API, 8301 Patuxent Range Road, Jessup, MD 20794
Tel: 301-776-7879
www.apiaudio.com
In a constant effort to improve the subtle details of our products, some
amount of change is inevitable. API reserves the right to modify or change any
of the features. specifications or performance of Its products without notice
and obligation.