RDL ST-LEQ1 Datasheet

STICK-ON® SERIES

Model ST-LEQ1
Loudness Equalizer

 Loudness Contour to Follow Volume
 Improved Aural Flatness at Low Levels
 Installer-Adjusted Loudness Equalization
 Automatic Loudness Equalization when

Used with any RDL VCA/Remote

The ST-LEQ1 is part of a group of products in the STICK-ON series from Radio Design Labs. The durable adhesives provided with the ST-LEQ1
permit permanent or removable mounting. Numerous available mounting accessories, brackets and rack-mount chassis are optionally available to
facilitate any system design. STICK-ONs are designed, built and rated for continuous duty in professional A/V systems.

Whenever audio levels are changed, there is an apparent frequency response change to the ear. This is particularly
noticeable in background music systems where economical speakers and low listening levels are typical.
The ST-LEQ1 is an inexpensive tool to make a significant improvement in the sound quality of such systems.

APPLICATION: The ST-LEQ1 has 2 line-level audio inputs and a single line-level audio output. The audio signal to
be equalized connects to the EQ INPUT. If it is desired to mix an unprocessed source with the output signal, this
second source is connected to the DIRECT INPUT. Loudness equalization is applied to the EQ INPUT signal as the
CONTROL voltage is varied. The equalized input is normally used for music; the direct input is typically used for
paging.

The ST-LEQ1 may be operated together with any equipment which provides a 0 to 10 Vdc control. It is specifically
designed to operate with other RDL equipment using 0 to 10 Vdc for level control. Because the ST-LEQ1 works with
any RDL VCA module, all RDL remote level controls are suited for use with the ST-LEQ1. RDL digitally controlled
attenuators provide an output terminal EQ RAMP to control the ST-LEQ1.

The line-level audio source is normally fed through the RDL VCA product first, then through the ST-LEQ1. The audio
output from the ST-LEQ1 feeds the system amplifier or other equipment. The CONTROL terminals to the ST-LEQ1
are wired in parallel with the 0 to 10 Vdc terminals on the RDL VCA or from the EQ RAMP terminals on RDL digitally
controlled attenuators. The remote volume control associated with the VCA/ST-LEQ1 combination is adjusted to
produce a normal low listening level, then the installer sets the desired loudness equalization on the multi-turn
trimming potentiometer on the ST-LEQ1. As the listening level is increased by the remote control, the loudness
equalization is progressively decreased until the audio is flat at higher listening levels. With the audio first routed
through the VCA, then through the LEQ1, the DIRECT INPUT of the ST-LEQ1 is both unequalized and unattenuated.
The DIRECT INPUT is typically intended for a paging signal input which will always be the same level regardless of
the setting on the remote volume control. If it is desired to mix in a paging signal while allowing its level to be
adjusted by the remote volume control, the audio may be routed first through the ST-LEQ1, then through the VCA.

Wherever a loudness equalizer is needed, the ST-LEQ1 is the ideal choice. Use the ST-LEQ1 individually, or
combine it with other RDL products as part of a complete audio/video system.

RDL  659 6th St.  Prescott, AZ., USA 86301  [phone]  FAX [phone]  www.rdlnet.com

STICK-ON® SERIES

Model ST-LEQ1
Loudness Equalizer

Installation/Operation

Declaration of Conformity available from rdlnet.com.

Sole EMC specifications provided on product package.

Specifications are subject to change without notice.

TYPICAL PERFORMANCE

Inputs (2): Line level (+4 dBu nominal)
Input Impedance: > 30 k (balanced or unbalanced)
Gain: Unity nominal (into 600 )
Output Impedance: 150  (balanced or unbalanced)
Headroom: > 16 dB (above +4 dBu)
THD+N: < 0.005% (flat response)
CMRR: > 50 dB (Either input, 50 Hz to 120 Hz)
Noise: < -90 dB below +4 dBu (flat response)
Frequency Response: 10 Hz to 40 kHz (± 1 dB)
Control Input: 0 to 10 Vdc
Equalization: Flat to –15 dB max @ 1 kHz (effective boost of low and high frequencies)
Ambient Operating Environment: 0° C to 55° C
Power: GROUND-REFERENCED, 24 Vdc @ 35 mA

Radio Design Labs Technical Support Centers

U.S.A. [phone], [phone]; Fax: [phone]

891-1020M

Europe [NH Amsterdam] (++31) 20-6238 983; Fax: (++31) 20-6225-287

0dB

-5dB

-10dB

Attenuation

-15dB

MAXIMUM EQUALIZATION FOR DIFFERENT CONTROL VOLTAGES

5Vdc or less

50 100 500 1k 5k 10k 20k

7.5Vdc

Frequency in Hertz

10Vdc
(flat)