RL 903K

RL 903K
The RL 903K is a main studio control room monitor with cardioid radiation characteristic from 35 Hz through 100 Hz for universal application. Main operational areas are audio, video and motion picture studios. By the cardioid characteristic those reflections caused by the wall behind the speakers are minimized. To enhance the low-frequency range we combined the coaxial arranged high- and mid-frequency driver unit with a powerful long-voice coil bass driver unit. Its coaxial arranged transducers ensure a sound impression with a high degree of homogeneity to a point source. We spend much effort in developing constructive ways to ensure a low degree of non-linear distortion. To keep short-term reflections small and achieve a high fidelity of sound we used a special arrangement for the high- and mid-frequency drivers and also designed the front side of the speaker asymmetrical. Although the cabinets dimensions a very compact, the system obtains a low-frequency cut-off at 35 Hz.

The three-way MOSFET-amplifier with active crossover is situated at the back of the cabinet and is easily accessible for maintenance. An intermittent LED indicates sound pressure levels within the overload margin of 3 dB and warns of clipping. Beyond this limit the output level of the high- and mid-frequency drivers get damped by 20 dB to protect the speaker's components.

Optionally, the coaxial arranged high- and mid-frequency driver unit can be supplied revolved by 90 degrees, that way the speaker can be installed either in vertical or horizontal position. To compensate their placement the speaker features two controllers to continuously adjust the low-frequency response.

There are various stands available as optional extras, which fit in the integrated appliance.
active three-way reference monitor for use in large audio-, video- and film production studios and in mobile broadcast vans
Maximum SPL
from 100 Hz ... 6 kHz

113 dB / r = 1 m (3.3 ft)
35 Hz ... 20 kHz ± 3 dB
Acoustic output level / PE = - 14 dBu

> 89 dB / r = 1 m (3.3 ft)
Directivity index
from 200 Hz ... 10 kHz

increasing from 4 to 12 dB
Inherent noise sound level
≤ 7 dB (A) / r = 1 m (3.3 ft)
Total harmonic distortion
measured at 96 dB / r = 1 m (3.3 ft)
from 100 Hz ... 10 kHz

≤ - 45 dB
Nominal Input level
+ 6 dBu adjustable
Input impedance
≥ 10 kOhm RC balanced
Electronic Crossover frequencies
250 Hz and 2.6 kHz
Nominal output power MOSFET-amplifier

180 Watt / 4 Ohm
100 Watt / 4 Ohm
100 Watt / 4 Ohm
Input Connector
Loudspeaker systems
Mid-range unit

200 mm (8") cone
160 mm (6.5") cone
25 mm (1") dome
Operation and Clipping indicator
LED on front side
Power requirements
Europe 230 Volt (± 10 %), AC, 50 Hz
USA & Canada 115 Volt, AC, 60 Hz
Power consumption
max. 300 Watt at full load
Mains Connection
IEC power connector
Dimensions (H x W x D)
481 x 285 x 293 mm ( 19 x 11.2 x 11.5 in )
28 kg (61.6 lbs)
Temperature requirements
for use
for storage

+ 15°C ... + 35°C (59°F ... 95°F)
- 25°C ... + 45°C (- 13°F ... 113°F)
45 ... 75 %
Design of the Cabinet
MDF-wood in ash black veneered; optional different veneers or colors
with holding device; optional without holding device
RL 903K Free field frequency response
RL 903K Total harmonic distortions
RL 903K Directional characteristic
RL 903K Gabelständer
Floor bracket stand 
Loudspeaker rotable mounted
Deliverable heights (Top edge loudspeaker): 1296 mm (51.0 in), 1411 mm (55.6 in), 1551 mm (61.1 in) and 1761 mm (69.3 in)
Base panel (W x D): 520 mm x 450 mm (20.5 in x 17.7 in)
Base panel and stabilisation panel veneered
Racks black powder-coated
RL 903K Standfuss
Integrated cable duct in the pedestal
Height (Top edge loudspeaker): approx. 1132 mm (44.6 in)
Base panel (W x D): 285 mm x 295 mm (11.2 in x 11.6 in)
Pedestal veneered
RL 903K Wandhalterung
Wall bracket
30° tilting und 30° rotable
Wall bracket black powder-coated
RL 903K Deckenhalterung
Ceiling bracket
Loudspeaker rotable mounted
Standard height between adapter plate and bracket: 300 mm
other length available
Ceiling bracket black powder-coated
Brochure and Documentation
Installation instructions for floor bracket stand models RL 901K - RL 903
Technical drawings
Technical drawing to the loudspeaker
Technical drawing to the floor bracket stand with details of the standard heights
Technical drawing to the pedestal
Test reports
Test report to the RL 901K, RL 903K and BASIS 4K