Outdoor column speakers of CU-500 series

We keep acquainting our readers with new public address speakers manufactured by Inter-M company. Following CU-400, we represent outdoor acoustic systems of CU-500 series for the Russian market. The new speakers stand out owing to their universality of implementation, long lifetime, excellent characteristics and modern design.


Series CU-500 serves for use in PA sound systems under the voltages of 70V and 100V. It comprises wall speakers of column type, namely, CU-510/520/530/540.

All the models have wide frequency range and serve for the installation both in buildings and in the streets. The outdoor use of the device should exclude a long direct penetration of heavy precipitations inside the speaker.

Expected date of delivery: January, 2011 year


Acoustic systems of CU-500 series have the original streamline shapes, without sharp corners. This gives the speakers a very elegant look. The housing of speaker is a durable aluminium frame closed at the top and bottom with ABS covers. There are several holes drilled in the bottom cover for a drainage of perspiration water, which can be accumulated as a result of abrupt drop of temperature and high humidity. Against the mechanical damages the speaker units are protected with decorative metallic grill having a distinguished logotype of Inter-M company. From the inside, a fabric dustproof filter is attached to the grill. The base of the system is a flakeboard, on which 4-inch speaker units and matching transformer are fixed. The flakeboard adds the necessary weight and required acoustic properties to the speaker. As the speaker can be used for the outdoor applications, this flakeboard has been specially treated with waterproof substance.

The housing of new acoustic systems strengthened by stiffening ribs. The sidewalls of the housing are not parallel and sound absorbing-materials fold the speaker units. As the result, practically no parasitic acoustic resonances exist in the housings of new models. All these measures are necessary to eliminate the unwanted overtones and to make frequency response characteristic of the speaker as smooth without obvious dips and boosts.

Fig.1 Design of CU-520

Having been treated with the special waterproof substance, a paper (cellulose) cones on a flexible suspension are used in the speaker units. Cellulose is the traditional material that provides the lightness of moving speaker parts, and consequently, a high sensitivity of speaker unit. This allows speakers to create sufficiently high sound pressure beginning from already first Watt of input power.

Matching transformer has a solid size. It is a common knowledge that such dimensions of the transformer are obligatory required to reproduce a low frequency portion of the claimed frequency range within 180-14000 Hz. The transformer normally has the taps from primary winding. Therefore, the user can connect any speaker of CU-500 series at full and half power to the speaker line.

The sealed cable output, which is placed in the upper part of the back side of the speaker, is used for connection to speaker line. The cable length of 30 cm is quite convenient for this purpose.

Fig. 2 Installation of acoustic systems of CU-500 series

Mounting brackets are delivered with the speakers and provide a secure mounting and adjustment of the loudspeakers to the wall in the horizontal and vertical plane.

Difference between CU and CS series

Name CU-520 CS-520
Rated power 20 W 20 W
Number of passbands 1 1
Sensitivity 94 dB 93 dB
Frequency range 18014000 Hz 25014000 Hz
Irregularity of frequency response characteristic 4 dB 10 dB
Size (WxHxD) 156x400x129 mm 158410116 mm
Weight 3 kg 2,5 kg

Graph 1. 
Frequency response curves of
CU-520 and CS-520

Speakers of CU-500 and CS-500 series are similar in terms of purpose and basic parameters. However, speakers of CU-500 series have a number of obvious advantages.

Firstly, speaker units of CU-500 models reproduce a wider frequency range of the signals at the same sensitivity. Reducing the lower limit of frequency range by 70 Hz made the reproduced sound "softer and more natural.

Secondly, owing to the special shape and design of the housings, parasitic acoustic resonances were minimized in loudspeakers, and therefore, frequency response curves became smoother. The curves do not have the pronounced lifts on the middles frequencies that is peculiar to PA speakers with metallic housings. In average, the irregularity of frequency response characteristic was reduced by 6 dB in comparison with the models of CS-500 series. This significantly improved the reliability of playback of recorded music and speech signals.

Third, new models have been made in accordance with modern requirements for the design of publi address acoustic systems. Their exterior provides a versatility of use and relatively "invisible" presence on a facade of building or in the interior of almost any room. And technical specifications, in turn, guarantee the quality and the comfort of listening the audio.

Specifications of CU-500 speakers

Name CU-510 CU-520 CU-530 CU-540
Rated power 10 W 20 W 30 W 40 W
Impedance 1,0/2,0 kOhm 0,5/1,0 kOhm 0,33/0,66 kOhm 0,25/0,5 kOhm
Frequency range 180 14000 Hz
Sensitivity 91 dB 94 dB 95 dB 97 dB
Color of front panel black
Material of housing Aluminium, flakeboard, ABS plastic
Size (WxHxD) 156x300x129 mm 156x400x129 mm 156x500x129 mm 156x600x129 mm
Weight 2 kg 3 kg 4 kg 5 kg

Graph 2. Frequency response curves of CU-500 speakers

Polar pattern diagrams of CU-500 speakers

Video presentation of CU-500 speakers

Xvid, 720x486
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