Dynacord CXM15 - Брошура - Сторінка 3

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The RCM-26 IRIS-Net module

a danger of overload). The tweeter is not,

however, fully switched off when this

occurs but driven via two light bulbs con-

nected in series, which offer secure prote-

ction against burnout. When the overload

condition no longer exists, the bulbs are

once again bypassed by the relay. A switch

on the panel allows you to choose between

Passive and Active modes.

In active mode, both the passive filter and

the high frequency protection remain in

the signal path, only the input to the passi-

ve crossover is now split so that the HF and

LF can be driven separately via pins 1 and 2

of the NL4 connector. This obviates the risk

of defects caused by faulty wiring. In active

mode, the only thing to bear in mind is that

the passive filter is already in the signal

path. The crossover frequency in the active

version can no longer therefore be raised

significantly beyond the 1.2 kHz of the pas-

sive filter, which is in any case something

best avoided. For active mode – naturally

for passive mode as well – Dynacord recom-

mends a power amplifier from its own

Power H series equipped with the control-

ler module IRIS-Net RCM-26. The H5000

power amplifier and the RCM-26 module

were already the subject of a detailed test

report in PRODUCTION PARTNER (Issue

10/2007) so we only need outline here tho-

se functions most relevant to the CXM 15.

IRIS-Net software and the RCM-26 module

The Intelligent Remote Integrated Supervi-

sion software platform (IRIS), which has

been available now for seven years, con-

tains the manifold control and supervision

functions for Dynacord and EV power

amplifiers and loudspeaker controllers

equipped with their own DSP systems.

Independently of any signal processing

functions, the RCM-26 module adds a two-

channel digital input and output in

AES/EBU format, a CAN bus interface and

two GPIO control and supervision conne-

ctors for external functions to the power

amplifier. The networking for the remote

supervision and remote control is handled

by the CAN bus.

To connect to the PC, a further USB/CAN

adapter is therefore needed. The UCC1

supplied for the test offers in addition to its

adapter function the possibility of listening

in to the signals of the connected amplifier

via an audio output, which is especially

practical when searching for errors.

For remote supervision, IRIS-Net offers a

series of useful functions both for the

power amplifiers and the connected loud-

speakers. In addition to pilot-tone supervi-

sion, these allow the load impedance of the

network and the prevailing thermal condi-

tions to be checked. Another very impor-

tant function is measurement of the impe-

dance of the connected loudspeakers. Here,

instead of a single reading, an entire impe-

dance curve for the frequency range 20 Hz –

20 kHz is measured. This can then be com-

pared with a stored tolerance mask (see Fig.

14) so that a reliable judgement can be for-

med as to whether the connected loudspea-

ker is still perfectly OK or in fact defective.

With this type of measurement, you can

make a reliable and at times highly specific

diagnosis of most loudspeaker errors. Such

a function is extremely useful for the

supervision of fixed installations but even

more so in the touring and rental sectors, as

it makes it possible to conduct a swift and

reliable check at the end of each show to

make sure all the loudspeakers connected

are still functioning correctly.

The RCM-26 controller in the H5000 power

amplifier offers the choice of running the

CXM 15 in either active or passive modes –

in each case with either IIR or FIR filters.

With 2 x 2.5 kW of sustainable power into 4

ohms, the H5000 naturally offers more

than enough power for the operation of the

CXM 15, so one can easily imagine a confi-

guration with four boxes per channel and a

total load of 2 ohms. In this case, the H5000

would deliver 3.3 kW per channel with 825

watts going to each box. The CXM 15's

power handling is given as 900 watts pro-

gram and 450 watts RMS, so this configura-

tion should suit it nicely. One H5000 can

power eight CXM 15s in passive mode and

four in active mode.

Measured values

The connectivity of the CXM 15 with its

individual LF and HF paths when set to bi-

amp mode makes it easy to measure the

two paths separately. What this reveals

immediately is how well the two interact in

the 1.2 kHz crossover zone. Fig. 1 illustrates

this nicely. Despite the simple design of the

passive crossover, the response when the

two paths are summed is linear. Between

200 Hz and 3 kHz, the sensitivity is just

under 100 dB; above 3 kHz it is around 103

dB. The fine interference structure in the

high frequency range is not the fault of the

driver but largely an unavoidable side-

effect of the grille, as the black line sho-

wing the response when the grille is remo-

ved makes plain. Since the grille inevitably

special reprint 12/09_01/10 production partner