Dynacord CXM15 - Opuscolo - Pagina 8

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D y n a c o r d C X M 1 5

TEST

The passive crossover of the CXM 15 with (on the right) the circuitry protecting the tweeter

The software is supplied with a large libra-

ry containing the measured values of many

Dynacord and Electro-Voice loudspeakers.

The difficult question that arises next is

which of the four controller modes to choo-

se. Whether the monitor is driven in two-

way active mode or passive is likely to be

determined by economic considerations or

the guidelines of the customer, so the choi-

ce boils down to that between FIR and IIR

filters. Figures 10 and 11 show the amplitu-

de and phase response of the CXM 15 in

passive mode without the controller in

green as well as with the controller and IIR

(blue) or FIR (red) filters. In terms of fre-

quency response, both versions with the

controller thanks to the equalization achie-

ve markedly lower corner frequencies at

the bottom end. Furthermore, the frequen-

cy responses achieved with the controller

are generally more linear and where there

are spikes, they are less sharp. The FIR ver-

sion goes into greater detail than the IIR fil-

ter. Far more marked are the differences in

their phase responses, where the FIR filter

in the midrange and higher frequencies

achieves a linear phase whilst the IIR filter

leaves the original curve of the box virtual-

ly unchanged. Summing up, one can say

that the FIR filter achieves what are all in

production partner 12/09_01/10 special reprint

all a somewhat smoother frequency res-

ponse and a linear phase response over

wide frequency ranges. The advantages of

the FIR filter are still more pronounced in

the active version. If you look at Figures 12

and 13, an extremely steep separation bet-

ween the LF and HF paths can be discerned.

With conventional analogue or digital IIR

filters, this would lead to pronounced pha-

se shifts. Not so with the linear phase FIR

filters, which make it possible to achieve

even here a linear phase response in the

medium and high frequency ranges. The

FIR filters for the active mode just like the

passive version introduce 5.3 ms of latency,

which at the speed of sound translates to a

distance of 1.8 m. This, even for a stage

monitor, is perfectly acceptable. With a ful-

ly digital signal chain in which A/D and

D/A conversion is performed in each case

once only, a further 3 ms at most will be

added, which still leaves us well inside

what is generally regarded as the limit i.e.

10 ms.

Summ ar y

The CXM 15 from Dynacord is a coaxial

loudspeaker optimized from the outset for

use as a stage monitor but one that is also

universally applicable: this is not at all the

same thing as a "multi-function box" that

you can – at a stretch – also use as a moni-

tor. The CXM 15 is for this reason very low

slung, compact and light in its construction.

The 15" coaxial chassis with its unusually

large high frequency horn offers the ideal

prerequisites for this task. The measured

results are correspondingly impressive,

with the very good maximum SPL values

particularly praiseworthy. The fact that you

can switch very quickly between active and

passive modes means that the hirer can

swiftly adjust the monitor system to the

wishes and budget of the customer. In com-

bination with the H5000 power amplifier

and the RCM-26 controller module, there is

the added option of IIR or FIR filtering

In the hearing tests, the box sounds fuller

than the frequency response would at first

lead one to expect. The directionality is pre-

cise with the coverage relatively strongly

focussed, though the runoff towards the

edges is even. Voices in particular are deli-

vered by the CXM 15 with great clarity,

which is precisely what is required from a

monitor. A high degree of presence in the

reproduction is often equated with "aggres-

sion" or "obtrusiveness", but this is not at all

the case here. The idea of using the CXM 15

in combination with a subwoofer as a small

club PA, side-fill or drum-fill is also one that

appeals. Bearing in mind the quality of the

performance and features offered, at

around 1,900 euros the CXM 15 has to be

considered good value. The 4,350 euros for

the power amplifier and 795 euros for the

controller module, on the other hand, may

at first sight seem less so. This is only relati-

ve in the overall reckoning, however, becau-

se you can drive up to eight monitors with

a single power amplifier. Since even in pas-

sive mode without a controller the CXM 15

is still a very good box, the choice exists

between a very wide variety of viable con-

figurations to match the needs and means

of the user.

◊

Text and measurements:

Anselm Goertz

Photos: Dieter Stork, Anselm Goertz (2)