Manual-4 features & applications – Rane MA 3 2003 version User Manual

Page 6

Manual-4

FEATURES & APPLICATIONS

Built to be driven hard

The MA 3 Ampliﬁer drives all three channels at the continu-

ous average rated power, indeﬁnitely. It is speciﬁcally designed to

operate in demanding commercial applications. Very low emis-

sions allow the Ampliﬁer to operate in close proximity to signal

processing equipment without causing excessive interference. The

CP 52, CP 64, DA 26 and SRM 66 may all operate next to the

MA 3 in a rack. The high eﬃciency “heat tunnel” design allows

the Ampliﬁer to process severely compressed signals reliably even

when installed in a rack with elevated ambient temperatures.

Forced air cooling keeps heat away from other equipment.

You won't hear other Zones

The MA 3 is designed to deliver foreground music, back-

ground music and paging signals to three diﬀerent Zones

without annoying crosstalk. A quiet oﬃce, for example, with a

paging signal only, will not hear foreground music playing in the

lounge. The high capacity linear power supply incorporates three

independent secondary supplies with independent bridge recti-

ﬁers and ﬁlters. The result is exceptionally good crosstalk ﬁgures

even with multiple channels driving full power into 4 ohm loads.

It’s OK to light the 0 dB Headroom indicator a lot

The high performance Limiter used in the MA 3 means all

the available power can be delivered to the load and not simply

held in reserve to avoid overload. There is no need to buy up to

four times the required power just to prevent occasional system

overload. The MA 3 can compress a signal with 9 dB of dynamic

power range down to a signal with 3 dB of dynamic power with-

out loss of speech intelligibility or excessive distortion.

With typical Ampliﬁers, when 40 watts is needed to achieve

a required average SPL of 80 dB, the contractor must buy an

Ampliﬁer rated at no less than 160 watts just to maintain 6 dB

of headroom. The ﬁgure below illustrates the performance of the

MA 3 Limiter.

No bad “spikes”

The MA 3 is designed to operate without interruption of sig-

nal with as little as 85 VAC available (120 VAC unit). Even if the

Ampliﬁer is operating at full power, the signal will not breakup

as the AC line voltage drops to 85 VAC. If the AC line drops

lower than 85 VAC the signal mutes without “spikes.” Once AC

power is restored, the signal restarts quickly without “spikes” or

signal breakup.

The good “SPiKe”

The power Ampliﬁers in the MA 3 are protected with Na-

tional Semiconductors’ proprietary SPiKe* protection circuitry.

SPiKe protection oﬀers a level of protection not available in

conventional ampliﬁers. It has the ability to instantaneously

monitor the temperature of the power device die, yielding a level

of reliability not achievable with discrete designs.

80 Hz Highpass Filters

Internal jumpers allow independently selecting 80 Hz,

-order Butterworth Filters for each channel. These Filters are

useful when using small bookshelf speakers or small constant

voltage distribution transformers. See the enclosed schematic for

locations of these jumpers.

Optional constant voltage distribution transformers

Up to three 70.7 V or 100 V constant voltage distribution

transformers may be mounted inside the MA 3. The optional

TF 407 is a 40 watt, 70.7 V transformer with 0.5 dB insertion

loss at rated power and a frequency response of 50 Hz to 15 kHz,

±1 dB. The optional TF 410 is a 40 watt, 100 V transformer

with .5 dB insertion loss at rated power and a frequency response

of 50 Hz to 15 kHz, ±1 dB. No external wiring or mounting is

required.

106715

*Spike is a registered

trademark of National

Semiconductor Corpora-

tion. SPiKe is an acronym

for Self Peak Instanta-

neous (Ke) protection

circuitry.

THD+N(%) & LEVEL(W) vs AMPL(dBu) 31 MAR 98 08:52:13

0.02

0.1

-5

Input Level in dBu

MA 3 Limiter