OPERATORS MANUAL MA 3 MULTICHANNEL AMPLIFIER QUICK START Sure, you say, "it's just a three channel amp, I'm in a hurry and I don't need to read the manual." But at least read this little section so you really know what to expect, and your installation can go even faster. Be sure the Amplifier is off before making any connections. Euroblocks make Amplifier connection easy. They are just like "snap on" terminal blocks. The balanced Input blocks are three-terminal female connectors. The Output blocks are twoterminal female connectors. Driving the MA 3 from a balanced source is recommended. If you must drive the MA 3 Input with an unbalanced source, we recommend using a cable that has two conductors plus a shield, and be sure to keep cable lengths as short as possible (under 10 feet). See Rane Note 110, "Sound System Interconnection" (contained in this booklet). Nominal speaker loads should be no lower than 4 ohms per Output. If you are running series or parallel combinations, be sure and check your total load impedance. For constant-voltage distribution, consider using the optional TF 407 (40 W / 70.7 V) or TF 410 (40 W / 100 V) transformer. Transformers may be installed inside the MA 3 on any number of Output Channels required. If you intend to use constant-voltage distribution transformers, you may want to read RaneNote 136 "Constant-Voltage Audio Distribution Systems" (contained in this booklet). Once Input and Output connections are completed, be sure all rear panel LEVEL controls are all the way counterclockwise. Now flip the POWER switch on. After a couple of seconds, slowly turn up each Channels' LEVEL control to the desired gain. Maximum yields the most effective dynamic range control for the built-in Limiter). If all is well, you will hear something pleasant. If not, re-check connections, put on a better CD, and read more of the manual. WEAR PARTS: This product contains no wear parts. Manual-1 FRONT PANEL DESCRIPTION Heat tunnel exhaust vents are located on the left of the unit. Large aperture vent slots are used for low noise. Air is taken in at the back of the unit and exhausts out the front. When installed in a rack, make sure there is ample room for air to exit. The sealed heat tunnel design does not require the use of an air filter. OUTPUT HEADROOM meters indicate the amount of remaining headroom (how much more signal can be applied before Limiting occurs). 0 dB OUTPUT HEADROOM remaining is indicated by a red indicator. When lit, any additional signal causes the Limiter to operate. It is possible to "compress" the signal as much as 20 dB with very little effect on sound quality. This gives the MA 3 the overload characteristics of a much larger amplifier, without the use of external compressors. The MA 3 was designed to be driven hard (heavily compressed signal) so it is not necessary to buy extra power to obtain the headroom required to prevent overload. 3 dB OUTPUT HEADROOM remaining is indicated by a yellow indicator. When lit, 3 dB of additional signal may be applied before Limiting. 6 dB OUTPUT HEADROOM remaining is indicated by a green indicator. When lit, 6 dB of additional signal may be applied before Limiting. 12 dB OUTPUT HEADROOM remaining is indicated by a green indicator. When lit, 12 dB of additional signal may be applied before Limiting. PWR: This yellow indicator lights when power is applied to the unit. See below. POWER switch: This control obediently turns the MA 3 on and off every time you poke it with your finger. Poking the top half of the switch turns the unit on when it is off. Poking the bottom portion of the switch turns the unit off when it it on. All three Channels have turn-on and turn-off muting to reduce switching transients. Manual-2 REAR PANEL DESCRIPTION IEC cord socket: This connector accepts a standard IEC line cord (included with 120 V domestic units). Plug this into a grounded AC outlet of 120 VAC (or 230 VAC if the MA 3 is internally wired for 230 V operation). OUTPUTS: Connect the speaker(s) to each of the three Channels by means of the Euroblock connectors with 18 to 12 AWG wire. Each Output may have an optional 70.7V or 100V distribution transformer installed inside the MA 3. These optional transformers are 40 watt devices with 0.5 dB insertion loss at rated power and a frequency response of 50 Hz to 15 kHz, ±1 dB. The 70.7 V transformer kit is the TF 407. The 100V transformer kit is the TF 410. INPUTS are balanced Euroblock connectors. We recommend the use of at least 18 AWG wire for reliability. Driving the MA 3 from a balanced source is recommended. If you must drive the MA 3 Input with an unbalanced source, we recommend using a cable that has two conductors plus a shield. Connect the (+) or "hot" source to the MA 3 (+) Input, the ground to the MA 3 (­) Input and connect the shield to the MA 3 shield input. Do not connect the shield on the source end. Shield connections go directly to chassis ground and should not be used as signal ground. Shield connection to chassis occurs via the screw found between the Input and Output connectors--keep this screw tight for improved EMI protection. When operating the MA 3 with unbalanced Inputs, be sure to keep cable lengths as short as possible. Refer to RaneNote 110, "Sound System Interconnection" (included in this booklet) for additional information. LEVEL controls adjust the input sensitivity for each of the three Amplifiers. The internal Limiters have maximum operating range (most amount of limiting before input overload) when the LEVEL controls are set to maximum. For best system noise performance, the input sensitivity may be reduced to send a "hotter" signal to the Amplifier. Here we go again! You get nothing for free. There are always tradeoffs to be made (better overdrive capability or lower system noise). The choice depends on your application. For additional information see RaneNote 135 "Setting Sound System Level Controls" available from our website or upon request from the factory. FAN SPEED: There are two fan speeds. The NORMAL setting (switch out) allows the MA 3 to deliver full rated continuous average power into 4 ohms, all Channels driven, with ambient room temperature of 22°C. Therefore, it is seldom, if ever, necessary to run the fan at the FAST speed. The exception might be a very hot environment and heavily compressed music into a demanding load. The only penalty for running the fan at the FAST speed is noise. Heat tunnel air intake: The fan draws air in through the finger guard on the rear of the unit. The air flow is directed down a sealed heat tunnel and exhausts through front panel vents. No filter is required as air flow is directed through an unobstructed, sealed tunnel and will not contaminate internal circuitry. Manual-3 FEATURES & APPLICATIONS Built to be driven hard The MA 3 Amplifier drives all three Channels at the continuous average rated power, indefinitely. It is specifically designed to operate in demanding commercial applications. Very low emissions allow the Amplifier to operate in close proximity to signal processing equipment without causing excessive interference. The CP 31, CP 52, CP 64 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, background 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 rectifiers 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 without 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. MA 3 LIMIT 2 No bad "spikes" The MA 3 is designed to operate without interruption of signal 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 National 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, 2nd-order Butterworth Filters for each Channel. These Filters are useful when using small bookshelf speakers or small constant voltage distribution transformers. 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. *Spike is a registered trademark of National Semiconductor Corporation. SPiKe is an acronym for Self Peak Instantaneous (Ke) protection circuitry. 31 MAR 98 08:52:13 60.00 55.00 THD+N(%) & LEVEL(W) vs AMPL(dBu) 1 50.00 45.00 40.00 THD & N in % 35.00 Output Power in Watts Power 0.1 THD & N 30.00 25.00 20.00 15.00 0.020 -5.00 0.0 5.000 10.00 15.00 10.00 20.00 Input Level in dBu ©Rane Corporation 10802 47th Ave. W., Mukilteo WA 98275-5098 TEL (425)355-6000 FAX (425)347-7757 WEB http://www.rane.com Manual-4 105227 ...