MA4 Multichannel Amplifier

MA 4 Multichannel Amplifier

This product has been discontinued
  • Universal voltage, power-factor-corrected power supply
  • Very low inrush current
  • 100 watts x 4 channels in 1U chassis
  • Built-in load monitoring
  • Remote fault reporting and redundancy switching
  • Optional 4-channel 70/100 volt transformers in 1U chassis
  • Adjustable high-pass filters and remote level controllable
  • Advanced dynamics control adjusts for sensitivity setting, load Z and temperature

This product has not been tested to the current CE requirements and is not available in markets requiring CE compliance.

MA 4 Multichannel Amplifier

The 100 watt per channel, four-channel MA 4 amplifier achieves unparalleled power density, reliability and features in a space saving 1U, 19 inch rack mount chassis weighing only eight pounds (3.6 kg). A universal-voltage switching power supply provides near perfect Power-Factor, reducing peak currents to ⅓ compared to non power-factor-corrected supplies. A long list of unique features ranging from constant load power to built in automatic redundancy switching to advanced dynamics control, qualify the MA 4 for the most demanding fixed installation applications. The MA 4 excels in music & paging systems, small conference rooms and speech reinforcement applications requiring multiple amplifiers. Advanced dynamics control algorithms adapt to changes in temperature, load impedance and sensitivity setting. The result is a truly plug-and-play amplifier that ensures excellent signal integrity at all times.


Power-Factor-Correction (PFC)

Near perfect Power-Factor with 1/3 the peak current and 1/2 the average current (green) compared to non power-factor-corrected supply with conduction of 3 ms (black). The response is measured at 100 watts. The MA 4 power supply design provides power-factor-correction with very low inrush current and overvoltage protection.

MA4 Compressor

Rear Panel Switches Control the Built-in Processing

A Soft-knee Compressor is provided with rms threshold relative to the limit threshold. The on/off setting affects all channels. This allows uncompressed operation with typical program material while reducing continuous sine-wave power. Ratio is 3:1; Attack is 1.5 seconds; Decay is 3 dB per second; Soft knee span is 10 dB.

A Downward Expander reduces noise in the absence of signal. The on/off setting effects all channels. The Threshold is –70 dBFS; Ratio is 3:1; Attack is 50 ms; Gain reduction is 10 dB / sec.

Selectable 20 Hz, 40 Hz, 60 Hz or 80 Hz High-pass Filters are provided. The on/off setting affects all channels. Filters are 12 dB per octave, Butterworth alignment.

MA4 Basic

Don't let those extra connections and switches intimidate you.
The MA 4 is a high-quality general-purpose amplifier and connects like any other.

MA4 with Remotes

Remote Level Control inputs are provided for each channel.

  • VR2 Remote Controls have been discontinued, however any linear potentiometers 10k to 100k Ω may be connected to the MA 4.
  • Clickless mute with switch (SPST switch; connect Vc to GND to mute).
  • Euroblock connector with strain relief (Vref, Vcontrol, GND).
  • One pot may control all four channels by daisy-chaining the Vc of the used port to the other three ports.

MA4 Fault Reporting

To operate an amplifier channel in low power standby with remote turn-on, set its rear panel switch to SLAVE. External +5 volts connected to the FAULT FLAG holds the amplifier in standby. Floating the FAULT FLAG or connecting it to ground turns the channel on.

MA4 Master and Slave

If you wish to have an amplifier channel report a fault to a control system or back up amplifier, set its switch to Master.

Individual FAULT FLAG ports are provided for each channel. The Fault Flag is held high (+5 volts) during normal operation and goes low (passive pull down) when a fault occurs. A detected fault is re-tested every 10 seconds.

Possible faults include: supply under-voltage, over-voltage, voltage imbalance, output short to ground, output short to supply, output short to output, clock not running, over safe temperature.

Any linear potentiometers 10k to 100k Ω may connect as remote channel level controls to the MA 4.

MT 4 Multichannel Transformer

This product has been discontinued

MT 4 Front

The MT 4 four-channel distribution transformer is packaged in a space saving 1U, 19-inch rack-mount tray. The fully isolated, high-performance toroid transformers provide flat frequency response within 1 dB from 40 Hz to 20 kHz. Each transformer is designed for an 8Ω 100 watt input, and 100 watt 70 volt or 100 watt 100 volt output. The recommended load for the 70 volt tap is 50 Ω. The recommended load for the 100 volt tap is 100 Ω. Convenient Euroblock connectors are provided on the rear of the chassis.

MT 4 Inside

TF4 TransformerThe MT 4 comes ready-to-use with four mounted transformers and strain-relief Euro connectors. This is ideal for any rack system that needs four high-performance 100 watt, 100 / 70 volt, isolated distribution transformers.

For 25 volt audio distribution systems, the transformers can connect 25V loads between its 70V and 100V taps (green and yellow wires). Thermal resistance of the transformer is only 1C/W and is lower when mounted in a MT 4 chassis.

Other creative combinations are possible. For example, the yellow/green pair can drive 8Ω loads near to the amplifier, with the red/yellow pair being simultaneously used for a 70 V system. Depending on loading of the 70 V system, this arrangement presents an impedance between 4 and 8Ω to the amplifier.

The transformers can be used at power ratings much higher than 100 W, provided that the low-cut frequency is moved up accordingly. Since voltage capability doubles with each octave, power capability quadruples each octave.

Please note: The MT 4 is only available as one tray with four transformers, the individual tray and single transformers are no longer sold separately.

MT 4 Transformer

MA 4 Support

Can I feed all channels the same signal just by connecting to one of the channels?

No. You can use jumpers to connect all input channel connectors (plus and minus required).

Can I run the unit below 4 ohms load?

Well, probably. They will not be damaged but you will obtain much less power output. The MA 3 will current limit as necessary. Its fan must be set to high speed. The MA 4 is a digital amplifier and handles lower impedance differntly than MA 3. It too should work fine, but it is advised to always follow directions and load amplifiers accordingly.

My system seems a bit noisy running through the amp. Is there something wrong with the equipment?

Not likely. The most common misconception is that amplifiers must be turned up all the way to achieve maximum output. This is simply not the case. Most amplifiers will reach full output (and clip accordingly) with sensitivity controls set between 12 and 2 o'clock when fed a + 4 dBu signal. Try turning down your amp(s) and verifying the clipping point. This can make a drastic improvement in reduction of noise.

What type of wire can I use to connect volume remotes?

For runs up to 200 feet any five conductor wire, 22 gauge or larger, will suffice. Use shielded wire for distances greater than 200 feet.

If the above doesn't answer your question:
Phone the Rane Factory at 425-355-6000, 8:30 AM to 5 PM PST, Monday to Friday.
Email is answered most weekdays from the Rane Factory Contacts.

MA4 Multichannel Amplifier