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HD-MA35A 35 Watt Mixer Amplifier with Power Supply - Constant Voltage Output 25 V, 70 V or 100 V

Three inputs with individual front-panel volume controls
Bass and Treble tone controls
Designed for background music with paging and music-on-hold
Master volume VCA controlled with remote adjustment capability
Manual or automatic (VOX) priority ducking
Balanced inputs and amplified outputs on detachable terminal blocks
Unbalanced inputs and outputs on RCA jacks
Includes power supply
High-efficiency Class D operation

Datasheet
Power Supply Included

The HD-MA35A is a three input audio mixer amplifier for systems demanding a broad range of features and high energy efficiency. Two output power amplifier zones are provided, 35 W (Zone 1) and 2 W (Zone 2). The Zone 1 output is driven from a high-efficiency Class D amplifier stage. The Zone 1 amplifier output level may be VCA controlled using various optional RDL remote controls, or by industry standard 0 to 10 Vdc or 0 to 10 kOhm controls. This output provides a constant voltage (25 V, 70 V or 100 V). The Zone 2 amplifier output drives an 8 Ohm speaker and/or 600 Ohm telephone equipment. The HD-MA35A is engineered and manufactured in the U.S.A.

The HD-MA35A features two mixers. The Zone 1 mixer is located on the front-panel providing user level and tone controls for the 35 W amplifier output. The tone controls adjust the equalization at the Zone 1 amplifier output. The Zone 2 mixer on the rear panel provides level trimmers normally set by the installer to provide music-on-hold and/or for background music in a small zone equipped with an 8 Ohm speaker. The Zone 2 section includes a 2 W amplifier and a 600 Ohm transformer-balanced MOH output.

The HD-MA35A has three inputs that are common to both mixers. Input 1 accepts a balanced mic or line level source. Inputs 2 and 3 accept unbalanced mono or stereo line-level sources.

Input 1 is switch-selectable MIC or LINE. Phantom voltage (IEC standard 24 Vdc) is switch-selectable for the microphone input. The line input is transformer isolated and accepts balanced or unbalanced, high or low impedance audio sources.

A paging source is normally connected to Input 1. This input is equipped with push-to-talk terminals and with an adjustable threshold VOX circuit with LED threshold indicator, either (or both) of which may be set to duck ("fade down" or "mute") inputs 2 and/or 3 by 25 dB when a paging signal is active on Input 1. The attenuated inputs fade up to normal volume when the paging message is finished.

Inputs 2 and 3 each provide unbalanced stereo RCA input jacks, summed to mono.

The HD-MA35A is equipped with a master VCA for remote adjustment of the Zone 1 amplifier output. A detachable terminal block is provided for direct connection of an optional RDL remote level control.

A balanced line-level output is provided on a detachable terminal block to feed the inputs of other audio equipment or power amplifiers. Ground-referenced 24 Vdc power is available on a rear-panel terminal block to power an optional external RDL module which may be mounted on the panel space provided. External module type examples: audio filtering or processing, mixing, isolation, twisted-pair sender/receiver.

The Zone 1 amplifier includes an analog compressor/limiter for audio fidelity noticeably superior to conventional class D amplifiers with digital limiting. Increasing the input gain can substantially increase the average output power beyond that of a standard 35 W amplifier. A red front-panel LED flashes when the compressor is preventing output clipping. Normal audio level signals remain unaffected by the compressor thereby preserving audio dynamics. The audio is compressed according to three dynamic time constants providing aural transparency while maintaining clean, unclipped amplified audio for input overloads of up to 20 dB. The HD-MA35A, with compression, is capable of producing average audio output levels and clarity normally expected from amplifiers with a much higher output power rating.

A blue POWER LED illuminates when the HD-MA35A is powered from its external 24 Vdc power supply (included). The power LED is dim when the mixer amplifier is in the standby mode, and is bright when the amplifiers are fully active. A front-panel pushbutton is provided to manually switch between standby and active modes. The power amplifiers are equipped with both thermal and output short-circuit protection. The high-efficiency Class D output stage produces minimal heat for all levels of expected voice or music modulation.

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Videos

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Applications

NOISE MASKING WITH PAGING

AUTOMATIC MESSAGE PLAYBACK WITH PAGING

AUDIO DISTRIBUTION OVER TWISTED PAIR

Amplifier Zones (2):

Zone 1 (Main): 35 W RMS, front-panel mixer (user controls); Zone 2: 2 W RMS (8 Ohms), rear-panel mixer (trimmers)

Audio Inputs (3):

Balanced, mic or line switch selectable on terminal block; 2, unbalanced stereo summing inputs on RCA jacks

Maximum Input Level:

Mic Input: -11.5 dBu; Balanced line input: + 19 dBu; Unbalanced Inputs: + 9 dBV (+15.5 dBV, one input); (for 1% THD+N at output)

Phantom Voltage:

24 Vdc (IEC 61938: 2013), switch-selectable for the mic input

Ducking/Muting Actuation:

Automatic (Input 1 VOX: rear-panel adjustable signal threshold with LED indicator) or Manual (contact closure to ground)

Ducking/Muting Release Delay:

4 seconds, nominal

Ducking/Muting:

Switch-selectable for inputs 2 and/or 3, 25 dB ducking attenuation, nominal

External RDL Module Power Output:

24 Vdc, 100 mA maximum, ground-referenced

Input level:

(to cross compressor threshold equaling 23 W amplified output)
Mic Input: -50 dBu (2.5 mV), (front panel gain at max.)
Balanced line input: -21 dBu (70 mV), (front panel gain at max.)
Unbalanced Inputs: -15 dBV (180 mV, front panel gain at max., both inputs driven)

Noise (line output):

Mic input: -68 dB, Balanced line input: -72 dB (below compressor threshold at max gain);
Unbalanced Inputs: <-85 dB (max gain)

Noise (amplified outputs):

Mic input: -68 dB, Balanced line input: -72 dB (below compressor threshold at max gain);
Unbalanced Inputs: <-75 dB (max gain)

THD+N:

< 0.5% (1 kHz at compressor threshold, main amp output); < 0.25% (line output, main)

CMRR: Mic input:

> 50 dB (50 Hz to 120 Hz); Balanced line input: > 80 dB (50 Hz to 120 Hz, transformer-coupled input)

Compressor:

Threshold 2 dB below rated output, automatically adjusting attack and release times

Frequency Response (mixer):

Mic to line output: ±1.5 dB (40 Hz to 25 kHz); Balanced line input to line output: ±1 dB (20 Hz to 20 kHz); Unbalanced line input to line output: ±0.5 dB (20 Hz to 20 kHz)

Frequency Response (Zone 1 amplifier):

Constant voltage: ±3 dB (50 Hz to 18 kHz); 4/8 Ohm: ±1 dB (50 Hz to 20 kHz)

Frequency Response (Zone 2 amplifier):

8 Ohm: ±1.5 dB (50 Hz to 20 kHz); 600 Ohm: ±1.5 dB (30 Hz to 18 kHz)

Tone Controls:

±10 dB @ 10 kHz, ±9 dB @ 100 Hz (front-panel) with center detent

Audio Outputs (2):

+4 dBu nominal (1.23 V), balanced, terminal block (FLAT); 0 dBu nominal balanced, terminal block (zone 2 mixer, 600 Ohm output)

MOH Output:

0 dBu nominal (775 mV), 600 Ohm transformer-isolated, >16 dB headroom

Power Amplifier Outputs (2):

Zone 1 (main): 35 W RMS (25, 70 or 100 V); Zone 2: 2 W (8 Ohms, on detachable terminal block)

Indicators (6):

Front-panel: Signal present (3; 1 per input, green), Compressor activity (red), Power (bright=on, dim=standby, blue); Rear-panel: Ducking/muting threshold (yellow)

VCA:

Zone 1 (main) master level, 0 to 10 Vdc control, detachable terminal block (compatible with RDL VCA wall controls)

Front-panel controls (6):

Zone 1 (main) mixer level controls (3, inputs 1 through 3), EQ (2, bass and treble), Power (latching pushbutton, on/standby)

Rear-panel controls (9):

Mic/Line switch (Input 1), Input 1 ducking/muting detector sensitivity trimmer, Phantom voltage switch (Input 1), Ducking control switches (2, to duck inputs 2 and/or 3), Zone 2 mixer level controls (3, inputs 1 through 3), HD-MA35: Output impedance switch 4 or 8 Ohms

Ambient Operating Environment:

0° C to 50° C Maximum; 20° C Recommended

Power Supply (included):

100 to 240 Vac, 50-60 Hz, 50 W; 24 Vdc output to amplifier chassis

Dimensions and Weight:

Height: 3.5 in.(8.89 cm); Width: 8.5 in.(21.6 cm); Depth: 6.75 in.(17.1 cm); Weight: 6 lb.(2.7 kg)

Package Type:

Cardboard Box

Package Dimensions:

10.75 x 9.125 x 3.9375 in.

Shipping Weight:

7.095 lbs.