Martin Audio MA1.3s Power Amplifier by Lab Gruppen – Used – Good Cond
£482.50 + VAT
Used Martin Audio MA1.3s in very good condition all round and only has a few small marks (rack rash) and is in perfect working order.
The MA1.3s is one of a range of power amplifiers that have been designed to combine reliability and high power with sonic excellence. Utilising an advanced switch mode power supply, the amplifier is characterised by a very high power-to-weight ratio in a lightweight, 2U package. The innovative technology at the heart of the MA1.3s enables it to set new standards in terms of sonic accuracy, impact and clarity.
The MA1.3s amplifier runs very cool due to a special patented copper cooling system. The amplifier’s bi-polar output devices are mounted directly onto a copper heatsink (copper conducts heat twice as efficiently as aluminium) and maximum heat dissipation is achieved by turbulent airflow over the heatsink’s geometric fins.
The MA1.3s amplifier features two proportional speed cooling fans which take in air from the front of the amplifier and exhaust from the rear. A horizontal pressure chamber between the heatsink and the cooling fans ensures that there is little difference in the operating temperatures of each output device. In contrast, a conventional tunnel design can result in a temperature variance of up to 40º between output devices.
SWITCH MODE POWER SUPPLY
The switch mode power supply (SMPS) is the modern solution to the problems of size and weight. Switch mode power supplies are not new – they are found in computers and televisions. However, the demands of high power audio are very different to these applications. The SMPS featured in the MA1.3s overcomes the size and weight constraints of conventional power supplies whilst at the same time avoiding the pitfalls of typical switch mode designs.
The low output impedance of the SMPS means that rail voltages do not sag under heavy load conditions. Additionally, the rail capacitors are being recharged at a much faster rate than those in a conventional power supply. The result is an exceptional fast transient low frequency performance at all power levels.
Efficiency is also maximised. With much smaller transformers than a conventional supply, there is much less loss due to transformer resistance and much less power wasted as heat in the power supply. Regulation of the SMPS means that the power amplifier will produce the same power output, even if the AC line voltage drops by 20%.
The MA1.3s amplifier has many advanced protection features that will protect both the amplifier and the speakers connected to it, under fault conditions. All protection circuits are independent and inaudible in normal use.
Clip limiters prevent dangerous clipped signals reaching the speaker. They work by monitoring the output to check for signals not present at the input i.e. distortion. If distortion exceeds 1% on an output, the limiter will reduce the input signal proportionally.
Thermal Protection circuitry prevents the amplifier from running at an unsafe temperature by muting the input signal when the internal temperature rises above 90ºC.
SHORT CIRCUIT PROTECTION
The MA1.3s amplifier is completely short circuit protected. The protection circuits permit very high peak currents, but maintain the output devices within their safe operating area.
MAINS VOLTAGE PROTECTION
This operates if the mains voltage falls outside its permitted operating range. If this occurs, the power supply will shut down until the correct mains voltage is restored.
DC AND VHF PROTECTION
Both DC voltages and high power VHF signals can cause damage to loudspeakers. The MA1.3s amplifier incorporates protection circuits which are activated when damaging DC voltages or VHF signals are present at the outputs.
MAX OUTPUT POWER
EIA AT 1 kHz AND 1% THD
8 PER CHANNEL 350 W
4 PER CHANNEL 650 W
2 PER CHANNEL 1100 W
8 BRIDGED 1400 W
4 BRIDGED 1600 W
MAX OUTPUT VOLTAGE
8Ω LOAD 53 Vrms
PEAK VOLTAGE, NO LOAD 78 V
DISTORTION THD 20Hz – 20kHz AND 1 W TO FULL POWER 0.07%
THD AT 1kHz AND –1dB UNDER CLIP 0.01%
DIM AT –3dB UNDER CLIP 0.008%
HUM AND NOISE <-105dB
CHANNEL SEPARATION @ 10kHz 70dB OUTPUT IMPEDANCE 30 mΩ
SLEW RATE 40 V/µs
GAIN SELECTABLE (dB) 20, 23, 26, 29, 32, 35, 38, 41
IMPEDANCE 10 kΩ
COMMON MODE REJECTION 50dB
FRONT PANEL GAIN CONTROLS 31 position detent
INDICATORS: PROTECT Yellow LED
INDICATORS: CLIP Red LED
INDICATORS: SIGNAL PRESENT (-40dB) Green LED
INPUT CONNECTORS Neutrik Combo
LINK CONNECTOR XLR-male
CLIP LIMITERS On/off each channel
LINK-SWITH CH. A-B
OPERATION VOLTAGE 130-270V
SOFT START Yes
PEAK INRUSH CURRENT 5 A
FULL OUTPUT POWER 180-260 V
MIN START VOLTAGE 175 V
115V OPTION Yes
CURRENT DRAW AT 4Ω/230V
QUIESCENT POWER (NO LOAD) 0.9 A rms
1/8 OF FULL POWER (-9dB) 5 A rms
1/3 OF FULL POWER (-5dB) 8 A rms
AT FULL POWER (0dB) @ 1kHz 1%THD 14 A rms
WIDTH 483mm (19ins) HEIGHT 88mm (3.5ins) 2U DEPTH (incl. handles) 325mm (12.8ins)
WEIGHT 7.9kg (17lbs)
architectural and engineering specifications
The amplifier shall have two channels each capable of producing an output of 650 watts continuous average power at 1kHz and 1% THD EIA into a 4 ohm load with both channels driven. Each input shall be electronically balanced and have a CMRR of 50dB at any frequency between 20Hz to 20kHz. Each channel shall exhibit distortion of no more than 0.01% THD at 1kHz and –1dB under clip. Hum and noise shall be at least 105dB below full rated output power and channel separation shall be greater than 70dB at 10kHz. The input gain shall be selectable by rear-mounted switches between 20dB and 41dB in 3dB steps. The amplifier shall have a switch mode power supply. The front panel shall have LED indicators for each channel that will activate to show channel on, signal present (-40dB), clip and protect mode; also, individual channel gain controls each with a 31-position detent. Input to each channel shall be via individual Neutrik Combo sockets with XLR-male link connectors. Power output for each channel shall be via a rear panel mounted Speakon connector.
Dimensions (W) 483mm x (H) 88mm (2U) x (D) 325mm (19ins x 3.5ins x 12.8ins). Weight 7.9kg (17lbs).
The amplifier shall be the Martin Audio MA1.3s