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Review by Ross Tester T he vast majority of audio equip ment available in Australia to day is imported. But there’s one Australian company which is determined to reverse that trend, at least in the public address area. Perth-based Altronic Distributors recently submitted one of their new Australian designed and manufactured Redback Phase 4 PA Mixer Amplifiers for our once-over. There are two models available, a 125W version and a 250W version which are apparently identical apart from the power. We received the 125 watt version. They say first impressions count and our first impressions were definitely favourable. If a PA Amplifier can be made to look good, Altronics have certainly succeeded. The amplifier is housed in a purpose-designed two-unit 19-inch rack mounting case, finished in matte black. And while the case is intended for rack mounting, it certainly doesn’t have to be used that way. They’re not lightweights: even the 125W model is around 12.5kg while the 250W version is a tad under 20kg. Case size is identical – 483 x 330 x 88mm. On the front panel are level controls for the six input channels which can be selected as 3mV balanced mic inputs (each with phantom powering) via 3-pin XLR sockets or as 200mV line or “aux” inputs via RCA sockets. (All inputs are on the rear panel). There is also a master volume control along with bass and treble controls (±10dB <at>10kHz and 100kHz respectively). There is also a LED bargraph VU meter, a large power switch and indicator LEDs showing power, peak level, fault condition and signal. On the rear panel are the input sockets previously mentioned, a “send/ receive” pair of RCA sockets which are preamplifier out and main amplifier in (these are normally bridged) Inside the Redback Phase4 PA Amplifier from Altronics. This is the 125W model – very clean inside and out. The “box” running left to right is in fact the fan-forced tunnel heatsink. The power amplifier itself is quite small, hidden by this heatsink. Top of shot is the input preamp, immediately below is the power supply module while the mixer PC board is virtually hidden under the lip at the front. 78  Silicon Chip and screw terminals for the amplifier output (4-16Ω and 70V/100V line) plus external power in (24V DC), PTT switched input and a VOX activated 24V DC output which can be used to power external relays (eg emergency sirens, self-closing doors, etc). There’s also mains input (via an IEC socket) and DC fusing. Inside the amplifier is a joy to behold: very nicely and cleanly laid out. In fact, for a moment we wondered where all the components were! The only PC boards immediately obvious were the main power supply board and the input preamps connected to the rear panel sockets on another Most of the inter-board wiring is done with IDC cable, á lá modern computers. The exception to this is power supply wiring and output wiring which is neatly laced together – all in all, a very professional package. One minor surprise was the use of a standard iron cored 100V output transformer while the power transformer was a (now almost conventional) toroidal type. This could be to get the power rating required in the 250W version which would require a much larger toroidal. The amplifier Output power is quoted at 125W can provide a trickle charge for 24V DC batteries. It also has input 1 priority and vox muting. Competitive price One of the biggest difficulties an Australian manufacturer faces is being able to keep prices at least on a par with the imports. Given the features of their amplifiers, Altronics have succeeded in making them more than competitive – they’re really good value. The 125W model (cat A1826) sells for $875 including gst, while the 250W model (cat A1836) sells for $1099 including gst. Both carry a five year manufacturer’s warranty. Popular On the left are the various power inputs and speaker outputs. Each of the inputs (right side) can be line or mic level, via RCA or Cannon connectors. board. The main power amplifier PC board is tiny – just 150 x 40mm – and is mounted on a long tunnel heatsink which lies transverse across the case. Also on this heatsink are two large bridges, one used as a rectifier while the other simply performs reverse-polarity protection when the unit is connected to 24V DC. An 80mm fan draws air from inside the heatsink and expells it through slots in the the front panel. One more board, containing the mixer components, lies almost hidden under a lip off the rear of the front panel. RMS, with frequency response (±3dB) of 50Hz to 15kHz at a total harmonic distortion of less than 0.5% at 1kHz. In terms of hifi, these aren’t particularly brilliant figures but this is not designed as a hifi amp – and for its purpose, those figures are more than satisfactory. Other “bells and whistles” include thermal overload and short circuit protection, along with a peak limited output. The fans only operate when required to and the availability of 24V DC powering (as well as 240V AC) means the amplifier can be used in “must work” situations such as emergency evacuation. The amplifier We first saw these amplifiers in the 1999 Altronics catalog and asked them several months ago if we could have a look at one. It was only quite recently, and after even more prodding, that they had just one spare unit to send us. According to Altronics’ Brian Sorenson, demand for these amplifiers has significantly outstripped the company’s ability to manufacture them. “Most of our orders are coming from the professional installation market,” he said. “Word has managed to get around very quickly about the Phase4 systems and we are even getting enquiries from offshore,” he said. “We’ve sent these amplifiers to New Zealand, the Pacific and even into Southeast Asia.” Now that is a coup: exporting Australian-made amplifiers to Asia! SC CONTACT: Altronic Distributors Pty Ltd; Perth, Sydney & Melbourne – (08) 9328 2199 October 2000  79