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PRODUCT SHOWCASE Luggable PA system from Altronics There are many so-called portable public address systems around, intended for schools, community groups, sporting bodies and the like. Most of these systems are, not to put too fine a point on it, rubbish. So it’s very refreshing to find a system which not only works but works well. The system is the “Black Max” Portable PA Unit from Altronic Distributors, in Perth. It is described as a rugged, heavy duty self-contained PA system and with that we cannot argue. The first thing you notice about the unit, even before taking it out of its carton, is the weight: some 13kg! That’s why we prefer to describe this 90  Silicon Chip system as luggable, as distinct from portable. True, it can be carried from place to place. True, it doesn’t need mains power with the optional field battery pack. True, it is completely self-contained. But just try carrying it over any distance and you’ll agree; it’s portable just like a suitcase full of bricks is portable! Not that we are trying to put this Black Max down. Far from it: that weight all comes because of the features and performance built in. And if you want performance, weight is a small consideration. To be honest, we’re also speaking from experience. This is not the first time we have come across the Black Max. Our first introduction to the unit was when, in another life, we needed a truly portable PA system for use at Surf Carnivals. Like the man who was so impressed with the shaver he bought the company, we were so impressed with the Black Max we purchased one. That was over two years ago and until now, it had done nothing to change that first impression! Now, having seen the new model, we are envious. It’s not only more rugged but sports a range of new features and even better performance. So what do you get for your money? We’ll start with the outside. The Black Max measures 430mm high, 300mm wide and 210mm deep. It’s made from heavy duty MDF covered in a thick crinkle-finish black PVC. All eight corners of the case are protected by heavy duty ribbed speaker box corners, as in professional sound systems, which also double as feet in either vertical or horizontal direction. There is an expanding carry handle on top and a “top hat” mount let into the base so that the unit can be used directly with an optional tripod stand or other mounting system. Almost the entire front of the unit is covered with acoustic foam, behind which (and hidden) is a grille to prevent damage to the speaker. The speak­er itself is a 2-way 200mm coaxial type. Rear panel facilities On the rear panel is the (optional) logic controlled, auto reverse cassette deck. While delightfully easy to use, if we have one criticism of this deck it is that it has no tape counter. Again, from experience, using a cassette deck without a counter in anything but back­ground music situations can be a real drawback. Cuing is very difficult, especially during “events” where various tapes are required. Below the cassette is the inbuilt mixer, offering two microphone channels, both with balanced (XLR) and unbalanced (6.5mm) sockets (3mV sensitivity, 200-600 ohms) plus left and right auxiliary (RCA) inputs (250mV, 100k impedance), which are of course summed to mono. Each input channel has its own level control so full mixing is available. Unfortunately, however, the auxiliary input level control also doubles as the cassette level control, so this can only be used for one or the other. The MIC 1 socket also has a switch which can be set to “wireless mic” where this option is fitted. The wireless microphone itself bears special mention, being a fully professional quality model with performance as good as any we have used, even in stage applications. Unlike some “el cheapo” wireless microphones which transmit in the 88-108MHz FM band, with obvious consequences, these microphone use the “professional” 200MHz band, with a choice of two frequencies to avoid other users in the same area. (We have found the wireless microphone reliable for up to about 100 metres or more line-of-sight, but have experienced breakthrough from a club with a mic on the same frequency almost 1km away!) A 6.5mm socket is provided for an extension speaker. There is a matching speaker available as an option or, the output can be used for other 8-ohm speakers. Indeed, when we are using our (older!) Black Max for beach use, we usually plug in a low impedance horn speaker for dramatically increased coverage. Rounding out the “control panel” is an IEC mains input socket and an on/off master switch. Unfortunately, there is no line level output on this new model, which precludes one of the features we have found most useful on the older model: using it to drive a larger PA system. We have found that the older Black Max, with a wireless microphone, makes a magnificent “front end” for our 350W beach PA system which we use at surf carnivals. BassBox® Design low frequency loudspeaker enclos­ures fast and accurately with BassBox® software. Uses both Thiele-Small and Electro-Mechanical parameters with equal ease. Includes X. Over 2.03 passive cross­over design program. $299.00 Plus $6.00 postage. Pay by cheque, Bankcard, Mastercard, Visacard. EARTHQUAKE AUDIO PH: (02) 9948 3771 FAX: (02) 9948 8040 PO BOX 226 BALGOWLAH NSW 2093 STEPDOWN TRANSFORMERS 60VA to 3kVA encased toroids Field battery pack Below all of the controls and inputs is one of the Black Max’s main features: a “field battery pack”. This option is much more than a collection of cells. Instead, it is a rechargeable pack which automatically charges when ever the mains is connected and can be left float charging indefinitely. It also contains a DC/DC inverter so that completely portable operation is at much the same output level as mains powered. Charging time from flat is approximately 10-12 hours and gives up to eight hours continuous operation. The amplifier itself is naturally hidden from view inside the case. It is rated at 40W RMS, with a frequency response of 50Hz to 20kHz and distortion of less than 0.07%. In use The most immediate reaction is the quality of sound reproduction. For a small “PA”, it’s almost “hifi”! With 40 watts to play with (and a genuine, measured 40 watts RMS, not the figment of someone’s imagination Harbuch Electronics Pty Ltd 9/40 Leighton Pl. HORNSBY 2077 Ph (02) 476-5854 Fx (02) 476-3231 in the back blocks of Taipei), the sound level is more than adequate for a quite large hall. We have used the system at the local high school hall on a number of occasions, with excellent results. With the optional extension speaker added on, the sound spread is, as one would expect, even better. It also performs more than acceptably outside, especially when the unit is mounted a metre or so off the ground. For this reason, we think that the optional heavy-duty stand is a must have item! One thing we have found from July 1996  91 experience, and many people have commented on, is the lack of acoustic feedback, even when working very close up and at high levels. There is nothing more annoying that being subjected to a PA system either on the verge of, or actually, breaking into feedback. You really do have to put the mic virtually in front of the speaker to make this one misbehave! For this alone the designers of the Black Max must take top marks! extension speaker, with 20-metre lead, sells for $279; the heavy duty tripod stand $140; and the field battery pack $395 All items are available through Altronics Distributors in Perth (09) 328 2199 or their authorised distributors. (R. T.) Boundary mics for permanent installation How much Performance of this type does not come cheap. But, as the man says, “ya gets what ya pays for”! The Black Max standard system (ie, unit with hard-wired microphone and no cassette player) has a recommended retail price of $595. With the wireless microphone receiver it jumps to $849, and with the cassette recorder as well it retails for $1190. Note that these prices do not include the wireless microphone itself: the hand-held model (as reviewed) sells for $335, guitar transmitters are available for $269 and lavalier (clipon) mics are $379. The other options mentioned: the Amber Technology announces the new Beyerdynamic MPC 22/23 Acoustic Boundary Microphones, designed for permanent installa­tion into table tops or ceilings. With a diameter of only 30mm, the microphones are suitable for recording and sound reinforce­ment applications requiring high quality reproduction of speech, including telephone and video conferencing systems, in board­ rooms, courtrooms and churches. KITS-R-US PO Box 314 Blackwood SA 5051 Ph 018 806794 TRANSMITTER KITS •• FMTX1 $49: a simple to build 2.5 watt free running CD level input, FM band runs from 12-24VDC. FMTX2B $49: the best transmitter on the market, FM-Band XTAL locked on 100MHz. CD level input 3 stage design, very stable up to 30mW RF output. •• FMTX2A $49: a universal digital stereo encoder for use on either of our transmitters. XTAL locked. FMTX5 $99: both FMTX2A & FMTX2B on one PCB. •connector FMTX10 $599: a complete FMTX5 built and tested, enclosed in a quality case with plugpack, DIN input for audio and a 1/2mtr internal antenna, also available in 1U rack mount with balanced cannon input sockets, dual VU meter and BNC RF $1299. Ideal for cable FM or broadcast transmission over distances of up to 300 mtrs, i.e. drive-in theatres, sports arenas, football grounds up to 50mW RF out. FMTX10B $2599: same as rack mount version but also includes dual SCA coder with 67 & 92kHz subcarriers. • AUDIO •soldDIGI-125 Audio Power Amp: this has been the most popular kit of all time with some 24,000 PCBs being since 1987. Easy to build, small in size, high power, clever design, uses KISS principle. Manufacturing rights available with full technical support and PCB CAD artwork available to companies for a small royalty. 200 Watt Kit $29, PCB only $4.95. AEM 35 Watt Single Chip Audio Power Amp $19.95: this is an ideal amp for the beginner to construct; uses an LM1875 chip and a few parts on a 1 inch square PCB. Low Distortion Balanced Line Audio Oscillator Kit $69: designed to pump out line up tone around studio complexes at 400Hz or any other audio frequency you wish to us. Maximum output +21dBm. MONO Audio DA Amp Kit, 15 splits: $69. Universal BALUN Balanced Line Converter Kit $69: converts what you have to what you want, unbalanced to balanced or vice versa. Adjustable gain. Stereo. • • •• COMPUTERS •to Max I/O Card for PCs Kit $169: originally published in Silicon Chip, this is a real low cost way to interface the outside world from your PC, 7 relays, 8 TTL inputs, ADC & DAC, stepper motor drive/open collector 1 amp outputs. Sample software in basic supplied on disk. •onlyIBM3 chips PC 8255 24 Line I/O Card Kit $69, PCB $39: described in ETI, this board is easy to construct with and a double sided plated through hole PCB. Any of the 24 lines can be used as an input or output. Good value. •• Professional 19" Rack Mount PC Case: $999. All-In-One 486SLC-33 CPU Board $799: includes dual serial, games, printer floppy & IDE hard disk drive interface, up to 4Mb RAM 1/2 size card. •PC104 PC104 486SLC CPU Board with 2Mb RAM included: 2 serial, printer, floppy & IDE hard disk $999; VGA card $399. KIT WARRANTY – CHECK THIS OUT!!! If your kit does not work, provided good workmanship has been applied in assembly and all original parts have been correctly assembled, we will repair your kit FREE if returned within 14 days of purchase. Your only cost is postage both ways. Now, that’s a WARRANTY! KITS-R-US sell the entire range of designs by Graham Dicker. The designer has not extended his agreement with the previous distributor, PC Computers, in Adelaide. All products can be purchased with Visa/Bankcard by phone and shipped overnight via Australia EXPRESS POST for $6.80 per order. You can speak to the designer Mon-Fri direct from 6-7pm or place orders 24 hours a day on: PH 018 80 6794; FAX 08 270 3175. 92  Silicon Chip Beyer claim the MPC 22 and 23 produce higher gain before feedback than typical boundary microphone designs. The MPC 22’s semi-cardioid response makes it suitable for multiple microphone installations while its integral low-cut filter eliminates low frequency rumble and unwanted surface-bound noise. The MPC 23’s half-spherical polar pattern offers a uniform pickup pattern and is ideal in single microphone installations. Both models feature an M20 x 1.5 threaded body with mating nut for direct installation into material to a maximum thickness of 57mm and are supplied complete with elastic bearing rings for mechanical isolation from the mounting surface. Termination of the microphones is via a male 3-pin XLR connector fitted in its base. Both models may be run with universal 8-52VDC phantom powering. Beyer MPC 22/23 microphones are available in white or black finish and have a recommended retail price of $375.00. For further information, contact Amber Technology, Unit B, 5 Skyline Place, Frenchs Forest 2086. Phone (02) 9975 1211; fax (02) 9975 1368. Flatbed printer has automatic head gap adjustment The new C-650 flat­ bed printer from C. Itoh is able to iden­tify the thick­ n ess of the paper being used and adjust the print head gap automatically, providing con­sis­t­ent print quality on all types of stationery. Friction feed and push tractors provide accurate feeding of both cut sheet and continuous paper. Unusual paper thickness (from 0.05-2mm) and different sizes can be handled. The C-650 paper feed is suited to special stationery such as multiple forms, labels, prescriptions and passbooks, and is capable of handling stationery sizes ranging from cheque cards to A4 landscape. Paper path handling is straight-through under software control or by 1-key touch operation. Both Centronics parallel and RS232 serial interfaces are standard and an optional serial interface with current loop and RS422 is also available, as is an auto sheet feeder. For further information, contact Anitech, 52/2 Railway Parade, Lidcombe, NSW 2141. Phone (02) 749 1244.