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Jaycar gets into wireless microphones W ith the possible exception of TV reception hardware, Jaycar Electronics have never been really big in radio frequency (RF) spectrum equipment. However, their first foray into radio (wireless) microphones is certain to set the proverbial feline amongst the grey winged creatures . . . The first thing we noticed about the new “Digitech” Wireless Microphone range from Jaycar was the prices. “Surely there is some mistake,” we thought. “A complete wireless mic system for not much more than others charge for the microphone alone?” No, Jaycar assured us. The prices were correct. “So are they toys?” we asked? (Yes, we’ve seen some of the junk being flogged on eBay and at the markets). “Most definitely not – they’re pro- fessional UHF systems. Would you like to have a look at one?” So it was that a day or so later not one but two of the three Digitech wireless microphone systems arrived at SILICON CHIP (the missing one was already out of stock!). Here’s what’s in the range: At the lower end, for want of a better word, is the AM4078 two microphone system. This is not a diversity system (see separate panel) – each microphone effectively has its own receiver. Claimed range is 60m – a figure which we were easily able to confirm during a field test. These units operate on the 740865MHz UHF band. Some of this band is occupied by band V TV (TV channels 59-69) but with 16 channels to choose from, there should be no problems finding an empty slot. The most important part of the equation, the price, we’ve left to last: it’s a very pleasant surprise at $199.00! Remember, this includes the two handheld mics (with batteries!), a plugpack adaptor (it operates on 14V DC) and a 1-metre 6.5mm to 6.5mm lead. The output to your amplifier can be separate (ie, one line per mic) or mixed to a single line out, while mic levels are individually adjustable. Audio quality sounds very natural (we’re not sure what the mic insert is – we didn’t have the heart to disassemble it). Receiver dimensions are 210 x 170 x 42mm. This type of system would be ideal for hall, club and church use. Middle of the range is a slightly more “upmarket” model, the AM4077. It too is a 16-channel system but this time features full diversity. “Hands-on” review by ROSS TESTER 42  Silicon Chip siliconchip.com.au However, it suits (and has supplied) just one microphone. Speaking of what is supplied, this system comes in a professional-style aluminium road case, so is obviously intended for professional applications. The LCD panel on the front of the receiver also gives you the received signal level in dB, making it very easy to find signal holes before they find you (in the middle of a performance or speech, for example!). The price of the AM-4077 is also another pleasant surprise at $249. If you’re looking for an all-round excellent performer, this one would be very hard to go past. Finally, the top-of-the-range AM4079 is virtually a combination of both the other systems. It’s a dual mic, dualdiversity, 32-frequency system (each mic can be selected to one of 16 channels) with a claimed range of 80-100m. As can be seen from our photo, there are four antennas (and each is removable for remote/powered antenna mounting). That’s because as a diversity system, there are two antennas for each channel and there are two channels. The twin LCD panels display channel selected, frequency and signal strength, so in a multiple-mic installation (eg, a theatre), channel conflicts between this and other brands can be avoided. Output is either via a separate balanced line for each channel, or via an unbalanced 6.5mm mono line with Jaycar’s “Digitech” AM4077 single channel diversity system comes complete with a quality microphone and an aluminium road case, as shown here. 16 user-selectable frequencies ensure there will be a vacant channel somewhere, UHF TV notwithstanding! On the opposite page is the top-ofthe-range AM4079 dual channel (ie two microphones) diversity system. the two channels signals mixed. The system includes two microphones with batteries, receiver unit in 19-inch rack-mount chassis, 14VDC plugpack and a 1-metre 6.5 mono plug to 6.5 mono plug lead. This system is also very attractively priced at $399 and there are generous discounts for multiple units. In use As we mentioned above, we gave both units a field test – more accurately, a “baptism of fire” using them for volunteer commentators at a major sports event. In the three areas most important to a commentator – range/dropouts, clarity and ease-of-use – the two Jaycar systems that we trialled performed as well as, or better than, we expected (the AM4079 easily spanned 150m). As we said before, audio quality was as good as any wireless mic system we have used in the past – and that includes some very expensive brands! If we can make one criticism, it is in the inclusion of 6.5mm audio cables. There is little point. XLR output sockets are provided on the receivers and the vast majority of amplifiers and mixers use either XLR or RCA sockets, so a different lead (or adaptor) is required anyway. SC What is Diversity? Wireless microphones are right behind the eight-ball when it comes to operating conditions. For a start, they are “flea power” – just a few tens of milliwatts maximum – so their range is going to be severely curtailed anyway. Second, the antenna orientation is all important. As with any transmitting and receiving antennas, the wireless microphone (which contains the transmitting antenna) and the receiver antenna should be aligned in the same plane for maximum performance. They seldom are. It’s natural for users to hold the microphone at any angle other than vertical! Some years ago, Shure published a chart of losses as the angle between the antennas increased – and they were a real eye-opener. The moral of the story: keep the microphone as vertical as possible! Third, with rare exception these days, radio mics use UHF – up around the 800MHz area. Lots of things – human bodies included – absorb UHF radio signals, so dropouts can be a real problem. Slightly changing position, or even changing the way the microphone is held, can suddenly siliconchip.com.au result in a mute performer. And multipath (reflected signals) can also cause receivers real angst! One of the most widely-used ways to minimise the effects of these (and other!) problems is to use a diversity receiver system. In this, just about everything from the antenna to the receiver output is duplicated. A monitoring system (these days, probably microprocessor controlled) continuously samples the output from both receivers and automatically and seamlessly switches to the best reception. Even if the antennas are not the desired wavelength (or greater) apart, invariably at any given instant one will be pulling in more, or better quality, signal than the other. On the front panel of a diversity receiver there are usually two LEDs, one for each diversity channel, which turn on as that receiving channel is selected. You can see them switch back and forth as you move the microphone around. Usually, as far as the audio output is concerned, it is impossible to detect which receiver is in use or when they switch. Nor is there any difference in output level between diversity receivers. 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