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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.
February 2007 43
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