HINTS AND TIPS
1. TOMORROW’S TECHNOLOGY
Poxy rechargeable batteries, why do they only seem to last five minutes?
You can thank Carl Jugner for that
He’s the Swiss scientist who in 1899 figured out the
chemistry of the nickel cadmium cell. Old Carl’s brainchild remained in
obscurity until the second world war, when someone worked out how to make a
sealed battery, that didn’t ooze toxic gunk all over the place.
It took another quarter of a century before nicads were
cheap enough for domestic applications. Now they’re everywhere, in mobile and
cordless phones, camcorders, personal and portable hi-fis, laptop and desktop
PCs, portable power tools, electric toothbrushes, nasal hair trimmers, and
much, much more; where would be without them?
Okay, but they’re still crap, compared with alkaline
batteries, which last a whole lot longer.
True, but compared with disposable batteries, nicads are
relatively cheap and still the most popular type of rechargeable battery, after
lead-acid car batteries.
But there must be something better?
There is, nickel metal hydride (NiMh) cells are similar to nicads,
but they don’t use highly poisonous cadmium, so they’re a wee bit greener, and
they don’t suffer anything like as much from the dreaded ‘memory’ effect.
Memory effect, remind me what that is?
That’s what happens when you give a nicad pack repeated
‘top-up’ charges. After just a few weeks of this sort of treatment the cells in
the battery (a battery is a collection of cells) develop different states of
charge. The fast chargers supplied with most cordless widgets cut off when they
sense one or more cells is fully charged, leaving the rest with only a partial
charge, so the battery appears to have reduced capacity. Nicad memory can be
avoided by only recharging when the battery is completely flat, and by using a
‘discharger’, which eliminates residual charge and puts all the cells in a
battery on an equal footing, prior to charging.
So nickel metal hydride cells are memory free?
More or less; they can be topped up without problems, and
they have a higher power density, which means they pack more energy into a
smaller space, but they’re around 25% to 50% dearer than nicads. They can’t
supply heavy loads for long periods either, which makes them unsuitable for
power tools, but they’ve become very popular on mobile phones and laptops.
Any other new ideas?
Lithium Ion (LiO) batteries are have an even higher
power-density than NiMh, and they’ve been turning up in increasing numbers on
lightweight electronic gadgets, like mobile phones, camcorders and notebook
PCs. Unfortunately they’re not compatible with regular nicad or NiMh battery
packs, and need specially designed chargers.
Is that good or bad?
Basically good. They have a much shallower, more predictable
discharge curve, so battery level meters are usually very accurate, and don’t
just bleep at you when the battery is about to expire. Needless to say they’re
more expensive, between two and three times as much as nicads of equivalent
capacity, but prices are coming down.
Any thing else to look forward to?
Just coming over the horizon are two new technologies.
Polymer batteries are related to Lithium ion, but new manufacturing processes
have enabled these very high capacity cells to be formed into thin sheets, or
indeed almost any shape a manufacturer requires. Applications include laptop PCs, cameras and mobile
phones. Lastly there’s the zinc air battery, they’re not re-chargeable, but
they are small, powerful, and last a very long time, potentially as long as the
working lives of the life of some products. Disposable electric razors
2. GETTING STARTED
CORDLESS ACTIVE SURROUND SPEAKERS
Multi-channel surround-sound systems have been around in
various guises for quite some time. They’re becoming more affordable, simple to
use, and add enormously to the enjoyment of watching movies at home, so why
hasn’t everyone got one? They will, one day, but a lot of people are still put
off by the price, the idea that it’s complicated, and involves lots of extra
boxes and wires.
That explains why TVs with ‘3D’, virtual and pseudo surround
sound systems, that use only the set’s own built-in speakers, have been so
successful. The crux of the problem is usually the rear-channel speakers, and
the fact that they have to be linked to the main AV amplifier or processor by cables.
The solution is obvious. Cordless rear
speakers. The technology is here,
infra-red cordless headphones are have been around for years, now
there’s also RF models, that work through walls, so why not speakers?
To date only a tiny handful of cordless speaker systems have
appeared, but why? To begin with no ‘cordless’ speaker system is entirely
without cables, quite the opposite in fact. To minimise the effects of
localisation a surround sound system normally needs two rear-channel speakers.
In a ‘cordless’ set-up one speaker will contain the amplifier and pickup
circuitry, with a cable carrying the audio to the other speaker. The sustained
volume levels required for surround sound operation preclude the use of a battery-powered
amplifier, so they have to be
mains-powered, which means a second cable, and provision for a nearby wall
socket. Then there’s a connecting cable and power lead on the transmitter unit;
all that to replace one or two thin speaker cables...
There are other design problems for IR systems. The ‘master’
speaker must be in clear line of sight of the IR transmitter. If the IR pickup is
shielded, behind furniture etc., some sort of remote sensor has to be used (yet
another cable). Speakers must also be unaffected by screen flicker, or IR signals
from remote controls etc.
Wireless or RF systems would seem to offer at least some
partial solutions. They don’t have to be in line of sight of the transmitter
unit, and they would suffer less from interference. Unfortunately the only
frequency band available for this sort of application is 49MHz, which is
already used by remote control toys, garage door openers, security systems and
a zillion other gadgets. That’s not a problem in most other EC countries, where
wireless audio devices have their own uncluttered frequency band.
At the moment cordless back channel speakers are available
from Hitachi, for their C2848 TV DPL TV and the Sony SAV-A55 DPL AV amplifier,
they’re both dedicated systems, that can only be used with specific products.
There’s a fair number of products available in other European countries but they’re not licensable for use in the UK;
the frequency band is question is currently allocated to amateur radio
Cordless rear-channel speakers would be an attractive option
for a lot of home cinema waverers but sadly, until there’s more choice, or
greater availability of accessory products, they’re unlikely to have much
3. ROADSIDE ASSISTANCE
Name Dave Campbell, via e-mail
Problem Is there an alternative to traditional back and
brown speaker cloth, asks Dave Campbell, who has noticed with interest the growing
number of speaker enclosures, that can be painted or disguised. Dave would like
to integrate his big old Wharfdales in with his decor, and is on the lookout for
something more colourful, to cover the front of his speakers.
Expert Reply Providing the material is acoustically
transparent, we reckon you can use almost anything. As a matter of interest the
highly authoritative ‘blind’ speaker tests conducted by our sister magazine Hi-Fi
Choice are carried out behind nothing more exotic than a black net curtain.
They tell us man-made fibres, in an open weave, seem to work best. A tighter
weave -- i.e. smaller holes -- may result in some roll-off of treble frequencies;
the same applies to thicker material. The easiest way to check suitability is
to hold the cloth up to the light, if you can see through it, then sound should
have no difficulty getting through as well. It’s easy enough to experiment, let us know what works the best.
Name Mark French, via e-mail
Kit Toshiba 3357DB DPL TV, Toshiba V-610 VCR, Scientific
Atlanta cable box
Problem Mark is looking for an easy way to upgrade his
system and wants to know if his Celestion 10 speakers would be better used for
the front or rear channels with the TV. On a slightly different note, he would
like to know why the NICAM indicator on his TV comes on when he is watching
cable channels. This is in spite of the cable box being connected to the TV by
daisy-chained aerial cables, via the VCR. Is he getting the ‘full monty’ from
the cable channels, including Dolby Surround?
Expert Reply Your Celestion 10’s will do most good as
outboard front-channel speakers, unless of course you feel like splashing out
on something a little more substantial, in which case they’ll still earn their
keep as rear-channel speakers.
The main benefit will be a wider, more clearly defined
soundstage, when compared with the TV’s own speakers, so it’s well worth doing.
Bell Cablemedia are one of the few companies to have NICAM on all channels. Since
the RF signal from the cable box passes cleanly through the VCR and re-emerges
on a spare channel, your TV simply treats it as another NICAM broadcast, hence the
indicator. NICAM stereo is transparent to Dolby Stereo information, so you
should be getting surround sound from the cable channels, that carry this kind
of material. Nevertheless, you might find picture and sound quality can be
improved by using a SCART connection from the cable box to the TV. Ideally you
should connect the cable tuner to the VCR, so you can tape cable channels,
however, the 610 is a fairly old model (circa 1991), and only has one SCART, so
bear that in mind when you come to replace your machine.
SPOILT FOR CHOICE
Name D. Cutts, via e-mail
Kit Kenwood KRV-7050 amp, Sony MDP-850 laser player, Philips
VR863 VCR Bose 501 front speakers, Kenwood CR-15 rears, Amstrad 25-inch TV
Problem Mr Cutts wants to upgrade his system, and knows the
Amstrad TV has got to go... However, he has the chance to buy one of the
following: Sony STR-GA8ES AC-3 AV receiver, Technics SA-TX50 THX AV receiver,
or Kenwood KR-V990D AC-3 AV receiver. He says he uses his system mostly for
movies, with a little music. He wants to know if he gets a THX system, will he
have to buy ‘special and expensive’ speakers. He also asks is THX ‘better’ than
AC-3, or is it the other way around, and which AV amp should he buy?
Expert Reply It’s a bit misleading to try and compare THX
with AC-3, they’re not necessarily competing technologies and are to extent
complimentary with one another. THX is a set of tight specifications for
amplifiers, processors and speakers, that builds upon the basic 4-channel Dolby
Surround system, but is entirely applicable to AC-3, otherwise known as Dolby
Digital. This is a discrete 6-channel surround system, (five full bandwidth,
plus one narrow band sub-woofer channel) sometimes referred to as Dolby 5.1.
Clearly AC-3 depends on specially mastered software, which currently is only
available on NTSC-coded laserdiscs. PAL laserdiscs do not have the capacity for
AC-3, and there’s still a question mark over the availability of AC-3 on DVD
software sold in Europe, which is more likely to use the MPEG audio or
‘Musicam’ audio system. If you go the AC-3 route you will almost certainly end
up importing discs, or relying on specialist suppliers. If and when DVD takes
off your options may be even more limited is regional coding will prevents discs
US imported from playing on European PAL decks.
You will have to upgrade your speakers for THX, if you want
to get the full benefit, and you will need extra channels of amplification if
you later buy a DVD player. We don’t know what sort of deals you’re being
offered on those AV amps, but the Kenwood and Sony amps would be the one’s to
go for if you’re happy with the software supply, and they would adapt most
easily to DVD.
Name Johannes Reykdal, Iceland
Problem Johannes is thinking about investing in a laserdisc
player, with AC-3 capabilities, and upgrade his existing system to suit; he wants
our opinion on the future of both formats. He’s concerned that DVD will kill them
both off in Europe, so should he wait for Musicam, or cross his fingers and buy
AC-3? Getting it right is very important, Iceland is an expensive place to
live, AV equipment prices are around 50% higher than the UK!
Expert Opinion Tough decision, but as far as DVD killing off
AC-3 and Laserdisc in Europe is concerned, it’s debatable that they ever took
off. Only a relatively small number of laserdisc players have been sold -- compared with VCRs -- and AC-3 is still very
much a specialist product, brought mainly by enthusiasts. We suspect DVD will
have little effect on either technology in the first few years anyway, though
you may find fewer titles are being released on laserdisc, as DVD takes hold,
so the supply of AC-3 software could eventually dry up. However, since AC-3 amps have six channels,
it should be possible to switch to a Musicam source fairly easily, provided the
amplifier in question has separate line inputs for each channel, and assuming source
components have independent outputs, or suitable decoder will be available. A
few ifs and buts, nevertheless if you’re feeling brave AC-3 should be a
reasonably safe option, but bear in mind what we’ve said about input sockets on
DPL ON A BUDGET
Name Anesh Kassen, South Africa
Kit - want’s to buy
Problem Having heard both the Aiwa NSX-V90 and Technics
SC-CH570 DPL mini hi-fi systems, Anesh is impressed. He would like to know
which is the best, or if there’s anything better in this price bracket?
Expert Reply I’m not sure what they cost in SA but both
packages sell for around £500 here. There’s not much else in that price band,
apart from the very likeable Akai TX700, now sadly discontinued in the UK, (not
sure about your neck of the woods, though), and the Kenwood UD-505. Of that little
lot the Aiwa system gets our vote. It’s marginally better specified, and a
whisker more powerful than the others; the very able Technics outfit is a close
ZOOM WITH A VIEW
Name Deke Roberts, Temple Cowley
Kit wants a widescreen
TV, but not just any one...
Problem After seeing a Philips widescreen TV in a local shop
some time ago Deke has set his heart on owning one. However, the feature that
caught his eye was the picture zoom control, which meant you could use any type
of source input -- from a video game to a laserdisc player, he says -- and enlarge it, to fill the whole screen. Now he’s got the money
to buy this set, but can’t seem to find it anywhere. He’s seen plenty of other
widescreen TVs, with fixed zoom options, but that Philips TV is the only one
The feature you’re describing sounds very much like ‘Movie
Expand’, which first appeared on Philips widescreen TVs about three or four
years ago. It electronically enlarges any image, irrespective of the original
format, to fill the entire screen. It used to be on almost all of their
widescreen models but now it’s only fitted to two current sets, the 32 and
Name A.R.Millner, Penistone
Kit Akai VSA77EK
Problem Now that his Akai surround-sound VCR is on its last
legs, Mr Millner is looking for a replacement. He has £800 to spend, but
following a lengthy run of problems with his present machine, is reluctant to
buy another Akai model. He’s considering an S-VHS deck, (he is also thinking
about a Hi8 camcorder), but he wants to know if he can expect any improvement
in the replay of pre-recorded movies.
Expert Reply Super VHS VCRs are generally built to a higher
standard, with more efficient heads and video processing circuitry. Compared
with an average quality mid-range NICAM machine, the picture from a Super VHS
VCR may look a little cleaner. However, if you’re asking will an S-VHS video recorder
magically transform a 250-line VHS recording into a 400-line image, the answer
has to be no. Off air recordings won’t look significantly better either.
The real benefit, though, will be apparent if you get hooked
on video movie-making. When you copy or edit recordings made on 8mm or VHS-C camcorders
the resulting ‘second generation’ recordings tend to look quite whiskery, subsequent
third generation dubs will be almost unwatchable. However, if you start out
with Hi8 original recordings, then edit to S-VHS, you can then make third
generation copies on VHS, that will
look almost as good as 8mm or VHS-C originals.
Name David J. Cheung
Kit Philips V813 VCR, Yamaha DSP-3090
Problem David says he was intrigued by a recent Hints &
Tips query, where the reader described a ‘raspberry’ sound coming from the soundtrack
of his VCR. David reckons he’s got a similar problem, though his video recorder
has been back to the shop several times, only to be returned as ‘no fault found’.
He would like to know if there’s a standard test, to adjust the tape guides.
Expert Reply Authorised service centres have access to a
range of specialised test equipment, and the necessary technical data, to carry
out these kinds of adjustments, but it’s
not something you can do yourself. Have you actually demonstrated the fault to
the engineer? If the noise is as you describe, it can only be the result of a
fault or mis-alignment, which they cannot fail to recognise and rectify? Is the
raspberry sound only apparent on older recordings, made on another machine? If
so then the other VCR is at fault. If, however, the sound is evident on pre-recorded
tapes, or recent recordings made on your machine, make sure the engineers hear
it for themselves, and insist they sort it out!
Name Bart Snoeck, Belgium
Kit wants a S-VHS VCR
Problem VCRs are considerably cheaper here than they are in
Belgium, according to Bart, who is in the market for an S-VHS machine. He wants
to know if he pops over and buys one here, will it work when he gets it back
home? Are there any shops we’d recommend, and if he can get one, will there be
any difference in picture quality.
Expert Reply Warm beer and soggy fish and chips, no problem,
but leave our VCRs well alone. In Blighty we use the PAL I system, Belgiummers
use PAL B and cable hyperband. The main difference between the two flavours of PAL
is the frequency separation of the video and audio signals. On PAL I the separation
is 6MHz, on PAL B it’s 5.5 MHz. What that means in practice, is a PAL I video recorder
will get a picture signal, but not the sound. There’s nothing to stop you using
the VCR for playback or camcorder dubbing though, if you use a SCART connection
to the TV; you just won’t be able to make off air recordings. Depending on the
model it may be possible to have the appropriate tuner module exchanged, either
here or locally, but it would invalidate the guarantee, and possibly soak up
the price difference. If you’re over this way it may be worth a stroll down
London’s Tottenham Court Road; several shops specialise in export models, but I
wouldn’t make a special trip.
Name Martin Kitchen, via e-mail
Kit Aiwa NICAM VCR, Nokia TV
Problem With the money he got for Christmas Martin brought
an Aiwa VCR. It clearly made an impression... he isn’t sure of the model
number, though he assures us it’s last years top of the range machine (probably
HV-FX3500). Anyhoo, he’s got it connected to his TV, using a standard SCART to
SCART lead. His question is, how much difference would a gold-plated SCART lead
make to picture and sound quality? He’s seen them on sale in Dixons for £15,
and others in a specialist hi-fi dealer for £30, but why the price difference?
Expert Reply It’s just possible you might notice something in
five years time, if the contacts on the standard SCART lead become intermittent
or noisy. Gold contacts won’t corrode or oxidise, but as far as any immediate
performance gains are concerned, forget it. Thirty quid for a SCART lead sounds
a bit steep, but that’s market forces for you...
Name E.C. Dinnair
Kit Sony KV-S3432 TV
Problem Since buying a Sony KV-S3432 TV Mr Dinnar has had
three problems. The first is a ‘dirty yellow’ vertical line, running the full
height of the screen, most noticeable on black and white programmes. The second
is a mauve patch on the top left hand corner of the screen, he tells us there
are no speakers or magnets nearby. The third happens rarely -- once a month
maybe -- and is a page of scrambled
teletext, that last for between two and ten seconds. The TV has been back to
the Sony repair centre, who returned it saying it was ‘well within their guidelines’.
Having spend £2000 on the TV he’s understandably a bit miffed.
Expert Reply The vertical line sounds like something
engineers call a ‘spook’. If so they can be real swines to diagnose and cure as
they’re often caused by obscure things, like dry soldered joints, loose connections
and even cables running too close to one another. That’s no excuse, but it’s
not unknown for spooks to disappear when the TV in on the bench, and reappear,
as if by magic, once it’s back in the customer’s home. The only solution is to
demand a home visit. You will need one in any case, to get rid of the mauve
patch, which is caused by residual magnetism, on the aperture grille inside the
tube. Normally the TV gets rid of small stray magnetic fields on its own.
However, it sounds as though it’s too much for your set to cope with, and it will
have to be manually ‘degaussed’. This involves waving a large coil of wire --
carrying an AC current -- in front of the screen, to erase the field. The
teletext problem sounds like it could be a glitch in the transmission, or
temporary interruption to the signal. It might be anything, from a bird
perching on your aerial, to a passing aircraft. As it’s only happening for a
couple of seconds a month, I really wouldn’t worry about it.
Name Marcus Clark, via e-mail
Kit wants to buy a 3D surround sound TV
Problem Marcus is thinking about buying a 25-inch NICAM TV.
He says his living room isn’t really
suitable for Dolby Pro Logic as the TV lives in the corner of the room, and the
family sit along the opposite walls. He asks if 3D stereo TVs, like the JVC
Phonic models, and the Sharp SRS range, are any better, or worse, than other
systems, and can any of them be upgraded to 5-speaker Dolby, at a later date?
Expert Reply Don’t write off DPL TVs altogether; you’ll
still get a fairly good surround effect, even if the TV is in a corner. Have
you thought about re-arranging the furniture? 3D Phonic and SRS both create a wide spatial effect, but there’s
no rear channel, and they can sound a bit unnatural. In the end they will fare
no better than DPL, if the TV is squashed in a corner. Of the two systems only
3D Phonic can be upgraded, the TVs have full spec DPL decoders built in, though
the front and rear channel outputs are at line-level, so you will need to add a
stereo amplifier and extra speakers.
R. Maybury 1997 1001