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HINTS AND TIPS

 

1. TOMORROW’S TECHNOLOGY

RE-CHARGEABLE BATTERIES

 

Poxy rechargeable batteries,  why do they only seem to last five minutes?

You can thank Carl Jugner for that

 

Who he?

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.

 

Then what?

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 anyone..?

 

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 enthusiasts.

 

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 impact.

 

3. ROADSIDE ASSISTANCE

 

MATERIAL BENEFITS

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.  

 

CABLE TIES

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.

 

DVD KILL-JOY?

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 the amplifier.

 

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 runner-up..

 

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 for him.

 

Expert Reply

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 28-inch 9631

 

AGEING AKAI

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.

 

RASPBERRY FOOL?

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!  

 

EC UNITY?

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.  

 

GOLD STANDARD?

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...

 

SONY SMUDGE

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.

 

3D OK?

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.

 

---end---

Ó R. Maybury 1997 1001

 

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