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Name                          Nigel Denney, Bromley, Kent               

Kit                               Kenwood KRV6060 DPL AV receiver, Acoustic Energy AE109 and AE107c speakers, Aiwa HV-FX3500 VCR, Toshiba 2552DB NICAM TV, gold SCARTs and interconnects

Problem                      A low volume ‘wet’ purring sound is how Nigel describes the noise that accompanies dialogue or low bass sounds on his system. However, it only happens on movies on tape, and it can be reduced by using the midnight mode on the VCR.


Expert Reply              The noise is almost certainly coming from the VCR, but confirm it by substituting a friends VCR, to see if the sound disappears. The usual suspects on hi-fi VCRs are mis-tracking and possibly head-switching noise. Compare a pre-recorded movie with a recording made on the machine. If the purring noise is only present on commercial tapes then mis-tracking is the most likely reason. Nigel doesn’t say whether the noise was present from day-one, if so it’s probably down to factory mis-alignment. If it has only developed recently it could be due to a build up of dirt on the tape guides, so it’s worth tying a run-through with a cleaning tape. ‘Wet’ types are better at removing stubborn deposits.  If that doesn’t work then it’s in need of a tweak. This can only be carried out by an engineer, with the right tools and a reference tape. If the noise is on both pre-recorded and home recorded tapes it might be due to a problem with the VCRs auto-tracking system, that and head switching noise both require expert attention.



Name                          Iain Macintosh, via e-mail                   

Kit                               Yamaha DSP A592 DPL processor, Mission speakers

Problem                      He say’s he really happy with his AV set-up, but Iain would like to move up a step on the home cinema ladder by adding an LCD projector. He has around £1000 to spend and would like to know what’s good, and what’s not?


Expert Reply             The only LCD projectors in Iain’s price bracket are single panel models, they’re getting better but the quality is still not that wonderful. Single element projectors work a bit like a normal slide projector, with an colour LCD screen mounted between the light source and the lens. The LCD screens used are similar to those used on pocket televisions, and the number of pixels that can be squeezed into the space is limited, consequently, by the time the image is magnified it looks quite coarse. None of the single element projectors we’ve tried are really suitable for home cinema, unless you’re willing to make a big compromise on picture quality. The alternative is a triple element projector, with one LCD panel for each primary colour. Unfortunately they are a lot more expensive, the cheapest one costs around £2500 (Sanyo PLC-400), so you’re either going to have to look around for a second-hand model, or keep on saving.  



Name              Phil Cohen, Bay Harbour, Florida                                   

Kit                   two Panasonic AGW1 multi standard VCRs

Problem            Phil want to know why Panasonic have withdrawn the multi-standard VCR (NV-W1 in the UK) from sale. He has a theory that it’s to do with Matsushita -- Panasonic’s parent company -- buying Universal Studios and MCA records, and wanting to prevent piracy. He want to know why, now that they have sold off their movie-studio interests, they don’t meet market demand and reintroduce it?


Expert Reply That’s a neat conspiracy theory but a spokesman for Panasonic UK told us that the reason it was discontinued was because it was a specialist product, with a high price tag -- it was last selling for around £2000 --  and following the launch of the Samsung multi-standard machine it was no longer competitive. Our contact at Panasonic also pointed out that it has been in production for around six years by the time it was deleted, which is something of a record for any VCR. He went on to stress that it had nothing whatsoever to do with the Matsushita-Universal partnership, and that there are no plans to reintroduce the NV-W1 or a replacement.  



Name              P.Mackrell, Dorking, Surrey                        

Kit                   Pioneer A400 amp Yamaha E1000 DPL processor, Sony 29-inch TV      

Problem            Mr M is in the market for a new TV. He has been looking at big widescreen models but is disappointed by the lack of choice, particularly with non-Dolby Pro Logic models. He has short-listed the Sony KP41S3 which he realises is not a widescreen model, but he suspects it will give a good widescreen picture, and is around £1000 cheaper than comparable 16:9 sets. He also likes the look of the KL37W LCD back projector, but want’s to know if it is worth the extra? Would it be a better long-term investment, because of the LCD technology, though he hasn’t read anything about the cost of replacement bulbs?


Expert Reply He is right, there is a dearth of large screen and widescreen TVs without Dolby Pro Logic, but look at it this way, once you’re into seriously big and expensive tellies -- circa £2000 to £4000 -- DPL processing is adding comparatively little to the price. Once you get to that sort of size the difference between 4:3 and 16:9 displays are less pronounced, and the Sony KP41 looks good, whatever its showing. Replacement bulbs for LCD projection TVs can be expensive, not far short of the cost of a replacement CRT projection tube.  Sony say a bulb swap works out at around £300, but older models are normally supplied with two spares as standard. They tell us that bulbs in the latest sets have a life-expectancy of between 8 to 10 years, with normal use, that hopefully won’t need replacing within the lifetime of the TV.



Name                          Michael Cook, Halifax, W. Yorks             

Kit                               A TV with a dirty screen...

Problem                      What is the best way to keep his TV screen clean, asks Michael Cook? Should he use furniture polish, or is there a more suitable proprietary cleaner?


Expert Reply             The high voltages floating around inside a CRT picture tube generate a lot of static electricity, that ends up on the faceplate and attracts dust like mad. Look for cleaners that include an anti-static agent. Some household polishes have them but we prefer the specialist cleaning foams developed for computer monitors as they do not leave any waxy residues that accumulate around the screen surround.



Name                          John Chappel, Marizion, Cornwall                                            

Kit                               TV and satellite receiver

Problem                      John is mystified by aerial downleads. He wants to know if there are different types and asks what sort of leads aerial installers use. Is it worth specifying a higher grade, when having an aerial fitted?


Expert Reply             The downlead is the coaxial cable that connects a rooftop TV aerial or dish to the TV, VCR or satellite receiver. It should be a low-loss type, with an impedance of 75 ohms. Whilst the cable can have an effect on signal quality -- particularly on longer runs of more than 25 metres -- the care taken during installation and alignment of an antenna, and subsequent weatherproofing,  will have a far bigger impact on picture quality. By all means ask the installer what grade of cable they’re using, but a knowledgeable CAI registered engineer should know what sort to use, to suit local signal conditions in  and the type of equipment.             




With digital TV just around the corner a lot of people are concerned about the prospect of being forced into buying a new television. Relax, there’s no need, and in any case it’s not going to happen overnight. In fact it could be a year or two before there’s anything worth watching on the new channels, moreover the existing analogue channels will continue, possibly for another ten years. Even if you want get connected from day-one, any reasonably recent TV, with at least one SCART AV socket, will be able to use one of the new digital set-top decoder boxes. If you’re already using the SCART socket for a VCR or satellite receiver (or both) then you may have to buy a SCART splitter cable or adaptor. If you’re in the market for a new TV now there’s no need to hold off, though it might be a good idea to shortlist models that have two SCART sockets.






Name                          C. P. Bradley, Chesterfield, Derbyshire                

Kit                               In the market for a AC-3 amplifier

Problem                      Mr Bradley wants us to settle an argument with a friend. The friend says it’s pointless buying a AC-3 amplifier/processor unless he was going to buy a laserdisc player since the VHS hi-fi soundtrack is incapable of carrying AC-3 sound. If this is true he wants to know why, since the video was recorded from the original film, and the end credits often state quite clearly it has a Dolby Digital soundtrack.


Expert Reply              Mr Bradley’s friend is right, Dolby Digital or AC-3 is a six channel digital recording system (aka 5.1: five full bandwidth hi-fi channels plus one narrow band channel for bass and effects); there’s simply not enough room to accommodate such a large amount of information on analogue VHS, so don’t believe everything you see in movie credits. There is space on NTSC (but not PAL) LaserDiscs for AC-3 data, though only just; it replaces one of the disused analogue sound channels. DVD has the capacity for multiple discrete soundtracks, including both AC-3 and the Euro standard MPEG audio, which also uses the 5.1 scheme, so there’s nothing to stop Mr Bradley getting a 6-channel amplifier. He’ll need one sooner or later, if he wants to keep up with home cinema technology.



Name                          M. A. Golden, Chadderton, Lancs 

Kit                               Cambridge Audio Disc Magic 1 and DAC Magic 2, Yamaha DSPE-492 DPL amp, Rotel RB850 and RB596AX,, Panasonic HD610, Pace Apollo STV, Mission speakers, Sony KPS41 back projection TV

Problem                      Mr Golden’s AV system has been built up over a number of years and now he wants to add a DVD player. He is considering buying a Yamaha DDP2 Dolby Digital processor, to use with his 6-channel Yamaha amp but following recent news reports about the ratification of the audio standard for PAL standard DVDs, he has some questions. Will DVD decks have both AC-3 and MPEG-2 processors, or will there be affordable external decoder boxes 


Expert Reply             Both probably. Several companies planning to launch DVD players in the next few months have said they have models that can process both audio protocols. Once production of the decoder chips ramps up there’s bound to be a good selection of outboard decoder boxes on the market, but you’re going to have to be patient. Unless you’re absolutely determined to be the first kid on the block with a DVD system, we think it will be a good idea to wait a little while, to see how things pan out. 



Name                          C. Oldfield, Portsmouth, Hants             

Kit                               Pioneer CLD-925 laserdisc player, Mitsubishi CT-32CW1BD TV

Problem                      Distorted reds, with fine vertical blue lines during NTSC LaserDiscs replay are spoiling the picture on Mr Oldfield’s TV. He’s has it checked by a service agent, but he would like to know if it is an inherent fault, or is it something he’ll have to learn to live with?


Expert Reply             Colour processing problems on NTSC LaserDiscs and tapes shown on PAL TVs, are not uncommon. Basically the TV is being tricked into doing something it wasn’t originally designed to do. To be fair to Mitsubishi and most other companies marketing AV equipment with NTSC replay facilities, usually warn there can be problems. Maybe we should be thankful it works at all. Our friends over the water -- where the NTSC discs come from -- do not have the equivalent facility (i.e. replaying PAL discs and tapes on NTSC equipment).  Reading between the lines in Mr Oldfield’s letter it seems this is happening in areas of high saturation, in which case backing off the colour and contrast might help -- most people have them set way to high in any case.



Name              Terry Noonan, Dulwich, South London

Kit                   Thinking about a Pioneer LD player

Problem            Not so much a problem but Terry has read a lot about laserdisc but is thoroughly confused by all of the audio systems used. Can we please cut through crap?


Expert Reply            On PAL discs the video information takes up a lot of room so the only possibilities are two analogue channels, or two full bandwidth uncompressed digital channels. It’s been almost ten years since the last PAL discs with analogue-only audio were made. The digital audio channels are almost identical to audio CD, (16-bit/44.1kHz); all laserdisc players can replay CDs. It’s a bit more complicated on NTSC discs, the video signal takes up less space, so there are several possible audio permutations, starting with the now obsolete twin analogue channels. Discs can have 2 analogue and 2 uncompressed digital channels or 1 analogue channel, 2 uncompressed digital channel and one compressed digital channel, (used for AC-3/Dolby Digital), or 2 analogue channels and one DTS channel. DTS is a relatively new 5.1 sound system, similar to AC-3 but with a much lower compression rate



Name              Peter Rodd, Chelmsford Essex

Kit                   Pioneer CLD-515, Philips CD player

Problem            The recent publicity over novelty laser pens has got Peter worried. With two inquisitive toddlers in the house he wants some assurance that laser disc and CD equipment is safe. There’s warning notices on the back of the boxes, saying there’s potentially harmful laser radiation inside, what’s’ to stop it getting out and damaging his children’s eyesight?


Expert Reply     LaserDisc and CD players, and all other optical disc systems, such as CD ROM, DVD, MiniDisc etc., have to conform to strict safety regulations. In theory the design of the deck and its cover, plus various interlocks and safety devices should make it impossible for anyone to stare directly into the laser beam. The actual power levels are very small, but eye damage could occur following prolonged exposure. Unlike laser pens, which mostly emit red light with a wavelength of 670 nanometres,  the lasers used on optical disc players are invisible, so service engineers have to take extra care when working on equipment. Unless Peter’s kids can figure out a way to dismantle his equipment, and override the safety interlocks, he should have nothing to worry about.




Laserdiscs can be mastered in two ways (or a mixture of both). The first is  standard play or CAV (constant angular velocity), where the speed of rotation is constant, like an LP record. CAV mastered discs last for up to 36 minutes per side (30 minutes on NTSC recordings), but they allow access to all replay functions, (still, slomo etc.). It’s possible to search to a single frame on a CA recording, and the signal-to-noise ratio is better (it actually improves as the pickup moves closer to the outer edge of the disc). The other type of disc is extended play or CLV (Constant Linear Velocity), where the speed of rotation slows as the pickup moves to the outside of the disc. CLV  mastered discs have up to 64 minutes per side, trick replay options are limited though most players have a still ‘field’ mode, and seek times are a lot slower, but the longer running times mean CLV discs have to be swapped or flipped over less often.



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