TV, DVD, AV receiver, Pace ITV Digital box
Problem: Philip keeps the TV muted and plays sound via his
receiver and speakers. He has been very impressed with the sound from his
system and recently decided to buy an ITV Digital box. While the picture is
superb, Philip does not feel the sound is as good as when his source was a
Panasonic VCR. In particular, he has had to take the sound source from the back
of the Pace box using the stereo leads; otherwise it is out-of-sync with the
picture. Philip uses SCART leads elsewhere.
and sound on ITV Digital are encoded using the MPEG 2 system (the same as DVD)
and has the potential to be as good as normal NICAM stereo, which is presumably
what Philip is getting from his Panasonic VCR. However, although NICAM is a
digital sound system there's less compression and it undergoes less processing,
which, incidentally, also accounts for the time difference between the analogue
and digital signals. The soundtracks on ITV Digital channels also travel
en-masse, as it were, as a 'multiplex' of signals containing the picture and
sound information for several channels plus data and text for all of the other
stuff we seem to need these days. What's more MPEG 2 encoding is 'dynamic'
which means the proportion of the data stream allocated to each of the various
components in the data stream constantly changes. Various other factors can
also affect performance and whilst the digital TV signal is quite robust if
Philip is living in a fringe reception area and the signal is weak then the
error correction systems in the receiver will have to work harder and this
could lead to a reduction in sound quality. Unfortunately there's nothing
Philip can do about the way the signal is processed but he could investigate
the possibility that he is getting a weak signal and if necessary, get a better
estate agent will tell you the three most important things when buying or
selling a house are location, location and location. The same holds true for
ITV Digital reception, a lot depends on where you live. If your picture is poor
or unstable you can either move house or to try a new aerial, and get it
installed as high as possible, the low power digital signals apparently do not
bend or 'diffract' – following the contours of the earth's surface -- as well
as analogue signals.
Bryan is having problems with the DVD playback on his PlayStation 2. The
picture appears to be stretched vertically on his 4:3 television. He has set
the TV as a 4:3 on the main PS2 menu but it won't let him change from 16:9 on
the DVD set-up menu. Is it this that's causing the problem and if it is why
won't it let him change it? Also, which gives the best picture quality, S-Video
or RGB? Can all of these go through the SCART connection?
doesn't appear to be a common problem on the PS2 and indeed all of the samples
we've tried allow you fiddle around with the Picture Size setting on the main
configuration menu – used to set the display shape for games playback and the
deeply buried DVD setup menu, which follows normal DVD player conventions with
options for 16:9, 4:4 and 4:43 Pan and Scan. That would tend to suggest that
Bryan's player has a problem and may need expert attention.
As for the
differences in picture quality between S-Video and RGB, it really depends on
the display device. On paper RGB should give the best results as the three
colour signals undergo fewer stages of signal processing; colours should be
sharper, purer and there should be less noise. However some TVs can produce an
indifferent picture in RGB and in some cases picture controls have limited
effect, or no effect at all on older models. Equally you can get good and not
so good S-Video performance, in short if you have both options give them a try
and see which one you prefer. The SCART connector format can be configured for
both S-Video and RGB but not at the same time, this is usually a function on
the setup menu (or a switch) on the source component. Also bear in mind that
only 'fully-wired' or Type 'U' SCART cables can carry RGB and S-Video.
2 is first and foremost a games console and DVD replay is very much a secondary
feature, as anyone who has struggled with the microscopic menus and awkward
controls – on the controller pad – will testify, but it can be made more
tolerable. The best way to improve the PS2's DVD user friendliness is to get an
infra-red remote control adaptor. They plug into one of the console's
controller sockets and are now widely available for less than £20.
Kit: Sony 36FS70 TV, chipped Sony 325 DVD
Previously, Douglas always used DVD's RGB output to view his discs (on Region
Two and Region One). Having got the new TV, he decided to try to compare RGB
and S-video performance. Both outputs gave excellent results on Region Two
discs (RGB through AV-1 and S-video through AV-2). However, when playing Region
One discs, whilst RGB is again excellent (through AV-1), outputting S-video
from the player to both AV-2 and AV-3 gives almost colourless images – even the
dedicated S-video terminal on the player gives a similar effect. Are Region One
and S-Video are perhaps not compatible, or is the problem related to the
chipping of the player or even the TV?
being equal an RGB connection between a DVD player and TV will usually look
better, colours tend to be richer blacks are blacker, whites are brighter and
the contrast range is broader and that's because the red green and blue video
information the decoders inside the player extract from the disc are piped more
or less directly into the TV's picture tube. S-Video, on the other hand is a
two-part signal, the player first has to convert the virgin RGB information
from the disc into a brightness or luminance (Y) component, and colour (C)
component, send it down a pair of screen cables to the TV or display device and
the TV then has to convert the Y and C components back into RGB signals, to
drive the picture tube.
differences between RGB and S-Video picture can sometimes be hard to spot on
Region 2 recordings on some PAL TVs but if we now factor in differences in TV
standards, then they can become more noticeable. Region 2 NTSC material will
tend to look better in RGB as once again the video information isn't messed
around with to anything like the same extent, whereas NTSC S-Video has to go
through extra layers of processing in both the player and on the TV. It's not a
problem; just use the signal system that gives the best results.
IMPORTANCE OF IMPEDANCE
DVP S735 DVD, Pioneer VSA E08 amp
Nathan has been offered a JM Lab Chorus speaker system. However the speakers
have a nominal impedance of 8 ohms and a minimum impedance of 3.6 and 3 ohms.
Nathan wonders what this means and wonders they would be OK to use with his amp
as it is rated at 6 ohms?
should try and avoid getting too hung up on the numbers. The word 'nominal'
means just that, it changes, in fact the impedance of a loudspeaker, which is a
measurement of its resistance to an alternating current (AC) can vary slightly
between identical models coming off the same production line and there are dips
and peaks in the value according to a whole variety of factors including room
temperature, humidity, the wires used to connect it to the amplifier, the
frequency of the signal it is handling, the design of the enclosure and
probably the colour of the wallpaper as well…
point to remember is that many amplifiers work most efficiently when the
impedance of the speakers they are driving have an impedance of around 2
ohms. Some are designed to work with a
slightly higher value but the point is when speaker impedance falls below 2
ohms the amplifier can start to overheat and there's a risk of damage through
overloading. When speaker impedance is higher than the amplifier's nominal
rating power will be lost and performance may be compromised. The figures
Nathan quotes indicate that the nominal impedance of the Chorus speakers is
well inside the safe operating parameters of the Pioneer amp, and they can be
speakers usually have a nominal impedance of 8 ohms and high-frequency
'tweeters' are usually rated at 16 ohms, but the impedance of most speaker
enclosures are either 4, 8 or 16 ohms, so why the discrepancy? It all depends
on the way the speaker(s) inside are wired up, and things like crossover units,
which are used to separate out the high and low frequency signals, and feed
them to their respective drivers.
Doug currently has an analogue TV and wants to make the switch to digital in
order to get the benefits of digital reception and also receive the free-to-air
channels. He has no interest in paying any subscriptions charges though. Doug
is also wary of using an integrated digital TV as he feels this severely limits
his choice of sets. He wonders if buys a digital decoder set-top box but
doesn't pay any subscriptions for a smart card, can he still receive the
free-to-air channels? Also, Doug wonders what are the differences between
digital terrestrial and satellite set-top boxes? Are they interchangeable?
surprisingly neither ITV Digital nor BSKYB are terribly keen on people
acquiring digital TV services without a subscription. Basically it works like this.
If you take out a subscription to a channel package – and this usually means
signing up for a year's contract -- you get a set top decoder box at a heavily
subsidised price, or free, or lent to you and in the case of satellite TV, the
dish and installation may also be thrown in, or provided at a reduced rate. The
deals and promos vary all the time but the starting point for both services is
around a tenner a month for a basic subscription.
is the cheapest way to get the free-to-view channels (over 40 TV and 45 radio
channels), there's a one-off installation fee (currently £100) and agree to
have the set top box connected to your phone line. ITV Digital carries 21 free
to air channels but won't supply you with a box without a subscription. Doug
might be able to persuade a dealer to sell him one but we've heard the retail
price is around £350. He may be able to find one second hand, or buy an IDTV.
Terrestrial and satellite set-top boxes are not interchangeable however a
low-cost decoder for free-to-air digital TV called Digital Television Adaptor
(DTVA) has been developed by Pace and Xcom; it's likely to go into production
well ahead of the proposed switch off of analogue TV services, which could be
anytime between 2006 and 2010.
Mission FS2-AV speakers, Sony STR-DB940 amp, Pioneer DV-636D DVD
Paul wonders if he were to put a pair of floor standing speakers in another
room, would he end up with a delay in the sound if used simultaneously with the
Missions? Paul would need to use approx. 20 metres of speaker cable from the
amplifier to the speakers.
We get some
odd letters… Clearly it all depends where Paul stands. Were he to be midway
between the two sets of speakers then the sounds would reach his ears more or
less simultaneously. If on the other hand he stood next to his new floor
standing speakers, then he would hear the sound from them straight away, but
the sound from the others would arrive a fraction of a second later. If you
want to get really geeky we can calculate the time difference but we have to
make some assumptions, namely that Paul's house is at or around sea level
(standard atmospheric pressure and normal C02 concentrations), furthermore
we'll work on the basis of an air temperature of 20 degrees C and a relative
humidity of 30%, in which case the speed of sound calculator at: http://www.measure.demon.co.uk/Acoustics_Software/speed.html
that it travels at 323.74 metres per second. Some simple sums on the HE office
abacus reveals that the time it takes for sound to travel the 20 metres between
Paul's Mission speakers and his ears (and this is very approximate) is 0.00617
seconds. No doubt there will those that will argue that such a time difference
is not only significant but also detectable by the human ear but quite honestly
we think Paul can rest easy and we can all get on with the rest of our lives…
Videologic DTS DigiTheatre home cinema system
Scott has this budget system in his bedroom to provide a ‘late night movie
experience’ and has noticed a distinct rattle coming from the subwoofer during
particularly bass heavy incidences. Is the limit of the system being reached?
Scott is now on his third replacement, all of which demonstrated this problem.
HE reviewed this kit in issue 78, and gave it a five star rating. Did your
review push the system to its limits?
test equipment well beyond the normal call of duty, and our reviewer noted that
the eight-inch driver on our sample did seem to have a relatively short throw,
but it wasn't considered to be a problem under normal listening conditions –
and that's what we're interested in – and the system as a whole performed well.
Obviously you can make any speaker or sub distort and eventually crash the end
stops, if you drive it hard enough, but that's not real world conditions, and
it doesn’t prove anything.
From the sound
of it Scott is trying to achieve the kind of cavernous bass effects that this
particular system is not designed to deliver. Nevertheless it is not unknown
for the components inside sub woofers to rattle, and they can certainly cause
other things around them to vibrate, so it's always worth trying them in
different positions. The Videologic DigiTheatre system works fine within the
confines of a medium size living room or bedroom, but if Scott wants the kind
of sub and amplifier that's capable of serious structural damage he's going to
have to look elsewhere.
AVR-3802 AV amp, Sky Digibox
Alwyn has just bought the Denon 3802 and is very impressed with it and it was
worth waiting for. However, Alwyn has learnt that the AVR-4802 can deal with
dts 24/96 DVD-Audio but the 3802 can't. Is Denon offering a software upgrade
for the 3802 and if so would it worth the effort given the paucity of
read that Pace has made a module to fit existing Sky digiboxes via the PCMCIA
slot at the rear, which enables said digibox to extract and output Dolby
Digital sound via optical/coax link. Is this true and are there any plans to
market such a device? He has no plans to move over to Sky+.
as though Alwyn has been doing a bit of web surfing, according to our man at
Denon the AVR-4802 is a US product costing $2500, and totally unrelated to the
3802. A European version of the 4802, called the AVR-A11SR, should be available
about now for £1800, and it will be the first amp to ship with 24/96 dts. No
upgrades are planned for the 3802, in fact this is quite a rare feature and
usually only found on high-end kit, costing considerable more than the 3802.
However, a dts 24/96 upgrade (hardware and software) is planned for the Denon
AVC-A1SE, probably by early 2002.
rumoured 5.1 upgrade for existing digiboxes is one of those things that is
almost certainly technically possible but unlikely to happen. For one thing the
market for such a device is likely to be relatively small; we suspect that the
number of Sky viewers, signed up to the movie packages with 5.1 sound systems
is not enough to warrant the production of such a device, or that it would be
prohibitively expensive. Moreover, it's likely to take a year or so before the
number of movies broadcast with 5.1 soundtracks makes the exercise worthwhile.
It's quite possible that the next generation of digiboxes will have the
facility and of course the option is there on Sky+ but because of the current
lack of material it's not being touted as a top-line feature.
and love good old Dolby B and C tape de-hissing, thrill to the multi-channel
surround sensations of Dolby Digital and now you can look forward to Dolby E. Relax,
there's no new boxes for you to buy, Dolby E is a behind the scenes technology,
used by broadcasters to encode up to 8 audio high quality audio channels, plus
data, into a stereo digital soundtrack. This will make it a lot easier for them
to quickly upgrade their systems to 5.1 Dolby Digital channel sound.
Toshiba MT1 projector, Yamaha DSP A3090 amp, Toshiba SD100 DVD player and an
NTL digital STB
This one has everyone stumped, says Mark. His DVD player is connected to the
projector via S-Video. The TV is run via composite video. He cannot leave the
S-Video connected permanently, as it disables the composite lead and he can’t
watch TV. The constant plugging and unplugging of the leads is resulting in trips
to his local AV shop to replace broken cables. Switchboxes do not work. There
is an input for a computer labelled RGB. Could this be used, Mark wonders.
to the good people at Toshiba the explanation is that SD100 is an entry-level
player and as such they would expect most users to only want to connect it to
one display device at a time, hence the facility to switch between composite
and S-Video... This seems like a rather spurious argument to us but the long
and short of it is that there is nothing Mark can do about it at the player
end, and it’s one of the other. However, all is not lost, if his aim is simply
to drive two display devices simultaneously then it might be possible for him
to ‘loop though’ a composite video output to the projector, through his TV.
This is on the assumption that his TV is a fairly recent model with two or more
SCART connectors. However, this would mean that the projector is only getting a
composite video signal, rather than the higher quality S-Video signal, but on
this type of setup it is unlikely that it will be that noticeable, if at all.
Pro-Logic Widescreen 32inch TV, Samsung DVD player.
Damian would like to make the next jump to digital surround sound, but is new
to this game. He feels that he wants to get a Dolby Digital or dts decoder,
processor, decoder or amplifier. The trouble is he would like to know what all
this means. Damian would like to have it so that he can “watch the DVD's with
the 5.1 surround sound effect - aeroplanes flying across the room type
thingy!!” He has a budget of around £300-£350 and hopes to negotiate the price
down, so that means a RRP of around £400.
got the right idea and the next logical step is for him to upgrade to digital
multi-channel surround but his budget is fairly modest and he must be realistic
about his expectations. Dolby Digital and dts (Digital Theatre System) are both
types of '5.1' surround sound system, originally developed for use in cinemas.
Basically 5.1 means the soundtrack has five high quality 'full bandwidth'
channels (right and left front stereo, centre-front dialogue, and right and
left rear stereo surround) plus one narrow band channel that carries only low frequency
bass sounds and effects. Technically Dolby Digital and dts are quite similar
but Dolby Digital (formerly known as A-3) is part of the DVD format and most
discs have it whereas dts is a fairly recent development and there are fewer
recordings. However, it's not a huge problem and these days most devices (AV
amps, DVD players etc) that have built-in 5.1 decoders can handle both types of
best bet is a packaged system, which will include an AV amp with built-in Dolby
Digital and dts decoders, plus a set of matching speakers, and preferably a
sub-woofer as well (for those bass effects). Time to name names; given the size
of his budget the Videologic Digitheatre DTS will give Damian the most bangs
for his bucks and should provide him with a good introduction to the joys of
STARTED 1 – DIGITAL TV SOUND QUALITY
of digital terrestrial and satellite sound has occasionally and somewhat
optimistically been compared with audio CD but it's a long way short of that.
In fact the MPEG 2 audio system used by both Sky Digital and ITV Digital
employs a bit rate that is around one tenth of that of CD. There are other
considerations, digital TV sound is highly processed, both in the studio – as a
hangover from the way analogue sound is handled -- and at various point along
the transmission chain. What's more the data is liable to corruption and
interference, which can result in audible 'artefacts' and even short breaks in
transmission resulting in dropouts. Nevertheless, for all that digital TV sound
is surprisingly good and with a strong signal such deficiencies as there are
tend only to be noticeable when listening intently to music, and only then when
the digi box hooked up to a decent hi-fi system and speakers – the audio
systems in most stereo TVs can hide a multitude of sins…The most obvious
effects of all of the processing is that higher frequency sounds and transients
– drums and percussion and so on – lack the sharpness and clarity of CD.
STARTED 2 – A QUESTION OF STANDARDS
in TV standards cause a lot of confusion when it comes to DVD so here's the low
down. Ignoring for a moment Regional coding, (more in a moment), in most cases
DVD players bought in the UK will be able to replay 525-line NTSC recordings on
ordinary PAL televisions. The majority of players made in the last year or so
either convert NTSC recordings into a 625-line PAL signal that can be viewed on
any TV, or partially convert the signal, (Pseudo PAL or PAL 60), which again
can be viewed on most recent PAL TVs. A few older players do not convert the
signal at all and the result will be a black and white picture on a PAL TV.
Several models also have the facility to replay a disc in it's 'native' format,
which means you get a NTSC video signal, this can only be played on a
multi-standard TV. Regional coding is a separate issue; this is a data 'flag'
on the disc that tells the player whether or not it is allowed to play it and
has nothing to do with TV standards. In case you are wondering Region 2 NTSC
recordings do exist – Japan is also Region 2 -- and there are also a growing
number of NTSC Region 0 (region free) discs.
Ó R. Maybury 2001, 0111