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Q I have a Hitachi 60 inch projection TV, a Yamaha RX-V2092 receiver, and RCA satellite and DVD systems. All are linked with S-Video cables. When I use the satellite recever the picture will break up for a split second once every two hours or so. Also, when I play a DVD movie the picture will break up once during the picture. Is this normal?
A What
you are experiencing is pixellation. It occurs when there is insufficient
digital data getting through to make a complete picture. I have
seen it with DVD players, and it also occurs with digital satellite
signals. If you are passing the output of the satellite receiver
and the DVD player through the receiver to the TV, try connecting
the satellite receiver and DVD player directly to S-Video jacks
on the TV. Other than that, it is something we have to put up
with occasionally. Digital video is just getting off the ground,
and there is lots of room for improvement.
Q I
have heard opinions that the audio quality when playing CDs from
a DVD player is comparable if not better than a standard $200
- $400 CD player. If I wanted to achieve better audio quality
than a DVD player, it was suggested that I would have to purchase
a high-end CD player in the range of about $1000 with digital
output. The DVD player's audio output is via digital coaxial,
and because of this connection the audio quality should be better
than the two channel output of a standard CD player. Do you agree
with this theory? I was considering purchasing a separate CD player
for about $300 and dedicate the DVD player strictly for video.
Should I save my money and continue playing my CDs on the DVD
player?
A DVD
players have two types of audio output jacks. One is the digital
coaxial or optical and the other is a set of coaxial stereo (two
channel) analog. The digital output sends a PCM 16/44.1 bitstream
when conventional CDs are played, a DD bitstream if DD DVDs are
played, a DTS bitstream if DTS DVDs are played (assuming you have
DTS out capability on the player), or a DTS bitstream if DTS CDs
are played. The analog jacks send decoded two channel analog stereo
regardless of the type of disc, except for DTS (DTS decoders are
not built into DVD players yet). My experiences so far are that
DVD players do not perform very well with conventional CDs. This
has to do with the laser beam having been optimized for the narrow
tracks of DVDs rather than the wider track of CDs. So, the digital
output of the DVD player, when using a CD, has considerable jitter,
in my opinion, and I would suggest getting the dedicated CD player
with a separate DVD player as you mentioned. I suspect that eventually
everything (music and movies) will be sold on DVDs rather than
the older CD format, so one player will handle it all. CDs, as
we know them right now, will become an outdated technology. Higher
sampling rates like the 24/96 format require more space than CDs
have.
Q I own a DVD player and have noticed that, when watching DVD movies, jagged edges occur around people when they are in motion. This is quite obvious when I am about 1 foot away from the screen but is not as noticeable when viewed at a normal distance. (I use an S-Video connection) Are these problems with the player, the connection, or DVD format in general?
A For
live or taped video broadcasts (where the original signal is video
rather than film), this is a motion artifact produced by the fact
that NTSC video is interlaced, that is, each frame (one complete
image on the TV screen) is made up of two fields of alternating
video lines that are shown in sequence. Each field is 1/60th of
a second, producing a frame that is 1/30th of a second. When the
video image is collected by the TV camera, the first field is
collected and then the second field. By the time the second field
of the frame is collected, moving objects have shifted in the
field of view. So, the frame is made up of two fields that have
the subjects in slightly different positions. This produces jagged
edges on those parts of the picture that are moving. Line doublers
take a look at what is in the line above and the line below, and
synthesize lines in between that are not jagged. This reduces
the motion artifacts, but it is a synthesized image (half of it
is), not a real one. Sometimes these jagged edges can occur with
video that has been taken from film (i.e., movies), even though
the fields for each frame are taken from a stationary film frame
(so the subject has not moved in between each of the two fields).
This probably results from the motion logic that is in the TV,
but I suppose it is possible that the DVD player is causing it
(DVD players downconvert the progressive scan movie on the disc
to an interlaced signal so that our NTSC TVs can show them). One
way to check this out is to take your DVD movies to the store
where you bought the player and see if it occurs there, with the
same model player connected to a different model TV. Then try
the discs with a different DVD player. One of the formats for
HDTV, namely 720p, uses progressive scanning rather than interlaced
scanning, so it won't have this motion artifact. The highest resolution
for HDTV, called 1080i, will have the motion artifacts because
it is interlaced.
Q Does anybody have suggestions for supressing the "speaker-pop" from the fridge or furnace turning on and off? It's exasperating since we put in a programmable thermostat (an isolation relay is now part of the furnace's circuit).
A This
is something I have never been able to get rid of completely.
The problem is that when big electric motors turn on and off,
there is a spark that occurs in the relay switch that causes significant
RF to be generated, and your hi-fi equipment picks it up. AC line
conditioners can help filter out the RF in the AC line, but the
AC cables for your components, which are in the circuit after
the AC line conditioner, still act like antennae, so the most
you can expect is reduction, not elimination.
Q I
upgraded my system by adding an Acurus 200X3 amp (for the three
front channels) to my Nakamichi AV-1 receiver, whose former 100
watt front channels now power the surrounds. All amp inputs are
fed from a Marantz 870 DD processor. Now I cannot use headphones
for late-night listening. The Nak headphone jack only provides
surround info, or none at all in straight stereo. Do I need to
add a headphone amp to my tape loop? Will the bypass outputs of
the 870 provide stereo to the Nak if I hook them up with a Y adaptor
to the main inputs? I love the impact the amp has made, but I
never expected this!
A The
problem stems from having rerouted the Nakamichi main amplifiers
to drive the rear channel signals instead, so even the tape loop
might only have the rear channel information. Thus, whatever you
connect to the main inputs still would not get to the headphones
in stereo mode, and you would only get rear channel info when
in surround mode. What you might do is use a speaker selector
box, like the ones sold at Radio Shack, and connect the outputs
of the Acurus front channel amplifiers to the selector box inputs.
One set of selector box ouputs goes to the speakers, and another
set goes to your headphones (a headphone jack can also be purchased
at Radio Shack, along with a headphone extension cord). Then,
you just select speakers during the day and headphones at night.
Headphone outputs on receivers sometimes have op amps in the circuit,
so you will probably get better sound for your headphones using
the Acurus to drive them.
Q I
have a Boston Acoustics Lynfield speaker system with the VR40
as fronts, VR12 center, VRS surrounds, and VR500 subwoofer, connected
to an Onkyo 919 receiver. The sound has been fantastic over the
years, but now there's a bright sound where the letters S and
CH, (when people are singing) has now become a little too pronounced.
I haven't done anything different except move a few of the components
around. Any help would be appreciated.
A What
you are hearing is called "sibilance", so your system
is "overly sibilant". It can be caused by a number of
things. One is the overuse of negative feedback in the amplifier
design, but that would have been there to begin with, not something
that changed over the years. Radio stations often sound overly
sibilant, depending on the reception conditions, so if this coincided
with moving the receiver, and it is mainly the radio where you
are finding this problem, try shifting the antenna or getting
a better antenna. Finally, speakers do suffer from aging, and
your tweeters would be the culprit for sibilance. An equalizer
could be used to reduce the output in the region of 6 kHz, but
since the excessive sibilance is probably distortion, it would
be like throwing a blanket over the sound. Turning the treble
control on the receiver down can help, and also putting a felt
pad over the tweeter in the center channel speaker.
Q Regarding
a reader's recent question about white vertical lines that appeared
on his TV when playing DVDs, another reader responded below.
A I
experienced a similar problem with my Sony DVP-7000 during the
first few months I had it. It was particularly bad on scenes with
high contrast; for example, when rolling the ending credits of
a movie. I'm not sure what caused - or solved - the problem, but
here are two things that I changed, and the reader might want
to try something along the same line (if he can): (1) I
defeated the macrovision copy protection. Luckily, I had an early
Sony that only required flipping a switch. (2) I re-routed my
S-Video signal directly into the TV, bypassing the receiver. While
this means I have to switch AV inputs on the TV along with switching
inputs on the stereo, I get a cleaner signal.
Q I
know that the principal reason for having pre-outs is to add an
external amplifier, but on my receiver (H/K AVR 55), what are
the two main-ins for?
A Main-ins
are present on many receivers. They are the inputs to the front
left and right receiver power amplifiers. Their most convenient
use is allowing you to purchase just a three channel outboard
power amplifier, and you re-route the pre-outs of the rear channels
into the main-in jacks (usually there is a set of jumpers that
connect front channel preamp outputs to the main-ins, and you
remove these to use the main amplifiers for another purpose).
You then connect the pre-outs of the front left/center/right to
the three channel power amplifier, and the speaker binding posts
of the front left/right on the receiver to your rear speakers.
This lets you have more power to the rear channels on receivers
that have high powered front channels and low powered rear channels.