HI FI static question?

Hi-Fi uses *two*, count them, *TWO*, the number 2, two heads in the helical
drum.  One head per channel.  One for the left Hi-Fi channel, and one for the
right Hi-Fi channel.  In audio terms, two audio channels *is* stereo, period.
Sony, the inventor of Hi-Fi, has called it Hi-Fi stereo.  NON-LINEAR Hi-Fi AFM
STEREO is one method, and the preferred method, to obtain stereophonic
reproduction from videotape.  The system you plainly call "stereo" is referred
to as *LINEAR* stereo, another method of obtaining stereo audio reproduction
from videotape, sometimes coupled with Dolby System to reduce tape hiss.
Highest frequency response for linear stereo: 15KHz at the fastest speed.  For
Hi-Fi stereo, it is 20KHz in all tape speeds.  Wow and flutter for linear
stereo varies from machine to machine, but is virtually non-existent with Hi-Fi
stereo.  Dynamic range is not impressive with linear stereo, while Hi-Fi stereo
averages dynamic ranges close to, or at CD quality (in the neighborhood of
around 80-100dB).  Hi-Fi stereo also does not have problems with high frequency
hissing noise, although it can have some problems with switching noise
(identified as a mild and muted buzzing noise).  - Reinhart

Of course there are.  However, you came across as saying that Hi-Fi means
mono, which is about as far from the truth as you can get.

I'm am simply trying to explain what Hi-Fi really is, so that it won't
confuse other readers.  However, you seem to be disputing me on this.

Well it's quite simple.  When you make a standard recording (by standard,
I mean you put a tape in and hit record, and SAP reception is NOT enabled)
with a Hi-Fi stereo VHS VCR, it records stereo audio on the Hi-Fi track.
In addition to this, it will also record audio on the linear track (most
likely, this will be mono) so that the recording is fully compatible with
non Hi-Fi VCRs.

When you play the tape back on a Hi-Fi stereo VCR, you have the option
(usually by the "audio monitor" button or by changing something in a menu)
of listening to either the Hi-Fi track, or the linear track.  On a lot (if
not all) of these VCRs, there are actually 4 audio modes:

Stereo, which means you are listening to BOTH left and right Hi-Fi
channels, with the left channel going to the left speaker and the right
channel going to the right speaker

L, which means that you are listening to the left Hi-Fi channel on both speakers

R, which means that you are listening to the right Hi-Fi channel on both
speakers

Linear (which on all modern consumer level VCRs is mono), which means that
you are listening to the linear audio track that is recorded on the top
edge of the tape by the stationary audio head.

I was speaking of the linearity of one or two audio tracks when recording them
in stereo, mono, or Hi-Fi and I was describing the differences between them. If
I have stated anything technically incorrect without a full clarification here
in this thread, then I apologize. My intention here was to point out that
during the process of recording there are technical differences between mono,
stereo, and Hi-Fi. I was speaking linearly in terms of how each individual
track (right and left channel) might be recorded during the process of
recording. of course, the actual processing used to reproduce the intended
recording in playback (for the initially recorded audio track(s)) is an
entirely different matter altogether.

Subject: Re: HI FI static question? CLSNOW
From: dmw @bellatlantic.net  (David Matthew Wood)
Date: 4/29/01 11:59 PM EST
Message-id: <dmwood-3004010059480001@adsl-­141-156-38-133.bellatlantic.ne­t>


Huh?  I don't understand what you mean by "difference between mono and Hi-Fi."
By this do you actually mean the "difference between the linear track and
and Hi-Fi track"?

It's not a matter of stereo or mono being different from Hi-Fi, as Hi-Fi
doesn't doesn't dictate whether it's mono or stereo.
All Hi-Fi really means is that it has a much improved frequency response.
I give another example:

With radio, AM stereo does exist but it's not Hi-Fi.  It has very poor
frequency response.  FM stereo also exists, and it IS Hi-Fi.  It has very
good frequency response.  

Also, if I listen with a half decent sound system, I can easily tell by
ear if I am listening to the Hi-Fi track or the linear track.  Heck, I can
even tell the difference with crappy TV speakers.  If I toggle back and
forth between Hi-Fi and linear while it's playing, it makes it even easier
to tell the difference, just like one of those A and B comparisons.
Granted, a stereo recording might help someone with an untrained ear, but
still it is quite possible to tell the difference if you record from a
mono source.  This goes more than double if you happen to make the
recording in EP mode.


You said that if a tape recorded in a certain machine is played back on
that EXACT SAME machine and you hear static, then it's an alignment
problem.  This is not true.  In fact, it's quite the opposite.

If you make a recording in a machine that's misaligned and then you play
it back in the same machine, the head to track alignment will be perfect
on that machine.  Naturally it will be way off if you play the tape in
another machine, but that's beside the point.

And I'm just saying that if you record something and then play it back in
that exact same machine and it is still staticy, then there is some other
problem.


Depends on the info given.  Heck, his problem might even be easily cured
if he adjusts the tracking control.  I'm actually suprised this was

MacroVision has not, and never will, affect the quality of Hi-Fi audio
reproduction.  MacroVision affects video only.  - Reinhart

Huh?  I don't understand what you mean by "difference between mono and Hi-Fi."
By this do you actually mean the "difference between the linear track and
and Hi-Fi track"?

It's not a matter of stereo or mono being different from Hi-Fi, as Hi-Fi
doesn't doesn't dictate whether it's mono or stereo.
All Hi-Fi really means is that it has a much improved frequency response.
I give another example:

With radio, AM stereo does exist but it's not Hi-Fi.  It has very poor
frequency response.  FM stereo also exists, and it IS Hi-Fi.  It has very
good frequency response.  

Also, if I listen with a half decent sound system, I can easily tell by
ear if I am listening to the Hi-Fi track or the linear track.  Heck, I can
even tell the difference with crappy TV speakers.  If I toggle back and
forth between Hi-Fi and linear while it's playing, it makes it even easier
to tell the difference, just like one of those A and B comparisons.
Granted, a stereo recording might help someone with an untrained ear, but
still it is quite possible to tell the difference if you record from a
mono source.  This goes more than double if you happen to make the
recording in EP mode.


You said that if a tape recorded in a certain machine is played back on
that EXACT SAME machine and you hear static, then it's an alignment
problem.  This is not true.  In fact, it's quite the opposite.

If you make a recording in a machine that's misaligned and then you play
it back in the same machine, the head to track alignment will be perfect
on that machine.  Naturally it will be way off if you play the tape in
another machine, but that's beside the point.

And I'm just saying that if you record something and then play it back in
that exact same machine and it is still staticy, then there is some other
problem.


Depends on the info given.  Heck, his problem might even be easily cured
if he adjusts the tracking control.  I'm actually suprised this wasn't
mentioned before.....or was it?  I honestly can't remember.

My point is that you don't need a stereo source to tell you whether you
are listening to the Hi-Fi track or not.




You mean Hi-Fi mode and linear mode.  Again, this does not mean stereo.

That doesn't make any sense, as mono and Hi-FI are not the same thing.

You might be able to find them in thrift stores, but you won't find it on
consumer VCRs made within the last several years, as doing so would only
up the price for something the consumer wouldn't want anyway - much like
how manufacturers don't see the need to put stereo RF modulators in stereo
VCRs, since they figure if you want good sound you won't use RF anyway
(same goes with certain satellite receivers, video game systems, etc.)

No, but two channels is all it takes to be able to reproduce a stereo recording.

I think you are confusing terms.  In no way does Hi-Fi dictate whether
it's mono or stereo.  

For example, let's say I have two telephone lines and a friend of mine
also has two telephone lines.  Suppose my friend calls both of my
telephone lines and plays music over the phone on both lines, putting the
left channel on one line and the right channel on the other.  Then suppose
I were to put a telephone on each of my two lines and hold one phone over
my left ear and the other phone over my right ear.  Even though I would be
hearing the music in stereo, it would in no way be Hi-Fi.

At the same time, I could be using my good headphones hooked up to my good
stereo receiver.  I would now be hearing this music in stereo, with the
added benifit of Hi-Fi.
Now suppose I hit the mono button on my receiver.  I would now be hearing
it with the left and right channels mixed, but it will still be in Hi-Fi.

Now with VHS VCRs, there are two ways to record audio onto the tape (well
unless of course you are using some kind of digital encoder).  One is with
the regular linear head which puts the audio track on the top edge of the
tape.  The very first stereo VHS VCRs actually had two audio tracks
recorded just like this.  Naturally, it sounded pretty bad.

Then came Hi-Fi VHS VCRs.  This means that the audio is layered under the
video track by two additional heads mounted on the drum along with the
video heads.  This allowed for far greater frequency responce, and a much
better signal to noise ratio (which is why Hi-Fi stereo VCRs do NOT have
Dolby NR).  You can either have two channel mono, one channel mono (by
that I mean something recorded on the right OR left only, and not both),
or stereo.

Even though this method yields far better results, a Hi-Fi stereo VCR will
still have a linear audio head, simply to make it compatible with non
Hi-Fi VCRs.  However, this track will be mono on most VCRs since there is
really no reason to have linear stereo when you already have Hi-Fi stereo
which is far superior.

Didn't I just say that in my post to which you are responding to?  I guess you
missed what I had typed in your haste to make a response.  - Reinhart

Subject: Re: HI FI static question? CLSNOW
From: dmw @bellatlantic.net  (David Matthew Wood)
Date: 4/29/01 7:37 PM EST
Message-id: <dmwood-2904012037410001@adsl-­141-156-38-133.bellatlantic.ne­t>


That, and Macrovision.

[ If you're going to test hi-fi recording and playback, you don't need a
station that broadcasts in stereo.  A mono source will do just as well if
all you're going to do is listen for noise.  Better still, record
something that has no audio to begin with, and crank the volume up when
you are playing it back.  Any Hi-Fi track misalignment will certainly show
up in this test. ]

If the program is recorded in mono and he wants 2 channel mono (Hi-Fi), he can
use an audio source that is mono to check to see if there is any difference
between mono and Hi-Fi. I also mentioned another audio test for stereo he can
use to confirm whether the problem exists in mono, Hi-Fi, Stereo, or a
combination of these audio modes the VCR is set to. Since stereo is different
from Hi-Fi and mono, it is important to really narrow down where the actual
mode(s) he is actually having problems with is specifically at.

   It is true that it could be another problem in conjunction with alignment
and/or instead of it on the VCR. These tests help the customer be able to
intelligently narrow down the problem to the VCR, so he can explain this to the
technician working on it, instead of check audio- audio not working right,
staticky sound on one of the channels. this helps to make the complaint with
the unit and getting to the cause of it easier to explain and understand.

[ If you have a problem when you are playing back a tape in the same machine
it was recorded in, then it indicates some other fault - not an alignment
problem.]

I never ruled out the possibility of the possible cause of the problem being
something else other than alignment. I was simply indicating that it is
possible that it could be an electronic alignment in the audio circuit (which
is something else), as well as the simple and standard statement about the
possibility of it being a mechanical alignment. Just because I stated the
mechanical problem first does not mean that it was the only problem I stated.
Further troubleshooting and seeing the actual device personally would have to
be done in order to accurately make a determination as to the cause, if it were
or turned out to be a problem with the VCR.




[ It's not about seperation though.  He's saying he's hearing noise.
It really makes no difference whether it's stereo or two channel mono. ]

Actually, sometimes it can make a difference. it certainly did with a goldstar
VCR I now own; Model GVRA225. I had experienced a similar symptom with it. it
turned out to be a very slight mechanical and audio deviation alignment and
head cleaning that had to be done on it, which corrected the problem in all of
t

Talk about a contradicition.  Two channel recording is stereo, regardless if
its two channel Hi-Fi or two channel linear.  If you're referring to linear
stereo, then, yes, Hi-Fi isn't linear stereo.  It would be Hi-Fi stereo, not
linear stereo.  The differences: Hi-Fi stereo is read using a dual set of
dedicated heads in the helical drum, while linear stereo uses two stationary
audio heads in the A/C head stack.  - Reinhart

That, and Macrovision.

If you're going to test hi-fi recording and playback, you don't need a
station that broadcasts in stereo.  A mono source will do just as well if
all you're going to do is listen for noise.  Better still, record
something that has no audio to begin with, and crank the volume up when
you are playing it back.  Any Hi-Fi track misalignment will certainly show
up in this test.


If you have a problem when you are playing back a tape in the same machine
it was recorded in, then it indicates some other fault - not an alignment
problem.



It's not about seperation though.  He's saying he's hearing noise.
It really makes no difference whether it's stereo or two channel mono.

All stereo VCRs I've seen now are Hi-Fi stereo VCRs.  If you are refering
to the L and R indicators in the display, all that means is that a Hi-Fi
track is present and it is what is being played back.  It is no indication
as to whether there's stereo or not.  The Hi-Fi track can either be
stereo, or two channel mono.  Or if someone goofed, it can be one channel
mono.

That said, I don't think you'll ever find a linear stereo VHS VCR anymore
- at least not in the consumer market.  Those were replaced with Hi-Fi
stereo VCRs many years ago, for good reason.

Well, Macrovision really only affects video.  Does nothing to audio.

It is *not* SCMS.  From what you're describing, it sounds like it's alignment
related.  Also, GoVideo and RCA VCRs are crap, period.  Buy a VCR from a more
reputable brand, like Mitsubishi.  - Reinhart

Two channel recording in Hi-Fi will NOT produce 2 channel stereo. True Stereo
has to have seperation of the right and left side for the audio being played
back as having a stereo affect, otherwise the affect is simple two mono
channels (this is basically the same mono signal recorded onto two channels
without the stereo seperation (Hi-fi). Hi-Fi and stereo recording are just not
the same and you can actually hear the difference.

Also, video recordings I have seen from the older movies especially are
recorded in mono, dual mono or Hi-Fi, and some older movies are in stereo. Most
of the new movies out on the market are recorded in stereo or in Hi-Fi. The
label on the video cassette will tell you what mode it is recorded in, whether
it is in stereo or another mode.

Subject: Re: HI FI static question? CLSNOW
From: lasernu @aol.com  (Lasernut23)
Date: 4/29/01 8:04 PM EST
Message-id: <20010429210445.10625.00000551­@ng-mn1.aol.com>

What the hell are you talking about?  A VCR that has Hi-Fi AFM, with exception
of monophonic Video8 decks, is *always* stereo!  However, this does not mean
that a videotape with Hi-Fi recorded contents would be stereo.  It would still
use both LEFT and RIGHT channels for the monophonic program, but both channels
would have the same audio program recorded if this were the case.

[More nonsense.  There must be LEFT and RIGHT separation if both L and R
channels are used, even if the recorded contents are monophonic.]

You are speaking of stereo recordings only, not Hi-Fi recordings. The recording
made will depend on the format of recording used at the time of recording the
audio portion. If you split a mono signal into left and right channel stereo,
it would still sound like a mono signal placed onto two audio channels, as you
are essentailly sending the same signal to two channels. With stereo, you are
sending different signals to two different channels and introducing seperation
between the right and left side, and it is a different technique from recording
Hi-Fi.

Like I've said before, *ANY* Hi-Fi VCR, with exception of monophonic Video8
decks, will be stereophonic.  - Reinhart

What the hell are you talking about?  A VCR that has Hi-Fi AFM, with exception
of monophonic Video8 decks, is *always* stereo!  However, this does not mean
that a videotape with Hi-Fi recorded contents would be stereo.  It would still
use both LEFT and RIGHT channels for the monophonic program, but both channels
would have the same audio program recorded if this were the case.

More nonsense.  There must be LEFT and RIGHT separation if both L and R
channels are used, even if the recorded contents are monophonic.

Like I've said before, *ANY* Hi-Fi VCR, with exception of monophonic Video8
decks, will be stereophonic.  - Reinhart

You are referring to depth multiplexing, but incorrectly.  Video is layered on
top of audio, but how it works is that video is recorded closer to the surface
of the tape while audio is recorded deeper within the tape, so they *never*
interfere with each other within the tape.  How, you ask?  Magnetic tape has a
unique property of recording higher frequency information closer to the surface
of the tape.  Since video information is substantially higher in frequency than
audio information, the video and audio tracks do not become blended.  Upon
playback, it becomes relatively simple to determine which track is which
through differences in frequency.  This means that the audio tracks *are not* a
part of the video track, which is further proven by the fact that VHS Hi-Fi and
PAL Beta Hi-Fi decks have separate helical heads for the Hi-Fi audio.  To say
that Hi-Fi audio is stored within the vertical blanking is stating that Hi-Fi
audio is recorded with the video, which isn't the case here.  NTSC Beta Hi-Fi
has its Hi-Fi track contained within the video, but the AFM subcarrier is
stored in the bandwidth space between the choma and luma carriers, which means
that, even though the Hi-Fi information is encoded within the video track, it
is not a part of the acutal video signal itself.  Besides that, the vertical
blanking greatly *lacks* the sufficient bandwidth to support an AFM carrier.

But I do not agree with most of your posts.  - Reinhart

hi

 actually,..this has happened with this unit from the get go,.....
It cant be worn parts or such,...    

      I also only use it to dub tapes....sometimes rental movies and
sometimes just tv recordings.     ( in sp mode,..unit not hooked up to
cable tv )

   IT seems to only happen on actual MOVIE VIDS,.......

  As for worn tapes,...i have noticed this on brand new MOVIE tapes.

   It may be an SCMS prob,....  i also noticed this LR read out flashing
prob on
a brand new RCA vcr i bought and took back a few months ago.

   I originally thought that symptom to be the tape itself.

    GIL

In article <18556-3AEBB733 @storefull-138.iap.bryant.webt­v.net>,

Is the static there on all tapes?  Or just on ones that weren't recorded
in that machine?  How is it when it's playing back its own recordings?

What about its own recordings?

It's not a copy protection issue.  More likely it's an alignment issue.

But not SCMS as we know it in CD audio.  SCMS forces the CD copier to convert
the PCM encoded audio into analogue midway, then back into digital during
duplication of CDs outside the predetermined limits.  Duplication would still
be possible, but the quality of the duplication would not match the quality of
the original because of the D-A-A-D conversion steps in the interim of the CD
copying process.(Which is why computer based setups are better, as they don't
have to deal with this SCMS crap.)  As for the copying MacroVisioned materials,
I believe that the GoVideo decks would detect the AGC spike in the vertical
blanking of the source and would stop duplication upon detection, returning a
"copy protected" message.  Non-MacroVisioned materials, however, shouldn't
trigger this, nor would the dual-decker encode the copy with "protection
coding", although such a thing is conceivable by adding some kind of
information in the vertical blanking.  Either way, this would have no bearing
on the quality of Hi-Fi audio playback (which is AFM analogue to begin with),
as per the original poster's statements.  His causes would be worn or dirty
parts in the tape path, or, most likely, a worn tape.  - Reinhart

On most of what you stated, I wholeheartedly agree. however, when an AGC spike
is detected in the vertical section electronically or this is a mechanical
imbalance with the video alignment, it will many times affect the audio,
because the video track is laid over top (in a helical pattern) of the audio
track (tracks 1 and 2), control track, and TBC. If any imbalance is found in
the video it can affect the audio. Even in some cases, it depends on the
crosstalk that occurs in the processing circuitry between the video and the
audio portions of the signal processing within the device. Also what might be
affected is the actual frequency response the device is capable of handling for
the audio range. if the frequency response of the device is low, the rest of
the audio portion is sometimes processed in the video section (beyond the range
of audio gets processed in the video).

Just to see if the problem is found in the audio only, I actually have
suggested for the original poster, Gil, to connect up a CD player to the VCR,
record onto VHS tape a stereo signal (in all audio modes) and in SP and EP tape
from the CD source. He can even connect up the VCR to an audio amp to test it
and confirm it to see if it is indeed a problem with the audio in the VCR.

Subject: Re: HI FI static question?
From: lasernu @aol.com  (Lasernut23)
Date: 4/28/01 10:58 PM EST
Message-id: <20010428235811.03140.00000081­@ng-fm1.aol.com>

But not SCMS as we know it in CD audio.  SCMS forces the CD copier to convert
the PCM encoded audio into analogue midway, then back into digital during
duplication of CDs outside the predetermined limits.  Duplication would still
be possible, but the quality of the duplication would not match the quality of
the original because of the D-A-A-D conversion steps in the interim of the CD
copying process.(Which is why computer based setups are better, as they don't
have to deal with this SCMS crap.)  As for the copying MacroVisioned materials,
I believe that the GoVideo decks would detect the AGC spike in the vertical
blanking of the source and would stop duplication upon detection, returning a
"copy protected" message.  Non-MacroVisioned materials, however, shouldn't
trigger this, nor would the dual-decker encode the copy with "protection
coding", although such a thing is conceivable by adding some kind of
information in the vertical blanking.  Either way, this would have no bearing
on the quality of Hi-Fi audio playback (which is AFM analogue to begin with),
as per the original poster's statements.  His causes would be worn or dirty
parts in the tape path, or, most likely, a worn tape.  - Reinhart

If you are using rental tapes, check them before you rent them. Many times,
rental tapes (or a bad source) from which you are copying from can result in a
bad copy, usually because the source tape (rental tape is damaged or worn from
excessive use or got munched in someone else's machines few times).

If you have purchased a brand new movie from the store, have you noticed
creasing at the bottom of the tapes or premature wear patterns? Lift the lip on
the tape and check exposed tape in moderately bright light to check in the area
you have trouble with it. You can also check rental tapes this way before you
actually rent them and place them in your machine. A deluxe tape
winder/rewinder is a good investment if you rent tapes frequently to be able to
determine the condition of tapes rather quickly and to give you and idea of
what the condition of the rental tapes are prior to using them. This way, if a
tape is damaged, you can find the damage tape, not use it in your machine and
take it back to the video store and tell them they have a damaged tape. I do
this when I occasionally rent the tapes. it works great and it preserves my VCR
from future harm.

   Have you actually recorded a program off the air that is broadcast in
stereo? Have you recorded a TV program (broadcast in stereo) in SP and EP
modes? How did it function for you when you did that?

   If the behavior is still the same when you use the signal from the tuner to
record a stereo broadcast off the antenna feed regardless of the speed you use
(I usually use EP to conserve tape), then you might very well have an alignment
problem.

If this does not occur when recording off the air, there are three causes for
it only doing it off of video tapes from the rental store or new pre-recorded
tapes.

1) alignment problem with the VCR's audio or control track, guidepost
alignment, dirty or misaligned head and head switching system, audio circuitry
(left and right deviation), or a power supply, servo problem. This would have
to be troubleshot by an experienced technician and diagnosed so that the
problem alignment of the audio circuit and/or the power supply, servo, tape
path, or control track could be made.

2) The video tape may be recorded that way. Some video tapes are recorded in
Hi-Fi mode and some are recorded in stereo mode. Some tapes recorded in Hi-Fi
will not have the seperation between the left and right channel just by virtue
of the way it is recorded. A Hi-Fi recording is not the same recording process
as stereo. Stereo has seperation between the right and left channel (dialogue
might be on both channels, but you might have the beginning of a sound effect
on the right panning out to both channels and then left, as an example). If it
plays stereo fine on the playback and only does this to the copy, then you
might have an alignment problem with the VCR, once aga

You forgot another cause, worn helical heads.

Get your facts straight, man!  This applies to consumer CD audio copiers, not
dual-deck VCRs.  I think you need to do more learning before you can consider
yourself knowledgeable about these things.  - Reinhart

Seems to me I recall another post indicating that there was an SCMS even in the
dual deck VCR's when dubbing from deck 1 to deck 2 on the same machine, even.
There has to be in order to limit the amount of copywritten material processed
through the circuitry. This way, a machine like this cannot legally crank out a
zillion bootleg videos.

Subject: Re: HI FI static question?
From: lasernu @aol.com  (Lasernut23)
Date: 4/28/01 0:36 AM EST
Message-id: <20010428013636.12875.00001353­@ng-cs1.aol.com>

You forgot another cause, worn helical heads.

[ Get your facts straight, man!  This applies to consumer CD audio copiers, not
dual-deck VCRs.  I think you need to do more learning before you can consider
yourself knowledgeable about these things.  - Reinhart ]

I am simply responding to a previous post and I did tell the truth. Copyright
management and copy protection has been in place even on single decks since
1986 here in the U.S. Dual Deck VCR's have to follow the same guidelines and
regulations regarding managing the transfer of copyrighted material.

Macrovision related problems? Yes. SCMS problems contributing to the
audio problems of the original poster? No.

--
[Remove bodies from address for email.]
{Friends don't let friends cross post.}

There are a number of reasons why this symptom occurs. These reasons usually
point to either a damaged tape and/or a problem with the VCR.

Does this happen in EP and SP modes or just one mode?

The first cause could be mechanical or some kind of an alignment problem, worn
pinch roller, or bad tape and/or a combination of these factors.

The second cause could be in the SCMS (serial copy managment system) of the
unit which actually keeps the full audio from being dubbed from one transport
to the other. Go video is famous for the copy only a portion of the audio.
Result is your prerecorded Hi-Fi stereo recording for the audio portion of the
tape turns out to be monophonic audio on the actual dub.

Now, for the expensive and time consuming part of the diagnosis:

The third and final possible cause might be the actual audio processing
circuitry (which is an electronic problem) with the VCR. There is a circuit
referred to as the right and left channel deviation that would also need to be
checked. This could be a number of electronics circuits to trace out, from a
part of the power supply (which drives the audio), on out to the actual audio
processing, deviation, audio control track alignment, or any other factors not
mentioned.

    Whenever there is a problem, you might also specify if the problem also
occurs when you are recording a TV program off the air (which is broadcast in
stereo) or if it just occurs when dubbing from one tape to the other. You might
also try informing us of whether the VCR has the symptom when the timer
functions are used. All of these factors point to the severity of the problem.

Subject: HI FI static question?
From: glya @webtv.net  (G Yanez)
Date: 4/27/01 2:40 AM EST
Message-id: <15483-3AE92265-188@storefull-­131.iap.bryant.webtv.net>

It probably indicates the tape is getting worn.  This is perfectly normal.
Get a new tape.  To know for sure that this is the case, get a brand new
tape and record whatever you want onto it and then play it back.  If there
are no sound problems then that proves it was the bad tape.  If that tape
has sound problems then you probably need your deck cleaned and the pinch
roller replaced.  It would also indicate that your VCR is damaging tapes.

-Aaron