#S-VHS surprise
24 messages in this thread
This has little-to-nothing to do with the Amiga, but this is as good as a place
as any for this question, and is just a point of curiousity anyway. About a
year ago I got an S-VHS VCR, I soon gave my TV to my mother and started driving
my old CBM 1702 monitor directly with the VCR's video(composite) output. The
picture improvement was excellent.
In any event, I had always promised myself that I would obtain an adapter to go
from the S-connector on the VCR to the chroma/lumina inputs. What I expected
to get was no change on direct signal viewing (one of the demodulation duties
is simply shifted from the monitor to the VCR) and some improvement on tape
viewing (the composite modulation/demodulation step is skipped) though not
much. This week I finally got around to it and received the adapter cable from
Redmond Cable.
Since I could do A/B comparisons between composite and "separate" with a
flip of a switch, I did some tests. The tape viewing from the separate
inputs was indeed _slightly_ better than the composite picture, but I was
surprised to find a slightly worse picture from the separate inputs when
viewing the direct cable signal than the composite version. The difference
in either case is minimal, but it still makes no sense to me. The
composite and S-cables are both run through the same physical path, and the
composite cable is just some cheapie (probably left over from a video game)
while the phono plug side of the separate cable appears gold-plated (though
I'm skeptical on that point). Anybody got any ideas? I can't figure it.
The demodulator in the VCR may not be as good as the demodulator
circuitry in the monitor….thus, viewing the separated outputs
(demodulated in the VCR) would show degraddation from viewing the composite
output where the demodulation is done in the monitor. The tuner and IF
circuits in your VCR breaks the RF signal into sound and video signals. The
composite output is the video signal at that point. However, for it to
generate the separated outputs…it has to further process that video
signal into the separated chroma and luminance signals. That's the output
of the separated signals. The monitor on the other hand, either takes the
composite signal and does it's own processing to get the chroma and
luminance signals…or it gets them directly from the separate outputs.
The other reason would be the circuitry in the monitor itself. The
composite input circuitry is (in theory) fully matched to the circuitry
that breaks out the chroma and luminace signals, while the output of the
VCR may not be fully matched (electricaly) to the chroma/luminance circuits
in the monitor. In either event, you'd get exactly what you see.
The monitor being a better demodulator did occur to me, but the signal
matching possibility hadn't. I am aware of production variations and the
possibility of having a "good" monitor and a "bad" VCR in the demodulator
department even though both pass their design tolerances. But the results
seemed a bit marked for that.
To give you an idea, at computer-viewing distances (@ 3 feet) the
difference between composite and separate is readily apparent, while at
TV-viewing distances (@ 8 feet) you'd really have to be looking hard to see
a difference. If I were watching one, then got up and switched it over, and
then sat back down across the room, I'd never spot the difference. The VCR
is a JVC HR-S7000U, and being the (at the time) high-end unit from a
reputable manufacturer I would assume the internal components were the best
that they could do for a consumer product.
The signals being mismatched is interesting. Unfortunately, my
understanding of impedance and its effects on a modulated signal are poor
at best. Oh well, thanks for your thoughts.
It's much like the difference between Beta and VHS…I can see a
very noticeable difference between the 2 at 'normal' distances (8 feet or
so), but looking in a TV showroom where the TV's are maybe 12 or 14 feet
away and seeing the two side by side (not likely anymore…don't find too
many places selling Beta units anymore)…it's not nearly as noticeable.
You'll see the same effect on a projection system…looks fine on a small
TV screen, but project it onto a large screen and the grain becomes very
noticeable. Even my 10 year old Beta system had a better quality picture
than my brand new VHS HQ system. The Beta was running at BetaII speed
while the VHS was running at SP (obviously it got even worse at LP and ELP
speeds). I haven't seen the VHS-S system yet, but I'd match my new Beta
against it and probably come out on top.
Funny you should mention that. In 1981, when I bought my first VCR, I looked
at all 3 formats (Beta, VHS, and 3/4") and didn't see a decisive difference in
2 different places. The scuttlebutt at the time was one had better definition
while the other had better color (can't remember which one was which now).
Since the rest of the world had already leaned heavily towards VHS (mostly
because of play time, of all things) I went with it and haven't looked back
since. Poor Sony (and more so, their patrons), if Beta is indeed as superior
as you state this is their 2nd superior technology to die on the whims of the
market. Remember Elcaset?
Jeff,
Yes, Beta is definately "better". My two machines (RCA VHS machine and
Sony Beta machine) are about the same age, (VHS is a year newer), cost about
the same and are hooked to the same antenna (in fact, the antenna goes into the
VHS and from the VHS to the Beta and then to the TV). I can tape the same
program with both, and switch back and forth between them and the difference
between them is clearly visible. In fact, on my Sony Triniton TV…I can't
tell the difference between "live" and "tape" on the Beta…on the VHS, at it's
best speed, the difference between live and tape is visible…although not
bad. Obviously ELP mode is significantly worse.
Yes, I do vagely recall Elcaset (it was El-cassette wasn't it?) my
memory tells me it was a better method of 1/4" audio tape recording but the
Phillips standard won out.
Don
Hear hear! My first VCR was also a Beta ($1200 !!) and it still looks better
than VHS machines. I have a newer Beta now, tho I guess I'll soon get a VHS
just for exchange purposes <sigh>.
People are just ill-informed and short-sighted (read: cheap?). I bought Beta,
6809, AMC/AMX and now Amiga. The crowd bought VHS, 6502, Mustang and now IBM.
Makes me crazy, sometimes <grin>. Kev
Sony's biggest mistake was in misreading the marketplace. People did not care
if Beta was better quality. They did care about recording time available.
-larry
Larry,
They also cared about cost…even a $50 difference out of $1000 was
enough to change lots of folks minds. The amount of recording time was a
factor, but not as big as the cost was. While originaly the VHS system
provided up to twice the amount of time as Beta did, Sony quickly added the
Beta II mode where an L500 tape gave you 2 hours just as a T120 gave you 2
hours. Of course, the VHS manufacturers then countered with the LP mode that
gave you 4 hrs on a T120 tape.
Back when all this was going on…Beta sales were actualy higher than
VHS, but as soon as the VHS folks started to lower prices…even by small
amounts, their sales took off. The vast majority of folks I talked to who
asked me about which they should buy…ended up buying VHS (I reccomended Beta
due to the video quality) because it was cheaper.
Obviously now, they buy VHS because it's the "standard", you should see
the trouble I went thru trying to locate a copy of ET on Beta…I was going to
buy it because my beta machine is stereo but the VHS isn't. I ended up renting
a VHS tape and looking at it once…oh well. The Beta was available, but by
special order only.
Don
Don,
I guess price was a factor as well, especially before VHS came out with the
longer playing times. It's interesting to watch the industry, and to see the
view of the companies when it comes to what the public wants and will pay.
-larry
Me, while I have VHS for recording TV shows and the like, I refuse to touch it
for prerecorded films. Neither would I touch Beta. I went laserdisk and never
looked back… <grin>
–>Steve Bennett
What, no Edsel? (My father was, for a _very_ short time, an Edsel dealer, and
it contributed significantly to his ultimate bankruptcy — which is to say,
this is an ironic comment, not a slam.)
?|^] Ray Lewis
<laughing> No sir, no Edsel. But I had a Corvair once… does that count?
"Unsafe at any speed: the IBM PC".
<grin>
I know you're aware of this, but I'll ask the obvious anyway. The VHS units
_are_ 4-head decks, aren't they? My first VHS unit was a 2-head deck, and the
SP speed wasn't all that great in comparison to the 4-head decks even at the
time. Like I said, I don't remember Beta being as impressive as you state.
I'm not sure of the spelling, but I do seem to remember that they used a
shorter, more phonetic spelling for cassette, probably to avoid confusion with
the Phillips compact type. It was indeed a 1/4" audio tape format, based
loosely on videocassettes and reel-to-reel audio. During play the tape was
pulled from the cassette (ala VCRs) and run across a trio of seperate erase,
record, and play head (ala reel-to-reels). The size of the cassette was
roughly the size of compact cassettes and not much thicker due to the compact
cassettes enlarged head area. They definitely had a better S/N ratio and I
believe they ran at 3-3/4 ips for a better frequency response.
The decks were made by several manufacturers (Sony and TEAC for sure, and I
think others) but I only saw them in audio magazines in advertisements and mail
order. Something like a year after I saw the first ad they disappeared and
people were writing letters to the editor complaining about being orphaned and
owning expensive paperweights. Never did see either tape or machines in retail
stores. I seriously considered getting a unit myself but decided to wait due
to a buddy's experience with quad, and I was leery of Beta due to this narrow
escape, so I could've been prejudiced.
Jeff,
No, not all VHS units are 4 head decks….many are still 2 head decks.
The idea of multiple heads was to optimize the heads for the various speeds or
task that particular set of heads did. To be honest, I forget if Beta ever
went to more than 2 heads. Both my Beta and VHS units are 2 head units.
Don
Don-
If I remember what the salesman told me a couple of years ago when I bought my
Beta, Beta doesn't _have_ to use with multiple heads because of the way the
tape is wrapped around the read/write "head". Since more tape is in contact
with the head, it has more time to cram a better signal onto the tape. Beta (I
think) is similar to U-Matic, 8mm, and DAT in this regard.
BTW, my deck has a Beta I mode also. The difference between this and HQ-VHS or
S-VHS is very apparent – especially with a digital TV. (One of these days I'll
upgrade to ED-Beta – which has a picture comparable to 1" commercial video!!!)
Just jumping in…
Douglas Toth
I have no idea if that has any bearing on a valid comparison between the 2
technologies. Comparing 2 alternate technologies almost always involves apples
and oranges, and I'm not interested in a "which is better" discussion anyway.
However, I would like to point out using a 2-head deck as a VHS yardstick isn't
particularly fair to it, as they have had 4-head decks as long as they have had
multiple speeds, and the original "SP" 2-head decks only had the better heads.
A valid point could be made that the vast majority of decks in service are
2-heads so it's representative, but it's still not a good yardstick.
To give you (or anybody else) an idea of the difference between the 2, not long
after I got my original deck I did a side-by-side comparison between my deck
and my brother-in-law's 4-head VHS deck. This was even before Dolby stereo
sound, much less HQ, digital enhancement, Hi-Fi, and anything else they've
tacked on so it's a valid comparison. The EP speeds were almost identical, too
close to call. But, you're familiar with increase of quality in going from EP
to SP on a 2-head deck? The improvement of his 4-head's SP over my 2-head's SP
was at least that. Not very scientific, I admit, but everybody there agreed to
that description. Even me, and I was hoping for a less marked difference.
Jeff,
I was only comparing a 2 head Beta vs a 2 head VHS HQ machine. I'm
sure that 4 and 6 head machies are in fact better. On a 2 head system, the
heads have to be a compromise between read and write useage, whereas on a 4
head system, you can optimize a set of heads for write and the other set for
reading (there is a difference).
Don
Hmmmm, that's not what I've always understood was the difference between 4and
2-head decks. You are, of course, right about the difference between the
optimal gap for record and playback heads (the record head should have a
smaller gap than the play head, from memory). However, what I remember is that
all the heads are combination heads. One set is sized to fit into the smaller
track afforded by the slower speed, this is the set in 2-head decks. The other
set is larger to avail itself of the extra track width afforded by the 3x
faster tape speed. Presumably this is more advantageous than separate
record/play heads.
Just going to the faster speed with the smaller EP heads improves the frequency
response with the extra tape/head speed plus a slight increase in S/N ratio
from the extra tape covered during the same field sweep. With the extra head
width given by using separate SP heads (one would assume triple) the increase
in S/N ratio is much improved, probably about the same as going from 4-track
cassette (stereo) to 4-track 1/4" reel-to-reel (as a rough guess).
Unfortunately I can't remember my source for this info, but it's probably audio
magazines from the turn of the decade. At least it's what I always thought.
Can anybody confirm this? Also, here's something I've always wanted to know
but never asked. What was the fifth head in a 5-head deck for? VHS Hi-Fi
requires an extra 2 heads as far as I know.
Jeff: Sony's not quite done yet. There's a new Hi-Band 8mm tape that'll start
going to market soon. It's supposed to have a picture better than S-VHS. I
saw an ad for a Canon Hi-8 camcorder recently for the low, low price of $2,000.
If I get that I'll have a Beta unit to watch, a VHS because everyone's got one,
and a 8mm just to be different.
Paul
And I thought _I_ had expensive hobbies! Whew.
The 8mm format has been out for almost 2 years now, and is showing little sign
of catching on anywhere but in camcorders. It's just now beginning to show up
in hand held combo VCR/TV's, but you've got me whether it will succeed there or
not. Biggest problem with the format, just like with the original Betamax
format, is the relatively short recording time. (An hour per tape, I
believe…)
It *does* produce nice images, but is NOT better than S-VHS or SuperBeta in
quality.
–>Steve Bennett
Steven,
Most of what you said is basically right, except 8mm can also record 2
hours in a slower mode.
And the new Hi-Band 8mm (Sony and Canon have camcorders out now) are
*supposed* to have resolution that rivals S-VHS. Over 400 lines resolution.
Yeah, AFTER I bought a S-VHS camcorder. <sigh>
Lloyd