pnovak@ihuxa.UUCP (Paul Novak) (10/18/84)
i'm in the market for both a vcr and a new tape deck.
i thought this would require two separate purchases.
my local vcr salespeople are trying to convince me that
i could use a hi-fi vcr for both purposes. they allege
that hi-fi vcr is simply the best tape recording technology
available (better than reel to reel, > 80 dB S/N,
> 60 dB channel separation, etc) and that audiophiles
are buying hi-fi vcrs simply for use as audio recorders
(the video recording is simply an additional feature).
at least one audio salesperson has confirmed this story.
unfortunately, no vcr salesperson has been able to supply
me with manufacturers specs.
i would be using a tape deck to copy a friend's extensive
compact disc collection which i would listen to only through
my stereo at home (cassette-like portability is not required).
i realize that with 5 or 6 hours vcr tapes, accessing the
selection you want would be a slow process. i am willing
to live with that if in fact hi-fi vcr will give me the
best sound.
i have a very limited knowledge of vcrs. any comments
from people with knowledgeable opinions, especially from
anyone who is using hi-fi vcr for audio recordings,
would be greatly appreciated.
paul novak
at&t bell labs
naperville, illinois
......ihuxa!pnovakfigmo@tymix.UUCP (Lynn Gold) (10/21/84)
> i'm in the market for both a vcr and a new tape deck. > > paul novak We have a Sony 5200 Beta Hi-Fi VCR. If I were you, I'd go with Beta. The sound quality is great, and, most important, the tapes are cheaper and smaller than VHS tapes. Some specs for Beta Hi-Fi (from the 5200 manual): Signal-to-noise 45dB Frequency response 20-20,000 Hz Wow and flutter 0.005% WRMS Dynamic range 80dB Hope this is helpful. --Lynn
herbie@watdcsu.UUCP (Herb Chong, Computing Services) (10/23/84)
I think you've got a typo somewhere because 45 dB SNR and 80 dB dynamic
range are not reasonable unless the reference recording level is absurdly
low. Besides, it looks bad when marketing.
Herb...
I'm user-friendly -- I don't byte, I nybble....
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BITNET: herbie at watdcs,herbie at watdcsupjk@hou2a.UUCP (P.KEMP) (10/25/84)
The 45 dB SNR probably refers to the video (luminance) SNR, while the 80 dB dynamic range spec. refers to the hi-fi audio. The hi-fi audio SNR is probably spec.'ed at 80 dB also. Paul Kemp ihnp4!hou2a!pjk
newton2@ucbtopaz.CC.Berkeley.ARPA (10/28/84)
These remarks relate to the seeming inconsistency (in Beta/VHS hi-fi
specs) between "45 dB s/n" and "80 dB dynamic range"
I see two possibilities (omitting degenerate cases like misprint in
ads, garbled reporting etc.):
"45 dB s/n" refers to the carrier-to-noise ratio of the FM carrier
which is used for each audio channel. This seems to me the least likely
explanation, both because it's an arcane spec and meaningless as a predictor
of audio performance without knowing the modulation index, and also because
I doubt the carrier-to-noise ratio really *is* as good as 45 dB.
Therefore, I incline toward this explanation: 45 dB is the *true*
signal-to-noise ratio *with signal present*, i.e. the instantaneous SNR.
Since the noise in any system has some signal-related component (e.g.,
modulation noise in direct analog tape recording), idle-channel noise
is (almost) always less than noise with signal present. The real kicker,
however, is that Beta/VHS are COMPANDED systems, so the noise in the absence
of signal can be 30dB or more below the noise with signal present. Decent
companders make intelligent use of spectral shaping, pre-emphasis, sliding band
filters or various combinations of the well-known techniques expounded by
R. M. Dolby ("An Audio Noise Reduction System", JAES 1967). "Naive" broadband
companders often suffer quite audibly from the different noise levels in
the presence/absence of signal- these "noise modulation" effects have
been discussed extensively here (everywhere).
The only reason I still have nagging doubt about this being the
true explanation of the VCR spec discrepancy is that I have *never*
seen an ad that correctly and honestly explained this dirty little secret
of broadband companders (except an informational piece put out by Dolby
Labs to explain why dbx's claims were fraudulent (or at least grossly
misleading)).
Regards,
Doug Maisel
_-----------------------------------------------ron@brl-tgr.ARPA (Ron Natalie <ron>) (10/29/84)
> I think you've got a typo somewhere because 45 dB SNR and 80 dB dynamic > range are not reasonable unless the reference recording level is absurdly > low. Besides, it looks bad when marketing. > Yes, doesn't it imply that the bottom 35 dB of your Dynamic range is buried in the noise? My stereo has infinite dynamic range, except you can only hear a finite amount it. What's the log of zero anyway? -Ron