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Conference napalm::commusic_v1

Title:* * Computer Music, MIDI, and Related Topics * *
Notice:Conference has been write-locked. Use new version.
Moderator:DYPSS1::SCHAFER
Created:Thu Feb 20 1986
Last Modified:Mon Aug 29 1994
Last Successful Update:Fri Jun 06 1997
Number of topics:2852
Total number of notes:33157

2368.0. "Dolby modulation ?" by SALSA::MOELLER () Mon Jun 11 1990 20:44

    Some kind of Dolby 'B' dilemma.
    
    Did a piece with a very fast arpeggiated EMAX bass line (like 64th notes)
    in a deep register - D0-F0.  Played electric piano and strings over it.
    Taped it on my Nakamichi 600 cassette deck on TDK SA90 tape, Dolby 'B'.
    
    When I listen to it without Dolby, it's bright, but otherwise fine. 
    WITH Dolby, the bass line seems to modulate the sustained strings, like
    rhythmically moving the fader on a mixer.  Weird.
    
    What's happening here ?  How could strong regular bass frequencies
    cause Dolby to modulate high sustained strings ?
    
    BTW, before I figured out that it was the Dolby switch position, I
    thought my ears were going..
    
    thanks.  karl
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2368.1Nak Playbak?QUIVER::PICKETTDavid - $ cat > | ccTue Jun 12 1990 02:218
    Karl,
    
         Are you playing back on the Nak too? I've heard all sorts of
    horror stories (mostly from the Aluminum-Eared AudioPILES) about Naks
    making tapes that sounded great on other Naks, but sound bad on other
    decks. I have not verified this firsthand.
    
    dp
2368.2MILKWY::JANZENTom 228-5421 FXO/28Tue Jun 12 1990 12:504
    A strong bass can saturate a tape but sound quiet because the ear
    doesn't hear well down there.  Dolby boosts highs in encoding so that
    compressing the highs on playback also compresses most tape hiss.
    Tom
2368.3AQUA::ROSTI'll do anything for moneyTue Jun 12 1990 13:287
    Like Tom said....it's possible you saturated the tape with your bass
    line...or maybe just the fact that it is fast is causing the Dolby to
    mistrack, after all, it is an analog processing system and there must
    be some lag in response?  I've heard this phenomenon ocassionally with
    busy drum parts.
    
    							Brian
2368.4Brief diversionDREGS::BLICKSTEINThis is your brain on UnixTue Jun 12 1990 13:463
    BTW, I read that Dolby will be coming out with a new NR system called
    Dolby S pretty soon.  It was briefly mentioned in this months Consumer
    Reports.
2368.5STROKR::DEHAHNTue Jun 12 1990 14:0811
    
    It definitely sounds like your overloading the tape with bottom. Is
    your bass line compressed? Have you tried re-recording without Dolby?
    Is it metal tape?
    
    Dolby S is the poor man's version of Dolby SR, a pro system that rivals
    digital in S/N and has the analog sound. It's been around for about 2
    years. Very popular right now.
    
    CdH
    
2368.6SALSA::MOELLERTue Jun 12 1990 17:3228
                      <<< Note 2368.5 by STROKR::DEHAHN >>>
>    It definitely sounds like your overloading the tape with bottom. Is
>    your bass line compressed? 
    
    Nah.  I just set the arpeggiator going on the EMAX and then
    disconnected it MIDIwise from the keyboard - so I was improvising
    electric piano (LOVE the chorused Kurzweil Rhodes, BTW) and strings
    over the repeating bass line.  The bass wasn't THAT loud compared to
    the other program material, and the peak-reading VU meters on the 
    NAK weren't close to saturation.
    
    >Have you tried re-recording without Dolby?
    Well, I tried, but couldn't get the same arpeggiated bass line going on
    the EMAX.
    
>    Is it metal tape?
    
    TDK SA90.
    
    I don't believe this is linked to the mythical 'NAK tapes only play
    well on other NAKs' issue. 
    
    thanks for the thoughts.  If I do something with this piece I'll dub it
    to 8track without Dolby decoding, whilst running it thru a stereo
    10band EQ to drop the high end...
    
    karl
    
2368.7meter no good at lo freqMILKWY::JANZENTom 228-5421 FXO/28Tue Jun 12 1990 18:213
    peak reading meters are not calibrated for low r extremely high
    frequencies.
    TOm
2368.8ever heard of 'too hot' a signal?HUNEY::MACHINWed Jun 13 1990 08:275
    ..and Dolby was never designed to operate at 112 degrees. 
    
    Suggest you lower the ambient temperature in Arizona and try again.
    
    Richard.