Conference napalm::commusic_v1

    Calling the new AKAI multitrack cassette recorder a 'mixer' is somewhat
    misleading.. it of course contains a mixer...
    
    I'm not familiar with the unit, but I'd like to say this.. your
    wife sounds pretty cool ! MY wife looks at electronics with baffled
    semi-irritated incomprehension... 
    
    kmII

    
    There was a review of this machine in one of the U.K. mags this
    month. they reckon it is one "the" best cassette based multi-track
    machine available. With a better SNR than, for example the Fostex
    M80.                                      
    
    The extra SYNC track is acheived by encoding the sync info onto
    track one with the music but "hiding" it like the carrier on an
    FM signal. The reporter was obviuosly impressed with the machine
    but 4 tracks for an asking price of 1300 pounds seems a bit steep
    to me.
    
    				Paul.
    

    I was wondering when someone would come up with a way to record
    the sync signal without wasting an entire track.  I even sent several
    "off the cuff" proposals to Yamaha on how to accomplish it.
    
    That is a VERY high leverage feature.  Sounds like a nice unit,
    but you didn't mention the price (preferably in U.S. dollars).

    	db

    The price at LaSalle's is $1500.  For reference the Tascam 246 is
    $1100.
    
    Dennis

    Excuse me, but won't there be some bandwidth loss or something on
    the channel that's being used for the sync?  After all, there's
    only *so much* info that can be stuck onto a track.
   

    re -1..
    
    Seems logical, but you're forgetting that the audio on ANY recorded
    tape 'shares' the track with another signal.. the bias signal, up
    about 100Khz.. so if the heads can create it on record and respond 
    to it during playback (questionable assumption), that means there's
    lots of bandwidth between say, 20Khz, the limits of audio, and 100Khz,
    where the bias signal lies... why not use it ?

    Ummm.  But, I thought the bias was mainly to erase the tape, since
    the frequency of the tape itself drops off rapidly after about 20kHz.
    My understanding was that the tape is 'saturated' with the 100 kHz
    signal to erase, but the 100 kHz signal itself does not remain on
    the tape in a detectable amplitude.  It sounded to me like what was 
    being done was having some signal (say, a 1kHz frequency modulated 
    signal) added to a track and subtracted at playback.  But, to do so 
    would reduce the signal on that track.  Also, if it is possible to put 
    *lots* of data in the 20-100 kHz band, why not stuff another whole 
    channel there?  Another possibility would be to stuff a 20 kHz signal 
    on the track and filter it off during playback, but this would mean a 
    reduction in bandwidth since all signals of that frequency would be 
    filtered off.  But, hey, I'm open to new ideas! :-)
    
    Steve

    
    I'me no electronics person but my understanding of the approach
    was that the signal was put on the tape in the unheard frequency
    ranges and then reconstituted on play back. I don't think that this
    would result in a loss of the heard frequencies.
    
    					Paul.

    Forgive the typing, I'm SET HOST thru two systems..
    
    Bias frequency is put on the tape WHILE RECORDING in order to increase
    the magnetic 'impressability'  of the tape.. I know there's a tech
    term for it.. but it 'excites' the magnetic particles and thus makes
    the signal representign ther audio spectrum much higher in level..
    
    Since the head can create it, it ought to be able to read it, opening
    possibilities of FM around a core frequency.. multiplexing right
    on a single track.. but if thisx were such a great idea why hasn't
    it been done commercially ? It may be that only a relativiely simple
    tone like a sync tone would not modulate lower (audio) frequencies.
    
    Why does

    re -1, the net demon got me.. I was gonna say, won't some of our
    engineers come and rescue this discussion?

    Here's a start with something official.  This was lifted from the
    Radio Shack Dictionary of Electronics:
    
    bias oscillator - An oscillator used in magnetic recorders to generate
    an ac signal on the range of 40 to 80 kHz for the purpose of magnetic
    biasing to obtain a linear recording characteristic.  Usually the
    bias oscillator also serves as the erase oscillator.
    
    magnetic biasing - The superimposing of another magnetic field on
    the signal magnetic field of a tape while a magnetic recording is
    being made.
    

    re .9  The word is Coerce as in: the bias current raises the 
    coerciativity of the tape; translated: 'the ease with which a
    signal may be recorded on a tape.' 
          
    The higher frequencies are at a higher state of excitation and
    produce a stronger change in flux patterns in the oxides on the
    tape than do the lower frequencies.  So you supply a bias current
    to get 'em all jumpin' and it'll be easier to force the flux's to
    run in a particular direction.
    
    The retention (another word) of the lower frequency signals is still
    weaker than that of the high's.  That is why there is standard (like
    NAB or IEC) tape EQ built into the deck's playback circuits.
                             
    Fredric
    

    The usefulness of recording more than one channel on one track
    is limited since everything on that track has to be recorded 
    and erased at the same time (assuming to the scheme suggested
    in these replies).  But, you could record things in stereo. 
    
    If you could record sync on *more* than one track, you could
    still mix 3 tracks down and record them on a 4th track along 
    with the sync (that used to be on one of the 3 tracks).
    
        sync & 1-\
         |     2--\__
         V     3--/  |
         |            --> 4 & sync
         |_____________________|  
    
    I always wondered why they didn't use FM recording on regular
    reel to reels, wouldn't they have a excellent S/N ratio and
    frequency response like Hi-Fi VCRs? 
    
    Fredric

    Does anybody really know if this machine records the 4th trk
    with a sync tone layered in somehow.  Maybe the machine is
    able to record 5 tracks on a cassette...
    
    Dave

    COERCIVITY !  Thanks, ya don't know how many nites I've laid awake..