Conference napalm::commusic_v1

>    Given that I have no access to meters, wave generators or other
>    techhead gear, am I going to be able to reasonably adjust the bias on
>    these decks?

	Some of that "techhead" stuff is needed to do bias adjustments. 
	This is one you can't do by ear.  If I ever knew before I've
	forgotten now how "bias" is defined.  It varies by tape type,
	which means that if you ever do set your bias up for a particular
	type of tape (e.g. TDK SAC90), your deck will give maximum
	performance for that type of tape only.  If you knew which tape
	Tascam used to set your bias adjustment in the first place you'd
	be all set. 
    
>    How do I tell when a head is becoming worn?

	The first audible clue will be an extremely gradual loss of high
	frequency response.  The first visible clue will be a slight
	groove (exactly the width of the tape) across the face of the
	head. 
    
>    How often should I demagnetize my tape heads, and what type demagger
>    should I use?  What happens if I slip and touch the head/capstan by
>    mistake?

	In a production environment (daily use of several hours) I would
	de-mag once a week.  I use a cheap unit that I bought at Radio
	Shack a long time ago.  It has a small cylindrical handle with a
	momentary contact switch on one end and a vinyl-covered pole
	piece extending from the other. 

	Don't worry about touching the head. I always touch the capstan. 
	In fact, I do the tape guides, too, on reel- to-reel decks. 

	Don't turn the de-magger on/off while it's close to anything in
	the tape path. Be sure to turn the deck off before you de-mag it.
	Do everything in slow-motion.
    
>    Are a Qtip and denatured alcohol suffient for head cleaning, or should
>    I use something else?
    
	I like alcohol.  The denatured stuff seems to work just fine. 
	I've seen some people mix a little Freon in to prevent the
	alcohol "film", but I don't think it's necessary. 

	One other thing: new tape heads are not perfectly polished.  They
	will wear out tapes much faster during the first forty hours of
	use, so don't run good tapes through your machine during that
	break in period. 

	Brad, I think maybe you should ship your Tascam out to me for a
	lengthy and in-depth checkout... *8^) 

	John

    I seem to remember hearing a rumor that alcohol causes head pitting
    (due to condensation?).  Is this true? 

    And, is there a problem using head cleaning fluid to clean the
    pinch-roller, or should I think about rubber cleaner of some sort? 

    On an unrelated note, what's the going rate for a Tascam 144 (4 track
    cassette w/Dolby B) in excellent condition? 

-b

    DON'T clean the pinch roller with any alcohol based cleaner....
    
    It'll cause the rubber/rubber compound roller to dry out, crack
    and do other ickums...
    
    Edd

    re 2,3 - use head cleaner to clean the heads, rubber cleaner to
    clean the rubber parts.  Tascam sells a recorder maintenance kit
    that has all the right stuff.
    
    len.
    

    In a little book I've got on "Making 4-track music", the guy recommends
    cleaning the pinch wheel with a piece of writing paper soaked in spit
    (yeah, saliva).
    
    Presumably, you shouldn't gargle with tape head cleaner first...
    
    Nick

	The spit advice is a new one for me.  I don't see why spit (or
	just plain water) shouldn't work.  The pinch roller shouldn't
	ever get too munged up anyway, since it only sees the backcoating
	of the tape; it's not like the oxide is getting ground into it. 

	Brad, one more thing.  Get an alignment tape for that machine. 
	This will help you two ways: (1) your tapes will play back on
	another properly aligned machine with maximum performance, and
	(2) you'll be able to catch head wear (because alignment tapes
	usually have several high frequency tones recorded at specific
	levels - as your head wears these tones will fade).  In
	anticipation of your next question:  No, I don't have any
	recommendations for specific tapes.  Get a couple, they do wear
	out.  And always de-mag your deck before you load the alignment
	tape (you don't want to partially erase your expensive tape with
	the residual magnetism that builds up on the head). 

    Well, I never intend to gargle with cleaning fluid, *OR* spit on my
    pinch roller.  (I like hot peppers, and that type of 'cleaning' may be
    more detrimental than a dirty roller.  8-) 

    As for the pinch roller contacting only the backcoating ... it contacts
    the same side of the tape as the heads!  What's the difference? 

    And the one question you *didn't anticipate - where do I *buy* an
    alignment tape (or do they even make one for a cassette)? 

-b

    Yeh, where do we buy them? (open reel)
    
    And, how much do they cost? (roughly)
    
    THANKS!  _John_

    I know Fostex sells them, cause they give a part number in the back of
    the service manual I've got.  I don't recall them giving a price,
    though.  Based on what the service manual cost, I don't expect the tape
    to be cheap.
    
    According to the procedures in the book, you pretty much need an
    oscilloscope to make any use of the tape.

>    According to the procedures in the book, you pretty much need an
>    oscilloscope to make any use of the tape.

	I always got by with the VU meter on the deck.  A scope might be
	helpful for checking the phase relationships between the
	channels, though.  You could probably get by if you just adjust
	for maximum playback on all channels simultaneously (at the
	highest frequency on the tape). 

	Where do you get alignment tapes?  Find out where the "techheads"
	go to buy stuff.  Big electronics supplies stores like Allied
	Radio used to list this kind of stuff in their catalogs.  Other
	sources would be media manufacturers (like Dysan, which sells a
	whole line of alignment disks for computers).  If your deck's
	manufacturer sells a tape, get it from them. 

	You're right about the pinch roller contacting the same side of
	the tape as the heads... on cassette decks.  I was visualizing a
	reel-to-reel machine when I wrote that.  As far as cleaning the
	pinch roller goes, it's not nearly as critical as the heads, so
	water should be OK.  You won't need to remove every last particle
	from the rubber.  Maybe Armor-All would work?? *8^)

    The phasing is important if you are trying to set the azimuth. 
    Otherwise a sensitive meter should do.  But I doubt a LED meter would
    tell you enough.
    
    Hmm, I wonder what the frequency response of my FET-VOM is?