Nortronics made 4 channel 4 track 1/4" and 4 channel 8 track 1/4" the latter configuration with the track width Richard Hess quoted.
1975 Nortronics was king of the mountain in tape heads.... today gone.
dnelson


--- On Fri, 3/12/10, Michael Biel <[log in to unmask]> wrote:

> From: Michael Biel <[log in to unmask]>
> Subject: Re: [ARSCLIST] 8-track cartridge degradation problems
> To: [log in to unmask]
> Date: Friday, March 12, 2010, 9:11 PM
> Steven C. Barr wrote:
> > ----- Original Message ----- From: "Ted Kendall"
> <[log in to unmask]>
> >> I just hod-rodded one of those Fostex 8 track
> things - surprisingly good!
> >>
> > "8-track" tapes used 1/4" tape, but arranged in an
> "endless-loop" format;
> > they actually, being stereo, used all eight tracks
> (.25"/8) on the tape.
>
> You have not taken into account that there is a guard band
> -- meaning "space" -- between the tracks.  They are
> narrower than .25/8 .
>
> > Metal
> > (IIRC) portions at either end of the cartridge
> signaled the player to play
> > the next set of tracks...
>
>
> In a continuous loop tape there is no "either end". 
> That is a cassette.  What they did was use a foil
> adhesive tape to splice the ends together, and this foil
> completed the circuit which moves the head down one step..
> > this would continue (as I discovered one drunken
> > night...?!) for as long as the player was
> operative...?!
> >
> Because when the fourth program plays the foil tells the
> head to bounce back to the top.  Sober people figured
> that out the first time they used their machine.
>
> > I would guess that the tape, if removed from its
> cartridge, c/would be
> > played on an r2r machine, providing it was capable of
> playing 8 separate
> > tracks on a .25" tape (standard r2r "stereo" on a back
> & forth format...?!)
> >
> > Steven C. Barr
> >
>
> Funny, there have already been 3 or 4 postings earlier
> today that discussed doing that very thing, including one
> that gave the actual width of the tracks.  21 mils.
>
> Dan Nelson wrote:
> > I modified a Viking R2R  deck with 2 Nortronics 4
> channel 1/4" tape heads. Each played  2 pairs of stereo
> tracks (4) the other head played the alternate channels.
>
> Are these the quad 8 heads Richard Hess mentioned? 
> Regular 4 channel 4 track heads wouldn't work with 8-tracks,
>
> Mike Biel  [log in to unmask]
>