According to  the Nortronics tape head  guide c1970, cassette head  specs were; 2trk mono .056 track width, 2 track dual channel .056 track width / .088 c/c spacing.

2 track stereo .020 track width .035 c/c spacing

4 track stereo; .037 track width - .071 c/c spacing. Standard for all mfgrs. 
I hope this helps

dnelson

 
Beautiful Music you will never forget, at; http://www.americanbeautiful.podbean.com/




________________________________
From: Tom Fine <[log in to unmask]>
To: [log in to unmask]
Sent: Friday, October 5, 2012 6:08 AM
Subject: [ARSCLIST] 4-track cassette format

Harken back to those wonderful days of the 80s ...

Does anyone know for a fact if the 4-track cassette format was standardized between the various manufacturers of PortaStudios and similar recorder/mixers (Tascam/Teac, Akai, Yamaha and perhaps others)? Should the dbx II track correctly between different machines? I have some tapes made on a PortaStudio, which I still have, and some made on either a Yamaha or Akai (long-gone, not findable, likely long ago trashed, I can't even remember what brand it was). I'd like to transfer all of the tapes to a DAW in the best quality possible.

At 3.75IPS with dbxII, I remember those recorders being surprisingly good with rock and roll music. I'm sure if you attempted a string quartet with that recorder, you'd hear all the flaws, but we were a heavy metal army back then.

-- Tom Fine