Originally Posted by Bill@WelcomeHome
what is your question, Julian? The tech specs listed are true for any machine. When I had tape, everyone around (US) was using NAB.
Yes, NAB was and is more common in US for 1/4" and wide track 15 ips formats in general. However, a considerable majority of 1/2" 8-tracks running 15 ips are IEC1, not NAB. Not 100% though, despite MRL's assertion in the "Choosing and Using document, as JRF told me one of his techs was having trouble with one of those Otari machines until he realized it had NAB audio cards. Only one he's seen, though.
IEC1 has the advantages of lower tendency to bass distortion (no record boost below 50 Hz) and better allocation of HF dynamic range: higher record eq roll off means less (wasted) HF headroom and less HF gain on playback. NAB allocates more HF dynamic range to headroom, more than you generally need, reducing the S/N ratio.
All that said, both my 3M and Otari 1/4" machines are running NAB and they sound just great, so it's easy to make too big of a deal about this.