Why broadcast audio tapes didn't use different azimuts to reduce diaphony ?

[david winter]

I'm just wondering why stereo tapes (2-track, broadcast) didn't use different azimuts like video tapes (i.e //// on L channel and \\\\ on R channel). This would have considerably reduced (if not totaly eliminated) the diaphony, and also allowed larger tracks of 3mm for example, thus better signal/noise ratio and more dynamics.

Any thoughts ? Was this ever envisioned ?

 

[lo.fi.love]

I'm just wondering why stereo tapes (2-track, broadcast) didn't use different azimuts like video tapes (i.e //// on L channel and \\\\ on R channel). This would have considerably reduced (if not totaly eliminated) the diaphony, and also allowed larger tracks of 3mm for example, thus better signal/noise ratio and more dynamics.

Any thoughts ? Was this ever envisioned ?

I'll admit I have no clue, but I want to know more about what you're asking. When you say "diaphony", do you mean phase cancellation / phase distortion?

 

[david winter]

I meant cross-talk. On another forum some people explained that using non-orthogonal gaps would have been disastrous to the bandwidth.

 

[The Ghost of FM]

I believe the term you're looking for is "Helical", as in helical scanning as apposed to linear.

For the most part, helical scanning was born out of the necessity of the deck to record much higher frequencies to capture video signals on tape compared to the much lower bandwidth requirements of audio.

Liner tracks for sound make good technical sense for ease of editing and for multi-tracking, which all would have been very messy to try and achieve with helical scanning.

Keep in mind too that cross-talk specs beyond 30 db would be good enough for FM radio broadcasting and most decent audio decks far exceeded that mumber. FM Radio has limitations in that regard as well as many others in terms of overall bandwidth.

Cheers!

 

[GCalo]

Sounds like photostatic muffler valve issue to me.