Dolby NR encoding - did it ever work

I don't use tapes anymore but as a Deadhead back in the day it took just a few experiences with Dolby NR to never use it. It just quashed dynamics and took the life out of recordings, "stepped on" was how I used to describe them. The one proviso there is I never really recorded any commercial recordings just live bootlegs.
Cheers,
Jon

Of course it worked although DBX was even more efficient.

Once Dolby NR was invented virtually no pre-recorded cassettes were issued without the now familiar DD symbol on the spine of the cover.

It achieved it's goal of reducing tape hiss. The penalty was perhaps not quite as terrible as Jon describes (otherwise it never would have achieved such widespread use on pre-recorded material) but you could easily discern such effects so home made recordings were better off without it.

One reason that commercial recordings used it was due to the poor quality tape which tended to shed its oxide easily and had virtually no surface polish.
HQ blank tapes such as TDK Super Avilyn (a high energy cobalt-doped ferric which was an offshoot of their video tape research), and Maxell, had a mirror finish (generating low noise) could use the "chromium dioxide time constant" of 70uS without the severe wear properties of that material thereby giving quite a few decibels of noise improvement without recourse to Dolby NR. (Not as much as Dolby obviously but enough to render tape hiss sufficiently insignificant.)
Hope this helps...

Yes, Dolby B and Dolby C both work. (Dolby A was a professional system.) They require careful level matching however, and that meant that many consumer rec0orders were often out of Dolby alignment. Better recorders such as Nakamichi offered built-in matching alignment tools.

There was plenty of commercial compact cassettes recorded with Dolby B (Dolby symbol on the label). Dolby C was much more effective but less common.

Jon said it exactly right. ( I was a taper Deadhead too, and came to the same conclusion.) You just had to live with some hiss.

When you played back a live concert recorded with Dolby, you would often play it back without the decoding. The highs were then too bright, but it was usually better than the alternative, a dead recording. (sorry about that.) In those days, we had tone controls...