Talk:Dolby noise reduction system

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You can always listen to a dolby tape on a not-dolby compatible (i.e. linear) tape deck - how is that possible? The material should sound awkward, but it doesn't. Is there something like backwards compatibility implemented in Dolby NR technology? Thanks, --Abdull 20:12, 10 Jun 2005 (UTC)

Dolby B simply compands the dynamic range of the audio to reduce noise. See Companding, if it's still unclear.

Actually, Dolby B isn't quite as simple as that. For one thing, it is frequency-dependent, operating principally above 5 kHz. It also doesn't really compress the dynamic range per se. By improving the signal-to-noise ratio during recording, the net effect is to more closely preserve the dynamic range of the original recording. Without decoding during playback, the signal will contain boosted high-frequency information (including tape hiss). It is still listenable—and may even sound better than decoded playback unless the Dolby tracking is accurate, which it often isn't—but it will contain surplus high frequencies and noise.Rivertorch 02:42, 7 October 2006 (UTC)

To the trained ear* a Dolby B recording played on non-Dolby B equipment would sound distorted, though people with trained ears would be using equipment with noise reduction, or more likely hand-tweaked record decks connected to industrial speakers via solid gold cables. *(probably if a normal person compared the playback with and without NR, they'd notice the difference as well as the extra noise) boffy_b 01:35, 6 January 2006 (UTC)

Can someone write a description of Dolby S noise reduction as used on domestic cassettes.

Dolby S was not used on US domesitc cassettes in the pre-recorded market. Lots of reasons behind it. Mostly because Dolby B was out first and was able to gain market acceptance, it was also the cheapest and easiest to implement. Dolby B tapes also didn't sound as bad when played on non Dolby playback systems, unlike C or S which tend to sound off without thier respective systems. Some places issued tapes in Dolby C and i imagine possibly Dolby S, but most of these were special orders from places specializing in audiophile releases, but they were never mass distributed. Most recordings using C or S are indviual recordings.DewDude 16:58 06 Oct 2006

The description of Dolby HX Pro is inadequate, and describes tape bias more than Dolby HX Pro. Can someone expand please?

No, not really. The reason being that HX Pro was a system that dynmically modified the bias signal applied to the recording dependant of the incoming audio signal. Higher frequencies don't need as much bias to be recorded as they're almost liner to the tape already. It's not a noise reduction method by any means, just an improvement of the way the audio was recorded onto the tape which would have a positive effect when played back on ANY player. It's difficult to expand it any further. --DewDude 16:50 06 Oct 2006

The link "Commercializing the Dolby Noise Reduction System" is broken and I could not find the appropriate article on a search of the target website (or elsewhere). --87.114.10.157 16:17, 4 December 2006 (UTC)

[edit] Dolby E

This page should probably have a discussion of Dolby E, even thought it's not really a noise reduction system. jhawkinson 03:56, 24 September 2007 (UTC)

[edit] Dolby HX Pro description - there is a sentence that does not make sense

The following sentence in the dolby hx section does not make sense:

"With fixed frequency and amplitude high frequency strong signals the amount of bias signal needed is reduced."

What on Earth does that mean? No really, I can't even guess what is trying to be said in this sentence.

I can't edit the text myself because I have absolutely no clue what was supposed to be intended by this sentence. I don't think it's simply a case of missing punctuation - it's absolute gibberish.

I hope someone can rewrite it,

Thanks

Daniel —Preceding unsigned comment added by Dpolwarth (talk • contribs) 23:10, 17 April 2008 (UTC)

I fixed the sentence, but the entire article needs copyediting. I'll try to get to that later today, but I'm wondering whether the HX section really shouldn't have its own article. The article, which is misnamed in the first place because it's about systems (plural), has "noise reduction" in the title. Although HX and HX Pro can boost the S/N ratio slightly, they are not NR systems per se. Rivertorch (talk) 23:48, 17 April 2008 (UTC)