Talk:dbx (noise reduction)

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dbx on all playback equipment

"Dbx did not achieve popularity in the consumer marketplace, as compressed recordings did not sound acceptable played back on non-dbx equipment; Dolby B won out instead, as its use of preemphasis gave far more acceptable results when played back on non-Dolby equipment."

Why didn't manufacturers presuade this by fitting dbX decoders on all new playbcak equipment?

Because they would have to pay for this extra circuitry that would have no use, unless the recording industry could be persuaded to make cassetes that did not play in any of the previously existing decks. Dolby B was good enough, the moderate improvement in sound quality of DBX wasn't worth the added complexity and cost.Algr (talk) 07:04, 2 December 2011 (UTC)[reply]

Fair use rationale for Image:DBXlogo.jpg

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BetacommandBot (talk) 07:04, 1 January 2008 (UTC)[reply]

dbx on vinyl

dbx was also used briefly on vinyl records ... and, in theory, gave them a dynamic range of up to 120db.

In practice ... dbx discs still did not achieve the full 90db range.

Is it 120dB or 90dB? 86.160.116.226 (talk) 10:08, 18 February 2008 (UTC)[reply]

Likely more like 90dB as not many analog devices back then could do 120dB of range. I would even venture to say none could. —Preceding unsigned comment added by 71.202.117.212 (talk) 04:15, 13 October 2010 (UTC)[reply]

Thanks for spotting this. It's really sad to see such incorrect information remaining uncorrected in the article for more than 11 years. I have corrected it now. --Matthiaspaul (talk) 15:44, 11 November 2017 (UTC)[reply]

Not an error, really. 120 dB was practically attainable with DMM LP process and pro decoder hardware (10V RMS output, 10 uV RMS noise floor). But in consumer reality, using either the NEC chipset, or the cheap Panasonic IC, it was 90+ dB - again, assuming best possible LP mastering and pressing quality, and no noises added downstream. Panasonic even claimed 110 dB dynamic range, but I struggle to see how they arrived at this figure given 450 mV RMS max output and 3 uV typical noise floor. Retired electrician (talk) 01:56, 6 September 2019 (UTC)[reply]

Request: sample of dbX encoded audio.

Can anyone upload a sample of what dbX sounds like if it is played back without the decoding? That would be interesting to listen to. I could provide some public domain sample audio if needed. Algr (talk) 07:09, 2 December 2011 (UTC)[reply]

Six years passed ... and there they are, commons:Category:Audio_files_of_dbx_noise_reduction. Too bad that my computer's mic input causes as much noise as cassette tape, but at least it gives the feel of timbre and dynamic manipulations. Retired electrician (talk) 19:59, 17 April 2017 (UTC)[reply]

Audio examples of dbx Type II noise reduction (Technics RS-B100 with independent AN6291-based dbx coders and decoders).</ref>


Source fragment	Coder action	Decoder action
Log scale, 60 dB vertical span

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dbx vs. Dolby

The dbx vs. Dolby section doesn't say which of the different Dolby systems is being compared. Gah4 (talk) 22:43, 12 November 2020 (UTC)[reply]

Here, for example (p.61) it's mostly vs. Dolby C (SR is mentioned as superior to all. Which makes sense, because apart from the one-of-a-kind Teac 860 from 1977 the consumer dbx was advanced simultaneously with the introduction of Dolby C. I suspect that there isn't much difference between comparing to B and comparing to C, they both follow the same philosophy and share the same benefits and flaws. Anyway, today the difference is encyclopaedic. Retired electrician (talk) 11:23, 13 November 2020 (UTC)[reply]

The section mentions four bands, so maybe it is A. Is SR also four bands? The description doesn't say that. Gah4 (talk) 15:58, 13 November 2020 (UTC)[reply]

No, four bands is strictly A. SR is two-band (three stages for highs, two stages for lows). S is two-band, too (two stages for highs and one for lows). They appeared when dbx was gone (SR 1986, S 1990), so all contemporary comparison should be to A/B/C. Retired electrician (talk) 12:26, 14 November 2020 (UTC)[reply]

"involvement" with DNR

The introduction claims that dbx was in some way involved with DNR, which AFAIK was developed by National Semiconductors. I could not find any source for this.92.200.129.37 (talk) 11:52, 4 November 2021 (UTC)[reply]

Technics M233X has Dolby B, C and DBX.

My Technics M233X has Dolby B, C and DBX. It was new in 1980, and has been in use all these years, playing through a Sansui R50 and Spendor BC1's. — Preceding unsigned comment added by 92.24.151.4 (talk) 19:52, 4 June 2022 (UTC)[reply]

The Teak V-800X also has all three. Mine sort-of still works, but not as well as it should. Gah4 (talk) 08:22, 26 May 2024 (UTC)[reply]

Undecoded dbx playback also exhibited large amounts of dynamic error, with audio levels going up and down constantly.

The article says:Undecoded dbx playback also exhibited large amounts of dynamic error, with audio levels going up and down constantly. I would have said that the levels don't go up and down, when they should. That is the whole idea of compression: less dynamic range. Gah4 (talk) 08:23, 26 May 2024 (UTC)[reply]

I think a good description of an unencoded dbx signal would be compressed (due to 2-1 compression) and too much treble (due to pre emphasis). ~Kvng (talk) 16:02, 29 May 2024 (UTC)[reply]

For undecoded Dolby B and C, you also reduce the treble to make it sound close to right. I did use a Teac V800X, and record some with dbx. I don't know that I ever tried listening to them undecoded. Gah4 (talk) 01:35, 30 May 2024 (UTC)[reply]