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Advanced Vinyl Technology

Wombat

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#1
This all passed me by at the time. Probably due to the distraction of babies, mortgage, new CD technology or even not particularly pushed in Australia.

The two technologies were the CX and dbx disc systems.

These links cover the basics:
https://www.philips.com/a-w/research/technologies/cd/black-giants.html

https://obsoletemedia.org/dbx-disc/

CX: https://www.americanradiohistory.com/Archive-Poptronics/80s/1982/Poptronics-1982-01.pdf

The discs are readily available on Ebay at affordable prices. The decoders are scarce. Not to worry though. In the Popular Electronics link, above, there is a DIY decoder project.

For deeper interest see here: http://www.jblproservice.com/pdf/Vintage JBL-UREI Electronics/UREI-1181.pdf

Some first-hand history: https://groupdiy.com/index.php?topic=67254.0;prev_next=next#new

Enjoy, discuss, build. :cool:
 
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Wombat

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#2
No one tried it?
 

solderdude

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#3
Despite the inferiority of impulse response and bandwidth (which we now know are not related) I went for the now obsolete, outdated and insufficient RBCD format that promised us all perfect sound for ever.

We all should have gone for dBX, Dolby S, or High-Com vinyl instead which may have saved us many discussions on the mentioned topics and we would never have known such a thing as convenience in the audio world.

Oh.... how we miss out on musicality and fabulous impulse response these days.
 

Wombat

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#4
So, you didn't try it? :rolleyes:
 

solderdude

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#5
Alas ... :(
I did hear a CD-4 album back in the days but was too young to appreciate the music back then.
 

solderdude

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#7
But ... I was told repeatedly by people that have far superior equipment and hearing that vinyl is already higher resolution than digital, and more musical as well.

Therefore it must be true as they can clearly hear it !
Long live the DR meter and impulse responses.
 

eliash

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#8
Sorry, I had to repost it here, because it was such an epiphany for me...

https://www.audiosciencereview.com/forum/index.php?threads/high-resolution-audio.6525/post-184411

13-23dB higher analog resolution is some 2-3bits more in digital. Not yet hitting CD level, but a good explanation, why vinyl sounds better than expected by pure SNR numbers! Therefore I guess the CX system reduces background noise, but not necessarily increases resolution in human perception of sound (maybe even annoys with "breathing" effects like cheap tape companders did).
 
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#9
Despite the inferiority of impulse response and bandwidth (which we now know are not related) I went for the now obsolete, outdated and insufficient RBCD format that promised us all perfect sound for ever.

We all should have gone for dBX, Dolby S, or High-Com vinyl instead which may have saved us many discussions on the mentioned topics and we would never have known such a thing as convenience in the audio world.

Oh.... how we miss out on musicality and fabulous impulse response these days.
Could you expand on the last sentence of your post? Was it sarcasm?

--D
 

solderdude

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#10
Yes, I was referencing to another thread where it was said that impulse response of vinyl is better.
It isn't of course as a needle simply can't move as fast sideways as a signal in a 192/24 file can.
 

Pluto

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#11
...and dbx disc system
If this is the same system as dbx noise reduction that chanced its arm against Dolby A in the 70s, then it was rightfully confined to the dustbin of history. There were two fundamental flaws:
  • In order to compete with Dolby A, it had to offer significantly better noise reduction. It's inventors quoted a headline figure of 20dB. This was overdoing it because...
  • It was a wide band system (unlike Dolby A, which opted for 4 independent companders) so, for example, any significant companding caused by a high frequency sound would cause audible low frequency "pumping". Dolby's use of narrow-band processors in combination with it's more modest (10-15dB) NR objectives made it an easy winner.
One of the best marketing decisions in audio ever made, IMHO, was the call to keep the Dolby A NR figure as modest as was needed to do the job necessary at that time. Had the system been pushed harder (and, therefore, its operation been more audible) it is highly likely that it would never have had the impact it did. The Dolby corporation would never have earned the vast amount from noise reduction, which in turn provided the R & D funding for repurposing the company who saw the digital writing on the wall when it came to analogue recording, and went on to reinvent itself as a specialist in shoving lots of tracks into space (then) sufficient for two. And we know what happened after that :cool:
 

Xulonn

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#12
An improved method of processing the sound of a rock being dragged down a ditch? :rolleyes: It's nice to see that modern vinyl fans are still seeing attempts to improving the technology they enjoy using, but like many older audio hobbyists and audiophiles, in my senior years, I have gone full digital.

Writing this comment inspired me to reminisce about my 66 years of enjoying recorded music - and I am writing a separate story about that in a new thread...
 

eliash

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#13
Yes, I was referencing to another thread where it was said that impulse response of vinyl is better.
It isn't of course as a needle simply can't move as fast sideways as a signal in a 192/24 file can.
Pic from one of my basement cabinets, technology from the last millenium. The High-Com is "breathing optimised" and was used with a Technics RS1506...to be honest, there was always some pain associated getting it working properly (from an engineering point of view) and not only once...

1561655800392.png
 

sergeauckland

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#15
If this is the same system as dbx noise reduction that chanced its arm against Dolby A in the 70s, then it was rightfully confined to the dustbin of history. There were two fundamental flaws:
  • In order to compete with Dolby A, it had to offer significantly better noise reduction. It's inventors quoted a headline figure of 20dB. This was overdoing it because...
  • It was a wide band system (unlike Dolby A, which opted for 4 independent companders) so, for example, any significant companding caused by a high frequency sound would cause audible low frequency "pumping". Dolby's use of narrow-band processors in combination with it's more modest (10-15dB) NR objectives made it an easy winner.
One of the best marketing decisions in audio ever made, IMHO, was the call to keep the Dolby A NR figure as modest as was needed to do the job necessary at that time. Had the system been pushed harder (and, therefore, its operation been more audible) it is highly likely that it would never have had the impact it did. The Dolby corporation would never have earned the vast amount from noise reduction, which in turn provided the R & D funding for repurposing the company who saw the digital writing on the wall when it came to analogue recording, and went on to reinvent itself as a specialist in shoving lots of tracks into space (then) sufficient for two. And we know what happened after that :cool:
Was dbx ever a serious competitor to Dolby A? I always saw it as a competitor (unsuccessful) to Dolby B. Dolby C was even better albeit with the requirement for much more accurate record/replay alignment. dbx had the great advantage that it was not level dependent in the way that Dolby's systems were. This made it much easier to use domestically, but exactly for the reasons you gave, that of band-splitting, pumping was always a potential problem. Dolby A split the spectrum into 4 bands, so differing LF/MF/HF energies wouldn't affect each other to a significant extent, so much reduced pumping, whilst Dolby B limited itself to HF where tape hiss was much more of a problem, so again much less affected by LF levels.

Dolby B was tried for FM broadcasting, but the lack of compatibility with receivers killed that idea. It would be interesting to try a Dolby encoded LP, but each LP would have to have some line-up tone available for setting levels, and/or all phono stages and cartridges to have standard outputs and gains. You can imagine how that would go down commercially! :facepalm:

S.
 

Ron Texas

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#17
In a way yes, since great companies like Shure for carts or (original) Thorens for TTs have left the arena, we find us in something like a post nuclear war scenario, trying to achieve, what was there before...I mean analog stuff of course...
Mad max for audiophiles...
 

eliash

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#18
Mad max for audiophiles...
Not really that violent, but the example I had in mind is a saved Shure V15 IV cart with a MR (micro ridge contour; bought in the middle of the 90´s) stylus, utilised until recently. From my perspective, it is not possible to obtain a similarly "advanced" performing product at a multiple of the original price (even with matched spending power adjustment).
 

Theo

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#19
I didn't try vinyl dbx, however I used a dbx processor when recording some live music on my Revox A77, that's a long time ago... I was pretty satisfied with the result. It did improve the SNR significantly, and I didn't notice any pumping effect. As I said, long time ago (that is before I could afford digital recording equipment) and I didn't do any measurement, quite a subjective opinion then!.
Anyhow, I wouldn't go back to the Revox when comparing with modern digital 24 bit recorders!
 

solderdude

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#20
I always found a well adjusted DNL (Philips) noise suppressor worked quite well and wasn't as bias level sensitive as dolby or other compressors.
Didn't work well with tapes other than ferro due the point where it started to work.
 
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