Re-mastered 78's

[Ted Kendall]

Originally Posted by Hartley118

Unfortunately, the merger also spelt the end of the New Process laminated quiet pressings. Quite why they were killed has always been a mystery to me because their audio quality was way ahead of its time. Perhaps they were too costly, or maybe they weren't suited to the mass-market HMV acoustic gramophones: the abrasive content in conventional shellac pressings was said to increase record life by sacrificing the needle rather than the record. Unfortunately it produced that familiar 'frying bacon' background that we took for granted until technology improved in the mid-1950s.

A Blumlein Columbia disc is identified with an impressed tiny letter 'C' in a circle. It would be great to hear one on a quiet laminated pressing, but I've never managed to find one. Maybe there aren't any.

Martin

The basic reason for the demise of laminated pressings after the merger was indeed cost, although it is also true to say that HMV were more fussy about wear testing than Columbia. A laminated pressing can tear up on peaks under a clumsy pickup, giving an unpleasant rasp. The worst thing about HMV stock shellac at this time was the introduction of cotton flock as a buliking agent - this is responsible for most of the crackle found on 78s these days, as the flock absorbs moisture, expands and causes pock-marks on the surface.

HMV did experiment with laminated pressings around 1930 - I have seen some Jack Hyltons of this type, the identifying mark being a depresed ring of about half an inch diameter around the centre hole. Whether these were WE or Blumlein I can't recall, and the experiment didn't last long. The whole reason for the merger was survival, and in that context it was logical to cut costs to the bone where this could be got away with. In fairness, the average punter probably wouldn't have noticed the difference at the time.

Worse, in some ways, was the situation after the war. EMI had the Transient True system, largely using RCA technology, without treble pre-emphasis, whilst Decca had the in-house FFRR system, with treble pre-emphasis, both claiming (and delivering) an extended frequency range. Unfortunately, neither company produced pressings quiet enough for the full benefit to be realised - and Decca pressings were worse than EMI. The extended frequency range limits the amount of straight filtering you can get away with, and I am sometimes reduced to trying to winnow out the top octave from a noisy surface with CEDAR. Not one of my favourite jobs...

[Ted Kendall]

Originally Posted by TIMTAPE

The old analog NR systems like Dolby, DBX, ADRES, ANRS, HiCom, Burwen could work well not because they were analog, or because they were old, but because they were double system, or companders. They pushed the programme above the system noise at the record end, the only place to do it. Then the playback decoding merely undid the compression.

Trying to expand down unwanted noise at the playback end is doomed to failure if unlike double system NR the recording was never intended to be expanded on playback. The result will never be transparent. All we can do is use it very sparingly and hope that not too many people notice the artifacts. It's not the fault of the tool. It just has an impossible task.

Whoa! Concealed assumption alert.

Mere complementarity does not an inaudible noise reduction system make.

Simple compansion around a noisy channel, be it analogue, digital or pink with purple spots, isn't a particularly good idea. Every analogue noise reduction system apart from Dolby has audible artifacts under some real-world conditions, usually on piano or bass guitar. If Dolby isn't lined up properly, you can hear that working, too. The art of it is to use the characteristics of human hearing to mask the noise modulation effects - Dolby A and SR use multiple bands, Dolby uses a sliding turnover.

The point of such as CEDAR NR-5 is to get the maximum subjective effect for the minimum actual interference with the signal. Thus, on a shellac 78, I can apply a gentle dip in the noise in the low kHz, where it is most troublesome, whilst leaving lower frequencies, with their ambience and reverberation elements, severely alone. The effect of this is not to reduce the noise to nothing, but to render its spectrum white or pink, something the ear recognises from nature and therefore discounts to a greater degree. Subjectively, the noise retreats behind the music and ceases to be annoying, without that ghastly processed sort of sound so beloved of some in the field. The trick here is to have enough frequency bands and to tailor the dynamics of the reduction process so that the ear masks the mechanics of the process - as Ray Dolby did, fifty years ago.

To my mind, if you can hear the processing in sound restoration, you have done a bad job. Excellence in this field consists of using the best tools with the lightest touch consistent with a natural-sounding result. In the nature of the beast, this results in noise amelioration rather then elimination, certainly as far as steady-state noise is concerned. However, nearly every transient disturbance can now be removed without audible damage to the wanted sound, given sufficent patience.

[Hartley118]

I totally agree about the disappointingly noisy pressings typically encountered with Decca FFRR 78s. Maybe they were the result of post-war quality problems in pressing materials, but the problem can literally mask the benefit of the extended HF range inherent in the FFRR process. The Decca engineers must have felt great frustration that their efforts weren't clearly audible to the end customer.

Martin

[Ted Kendall]

I think the problem with the post-war Decca material was an excess of filler and poor grading and mixing of the same. I've had really nice Django Reinhardt discs, otherwise E+, disfigured by lumps of unmixed filler expanding and popping the playing surface with a flap a millimetre across. Granted, there was a shortage of shellac - some of the small label American pressings of the time play like cinder tracks - but Decca could have played the hand they wre dealt better.

Something I forgot to mention is that, although EMI's UK pressing was all on stock shellac post-merger, nearly all the remote outposts - France, Germany, South America, Australia - retained the Columbia plant and methods, including laminated pressings. Thus, for example, George Formby and Django Reinhardt can sometimes be found on Australian pressings of wonderful quality. This wasn't just the pressing - the preparation of the metal was usually top-drawer, too.

[Ted Kendall]

Originally Posted by Phil G4SPZ

Somehow the associated surface noise is just part of the experience, and was the type of sound that people would have heard from records, certainly up to the 1950s.

Up to a point, yes - but it is really surprising just how little crackle is present on an EMI stock shellac pressing which has been kept safe and dry since birth. Nearly all the crackle in fact comes from deterioration caused by mositure, aside of course from the attentions of steel sprags in pickups capable of doing people, never mind records, serious damage, which was par for the course in period.

[John10b]

Ted what is “...steel sprags in pickups ...”
Sorry to be dim but I’m enjoying readings yours and others contributions to this fascinating subject. Most is going over my head but it still makes good reading, and I’m learning every day.
Cheers
John

[Ted Kendall]

Sorry, John, I've been pushing hard lately, so the language is getting more fanciful and the typing more error-prone.

This was just a description of the run-of-the-milll electrical pickup of the 1930s - a large steel needle mounted in a heavy pickup with a tracking force measured in ounces, which was injurious to the record and would be injurious to the user if it dropped on his hand...

[Hartley118]

Originally Posted by Synchrodyne

Given that the original question was about what was done (or not done) in the pre-digital era, some timeline information might be appropriate.

The consumer level noise blankers appear to date from 1977.

The SAE 5000 was announced, reviewed and advertised in Audio magazine 1977 June.

The Garrard MRM101 was mentioned as being forthcoming in Wireless World 1977 November p.57.

The first Packburn professional unit, the Model 101, was introduced in 1982, see: http://www.packburnelectronics.com/history/.


Cheers,

Here's a little more history on disc noise reduction that may be in the category of "Not a lot of people know this":

It was in 1983 that we launched the first Neve DSP digital studio mixing desk system. At the launch I remember meeting a senior engineer from the British Library National Sound Archive (previously the British Institute of Recorded Sound). Over a long lunch we then enjoyed a long conversation on the opportunities presented by digital audio processing.

Shortly afterwards we had a visit from the then Director of the National Sound Archive (NSA), Dr Christopher Roads, an ebullient ex-historian and archaeologist. Cutting a long story short, that resulted in a contract to build a digital audio transfer desk with full signal processing, digital and analogue inputs & outputs etc etc.

Almost as an afterthought, Dr Roads wanted an additional requirement in the spec: to include the digital reduction of spurious background noise on the original recording. That was outside the scope of the Neve processsing software at the time and I thought it sounded rather tricky, so resisted the temptation to say yes. What I did, however, was to offer to cooperate with a university research programme to be financed by the NSA. I suggested one or two university departments that at the time had a reputation for audio work. Dr Roads, however, was adamant: he wanted it done at Cambridge!

So we explored a bit and found a group in the Cambridge Electrical Engineering Department doing some useful digital signal processing research. I remember that, whilst they had ready access to one of the world's most powerful mainframe computers, most of the processing was done in non-real time on BBC micros!

The principle of the prototype noise reduction system was a dynamic band-pass filter system matched to the signal content which inherently rejected the noise. The tricky part was differentiating between the wanted signal and the unwanted noise.

As tends to be the way in Cambridge, out of that research sprang a commercial company some 5 years later. That company was CEDAR. There's more detail on the Cambridge University website at:

https://www.enterprise.cam.ac.uk/new...-worlds-audio/

As Ted has pointed out, today's CEDAR systems are a whole lot faster and more sophisticated than those slow original processors, but, as far as I know, the original operating principles remain.

Martin

[John10b]

Wonderful stuff plenty to read and try and digest, thanks Martin.
Synchrodyne posted link in #22.
Cheers
John

[TIMTAPE]

Originally Posted by Ted Kendall

Whoa! Concealed assumption alert.

Mere complementarity does not an inaudible noise reduction system make.

Simple compansion around a noisy channel, be it analogue, digital or pink with purple spots, isn't a particularly good idea. Every analogue noise reduction system apart from Dolby has audible artifacts under some real-world conditions, usually on piano or bass guitar. If Dolby isn't lined up properly, you can hear that working, too. The art of it is to use the characteristics of human hearing to mask the noise modulation effects - Dolby A and SR use multiple bands, Dolby uses a sliding turnover...

Sure, for example DBX could noise pump on a solo bass guitar. But my point was the comparison between old compander NR and today's playback only, expander only types which range from free software to the latest CEDAR.

Back in the mid 60's Ray Dolby could claim his (properly aligned) Dolby A system reduced tape noise transparently across the audible range by 10db. Let's compare that to the best 2018 CEDAR broadband Denoiser. Can it also achieve an objective reduction of disc or tape noise of 10db, across the full audible range? If not, what can it achieve in objective, measurable terms?