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Old 13th Jul 2018, 1:27 am   #1
martin.m
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Default Re-mastered 78's

I hope I have posted this in the correct section. With today's digital wizardry and computers it is possible for record companies to re-master old 78rpm records and remove nearly all of the clicks crackles and general surface noise without affecting the audio. How was this done in the 60s and 70s before digital processing came along? Charles Penrose's "The laughing policeman" from 1926 was re-issued on a vinyl single way back in 1973 without any crackles or surface noise. I have a 1960s vinyl album of George Formby songs that must have been re-recorded from 78rpm records, again without any background noise. How would this have been done without using modern digital tools?
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Old 13th Jul 2018, 3:49 am   #2
Synchrodyne
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Default Re: Re-mastered 78s

I have a vague notion that analogue noise blanker circuits intended to reduce or eliminate click and pops from gramophone disc replay back were available back in the 1970s, perhaps even earlier than that. John Linsley Hood (JLH) incorporated one in his 1982 Wireless World modular preamplifier. I suspect that such devices were somewhat, but not fully effective. Thinking about this, to the extent that the blanker responds to rate-of-rise rather than amplitude, one would perhaps want a side chain from very soon after the cartridge input that was wide bandwidth, no de-emphasis and could handle very big peaks, so that the noise pulse stayed intact, no loss of wavefront steepness and no clipping, right up to the switching circuitry. [Edit - perhaps also a cartridge with a very wide bandwidth (CD-4 type bandwidth) so that the noise pulses came off the record "in good shape".]

Other than that, I imagine that low pass filters would have been used in transcribing from old 78 rev/min gramophone discs, presumably of the variable type to enable an optimum trade-off between useful information loss and intrusive noise in each case. A professional version of the Quad filter as used on its QCII through 44 control units, perhaps.

I have attached a couple of pages from the JLH WW article. The full sequence of articles in connection with the 1982 modular preamplifier was:

WW 1982 October p.32ff Modular Preamplifier Part 1
WW 1982 November p.60ff Modular Preamplifier Part 2
WW 1983 January p.46ff Modular Preamplifier Part 3
WW 1983 February p.79ff Modular Preamplifier Part 4

The noise blanker is dealt with in Parts 3 and 4.

There were two related preceding articles about the ICs used in the design:

WW 1981 October p.43ff Integrated Circuit Design
WW 1982 September p.80ff Third-Generation Op-Amps RCA CA3140 and TI TLA071.2

All of the above are available at: https://www.americanradiohistory.com/.


Cheers,
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Last edited by Synchrodyne; 13th Jul 2018 at 3:56 am.
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Old 13th Jul 2018, 4:05 am   #3
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Default Re: Re-mastered 78s

I've often thought how this was done, I've had collections of 1930's dance band recordings re-issued on LP's from the 1970's and some sounding remarkably good in regards to reducing the surface noise.
I just assumed mint copies of these recordings were found as masters.
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Old 13th Jul 2018, 4:57 am   #4
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Default Re: Re-mastered 78s

Well before JLH's preamp, the commercial click blanker of the early 1970s was the Garrard Music Recovery Module. It used a few milliseconds worth of 'bucket brigade' analogue delay to give the click recognition circuitry some time to work over and a simple interpolation filled the gap.

Noise blankers were previously found on expensive HF receivers, then the onset of the Russian Woodpecker "Duga-3" impelled them into most amateur radio transceivers. The power supply for the woodpecker came to a very spectacular end with a terrible death-toll.

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Old 13th Jul 2018, 7:16 am   #5
Ted Kendall
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Default Re: Re-mastered 78s

Before the advent of such devices as the Packburn, getting a decent 78 transfer was all about the source, as opposed to today's position, where it is mostly about the source!

EMI had (and have) an extensive archive, where the shellac pressings have never been damp, and rarely if ever played. The lack of crackle on some of these has to be heard to be believed - they really did leave the factory practically crackle-free. Also, a lot more metal was still extant in the 60s (there was a mass cull in the early 70s before sense prevailed) and this could either be transferred direct or used to make vinyl pressings. When EMI didn't have pressings themselves, they went to collectors - the Original Dixieand Jazz Band issue on Music for Pleasure was largely taken from this source, and caused a lot of ill feeling when some collectors got somebody else's records back...

Decca junked just about all their coarse groove metal in 1962, but the stampers were run through the press one last time to strike up to six vinyls off each stamper. The metals weren't prepared is any way, and if they split in the press or were corroded, that was just too bad. These test pressings still circulate among collectors - one turned up a previously unreleased take of "My Sweet" by the Quintette of the Hot Club of France, which I mastered for CD.

The Laughing Policeman is an interesting case - it is a very early electrical recording, using the unmodified Western Electric system, which was very linear over its 5kHz bandwidth. The sound is remarkably natural and "present" - part of this is the 2.8 kHz peak in the WE microphone. The reason we can hear so far into the recording is that it was issued by Columbia, using their "silent surface" - a laminated pressing which really was as near as dammit noise-free - in good condition, it can nearly be taken for vinyl, although the different response of the pickup on a harder surface gives it away. I remember doing this for CD, and was bowled over by the sheer sense of Penrose standing there in the plane of the speakers. Marvellous record - with Ted Heath on trombone, too - what's not to like?

I mentioned the Packburn - this was the first device really to tackle shellac noise such that the cure wasn't worse than the disease. Straightforward blankers don't work on shellac crackle, although they are OK up to a point for a few clicks per rev on vinyl. The trouble is that they leave a low level thump in place of the click, and whilst this may pass unnoticed on occasional operation, trying to deal with anything denser just results in a continuous burble. The Packburn used a stereo pickup to seek out the quieter groove wall at any instant, and followed this with a blanker for the big clicks that were left. However, the blanking action was different from other devices, which either muted the signal briefly (Garrard) or substituted a delayed signal from before the click (SAE). The Packburn switched to the output of a low-pass filter, which took most of the energy of the click away but also preserved a continuous waveform, so that bumping and burbling was much reduced.

Continuous application of a low-pass filter to clicks and crackle is, to my, mind, worse than useless - all it does is spead them out over a longer period and crush them down into the wanted signal. Cheap, perhaps, but ineffective.

Mastering at the time was to tape, and some big clicks could be cut out, although this technique ("cut and shut") could affect rhythm noticeably if carried out carelessly or to excess. John RT Davies refined Ron Geesin's idea of scraping off oxide at the point of the click, and brought this technique to a pitch of perfection which was only fully superseded when CEDAR developed a manually-operated version of DeClick around 2000.

Last edited by Ted Kendall; 13th Jul 2018 at 7:27 am.
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Old 13th Jul 2018, 7:59 am   #6
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Default Re: Re-mastered 78s

It's easy to get carried away with wanting, or expecting no background noise but often the problem is not so much background noise as groove distortion.

In this "Laughing Policeman" track the background noise doesnt really bother me but the distortion in voice peaks grates. It can be very difficult if not impossible to remove it.

https://youtu.be/hI1nPd7hezM

As Ted said, finding a good source disc is still a very important part of a good result.
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Old 13th Jul 2018, 8:22 am   #7
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Default Re: Re-mastered 78s

Excellent discussion on a fascinating subject.
Cheers
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Old 13th Jul 2018, 8:25 am   #8
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Default Re: Re-mastered 78s

Audacity is the modern software for doing all this

https://manual.audacityteam.org/man/...m_records.html
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Old 13th Jul 2018, 10:35 am   #9
Ted Kendall
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Default Re: Re-mastered 78s

For some, maybe. I do this for a living and I use CEDAR. It's cost me a packet and is worth every penny.
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Old 13th Jul 2018, 10:48 am   #10
Ted Kendall
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Default Re: Re-mastered 78s

Quote:
Originally Posted by TIMTAPE View Post
It's easy to get carried away with wanting, or expecting no background noise but often the problem is not so much background noise as groove distortion...it can be very difficult if not impossible to remove it.
Removal of hiss is something to be undertaken reverently, discreetly and soberly - it's quite easy to make a right hash of it. Peak distortion has two components - the hash at HF caused by the uncontrolled stylus movement in a worn groove, and the blasting intermodulation at lower frequencies. Judicious use of CEDAR Retouch allows removal or at least amelioration of both of these, to the point where it doesn't sound as if it was damaged in the first place, which is after all the sovereign aim.
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Old 13th Jul 2018, 11:24 am   #11
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Default Re: Re-mastered 78s

Thanks Ted for the info about Retouch. Do you know of any audio examples of Retouch successfully removing or reducing peak distortion on discs? Can it be automated to any degree?

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Old 13th Jul 2018, 12:04 pm   #12
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Default Re: Re-mastered 78s

Ted talks of “Judicious use .....”. How very important that must be.
If I may digress, when I was at a conference in Amsterdam many year ago, the BBC was talking about cleaning up old war films, the discussion was interesting and concluded by saying great care had to taken not to remove actual events in a battle, explosions etc.
I’m not sure how that worked but it was interesting.
Hope you didn’t mind that digression but talk of removing noise etc from records brought back memories of that discussion.
Cheers
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Old 13th Jul 2018, 12:52 pm   #13
Ted Kendall
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Quote:
Originally Posted by TIMTAPE View Post
Do you know of any audio examples of Retouch successfully removing or reducing peak distortion on discs? Can it be automated to any degree?
I don't have any before-and-after examples to hand, but one CD which is a tour de force of restoration technique is SOMM 264, "Kathleen Ferrier Remembered". This took three months of my life and every tool in the box. With regard to Retouch, this was extensively used for peak distortion, intrusive swishes, heterodynes...you name it. At several points, removal of a swish demanded substitution of slivers of innocuous noise between the visible harmonics of the signal -the software allows this degree of resolution.

Can it be automated? In fifty years, maybe, given the progress in sound restoration over the last fifty.
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Old 13th Jul 2018, 3:31 pm   #14
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Default Re: Re-mastered 78s

A much better software is Magix Audio Cleaning Lab. You have much greater control of the clicks, pops and noise removed. You don't even need a 78 rpm record player. As long as the stylus has a tip suitable for playing 78's, then the software will change it to the correct speed played back at either 45 or 33.
The software will output to any format you want. It comes in different versions and is easy to use. The earlier versions are of course cheaper than the newer ones.
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Old 13th Jul 2018, 3:51 pm   #15
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Originally Posted by Ted Kendall View Post
I don't have any before-and-after examples to hand, but one CD which is a tour de force of restoration technique is SOMM 264, "Kathleen Ferrier Remembered". This took three months of my life and every tool in the box. With regard to Retouch, this was extensively used for peak distortion, intrusive swishes, heterodynes...you name it. At several points, removal of a swish demanded substitution of slivers of innocuous noise between the visible harmonics of the signal -the software allows this degree of resolution.
Yes I'm familiar with that recording, being a long time KF fan and owning copies of various KF recordings. I read your detailed liner notes in the Somm CD and while listening to various tracks on that CD I was aware that I was listening to "after" but without a "before" reference it's always hard to assess how well the digital restoration tools did their work.
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Old 13th Jul 2018, 8:53 pm   #16
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Default Re: Re-mastered 78s

It would be nice if someone would release a cleaned up recording of "Go now" by the Moody Blues as the last minute is and has always been very distorted. This has been discussed at length in many places on internet forums and it seems even the actual master recording is the same and no decent version of that recording ever existed!


http://forums.stevehoffman.tv/thread...-harsh.242970/
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Old 13th Jul 2018, 8:54 pm   #17
Ted Kendall
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It isn't appropriate in my view to include "before" samples on a commercial CD, as it draws attention to the engineering at the expense of the music. However, we did launch the CD at a gathering at St Sepulchre's, London - one of the last musical events there before the musician's church was denied to them by zealots, incidentally - and there I played some comparisons of origination material and issue. Well, over half the people who came bought a copy on the way out, so at least the engineering didn't get in Kaff's way!

Somewhere I still have the samples - if you PM me with a suitable address I'll send them over.
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Old 13th Jul 2018, 9:04 pm   #18
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Originally Posted by michamoo View Post
It would be nice if someone would release a cleaned up recording of "Go now" by the Moody Blues as the last minute is and has always been very distorted. This has been discussed at length in many places on internet forums and it seems even the actual master recording is the same and no decent version of that recording ever existed!
Doesn't surprise me - it's not the only case where the master take has technical faults which are trumped by artistic or commercial considerations. The choral passages in Bohemian Rhapsody are pretty distorted, supposedly by the VCAs in the desk, and the Giulini/Philharmonia Verdi Requiem from 1963 has horrendous distortion in the Dies Irae. Still, that was the approved take, so it was issued. BBC Transcription Service recorded the work with the same forces at about the same time, and their tape is beautifully clean.

And all this is before we get into the realms of intentional distortion for effect.
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Old 13th Jul 2018, 9:18 pm   #19
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Default Re: Re-mastered 78s

Quote:
Doesn't surprise me - it's not the only case where the master take has technical faults which are trumped by artistic or commercial considerations. The choral passages in Bohemian Rhapsody are pretty distorted, supposedly by the VCAs in the desk
The multi track masters were given a hard time with so many overdubs for this part of this song, so it's not surprising they are distorted.

Supposedly the tapes were almost clear as most of the oxide had been worn away by the number of passes over the recording heads.
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Old 14th Jul 2018, 12:26 am   #20
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Originally Posted by Ted Kendall View Post
Somewhere I still have the samples - if you PM me with a suitable address I'll send them over.
Thanks Ted, PM sent.
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