History of lead-in and lead-out grooves?

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Bob Dillon
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Re: History of lead-in and lead-out grooves?

Post by Bob Dillon » 03 Jun 2019 18:12

They could use two or three recording horns at once too.

I'm not sure a larger recording horn would translate to a louder cut since the sound energy would be less directly funneled / focused on the recording diaphragm.

With electrical vs. acoustic, it seems like with a limiter in the chain and so forth, they could at least minimize blasting / odd eccentric peaks, that might spoil the wax - make the whole thing more linear - so they could cut a bit louder overall. Whereas with acoustic it was (relatively) uncontrolled.

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Re: History of lead-in and lead-out grooves?

Post by Bob Dillon » 03 Jun 2019 19:24

Kind of long, but informative article : https://www.antiquephono.org/sound-subs ... j-wakeman/

"Any diaphragm, whether made of glass, mica, metal, or some other material, has a resonant point or points which result from its size, thickness, compliance, and strength of clamping. These irritating resonant peaks seem to be common to mica diaphragms. When a sound wave that is approximately of the same resonance point as a diaphragm is thrown mechanically on that diaphragm, there is an irritating blast of sound(s) coming from the reproducer. The ideal diaphragm should have resonant points above that of vocal or instrumental vibrations and possess the necessary resilience to transform sounds without distortion and at the same time carry the loudest sounds without over-vibration."

He's talking about phonograph diaphragms here which commonly used mica, but I think the same for be said for recorders as well.

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Re: History of lead-in and lead-out grooves?

Post by H. callahan » 05 Jun 2019 08:55

I think that a bigger recording horn was able to catch more of the energy of sounds. I think this effect has its limits, but a bigger horn should be able to bring more energy to the diaphragm.

Also i think that the friction of the wax during recording does provide some sort of "natural limiter", as the bigger the modulation of the cutting stylus the more resistance the wax will set against the cutting stylus.
And as the energy of the cutting stylus is smaller with acoustic recording excessive modulation may not be possible to be cut anyway. Though if there is some sort of "natural limiter" excessive modulation still would result in distortion - and i see the problem of resonant points of the diaphragm itself.
These might be the reason for glass diaphragms break during recording and a reason to favour other diaphragm-material for recording.
But when other material than glass was used still distortion was possible to occur, which might have been the reason to limit volume to avoid distortion. Also glass still shoud be more stiff than a thin metal diaphragm, so though a glass diaphragm is more troublesome to use it still should be more favourable regarding sound quality.

But if resonant points of the diaphragm indeed are cut without loss in modulation into the wax i can see that overlapping grooves can appear.
Nice article btw. .

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Re: History of lead-in and lead-out grooves?

Post by H. callahan » 06 Jun 2019 01:20

By accident i stumbled across this video:

https://www.youtube.com/watch?v=sQ6KmeLjLCs

It´s pretty detailed about acoustic record production and states the recording diaphragm to be made of glass - but what struck me most is that they state the wax-matrix to be played back to check for quality! And they listen to it with a horn so they must be using a soundbox and not an electrical pickup! I would not have dared to play a wax-matrix with a soundbox, but it seems to be possible; at least once i guess.

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Re: History of lead-in and lead-out grooves?

Post by Bob Dillon » 06 Jun 2019 02:31

Once, yes. It is my understanding that once a wax was played (at least on a mechanical player) it was destroyed, or rendered not usable for plating.

So, aside from checking for technical flaws (presumably prior to commencing the serious recording work) you would have to otherwise wait like a couple weeks until shellac test pressings came back from the factory, if you wanted to further judge the take on it's musical merit, how it came out on disc.

I've seen that film before, but it was fun to watch again.

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Re: History of lead-in and lead-out grooves?

Post by H. callahan » 06 Jun 2019 07:05

I was just puzzled because the film makes it seem that they listen to the wax mechanically, and if the cut was good they sent it off for plating.
On the other hand if they froze the matrix really hard... ( :wink: )

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Re: History of lead-in and lead-out grooves?

Post by Bob Dillon » 06 Jun 2019 17:59

I think the sequence of the scene was set up for the benefit of the audience. They didn't freeze the wax and then play it, before they sent it off to the factory. Wax contracts and expands upon exposure to heat and cold extremes. Frozen wax also has the possibilty of cracking or shattering. You'll notice in the film they refer to the "perishibility" of the wax master.

You also notice when Ms. Ponselle is singing some of the "orchestra" (really more like a band) is shown beside the recording horn. If they were really recording they would have been set up pretty closely behind her in a semi-circle.

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Re: History of lead-in and lead-out grooves?

Post by Bob Dillon » 06 Jun 2019 20:09

Bob Dillon wrote:
06 Jun 2019 17:59
You also notice when Ms. Ponselle is singing some of the "orchestra" (really more like a band) is shown beside the recording horn. If they were really recording they would have been set up pretty closely behind her in a semi-circle.
I think I take this back. They used to array the musicians around the horn (s) in different ways to record, so that scene is probably not innaccurate. You see the flute guy right up close where he belongs. I do think that she should have been facing the horn instead if away from it however. That was probably for the benefit of the film.

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Re: History of lead-in and lead-out grooves?

Post by H. callahan » 07 Jun 2019 02:55

I don´t assume they froze the matrix, i was joking which is why i put a " :wink: " in brackets.

Even if the matrix could be frozen, the wax would shrink to some extend and by that the modulations of the groove was altered - not making it possible to judge the quality of the recording.

Still i think its amazing that one can play a wax-matrix once to judge quality of recording. Due to extreme wear during onetime playback the sound quality should be horrible, not making it possible to judge recording quality.

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Re: History of lead-in and lead-out grooves?

Post by Bob Dillon » 07 Jun 2019 03:11

H. callahan wrote:
07 Jun 2019 02:55


Still i think its amazing that one can play a wax-matrix once to judge quality of recording. Due to extreme wear during onetime playback the sound quality should be horrible, not making it possible to judge recording quality.
That's been my thought too. How would you do that ? I would think a playback needle on a mechanical setup would carve out the wax to such extent that it would be just a wild guess as to the quality. But nobody said the life of an acoustical recording engineer was easy.

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Re: History of lead-in and lead-out grooves?

Post by H. callahan » 07 Jun 2019 04:43

Maybe it was possible to play a matrix once without destroying it - at least i have seen in another video a normal horn, tonearm and mechanical soundbox attached to the lathe cutter.

https://www.youtube.com/watch?v=8d9sNe2OWyI

They allready do record electrical, but when you look at 8:00 you will see that there is a horn, tonearm and mechanical soundbox attached to the cutting machine at the right. The horn is a bit hard to recognize because of the "ifmudge"-logo, but it may indicate that it was common practice to play the wax with a mechanical soundbox.
...

Also when looking for this video, i think i also found the video i was reffering to about variable pitch some days ago:
https://www.youtube.com/watch?v=zbHBxjFxBbo

...just to find out that it is exactly the same video you allready posted.

This means i must have been misremembering the recording engineer being patted onto his shoulders to adjust variable pitch, but when you look at 1:39 you´ll find there is a hand wheel on the cutting machine which does turn at its own. But at 1:44 the engineer does operate the wheel a lot faster by hand - by that changing pitch and probably cutting the lead-out.
The diaphragm used on this recording box doesn´t look like metal to me, so my assumption that one cannot cut a lead-in/-out with a glass-diaphragm might be wrong.
But they were able to vary pitch during recording which can prevent overlapping grooves.

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Re: History of lead-in and lead-out grooves?

Post by Bob Dillon » 07 Jun 2019 20:09

H. callahan wrote:
07 Jun 2019 04:43
Maybe it was possible to play a matrix once without destroying it - at least i have seen in another video a normal horn, tonearm and mechanical soundbox attached to the lathe cutter.

https://www.youtube.com/watch?v=8d9sNe2OWyI

They allready do record electrical, but when you look at 8:00 you will see that there is a horn, tonearm and mechanical soundbox attached to the cutting machine at the right. The horn is a bit hard to recognize because of the "ifmudge"-logo, but it may indicate that it was common practice to play the wax with a mechanical soundbox.
...

They may have played it, I'm sure they played test waxes to see how the equipment was functioning at least. One reason that they may have still used an acoustical playback system in that studio in 1928, was that early electrical horseshoe magnet phono pickups were heavy, heavier than a mechanical reproducer / soundbox.

I've seen another photo somewhere of a electrical recording lathe on a mobile recording truck in the late 1920's. It also had an acoustical horn and mechanical reproducer playback setup.

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Re: History of lead-in and lead-out grooves?

Post by Bob Dillon » 08 Jun 2019 00:49

H. callahan wrote:
07 Jun 2019 04:43

But they were able to vary pitch during recording which can prevent overlapping grooves.

http://www.charm.rhul.ac.uk/history/p20_4_1.html

Under heading : The Recording

"In fact, the engineers did have the ability to vary the lathe’s transit speed resulting in closer groove spacing and longer playing time. In the early 1920s, HMV experimented with sides lasting over 8 minutes, but they were never commercially issued."

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Re: History of lead-in and lead-out grooves?

Post by H. callahan » 08 Jun 2019 03:58

But thinking about it if earliest recording machines did not have variable pitch, this could explain why earliest records do not feature lead-ins and -outs, respectively only post-cut lead-ins and -outs.
Maybe the first recording machines were technically oriented to phonographs which did not need var. pitch due to producing a vertical cut. But when they found out that playtime of a lateral cut can be increased by varying pitch they may have added it to later recording machines.

Regarding volume of acoustic recordings, there is an interesting paragraph in the article you posted:

" Standardisation and its effect

From here on, technical developments were rather slower, and it might be argued that the vividness of these early recordings was lost as the move towards a standardised and smoother sound was called for – this for reasons of record wear. The louder and more vivid the recording, the more easily the record wore out when played with the heavy and stiff playback arms of the day."

This seems like they actually could record louder, but stopped to reduce wear on the final shellac record.
...

When i first saw the horn, arm and soundbox in the video "How a Columbia record is made 1928", i considered it to be there because most grammophones in 1928 still were mechanical machines, featuring horns and soundboxes. So my assumption was that they wanted to be able to test how this electrical recording would sound on an average, mechanical grammophone - and if necessary to alter settings for best sound quality with pure mechanical playback.

But thinking about it, maybe it not only was possible to play a wax-matrix once with a mechanical soundbox, maybe there even was some benefit in playing the wax once with a soundbox:

The wax has to be warmed up to make it cut easier. Of course the wax should not be too warm, as then the groove would collapse, but it could be made pretty warm without the groove collapsing. But when the groove is cut, wax will be cut off the matrix producing fine hairs of wax as can be seen in the video "The Immortal Voice (1923)..." .
But these wax-hairs still will be warm, just like the matrix, so if tiny pieces break from the wax-hairs they might fall into the just-cut groove and stick there - due to both, wax-hair and groove, still being pretty warm.
When the matrix has cooled to room temperature, those tiny pieces of wax sticking in the groove no longer could be brushed off, as they might have bonded to the groove.
If now the wax was played once with a mechanical soundbox, those tiny wax-pieces would be driven out of the groove.

Also the frequency range of an acoustic recording is limited, it is said that frequencies above 4kHz cannot be recorded. But if 4kHz is the limit of recordable frequencies this does not mean that no frequency above 4kHz is cut into the record - there still might be frequencies like 4.3kHz cut into the groove, but with reduced modulation and therefore these frequencies were distorted.
Now when playing a record, no matter if its a vinyl, shellac or cylinder, the highest frequencies are the first to suffer from wear.
If a wax matrix was played once with a soundbox, it would drive out the highest frequencies, which are distorted anyway because the highest frequencies on an acoustic recording cannot be cut lossless into the wax.
By playing the matrix once the frequency range of the recording would be reduced, but as the highest frequencies are distorted anyway the sound quality of the final record should be improved as the distorted freqeuncies were removed by playing the wax once.

Also there has been research on cutting styli for microgroove, longplay records. It did show that the blades of a cutting stylus will produce a rough groove-surface, which does reduce SNR, if the blades are as sharp as possible. If the blades of the cutting stylus are rounded, on a microscopical scale only of course, the cutting stylus will produce a smoother surface of the groove, resulting in better SNR.
Maybe the same does apply to a shellac record and when playing the wax matric once the needle of the soundbox will smooth out the surface of the groove - resulting in fewer "shellac-roar".
...

So maybe it not only is possible to play a wax-matrix once without excessive wear, maybe there even are benefits like driving out wax particles sticking in the groove, driving out highest frequencies which are distorted anyway with an acoustic recording and smoothing out the surface of the groove to improve SNR.

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Re: History of lead-in and lead-out grooves?

Post by Bob Dillon » 08 Jun 2019 19:16

H. callahan wrote:
08 Jun 2019 03:58
But thinking about it if earliest recording machines did not have variable pitch, this could explain why earliest records do not feature lead-ins and -outs, respectively only post-cut lead-ins and -outs.
Maybe the first recording machines were technically oriented to phonographs which did not need var. pitch due to producing a vertical cut.
Interesting theories.

Aside from Edison Diamond Discs (from 1912 on) and Pathe (sapphire ball vertical discs) there aren't any vertically cut shellac discs being made by any company in the earliest days. There were quite a few between WWI era and the start of the 1920's. Fly-by-night companies, like Rex, Playerphone, etc. Also companies that started doing vertical, like Paramount, Okeh, that switched to lateral in the early 20's. Had to do with existing and expiring patent issues. Convoluted stuff. After 1920-21, it was Edison alone that was left producing vertical discs in the U.S.

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