78 noise

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H. callahan
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Re: 78 noise

Post by H. callahan » 08 Aug 2019 06:59

Coffee Phil wrote:
07 Aug 2019 07:04
Hi H callahan,

You state that it is not possible to cut a record constant amplitude using acoustic recording. Can you support this using the laws of physics?
...
Unfortunately my knowledge of physics and mathematics is not sufficient to proof this, but i know that low frequencies produce greater modulations than higher frequencies. It is low frequencies which make your speaker vibrate and it is low frequencies which try to tear down your trousers when you´re in a disco.

This should mean that low frequencies produce greater modulations than high frequencies having the same volume, as same volume should mean same ammount of energy - and as a high frequency has to move a diaphragm for example more often left and right per second than a low frequency, the mechanical energy of the high frequency will be spent on moving the diaphragm often per second, so there isn´t much mechanical energy left for moving the diaphragm far to the left and right.
A low frequency will move the diaphragm only a few times left and right per second, so there is a lot of mechanical energy left moving it far to the left and right, therefore having geater modualtion.

This again is what happens with acoustic recording, respectively is what constant velocity means. If there wasn´t such a thing, low frequencies producing greater modulations than higher frequencies having same volume, the RIAA-EQ for recording and playback of records was not needed.
Coffee Phil wrote:
07 Aug 2019 07:04
...

Also give some sort of a rational explanation of why acoustic records sound very bright and lack bass when played back with velocity responding EQ (actually no EQ with a magnetic cartridge) and sound correct with amplitude responding EQ.

Phil
As i said:
H. callahan wrote:
07 Aug 2019 03:55
...

It may be possible that they tried to tune the acoustic recording equipment into some sort of RIAA-EQ, as reduced volume on bass was easier to cut and emphasised treble was desperately needed for higher frequencies not getting lost due to constant velocity, plating and pressing. So playing them back at RIAA might help to make them sound more right, but from a technical point of view they cannot be constant amplitude.

...

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Re: 78 noise

Post by Coffee Phil » 08 Aug 2019 19:26

Hi H. callahan,

Think about this for a moment: You state that it is not possible to cut a record with acoustic methods which is constant amplitude, then you admit that you are not sufficiently conversant in mathematics and physics which are the disciplines required to make such a statement.

You also suggest that some sort of "tuning" may have been used to reduce the modulation for bass and increase it for treble as an attempt to achieve some sort of RIAA curve. It is not likely the engineers at the time were thinking RIAA as it was adopted decades later. When electrical recording came out the need for EQ became apparent. The velocity responding cutters had to produce records which sounded correct on old players which were playing the acoustic records. The EQ made the records constant amplitude over much their range in an effort to be compatible with records cut with acoustic cutters. That suggests that acoustic records are more or less constant amplitude over much of their useful range. RIAA is constant amplitude from 50 to 500 Hz, then constant velocity from 500 Hz to 2120 Hz, returning to constant amplitude from 2120 Hz to the upper end of audibility. Those inflection points of coarse are the Bodie approximations. The actual slope transitions are more curved.

Phil
H. callahan wrote:
08 Aug 2019 06:59
Coffee Phil wrote:
07 Aug 2019 07:04
Hi H callahan,

You state that it is not possible to cut a record constant amplitude using acoustic recording. Can you support this using the laws of physics?
...
Unfortunately my knowledge of physics and mathematics is not sufficient to proof this, but i know that low frequencies produce greater modulations than higher frequencies. It is low frequencies which make your speaker vibrate and it is low frequencies which try to tear down your trousers when you´re in a disco.

This should mean that low frequencies produce greater modulations than high frequencies having the same volume, as same volume should mean same ammount of energy - and as a high frequency has to move a diaphragm for example more often left and right per second than a low frequency, the mechanical energy of the high frequency will be spent on moving the diaphragm often per second, so there isn´t much mechanical energy left for moving the diaphragm far to the left and right.
A low frequency will move the diaphragm only a few times left and right per second, so there is a lot of mechanical energy left moving it far to the left and right, therefore having geater modualtion.

This again is what happens with acoustic recording, respectively is what constant velocity means. If there wasn´t such a thing, low frequencies producing greater modulations than higher frequencies having same volume, the RIAA-EQ for recording and playback of records was not needed.
Coffee Phil wrote:
07 Aug 2019 07:04
...

Also give some sort of a rational explanation of why acoustic records sound very bright and lack bass when played back with velocity responding EQ (actually no EQ with a magnetic cartridge) and sound correct with amplitude responding EQ.

Phil
As i said:
H. callahan wrote:
07 Aug 2019 03:55
...

It may be possible that they tried to tune the acoustic recording equipment into some sort of RIAA-EQ, as reduced volume on bass was easier to cut and emphasised treble was desperately needed for higher frequencies not getting lost due to constant velocity, plating and pressing. So playing them back at RIAA might help to make them sound more right, but from a technical point of view they cannot be constant amplitude.

...

H. callahan
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Re: 78 noise

Post by H. callahan » 09 Aug 2019 06:47

Coffee Phil wrote:
08 Aug 2019 19:26
Hi H. callahan,

Think about this for a moment: You state that it is not possible to cut a record with acoustic methods which is constant amplitude, then you admit that you are not sufficiently conversant in mathematics and physics which are the disciplines required to make such a statement.

You also suggest that some sort of "tuning" may have been used to reduce the modulation for bass and increase it for treble as an attempt to achieve some sort of RIAA curve. It is not likely the engineers at the time were thinking RIAA as it was adopted decades later. When electrical recording came out the need for EQ became apparent. The velocity responding cutters had to produce records which sounded correct on old players which were playing the acoustic records. The EQ made the records constant amplitude over much their range in an effort to be compatible with records cut with acoustic cutters. That suggests that acoustic records are more or less constant amplitude over much of their useful range. RIAA is constant amplitude from 50 to 500 Hz, then constant velocity from 500 Hz to 2120 Hz, returning to constant amplitude from 2120 Hz to the upper end of audibility. Those inflection points of coarse are the Bodie approximations. The actual slope transitions are more curved.

Phil
I may not be able to speak the mathematical/physical language, but this musn´t mean i´m wrong.
Are my explanations wrong? Is nature of sound constant amplitude?

I have been looking up my physics books for about an hour and was not able to find a formula which does express what i mean - so just for you i´ll make up a formula:

A=V/F

A= amplitude

V=volume

F=frequency

I don´t know if that is correct, maybe it also is A=V/2F or A=V/F^2, but i know that its accurate when i say nature of soundwaves is not constant amplitude.

I´m not saying that engineers of that time were thinking exactly RIAA, but similar. As i said:

"It may be possible that they tried to tune the acoustic recording equipment into some sort of RIAA-EQ, as reduced volume on bass was easier to cut and emphasised treble was desperately needed for higher frequencies not getting lost due to constant velocity, plating and pressing."

When electrical records came out there was no need for EQ for recording. They still could have cut the records with constant velocity with an electrical cutting head, but then the sound quality and FR would have equaled them acoustic recordings more or less.
They did introduce EQ on electrical recording to overcome problems of constant velocity, so electrical recordings did have extended FR in comparison to acoustic records. If they needed EQ to adjust electrical recordings to the properties of acoustics, electrical recordings should not have greater FR than acoustics, but they do. A lot. Acoustics only have 3kHz at best while electricals go up to 5kHz easily, and way beyond.
...

One more example, which regretfully isn´t in the mathematical/physical language:

Let´s say there is an acoustic guitar and the lowest note it can play was 100Hz. You plug the string to make it vibrate at 100Hz and a certain amplitude and you need some ammount of mechanical energy to do so.
Now you press the string down in the middle to create a 200Hz frequency when being plugged. When oscillating at 200Hz the string does have to move double as much per second, at double the speed at least - so if you want it to oscillacte at same amplitude as at 100Hz you´ll have to bring up double the mechanical energy at least, maybe even four times as much.
To make it oscillate with same amplitude at 400Hz you´ll need four times the mechanical energy at least, at 800Hz its 8 times at least, at 1600Hz its 16 times, at 3200Hz its 32 times and at 6400Hz it was 64 times at least.

This would mean that playing a high note on an acoustic guitar would take the player 64 times the force at least to play this high note at same volume, if nature of soundwaves was constant amplitude - which it is not.

Playing a high note having the same volume on a guitar does not take 64 times the force, but about the same.
Therefore i conclude that nature of soundwaves is not constant amplitude but velocity.

I know this is not mathematical/physical language, but please tell me whether i´m wrong or right with that statement.

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Re: 78 noise

Post by Bob Dillon » 09 Aug 2019 18:02

A rundown of EQ as it pertains to old records, with a liberal dash of brevity : https://midimagic.sgc-hosting.com/mixphono.htm

Coffee Phil
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Re: 78 noise

Post by Coffee Phil » 09 Aug 2019 20:01

Hi Bob,

Thank You! What you linked does state that acoustic records are largely constant amplitude cut. My experience with acoustic records and my phono stage which with other playback curves can provide constant velocity or constant amplitude leads me to agree with that.

There is literature out there which says constant velocity so this has led to discussion (arguement). The fact that early electrical cutting heads were constant velocity and had to be equalized to make electrical records sound correct on machines which had been happily playing the old acoustic records also supports those of us in the constant amplitude camp for acoustic records.

Phil
Bob Dillon wrote:
09 Aug 2019 18:02
A rundown of EQ as it pertains to old records, with a liberal dash of brevity : https://midimagic.sgc-hosting.com/mixphono.htm

josephazannieri
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Re: 78 noise

Post by josephazannieri » 09 Aug 2019 20:44

Yo analysts of noise, and acoustic record freaks:

I have seen pictures of old acoustic record studios, and what they did was they stood the band and the singer up in front of a huge horn which funneled down to a small diaphragm which attached to a cutting stylus. The sound waves pushed against the diaphragm and the stylus, and cut an up and down groove into the record, regardless of whether the medium was a cylinder or a flat disc. This gave a resulting up and down groove which, on playback, pushed a small diaphragm in and out. The diaphragm was at the base of a bigger horn, which amplified the sound. Unfortunately, the sound, both in recording and playback took on the characteristic frequency response curve of the horns used for recording and playback. But, since there were no electronics in this process, there was no equalization that could be applied. I expect that these recordings were not true constant amplitude due to the irregularities in amplitude caused by characteristics of the horn used to make the recording.

Years ago, there was a system called Soundstream which was used to restore old recordings. What they did was they played the acoustic recording and analyzed the frequency irregularities cause by the process, and then they applied a reverse algorithm to the acoustic recording which flattened the response out, making a less "horny" sound. I have a copy of a Soundstream- processed 1924 acoustic recording of the Paul Whiteman band playing a shortened version, about 7 minutes, of George Gershwin's "Rhapsody in Blue." The process gave a remarkable result, though not exactly the same as a modern recording. I sent a copy of this recording to Phil, and I am sure that he will agree that the characteristic "horny" sound was no longer present.

As an aside, in my days as a theatrical sound man, I was once required to play a director picked modern recording to make it sound like an acoustic recording. I did not use filters in making the tape (It was 1976). What I did was play the modern recording through a 2 inch transistor radio speaker that I taped into the base of the horn of a prop acoustic record player. I then ran the playback, with the treble turned down, into the speaker. The result was a room-filling playback that returned the "horny" sound to the modern recording.

I am of the opinion that the question of whether an acoustic recording is indeed constant amplitude is answered at least experientially and anecdotally by reference to these anecdotes concerning elimination and addition of the "horny" sound characteristic, rather that by a theoretical or mathematical process. And good luck from that experiential and anecdotal old guy, whose motto is "It's all in the horn!",

Joe Z.

P.S. In closing I am not going to describe myself as "that horny old guy," because that's too easy, and, anyway, I am getting too old for that kind of stuff.

Joe Z. again

Bob Dillon
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Re: 78 noise

Post by Bob Dillon » 09 Aug 2019 21:31

josephazannieri wrote:
09 Aug 2019 20:44
:

I have seen pictures of old acoustic record studios, and what they did was they stood the band and the singer up in front of a huge horn which funneled down to a small diaphragm which attached to a cutting stylus. The sound waves pushed against the diaphragm and the stylus, and cut an up and down groove into the record, regardless of whether the medium was a cylinder or a flat disc. This gave a resulting up and down groove which, on playback, pushed a small diaphragm in and out.

Years ago, there was a system called Soundstream which was used to restore old recordings. What they did was they played the acoustic recording and analyzed the frequency irregularities cause by the process, and then they applied a reverse algorithm to the acoustic recording which flattened the response out, making a less "horny" sound. I have a copy of a Soundstream- processed 1924 acoustic recording of the Paul Whiteman band playing a shortened version, about 7 minutes, of George Gershwin's "Rhapsody in Blue." The process gave a remarkable result, though not exactly the same as a modern recording. I sent a copy of this recording to Phil, and I am sure that he will agree that the characteristic "horny" sound was no longer present.

All cylinders are vertical cut. Most flat discs are lateral (side to side) cut, although some, like Edison discs, are vertical.

There's some controversy over what Soundstream actually did. It was claimed that they used a computer to analyze the signal, and remove the horn resonances. Some doubt that it was really that sophisticated. The most significant project they applied the 'process' to was to restore the majority of the recordings of Enrico Caruso, which were issued on LP and then CD. I have the RCA/BMG box set of the Soundtream 'restored' Caruso recordings. I believe they are still available now if you buy any RCA/BMG CD of Caruso. This is one of the Soundstream restorations here, which I can tell by the sound of it, because I have the cut on CD : https://youtu.be/QFao74s6jAY The quality of the Soundstream restorations range from enjoyable, like the link there I posted, to a bit odd, with an overly bass-y, rumbly sound and less 'top end'.

Soundstream 78 restoration in the end wasn't employed extensively. I don't know of much else of what was restored apart from Caruso, some John McCormack recordings (which I also have an LP of) and Luisa Tetrazzini. I have also the RCA LP of Caruso too, called A Legendary Performer, from about 1976, which was how the Soundtream stuff first came out. In the booklet that comes with the LP, there is a picture of Thomas Stockham (of Soundstream) posing in front of a big mainframe computer, with a turntable in the foreground, and IIRC, a printer feeding some kind of printout on paper. This was supposedly the system employed. I should dig the LP out and look again.

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Re: 78 noise

Post by josephazannieri » 09 Aug 2019 22:05

Yo Bob Dillon and other noisy guys:

Thank you for pointing out that Caruso recording. It's a stunning result after only hearing his unaltered acoustic recordings, again as a theatrical sound man, for a local production of "Lend Me A Tenor." The RCA "Rhapsody in Blue" is a similar result. The point of my meandering discussion was that though theoretically they should be constant amplitude, in actuality acoustic recordings are shaped and controlled by the horns used to make them.

I was under the impression that most of the Edison and other acoustic discs were hill and dale. How could you get a side to side groove with an acoustic recording process? Some system of levers to convert the in and out motion to side to side?

You are right about the Soundstream process not being used much. The only such record I have seen is the one I have discussed. Thank you for your link, and good luck from that verbose old geezer,

Joe Z.

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Re: 78 noise

Post by Bob Dillon » 09 Aug 2019 22:17

josephazannieri wrote:
09 Aug 2019 22:05

I was under the impression that most of the Edison and other acoustic discs were hill and dale. How could you get a side to side groove with an acoustic recording process? Some system of levers to convert the in and out motion to side to side?

Pretty much just by which way the recording head was oriented. If you watch here starting at 4:40 : https://youtu.be/sQ6KmeLjLCs demonstrates it pretty well. The soundwaves from the horn strike the diaphragm from the side.

Most Edison Diamond Discs and Pathe discs are vertically cut, they are the most significant. There are some other more minor examples as well. But the other majors of the acoustical disc period, like Victor, Columbia, Brunswick, used lateral recording exclusively.

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Re: 78 noise

Post by Coffee Phil » 09 Aug 2019 22:30

Hi Joe,

I have to play that CD which you sent me again. Thanks again! As I remember it did sound good and I am a big Gershwin fan.

I am going to get nitpickey on you again and agree with Bob. There are Indeed acoustic cut lateral records and I have a decent amount of them. The John McCormack record which I pictured is an example.

I agree with you that acoustic cut records are not likely pure constant amplitude for the reason which you gave. Also at higher frequencies the mass of the diaphragm and cutting stylus will make it move more to constant acceleration. That is from Mr. Newton. F=MA

I need to get some real work done but before I do I’ll get out that CD and give it a listen.

This is also a reminder that I promised you a CD of some Gershwin stuff.

Phil

PS: More Nitpickey stuff. You said that with out electronics EQ could not be applied. Well to be sure network theory was primitive then but in the late twenties Western Electric engineers designed an acoustic machine to take advantage of the new electric records. I heard such a machine in an antique store and was blown away. They wanted $1100 for it. I waited for the price to drop or to convince myself to pay the price. The store and the machine went away before I moved on it.

josephazannieri wrote:
09 Aug 2019 20:44
Yo analysts of noise, and acoustic record freaks:

I have seen pictures of old acoustic record studios, and what they did was they stood the band and the singer up in front of a huge horn which funneled down to a small diaphragm which attached to a cutting stylus. The sound waves pushed against the diaphragm and the stylus, and cut an up and down groove into the record, regardless of whether the medium was a cylinder or a flat disc. This gave a resulting up and down groove which, on playback, pushed a small diaphragm in and out. The diaphragm was at the base of a bigger horn, which amplified the sound. Unfortunately, the sound, both in recording and playback took on the characteristic frequency response curve of the horns used for recording and playback. But, since there were no electronics in this process, there was no equalization that could be applied. I expect that these recordings were not true constant amplitude due to the irregularities in amplitude caused by characteristics of the horn used to make the recording.

Years ago, there was a system called Soundstream which was used to restore old recordings. What they did was they played the acoustic recording and analyzed the frequency irregularities cause by the process, and then they applied a reverse algorithm to the acoustic recording which flattened the response out, making a less "horny" sound. I have a copy of a Soundstream- processed 1924 acoustic recording of the Paul Whiteman band playing a shortened version, about 7 minutes, of George Gershwin's "Rhapsody in Blue." The process gave a remarkable result, though not exactly the same as a modern recording. I sent a copy of this recording to Phil, and I am sure that he will agree that the characteristic "horny" sound was no longer present.

As an aside, in my days as a theatrical sound man, I was once required to play a director picked modern recording to make it sound like an acoustic recording. I did not use filters in making the tape (It was 1976). What I did was play the modern recording through a 2 inch transistor radio speaker that I taped into the base of the horn of a prop acoustic record player. I then ran the playback, with the treble turned down, into the speaker. The result was a room-filling playback that returned the "horny" sound to the modern recording.

I am of the opinion that the question of whether an acoustic recording is indeed constant amplitude is answered at least experientially and anecdotally by reference to these anecdotes concerning elimination and addition of the "horny" sound characteristic, rather that by a theoretical or mathematical process. And good luck from that experiential and anecdotal old guy, whose motto is "It's all in the horn!",

Joe Z.

P.S. In closing I am not going to describe myself as "that horny old guy," because that's too easy, and, anyway, I am getting too old for that kind of stuff.

Joe Z. again

Bob Dillon
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Re: 78 noise

Post by Bob Dillon » 09 Aug 2019 22:49

Bob Dillon wrote:
09 Aug 2019 22:17
josephazannieri wrote:
09 Aug 2019 22:05

I was under the impression that most of the Edison and other acoustic discs were hill and dale. How could you get a side to side groove with an acoustic recording process? Some system of levers to convert the in and out motion to side to side?

Pretty much just by which way the recording head was oriented. If you watch here starting at 4:40 : https://youtu.be/sQ6KmeLjLCs demonstrates it pretty well. The soundwaves from the horn strike the diaphragm from the side.

Most Edison Diamond Discs and Pathe discs are vertically cut, they are the most significant. There are some other more minor examples as well. But the other majors of the acoustical disc period, like Victor, Columbia, Brunswick, used lateral recording exclusively.
Your impression is correct in a sense. Looking again at the video above, the soundwaves are indeed pushing the diaphragm in and out, but in the end result is still producing a disc with a laterally modulated groove rather than hill and dale / vertical. In the case of a vertically cut cylinder recording, the recording head lays parallel above the surface of the cylinder being cut. I assume that in a vertical disc recording set up, it would be the same.

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Re: 78 noise

Post by H. callahan » 10 Aug 2019 07:21

Coffee Phil wrote:
09 Aug 2019 20:01
Hi Bob,

Thank You! What you linked does state that acoustic records are largely constant amplitude cut. My experience with acoustic records and my phono stage which with other playback curves can provide constant velocity or constant amplitude leads me to agree with that.

There is literature out there which says constant velocity so this has led to discussion (arguement). The fact that early electrical cutting heads were constant velocity and had to be equalized to make electrical records sound correct on machines which had been happily playing the old acoustic records also supports those of us in the constant amplitude camp for acoustic records.

Phil
So your theory is that electrical recording heads had to be equalized to make records sound ok on acoustic machines. And what happened when electrical playback became common? Did they stop to EQ and went back to constant velocity?

According to your theory all the RIAA stuff wasn´t necessary on electrical playback.

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Re: 78 noise

Post by H. callahan » 10 Aug 2019 07:25

josephazannieri wrote:
09 Aug 2019 22:05
Yo Bob Dillon and other noisy guys:

Thank you for pointing out that Caruso recording. It's a stunning result after only hearing his unaltered acoustic recordings, again as a theatrical sound man, for a local production of "Lend Me A Tenor." The RCA "Rhapsody in Blue" is a similar result. The point of my meandering discussion was that though theoretically they should be constant amplitude, in actuality acoustic recordings are shaped and controlled by the horns used to make them.
...
How could acoustics be constant amplitude?

To move the diaphragn at double the speed (double frequency) but same amplitude it takes double the mechanical energy at least. Double the frequency again and you´ll need four times the energy at least.
Where is this additional energy to come from, when you´re recording acoustic where no boost of frequencies can be made like with an electrical amplifier?

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Re: 78 noise

Post by josephazannieri » 11 Aug 2019 07:35

Yo Phil, Bob, and H.C:

Thank you Bob for posting that Link to Youtube, which appears to show that the method to get a lateral cut acoustic record is exactly what I surmised. There is a system of levers with a pivot near the stylus. This takes a relatively large motion of a diaphragm and reduces it to a relatively small side motion of the cutting stylus in a wax disc. On playback, the small motion of the stylus in the groove is levered so that it produces a relatively large motion of the diaphragm, providing some mechanical amplification. I would think that the diaphragm and lever combination would likely have some frequency and amplitude irregularities.

I did note one error in the film, which had nothing whatever to do with the description of the recording process, which was enlightening to me. In my digressive way, I can't resist bringing it up. There is a card near the end, which describes "Enrico Caruso as Pagliacci on the stage of the Metropolitan Opera House." This is incorrect, but it is a common error. I Pagliacci is the title of the opera. The Pagliacci are a troupe of actors. The character's name is Canio. He stabs his faithless wife to death as the audience watches, seeing only what they think is a play. My reference is Felix Mendelsohn's wonderful little book, "The Story of A Hundred Operas," at page 226.

And good luck from that well leveraged, digressive old opera fan,

Joe Z

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Re: 78 noise

Post by Bob Dillon » 11 Aug 2019 13:24

Yes. The "lever" is generally referred to as the needle bar, in gramophone parlance.

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