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Poster: R Pal Date: Nov 9, 2021 4:21am
Forum: georgeblood Subject: Re: Acoustic records recording speed

This is an important topic.
The Sousa comparison examples are not ideal as the physical discs in the recordings are of different quality and condition. A better example test would be to use the same disc and digitize it at several speeds. Also loop examine the stylus before each different recording and clean the disc.

Please make such speed tests on you own equipment and post the results. If possible, post photos of the equipment and digitizing process.
I still find the best overall experience comes from a fully wound Aeolion with a fairly fresh needle.

Emails are not received at this accounts address.

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Poster: discs-78rpms Date: Nov 16, 2021 8:45pm
Forum: georgeblood Subject: Re: Acoustic records recording speed

Thanks for your reply.

It's unfortunate that records did not start indicating playing time until much later; that information would help to gauge the record playing speed.

But setting aside the example archive items of the same (but differing condition) record, there is the information from the record covers or envelopes. For each of the links above to covers, the cover indicates that the particular record label should be played at 80rpm. Based on that information I would recommend digitizing these acoustic labels at 80rpm and tweak from there based on the further research you are doing.

As remarked from the Columbia Granfonola cover (

"Columbia records are uniformly recorded at a speed of 80 revolutions per minute.

We cannot too strongly impress upon our patrons the fact that to obtain the best results in reproduction, the instrument upon which the record is being played should be running at exactly that speed."

Thanks again.

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Poster: brewster Date: Nov 12, 2021 7:55pm
Forum: georgeblood Subject: Re: Acoustic records recording speed

I agree it is important. At an ARSC there was a presentation to try to figure out how to figure out the speed (as I recall it is by figuring out what middle C is and such).

Is there a way to automate this? If so, we could apply it to all of our recordings.

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Poster: R Pal Date: Nov 15, 2021 5:33pm
Forum: georgeblood Subject: Re: Acoustic records recording speed

Hi Brewster,
I don't have time to do any meaningful narration right now but a video is at the link.
The video is of RCA Victor 20-30150B through an microscope depth gauge which I have used to inspect rotogravure print rollers and intaglio plates for the past 40 years. The white light is from the side of the lens and the green light is passed through a half silvered mirror from directly above. A much higher power lens is available but unless I explain what the image is it just looks like grainy images. The shiny lines are the top of the groves and the darker areas are the grove sides.
There is a lot of info in the video but I have only a few minutes.
I placed a 78 needle about 1/10th of an inch above the record and moved the focus up to see how the needle size compares to the groves. I was startled to see the rust as the needle looks clean. The focal plane is about 3 microns and it looks like the grooves are about 80 microns deep. The width measurement reticle is put away somewhere and as I wrote above I hurrying to an meeting so I don't have a groove width. I'd like to check that someday. I'd also like to make a 3d view using the measurements
Do you have any broken 78s that I could use for a side view. I sliver would help me verify the depth.

The automated speed problem discussed above needs more time and I don't have any for several weeks. The email address for this account is non-functional but thanks for the Archive.

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Poster: brewster Date: Nov 15, 2021 6:03pm
Forum: georgeblood Subject: Re: Acoustic records recording speed

So good! Yes, we have broken 78's (unfortunately)

lets connect when you have more time to figure out how to make better transfers.


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Poster: discs-78rpms Date: Nov 19, 2021 7:56pm
Forum: georgeblood Subject: Re: Acoustic records recording speed

I've created a test item that has two audio files - one at 78 rpm and one at 80 rpm for an acoustic OKeh record (4175A - Just like a Gypsy): When you listen there seems to be a difference in the harmonizing of the trio between the two audio files (which is toward the end of the song).

I also noticed that the Sterling Trio recorded the same song "Just Like a Gypsy" on a Victor record (which we know should be digitized at 78rpm): The Victor record could be used as sort of a control to see which audio versions 78 or 80 is more similar in how the trio harmonizes.

Hope this is useful to you.

Thanks for looking into this topic.

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Poster: R Pal Date: Nov 20, 2021 4:59am
Forum: georgeblood Subject: Re: Acoustic records recording speed

Your examples will not display and are giving an error for some reason. Your speed change during playback causing a difference thought is correct though. I hope your examples finally get to be heard.
During some minor needle tests I also found that weight of the stylist is another factor that deserves attention.
I also find that the microscopic examination of stylist has been done since records were first being fabricated. So I will not go beyond saying that when digitizing, make sure your needles are as close to the correct configuration as possible for the record being digitized .
But this 'A'nalog recording data collection portion of the A/D process does not touch on the 'D'igital speed adjustment automation portion. It looks to me like that needs to be done post digitization in order to adjust the sound to the correct pitch. And in that will require sound wave analysis software which is beyond my current budget.

I'll buy a lottery ticket and hope.
As always, the email associated with this account has closed so don't try emailing me.

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Poster: discs-78rpms Date: Nov 20, 2021 9:05pm
Forum: georgeblood Subject: Re: Acoustic records recording speed

Try the URLs:

Sorry, the forum software included the sentence period when it formatted the URLs from the text - which I did not expect.

I agree on the digital (post-data collection) speed adjustment comment. The best practice would I think be to try to use exact analog speed recommended by the record company and then perhaps tweak digitally from there. Also, trying to digitize an acoustic record with a magnetic cartridge complicates the issue.

Good luck on your lottery ticket.