Diamond Discs: Why 150 TPI?

[Lucius1958]

Here is a question that has been puzzling me:

Edison had (relatively) successfully introduced 4 minute cylinders in 1908, with 200 tpi. About the same time, research on the disc records and machines was beginning. Why, then, did they choose 150 as the disc standard?

200 tpi would have represented a significant advance over contemporary disc technology, with nearly 6 ½ minutes of playing time over a 10 inch side, and close to 9 minutes on a (projected) 12 inch side. Diamond styli could be ground to that standard, as the Diamond cylinder reproducers proved.

Was the advantage in playing time deemed unimportant? Was it a personal decision by TAE? Are there any surviving minutes documenting this issue? Discuss...

- Bill

[Inigo]

Interesting!

[VanEpsFan1914]

Are you sure we really need nine minutes of "I'll take you home again, Kathleen?"

All kidding aside, that would be wonderful if he had invented that for classical music. A 9-minute 12" disc could let a machine give the whole Poet & Peasant Overture, for example, or Beethoven's 3rd Leonora overture, without flipping over discs. And of course the DD motors have plenty of power.

My only guess is that 150tpi would be closer to the regular 78rpm record, and that perhaps Edison was just trying to clone the Victrola. Maybe needle changing and disc fragility were considered to be bigger priorities.

Also, perhaps the grooves would have been too easily crushed at 200tpi.

[recordmaker]

I think this was due to the experience Walter Miller had with the Amberol 200 TPI groove, the 2 minute 100 TPI groove allows for more volume and bass response without echo or blasting, the 4 minute groove had to be recorded with a thinner tone and less volume mostly because of the width of the groove.
Cutting the narrower groove on a wider spacing gives more room for dynamic range and bass response.
The reversion to 100 TPI would have been a retrograde step in recording time and the 10 inch diamond disc could run for longer than the Victor 12" product and with big savings on production materials and equipment.
Viewed from the context of the time it was a very well calculated decision and consider that the 4 minute cylinder was running alongside at the the time then the repertoire and arrangements for the music were already being produced.
in the background the 12 inch record with the same pitch was being experimented with and would if needed give nearly 7 minutes per side.
The groove on the diamond disc and the diamond are the same size as the Amberol by the way. and the Blue Amberol and the diamond were introduced at the same time as the Diamond discs which is certainly not a coincidence.

[gramophoneshane]

My guess is that at 150 TPI it gave 4-5 mins of playing time, which was all that was needed for most traditional and popular songs at the time.
It would have kept the records at 10" which had become the standard at the time (along with 12"), where at 200 TPI the disc would have been 8.5"-9" for the same 4-5 min recording.
It may have also been needed to give superior sound quality and equal volume to what ordinary 78's had at the time.
A smaller groove would have reduced volume and durability, which is demonstated with Edison later long play discs.

[JerryVan]

Are you sure we really need nine minutes of "I'll take you home again, Kathleen?"

Or, "Uncle Josh & Aunt Nancy Put Up the Kitchen Stove"

[Curt A]

Are you sure we really need nine minutes of "I'll take you home again, Kathleen?"

Or, "Uncle Josh & Aunt Nancy Put Up the Kitchen Stove"

But, on the positive side, UJ & AN could have Put Up The Kitchen Stove AND Bought A Phonograph on the same side...Haw, Haw, Haw...

[Lucius1958]

I think this was due to the experience Walter Miller had with the Amberol 200 TPI groove, the 2 minute 100 TPI groove allows for more volume and bass response without echo or blasting, the 4 minute groove had to be recorded with a thinner tone and less volume mostly because of the width of the groove.
Cutting the narrower groove on a wider spacing gives more room for dynamic range and bass response.
The reversion to 100 TPI would have been a retrograde step in recording time and the 10 inch diamond disc could run for longer than the Victor 12" product and with big savings on production materials and equipment.
Viewed from the context of the time it was a very well calculated decision and consider that the 4 minute cylinder was running alongside at the the time then the repertoire and arrangements for the music were already being produced.
in the background the 12 inch record with the same pitch was being experimented with and would if needed give nearly 7 minutes per side.
The groove on the diamond disc and the diamond are the same size as the Amberol by the way. and the Blue Amberol and the diamond were introduced at the same time as the Diamond discs which is certainly not a coincidence.

That makes the most sense. Thanks!

- Bill

[shoshani]

Are you sure we really need nine minutes of "I'll take you home again, Kathleen?"

Or, "Uncle Josh & Aunt Nancy Put Up the Kitchen Stove"

Nine Minutes of Harry Humphrey's Explanatory Talk was such a poor seller it had *two* big red stars on the label.