The 45rpm format, the one we all know & love.

Who decided this would be the optimum speed and for why, what are the technical reasons

Anyone know?

M.

tell you what that is a very interesting question

chris

"The 45 rpm speed was the only speed to be determined by a more precise scientific approach conducted by RCA Victor in 1948. RCA showed that the optimum use of a disc record of constant rotational speed, occurs when the innermost track diameter is half that of the outermost recorded diameter. Given the adopted CBS vinyl groove dimensions (microgroove) and certain assumptions about the bandwidth and tolerable distortion, RCA plugged the numbers into their algorithm & a speed of 45 rpm was shown to be the optimum for this 7" record size format."

Ah, it makes perfect sense!

From this site: https://www.videointerchange.com/vintage_78s.htm

Some other interesting info there.

Edited February 27, 200916 yr by Eridu

  Eridu said:

"The 45 rpm speed was the only speed to be determined by a more precise scientific approach conducted by RCA Victor in 1948. RCA showed that the optimum use of a disc record of constant rotational speed, occurs when the innermost track diameter is half that of the outermost recorded diameter. Given the adopted CBS vinyl groove dimensions (microgroove) and certain assumptions about the bandwidth and tolerable distortion, RCA plugged the numbers into their algorithm & a speed of 45 rpm was shown to be the optimum for this 7" record size format."

Ah, it makes perfect sense!

From this site: https://www.videointerchange.com/vintage_78s.htm

Some other interesting info there.

Thats just wot I thought

Thanx for the answer

M.

  Chris-od said:

tell you what that is a very interesting question

chris

Yes I thought it up all by myself Chris

I actually did a piece of work on this for my degree.

The 45 rpm speed was the only one to be decided by a precise optimization procedure (by RCA Victor in 1948). Calculus was used to show that the optimum use of a disc record of constant rotational speed occurs when the innermost recorded diameter is half the outermost recorded diameter. That's why a 7-inch single has a label 3 1/2 inches in diameter. Given the CBS vinyl groove dimensions and certain assumptions about the bandwidth and tolerable distortion, a speed of 45 rpm comes out of the formula.

PETER COPELAND

British Library National Sound Archive

London

Everybody get that?

  jumpinjoan said:

I actually did a piece of work on this for my degree.

The 45 rpm speed was the only one to be decided by a precise optimization procedure (by RCA Victor in 1948). Calculus was used to show that the optimum use of a disc record of constant rotational speed occurs when the innermost recorded diameter is half the outermost recorded diameter. That's why a 7-inch single has a label 3 1/2 inches in diameter. Given the CBS vinyl groove dimensions and certain assumptions about the bandwidth and tolerable distortion, a speed of 45 rpm comes out of the formula.

PETER COPELAND

British Library National Sound Archive

London

Everybody get that?

was just discussing the topic Joan and you have said more or less what we said so you saved me typing it out.

thanks

chris

  MarkWhiteley said:

The 45rpm format, the one we all know & love.

Who decided this would be the optimum speed and for why, what are the technical reasons

Anyone know?

M.

In 1948 the Columbia company had perfected the 12" Long Playing Vinyl disc . Spinning at 33 rpm , the new format could play up to 25 minutes per side . This new record medium also had a much lower level of surface noise than did its older shellac cousin . However , Columbia's big rival , RCA Victor then produced the seven inch 45 rpm vinyl disc . These could hold as much sound as the 12" 78 rpm discs they were to replace , but were much smaller and attractive .

Malc Burton

  jumpinjoan said:

I actually did a piece of work on this for my degree.

Wow Joan, you got a degree on 45's Im sooooooooooo impressed

M.

  MarkWhiteley said:

Wow Joan, you got a degree on 45's Im sooooooooooo impressed

M.

Behave you

  jumpinjoan said:

Behave you

I have got Three Degrees on 45s ..........

Malc Burton

  Eridu said:

"The 45 rpm speed was the only speed to be determined by a more precise scientific approach conducted by RCA Victor in 1948. RCA showed that the optimum use of a disc record of constant rotational speed, occurs when the innermost track diameter is half that of the outermost recorded diameter. Given the adopted CBS vinyl groove dimensions (microgroove) and certain assumptions about the bandwidth and tolerable distortion, RCA plugged the numbers into their algorithm & a speed of 45 rpm was shown to be the optimum for this 7" record size format."

Ah, it makes perfect sense!

From this site: https://www.videointerchange.com/vintage_78s.htm

Some other interesting info there.

So does that mean when you get a 7" playing at 33rpm or a 12" playing at 45rpm, that the optimum sound quality isn't there? (never mind the ins and outs of pitching a record).

Jordi

  Malc Burton said:

I have got Three Degrees on 45s ..........

Malc Burton

Very Sharp!!!

........then along comes a clever B*gger and plays a 7" at 78rpm...........

Hello and Welcome to ..........................Pinky and Perky .

Edited February 27, 200916 yr by KevH

  MarkWhiteley said:

The 45rpm format, the one we all know & love.

Who decided this would be the optimum speed and for why, what are the technical reasons

Anyone know?

M.

Cos that's how fast the decks go round, somebody had to invent them

  Eridu said:

"The 45 rpm speed was the only speed to be determined by a more precise scientific approach conducted by RCA Victor in 1948. RCA showed that the optimum use of a disc record of constant rotational speed, occurs when the innermost track diameter is half that of the outermost recorded diameter. Given the adopted CBS vinyl groove dimensions (microgroove) and certain assumptions about the bandwidth and tolerable distortion, RCA plugged the numbers into their algorithm & a speed of 45 rpm was shown to be the optimum for this 7" record size format."

Ah, it makes perfect sense!

From this site: https://www.videointerchange.com/vintage_78s.htm

Some other interesting info there.

Only tells half the story really.

RCA & CBS played a major part in it via microgroove but also has something to do with gear & belt ratio's.

Subtract 33 from 78 & you come up with 45. Simple really innit!

  jordirip said:

So does that mean when you get a 7" playing at 33rpm or a 12" playing at 45rpm, that the optimum sound quality isn't there? (never mind the ins and outs of pitching a record).

Jordi

Good question Jordi.

Have asked something similar before & never got much of an answer.

What's the better quality - A 5 minute long 12" single that plays at 45 rpm or a 5 minute long 12" single that plays at 33 rpm?

  viphitman said:

Very Sharp!!!

Don't encourage him

I'll think you'll find that if you take 33 from 78 you get 45 which was why the RCA engineers chose 45, Simples!

  Eridu said:

"The 45 rpm speed was the only speed to be determined by a more precise scientific approach conducted by RCA Victor in 1948. RCA showed that the optimum use of a disc record of constant rotational speed, occurs when the innermost track diameter is half that of the outermost recorded diameter. Given the adopted CBS vinyl groove dimensions (microgroove) and certain assumptions about the bandwidth and tolerable distortion, RCA plugged the numbers into their algorithm & a speed of 45 rpm was shown to be the optimum for this 7" record size format."

Ah, it makes perfect sense!

From this site: https://www.videointerchange.com/vintage_78s.htm

Some other interesting info there.

F++CKIN KNEW IT

I'm pretty sure it's 45rpm 'cos if it's any faster it sounds like Pinky & Perky, and any slower it sounds like a drunk.

Edited February 27, 200916 yr by KevinKent

  Malc Burton said:

I have got Three Degrees on 45s ..........

Malc Burton

I bet you've got stars on 45 as well lol

Gazza