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Old 10th Nov 2018, 10:51 am   #1
Panrock
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Default Why both 33 and 45 ?

Prompted by another recent thread in this section, why were two speeds used for microgroove records... 33 and 45 rpm, when 33 rpm was clearly thought sufficient for good fidelity?

To hazard a guess: 45 rpm gave the right duration to fit a standard song length (that previously went on a 10-inch 78) onto a 7-inch disc. But that then begs the question, why use a 7-inch disc and not something smaller?

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Old 10th Nov 2018, 10:54 am   #2
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Default Re: Why both 33 and 45 ?

45 was introduced deliberately, to provoke a 'format war'.
It was derived by subtracting 33 from 78, for that purpose alone.
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Old 10th Nov 2018, 11:04 am   #3
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Default Re: Why both 33 and 45 ?

They were competing standards for a while - LPs were introduced by Columbia and 45s by RCA.

https://en.wikipedia.org/wiki/LP_record
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Old 10th Nov 2018, 11:13 am   #4
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Default Re: Why both 33 and 45 ?

So it was the colonials again mucking up standards? And again with CDs and TV standards?
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Old 10th Nov 2018, 12:19 pm   #5
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Default Re: Why both 33 and 45 ?

It was the International Capitalists, as Icke might call them.
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Old 10th Nov 2018, 12:29 pm   #6
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Default Re: Why both 33 and 45 ?

On a related topic, how much quality was lost using microgroove at 16 rpm? I have an unverified memory that this may have been used for Talking Books for the Blind.

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Old 10th Nov 2018, 12:49 pm   #7
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Default Re: Why both 33 and 45 ?

The only application of 16 rpm that I came across was for Linguphone records (probably wrongly spelt) which didn't need super Hi Fi.

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Old 10th Nov 2018, 12:54 pm   #8
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Default Re: Why both 33 and 45 ?

Here is a reference to RNIB using 24rpm for some early talking books (1935):

https://audiobookhistory.wordpress.c...-talking-book/
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Old 10th Nov 2018, 1:01 pm   #9
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Default Re: Why both 33 and 45 ?

I believe that, as with so many innovations, it was the Western Electric engineers who introduced the 33 1/3 rpm speed in the 1920s when the first film sound tracks were recorded on disc. The obvious speed to use was of course 78 rpm, but the disc needed to play for 10 minutes, the length of a reel of film at that time. So the speed was reduced pro rata. A 12-inch 78 can play for a little over 4 minutes, so if a 10 minute playing time is needed, you end up with a speed a bit more than 30 rpm. Why was such a precise 33.333 rpm decided on? Does anyone know? Perhaps it suited available gear ratios on film projectors?

So when CBS introduced the long-playing record in 1948, they didn't need to reinvent the 33 1/3 rpm speed. They did, however, need to develop the microgroove recording process. Fortunately, sapphire styli were becoming established for replay: steel needles would have been an unlikely solution!

When CBS patented the LP, there was clearly panic at RCA. They decided to do something entirely different by going small, with the 7-inch disc. The public had by then got used to autochangers, so RCA designed the smallest and fastest changer ever (pictured below), hoping that the public could cope with short breaks in the music every 5 minutes or so. The player pictured is actually branded HMV, and was sold in the UK to compete with the Decca group LP introduced in 1950. HMV resisted the new-fangled LP until 1953!

Why 45 rpm? Perhaps, as suggested, in order just to be different. However, it's certainly arguable that, if the 7-inch disc is to be recorded to a smaller inner radius than the 12-inch LP, then audio quality dictates the higher rotational speed in order to maintain a minimum required surface speed.


Martin
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Old 10th Nov 2018, 1:12 pm   #10
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Default Re: Why both 33 and 45 ?

Are there any published audio frequency specs (say 3dB) for 16, 33, 45 microgroove, and 78 rpm records?

The 78 rpm on my Dynatron can sound every bit as good as an LP.

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Old 10th Nov 2018, 2:27 pm   #11
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Default Re: Why both 33 and 45 ?

33 1/3 rpm may have been chosen to give a gearing ratio that was a whole number when using a synchronous motor operating at either 50Hz or 60Hz.
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Old 11th Nov 2018, 6:41 pm   #12
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Default Re: Why both 33 and 45 ?

As #9, I always assumed it was because the groove on singles went closer to the centre than on LPs and the speed was increased to compensate. There was also a theory that the first track on an LP was of better quality than the last track (on the same side).
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Old 11th Nov 2018, 6:56 pm   #13
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Default Re: Why both 33 and 45 ?

Surely, that's more than a theory, given that the linear speed will be greater at the outside. How much of a difference it makes is another matter.
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Old 11th Nov 2018, 8:36 pm   #14
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Default Re: Why both 33 and 45 ?

Compliance problems are certainly worse at the end of an LP side compared with the start.
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Old 11th Nov 2018, 10:45 pm   #15
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Default Re: Why both 33 and 45 ?

"Madam X" or the 45 as we call it now was RCA's way of reducing the size of the record down. They worked on it in secret hence the name and if anyone asked what they were doing would say "home audio tape" which in 1949 everyone thought impossible.

Enter the 1950 war! Vinyl was a essential war product so the smaller 45 used less than the 33 12inch.

The Jukebox was stage three. They don't play 33 LP.
You could get 100 records on a Jukebox, so the top 100 was born!
Stage four was pop music and the teenager. The Dansette record player in the bedroom playing 45's.

Disk Jockeys also liked them, you didn't get a back ache lugging 45's around, unlike 78's.
But one American DJ did like the music on 78's and called them "oldies but goodies".
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Old 11th Nov 2018, 11:00 pm   #16
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Default Re: Why both 33 and 45 ?

Wow. A fascinating thread. Thanka

David
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Old 11th Nov 2018, 11:38 pm   #17
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Default Re: Why both 33 and 45 ?

Quote:
Originally Posted by Panrock View Post
Are there any published audio frequency specs (say 3dB) for 16, 33, 45 microgroove, and 78 rpm records?

The 78 rpm on my Dynatron can sound every bit as good as an LP.

Steve
From 1955 onwards, 33, 45, 78 were all specified flat from 30Hz to 15kHz. What was actually achieved was up to the art of the recording engineer. I can't find any reference to 16 rpm discs, but assume they're unlikely to be specified beyond 8kHz.

Of course, the replay equalization needed to be right, and 78s (to put it basically) were recorded with rather less bass cut and treble boost than microgroove records. Depending on the EQ of your Dynatron, you may prefer the 78 sound. I do find that late 1950s 78s seem to have a certain midrange 'punchiness' that the equivalent microgroove discs lack. Maybe the disc cutting engineers had coffee bar juke boxes in mind - or perhaps my replay EQ isn't quite right.

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Old 12th Nov 2018, 12:11 am   #18
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Default Re: Why both 33 and 45 ?

CBS if I recall correctly but it could have been RCA first issued 33 1/3 in about 1933 but it was wide groove and on shellac, it may have been wide groove on vinylite. RCA developed Vinylite as far as I know. So they all stole off each other. There was some lectures given by who ever the top bod at EMI was in or around 1950 and the ideal speed if I recall correctly was 55 rpm. It's in the early post war issues of BSRA (British Sound Recording Association) pamphlets I have the one issued after WWII the first meeting since 1939, along with a lot of the others right up to about 1955, found in 1936 and I believe the UK equivalent of AES merged into something or other in the late 1960's.

There were BS (British Standards) issued for tape speeds, track width, records all speeds which included details on lead in, lead out, banding, disc size etc. Again in BSRA along with standards for tape reels etc etc. Standardised globally circa 1954 with the introduction of RIAA (which is the RCA Orthophonic Curve used for 45 rpm discs.

EMI adopted 45 rpm and LP in or around June 1952, Decca having introduced 33 rpm in 1950. AR Sugden (Connoisseur) had a two speed turntable in 1950 and 3 speed in 1952, preceded by 78 rpm only in 1948. His cutting lathe did the same, his stereo cutting head was in development from 1952 and was shown at the Audio Fair at the Russell Hotel in May 1956 the same time as Peter Walker (Quad) showed the ESL 57. Vertical, Horizontal was Arthur Sugden's format for stereo disc, he had the UK majors at his door along with stereo tape machines to cut some masters. EMI discovered the Blumlein Patent as Bell Labs were trying to take all the claim, so through international agreement 45/45 stereo was decided upon as the international format and Sugden's method passed in to history and remains mostly forgotten, he is mentioned in Audio Amateur circa 1989. Which can be found here: https://www.americanradiohistory.com/Audio_Amateur.htm

I suspect although his was the first stereo disc format demonstrated, that others were working on it as stereo tape had been around since 1952 in US (not commercially until the about the same time as UK. EMI and Decca were making stereo tapes from 1954 as masters. His concern was that stereo tape would oust the disc, so he set about developing a stereo cutter head.

I suspect the reason a standard was found for RIAA was due to the development work in Stereo disc recording, interchange of tapes, master discs and a global standard for all of them makes sense. IEC is better than NAB as a tape Equalisation so not all things American are better.

Last edited by Stevie342000; 12th Nov 2018 at 12:13 am. Reason: added info
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Old 12th Nov 2018, 12:54 am   #19
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Default Re: Why both 33 and 45 ?

Some of the later 78rpm discs were pressed in vinyl. I recently found one by Pye, dated 1958, in a charity shop, and bought it out of interest ( only 30p). I don't have a working 78 turntable at present, so can't comment on the quality.
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Old 12th Nov 2018, 1:08 am   #20
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Default Re: Why both 33 and 45 ?

Quote:
Originally Posted by emeritus View Post
Some of the later 78rpm discs were pressed in vinyl. I recently found one by Pye, dated 1958, in a charity shop, and bought it out of interest ( only 30p). I don't have a working 78 turntable at present, so can't comment on the quality.
You don't need one. These days if you get a 78 stylus, you can play it back at 33 or 45, record it to a computer and the software will adjust the speed to 78, with one click.
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