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Old 12th Nov 2018, 2:17 am   #21
Synchrodyne
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Default Re: Why both 33 and 45 ?

There is a good discussion of turntable speeds and record diameters for microgroove recording in this Wireless World 1951 June article “Gramophone Turntable Speeds – What is the Best Speed for Microgroove Recording?” by G.F. Dutton of EMI.

WW 195106 Turntable Speeds.pdf

Here is the summary from that article:
Summarizing, it can be stated that:

(a) 12in records can be played at either 33 or 45 r.p.m. with good quality to 18 minutes. At 45 r.p.m. the 10 inches per second limit is reached at just over 20 minutes: at 33 r.p.m. this limit is extended nearly to 22 minutes. The rise of distortion is illustrated in Fig. 9(a).

(b) 10in records can, in the extreme, be played to 14½ minutes at either speed, but the last 4 minutes of playing will have noticeably better quality on the 45-r.p.m., record. The lower distortion in the latter case is indicated in Fig. 9(b).

(c) For smaller records, the higher turntable speed is unquestionably better: by this means popular 5-minute recordings can be made comfortably on 7in discs. The advantage is clearly shown in Fig. 9(c).

The conclusions were well-backed by maths and graphs.

One could say that notwithstanding the non-technical factors that led to the appearance of two microgroove record speeds in the late 1940s, in fact having two speeds was technically justified for the range of record diameters commercially needed, and that the two used were each adequately close enough to the numbers that would have been derived from ab initio calculations.

There was an earlier thread on 16⅔ rev/min records, see: https://www.vintage-radio.net/forum/...d.php?t=141257.

This article, “The Fourth Speed”, from Popular Electronics 1957 August provides quite a bit of background. Therein it was stated that at the time, the frequency response went to around 9 kHz, although improvements were expected.

PE 195708 The Fourth Speed.pdf


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Old 15th Nov 2018, 11:46 am   #22
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Default Re: Why both 33 and 45 ?

As far as I was aware, Seeburg and RCA co developed the 45 rpm single because of jukeboxes. The M100A Jukebox was a mighty beast, holding 78rpm records in a vertical stack, these were heavy, fragile and wore out quickly. The M100B was the first jukebox to use the new 45rpm records, they were light, better groove noise, and you could get more of them into the space, this bought about jukeboxes that could take 80 or even 100 singles to give 160 or 200 plays respectively. With 78's I think the limit was 50 records to give 100 plays.

The first 45's were on coloured vinyl with the colour denoting the genre of the content, with the first ever being a green vinyl single called Texacarna Baby. I have a copy of this 45 and the sound quality for something dating from 1948/9 is quite amazing.
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Old 15th Nov 2018, 12:46 pm   #23
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Default Re: Why both 33 and 45 ?

I remember in my classical vinyl collecting days during the 70's / 80's a period when some recordings were issued on 12 inch but at 45 rpm.
Apparently the faster speed improved the audio quality, I think it was a bit of a fad, I certainly couldn't hear much more of an improvement compared to the standard 33.
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Old 15th Nov 2018, 1:24 pm   #24
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Default Re: Why both 33 and 45 ?

Those big 45s were louder and usually had 4 tracks on them including a longer version and a short radio version.
I have got a couple of them.
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Old 15th Nov 2018, 2:19 pm   #25
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Default Re: Why both 33 and 45 ?

As stated in #2 it was a probably a deliberate format war:

The story is that David Sarnoff gave his engineers the brief to do anything as long as it was incompatible with Columbia's LP system. They failed in that it was still micro groove, but they achieved the rest and backed it up with a lot of facts and figures to say why it was designed by science, not out of spite honest.

In reality the world had tired of a system that could not record longer pieces of music without a break and Peter Goldmark's invention of the LP solved that problem. Eventually the 45 found its natural home with 3 minute pop songs so everyone was happy.

HMV did try to sell a badged version of the RCA 45 changer in about 1951, but it soon faded from the market, beaten by the 3 speed units that could play everything.
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Old 15th Nov 2018, 2:25 pm   #26
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Default Re: Why both 33 and 45 ?

Quote:
Originally Posted by Refugee View Post
Those big 45s were louder and usually had 4 tracks on them including a longer version and a short radio version.
I have got a couple of them.
IIRC 12" 45s started out in the disco era for extended songs & continued through various dance genres.

I assume 45rpm was used so DJs didn't have to switch speeds on their decks.
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Old 16th Nov 2018, 8:40 pm   #27
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Default Re: Why both 33 and 45 ?

I was explaining the limitations of cutting records to my daughter today and how the Rolling stones produced an LP [AFTERMATH] of extended length beyond the usual 22 minutes a side or so [although that was perfect for taping two LP's on C90 cassettes]. I said the Stones had a top class engineer doing the cutting very carefully to maximise the quality. In the end it was a little muddy but other wise very acceptable if not that Hi Fi. l mentioned that the EP was a sort of half way house ie holding 4 tracks at 45 rpm. No comment on these so far. The info put up by Synchrodyne at post 21* [c] seems to "chime" with the EP mode being adopted. Any expert comment on this technical factor?

Was the EP a commercial move to make more sales? We thought so at the time but even so they were very popular as it was often a cheaper concentration of existing hits, new or live material.

Re Clive's comment at 23 re faster speeds people used to quote that as a rule of thumb re Record and Tape speeds but I suppose LP's at 45 would not be as practical. A lot of 78's have an amazing quality and presence spinning round at somewhere in the region of 80 rpm so that seems to support the argument somewhat! It must have seemed a fantastic break though though when it became possible to get long recordings on vinyl at 33 rpm-as opposed to a suitcase full of 78's.



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Old 16th Nov 2018, 8:52 pm   #28
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Default Re: Why both 33 and 45 ?

I had one or two 7 inch EP’s, probably correct about marketing, more tunes than a ‘single’ but a lot less money than an LP.
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Old 16th Nov 2018, 9:17 pm   #29
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Default Re: Why both 33 and 45 ?

There's a fair few pressings of LP's around that play at 45RPM, I have several in my collection. At least two, Bob Dylans "modern times" and Rodrigo y Gabriela's "Area 52" are released as double LPs and the tracks are not cut too close to the centre. As to whether the quality is better because of it can be argued as there are no 33 rpm versions that i know of to compare against.
But in any case there are a few 45 rpm LPs that have been issued and are still being issued or are remaster/reissues of previous works.

Andy.
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Old 16th Nov 2018, 10:15 pm   #30
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Default Re: Why both 33 and 45 ?

Quote:
Originally Posted by dave walsh View Post
I was explaining the limitations of cutting records to my daughter today and how the Rolling stones produced an LP [AFTERMATH] of extended length beyond the usual 22 minutes a side or so [although that was perfect for taping two LP's on C90 cassettes]. I said the Stones had a top class engineer doing the cutting very carefully to maximise the quality. In the end it was a little muddy but other wise very acceptable if not that Hi Fi.
I recall that some of the budget labels like K-Tel and Hallmark used to cram up to 10 tracks onto each side of a 12" album. Unlike the above mentioned Rolling Stones album, those brands didn't really care about quality so their records tended be fairly quiet and sounded a bit flat.

The Elvis Costello and the Attractions album "Get Happy" had 10 tracks on each side but most were under 3 minutes long so the total playing time was about 48 minutes. I had a copy at the time (I now have it on CD) and don't recall any sound quality issues. As with a lot of their music it was quite compressed and unrefined, probably produced with MW radio in mind, so they could get away with it. There was even a comment on the sleeve notes about potential groove cramming, as mentioned on the Wikipedia article.

https://en.wikipedia.org/wiki/Get_Ha...ostello_album)
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Old 16th Nov 2018, 10:32 pm   #31
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Default Re: Why both 33 and 45 ?

When Don Mclean's American Pie was released as a single it had to be over 2 sides as the mastering engineers found it was impossible to fit the whole 8 minutes on 1 side without messing the sound quality too much.

In the early days of LPs some were 10 inch, which was occasionally used a "medium play" or "mini album" format since then.
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Old 16th Nov 2018, 10:49 pm   #32
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Default Re: Why both 33 and 45 ?

The 45 rev/min “EP” was probably commercially driven. Perhaps it was an exercise in how to get a bit more out of the 7-inch 45 rev/min disc than was originally envisaged. Recording at lower average levels, with some compression might have been used in order to get closer groove spacing. I don’t know if RCA issued a paper or technical article on this development, which was c.1952.

The original 45 rev/min work was well-documented in an article in RCA Review for 1949 June. This may be found the excellent American Radio History site, https://www.americanradiohistory.com..._Issue_Key.htm. I have extracted the article, which runs to 18 pages, and is entitled “A Record Changer and Record of Complementary Design”.


RCA Review 194906 Record Changer.pdf

The derivation of the rotational speed was quite interesting. For the changer to function relatively quickly, that is within one revolution of the record, the maximum rotational speed was 1.2 rev/s, or 50 rev/min. Allowing a working margin suggested a speed a little below that, namely 45 rev/min. It would appear that the earlier notion that disc rotation speed should be the quotient of integral division of 1800 rev/min (the speed of a 4-pole synchronous motor operating on a 60 Hz supply) was still in vogue. 78.26 rev/min was 1800/23, 33⅓ rev/min was 1800/54, and now 45 rev/min was 1800/40.

RCA then did the calculations which showed that 45 rev/min was indeed a better choice than either 33⅓ or 78.26 rev/min, the latter also introducing complications from the record changer viewpoint. Minimum volume of material for the desired playing time was one of the objectives. Another was 5⅓ minutes playing time with a terminal linear velocity of 11.5 in/s. In fact the disc dimensions allowed 7¼ minutes playing time at a terminal linear velocity of 10.0 in/s, which was acknowledged as producing lower quality. I’d guess that the lower terminal linear velocity was used for EPs.

A comparable article on the LP was probably provided an article in the IRE Journal for 1949 August, now available (for purchase) as an IEEE paper, at: https://ieeexplore.ieee.org/document/1698116, “The Columbia Long-Playing Microgroove Recording System”, by P. Goldmark et al.

I haven’t seen that paper, but I imagine that it includes the rationale for the 33⅓ rev/min speed choice, beyond the fact that this was an established transcription record speed. I’d guess that it was taken as an “in the ballpark” starting point, with subsequent calculations confirming that no departure from it was materially beneficial.


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Old 16th Nov 2018, 10:56 pm   #33
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Default Re: Why both 33 and 45 ?

Bohemian Rhapsody by Queen is six minutes and did fit on one side of a 45 while sounding good. Must have been a challenge for the mastering engineers with the different sections probably requiring different conditions.
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Old 17th Nov 2018, 12:52 am   #34
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Default Re: Why both 33 and 45 ?

That's a really good response folks as I thought I could well be on the wrong "track" with my questions. Currently I'm checking out the "More Blood On The Tracks "official" bootleg re Dylan but that's something else all together! It was all about money in the end I suppose but records and magazines were the equivalent of the Internet back then only more exciting in terms of access to information! Personally I avoided the budget labels that Paul mentioned [mainly because of the content] but not one or two of the blues ones that turned out to be gems! Overall if you are a true enthusiast [in my view] it's content first and quality second. AFTERMATH needed to accommodate an eleven minute Je t'aime type blues riff at the end, re Mick Jagger missing his girl friend, which apparently only finished when someone threw a coat at the Bass Player Bill Whyman!


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Old 17th Nov 2018, 8:07 am   #35
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Default Re: Why both 33 and 45 ?

This is fascinating.
The Beatles issued Magical Mystery Tour on double EP in the UK and 12in LP in the States. I have copies on both formats so I must try a comparison, although my old ears probably won't notice any difference.

As a side note I have some 16 inch Pathe disks that run at 120rpm, centre to edge and vertically modulated. I have modified a Technics direct drive turntable to run at that speed, I just need to finish the extra long arm before playing them.

Peter
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Old 17th Nov 2018, 9:16 am   #36
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Default Re: Why both 33 and 45 ?

It isn't just a question of loudness on the cut - the other major factor is groove packing, that is how close you can get a turn to its neighbours without overcutting or pre-echo. Among other things, dynamic range has to be considered - a big peak naturally needs a degree of Lebensraum. DMM has an advantage here, as the cut medium is stiffer, and there have been some very clever devices which calculate the available space in several segments of the disc as it is being cut, rather than spacing the whole turn. You can then use this space to cut at a higher level, to gain more playing time or to finish at a greater recorded diameter, thus reducing distortion.
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Old 17th Nov 2018, 10:01 am   #37
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Default Re: Why both 33 and 45 ?

Akin to all the above, back in the early 1960s, World Record Club were issuing 12" Lps of Classical music which had been produced using a variable width (if that's the right word') groove spacing, wide for loud passages of music, narrower for quieter sounds -this gave increased playing time per side. Somewhere I may still have the article(s) from the WRC Magazine which described the process.
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Old 17th Nov 2018, 10:34 am   #38
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Default Re: Why both 33 and 45 ?

I read somewhere that Neuman, the manufacturer of cutting lathes, developed the first versions of the technique. This was in the early 1950's.
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Old 17th Nov 2018, 2:53 pm   #39
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Default Re: Why both 33 and 45 ?

Quote:
Originally Posted by Synchrodyne View Post
The 45 rev/min “EP” was probably commercially driven. Perhaps it was an exercise in how to get a bit more out of the 7-inch 45 rev/min disc than was originally envisaged. Recording at lower average levels, with some compression might have been used in order to get closer groove spacing. I don’t know if RCA issued a paper or technical article on this development, which was c.1952.

The original 45 rev/min work was well-documented in an article in RCA Review for 1949 June. This may be found the excellent American Radio History site, https://www.americanradiohistory.com..._Issue_Key.htm. I have extracted the article, which runs to 18 pages, and is entitled “A Record Changer and Record of Complementary Design”.


Attachment 172944

The derivation of the rotational speed was quite interesting. For the changer to function relatively quickly, that is within one revolution of the record, the maximum rotational speed was 1.2 rev/s, or 50 rev/min. Allowing a working margin suggested a speed a little below that, namely 45 rev/min. It would appear that the earlier notion that disc rotation speed should be the quotient of integral division of 1800 rev/min (the speed of a 4-pole synchronous motor operating on a 60 Hz supply) was still in vogue. 78.26 rev/min was 1800/23, 33⅓ rev/min was 1800/54, and now 45 rev/min was 1800/40.

RCA then did the calculations which showed that 45 rev/min was indeed a better choice than either 33⅓ or 78.26 rev/min, the latter also introducing complications from the record changer viewpoint. Minimum volume of material for the desired playing time was one of the objectives. Another was 5⅓ minutes playing time with a terminal linear velocity of 11.5 in/s. In fact the disc dimensions allowed 7¼ minutes playing time at a terminal linear velocity of 10.0 in/s, which was acknowledged as producing lower quality. I’d guess that the lower terminal linear velocity was used for EPs.

A comparable article on the LP was probably provided an article in the IRE Journal for 1949 August, now available (for purchase) as an IEEE paper, at: https://ieeexplore.ieee.org/document/1698116, “The Columbia Long-Playing Microgroove Recording System”, by P. Goldmark et al.

I haven’t seen that paper, but I imagine that it includes the rationale for the 33⅓ rev/min speed choice, beyond the fact that this was an established transcription record speed. I’d guess that it was taken as an “in the ballpark” starting point, with subsequent calculations confirming that no departure from it was materially beneficial.


Cheers,
I was thinking the speeds were due to motor speeds being geared down, but hadn't managed to work out speed would work for all 3 without some difficult ratios.
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Old 17th Nov 2018, 3:18 pm   #40
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Default Re: Why both 33 and 45 ?

In the 1970's there was a demand for a longer playing 7" record not offered by 45 EP.
So existed the "maxi-single" cut at 33, although if such a record became a hit, a 45
version was also issued, presumably for jukebox distribution.
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