7" vinyl single specification

[af024]

There's quite a bit about RIAA equalisation on the www, but I cannot see anything which illustrates the physical specification - i.e. OD, run-in track width, max recording area width, where the run-out must start at the latest, is there something stating how fast the run-out must be and where the locked groove should be, what's the hole ID (small hole and large jukebox hole) etc, max/min thickness, where were the raised bit located, were they all notched the same way so that they interlocked properly on auto-changers, what are the specification tolerances? What diameter for the label?

Strange how there seems to be nothing out there. I was hoping for something like a published drawing.

With auto-changers and jukeboxes expected to cue-up, play and properly eject each and every single, it's clear that there must be some givens parameters.

So does anyone know?

Looking forward to hearing from you.

Regards,

Andy

[Nuvistor]

Its the RCA large spindle specification, any help.
http://www.aes.org/aeshc/docs/record...y/speed45.html
Frank

[barretter]

Have a look at
www.aardvarkmastering.com/riaa.htm

it may contain answers to some of your questions in the section on dimensional specifications for 45rpm discs.

[Edward Huggins]

There was a huge difference in the cutting pitch when it came to EPs. To get to 7 mins per side at 45 rpm (there being 7" 33 rpm discs also) these grooves are very fine, much more lowly modulated and so generate less output. Many hit singles lasted less than 2 mins and their grooves were very coarse - and sounded quite loud even on a vanity case player!

[Hartley118]

I understand that the cutting engineer's brief was to push as much level as possible on to a 45 single so that its sound would stand out on the jukebox in the Diner or Coffee Bar. As a result they need a quality cartridge to track them properly - a paradox when compared with the tracking inability of the usual high output 'Dansette type' cartridge.

Martin

[Nuvistor]

Originally Posted by Edward Huggins

There was a huge difference in the cutting pitch when it came to EPs.

Would that be covered by the specification of grooves per inch 16 to 32?

Frank

[Edward Huggins]

I would assume so, but others may be better informed.

[Tom_I]

The specification of 16 to 32 grooves per inch is for the lead-in spiral, not the playing area.

[Nuvistor]

Quite correct, use my other glasses next time.

Frank

[af024]

Some useful snippets there, thank you. I'm not sure whether the final entries regarding the RCA document became the final standard. Things may have moved on again since the theoretical study (as they do sometimes), but it's certainly an interesting read. The other article also answers one of my questions regarding which side wall was for which channel.

Keep it coming guys - thank you.

Regards,

Andy

[iantommo]

I do know that there was a British Standard specifcation for the serrated anti-slip rings an British 45's but apart from that I know nothing

[dseymo1]

That's interesting - I'd always thought the rings were an ad hoc sort of thing invented by some of the record companies.

[Focus Diode]

Originally Posted by iantommo

I do know that there was a British Standard specifcation for the serrated anti-slip rings an British 45's but apart from that I know nothing

Extra run in grooves were also introduced around 1962.
Look at a Decca group 45 issued in 1960 for example then compare with a 1963 release. Think it was introduced to avoid the risk of the stylus jumping off the record which could happen with auto-changers with just the one long run in groove.

Brian

[af024]

Comparing this:-

‘Careful testing of large numbers of records played with a pickup of 5 grams stylus force under different conditions of stylus and record wear, developed the fact that the minimum label diameter to provide adequate traction was 3-1/2 inches*1. This required that the minimum diameters of the concentric finishing groove and the last music groove be 3-7/8*2 inches and 4-1/4 inches respectively. This diameter provides a radial length of about 7/8 inch, which is sufficient for printing requirements.’

this:-

‘2. With the depressed music area design, which reduces record scuffing, the diameter is 6-7/8 inches*3 compared to 8-1/8 inches at 33-1/3 or 7-1/2 inches at 78.26 revolutions per minute.’

and this:-

‘A study of the characteristics of the record changer indicated that it would be desirable to provide a landing area of 1/8-inch*4 radial length outside the music grooves. By combining the above equations, substituting the desired parameters and adding the landing area ..’

with a UK RCA pressing from 1972, RCA 2164, THE SWEET – ‘POPPA JOE’ to be precise,

*1 The diameter of the label on RCA 2164 measures 3-5/16 inches compared with 3-1/2 inches above. Interestingly though, if you measure the diameter of the extremities of the serrated ring, you get the 3-1/2 inches.
*2 The locked groove diameter on RCA 2164 measured 3-3/4 inches in diameter compared with 3-7/8 above. I suppose being smaller, it provides a bit of safety margin to guarantee an auto-trip function.
*3 The OD of the entire RCA 2164 single is 6-7/8 inches. I always thought it was 7” (so what do I know!?)
*4 The landing area (run-up) on RCA 2164 measures a tiny bit over 1/8 inch.

The lead out on RCA 2164 looks as if it’s something like 1/4 inch per revolution (i.e. 4 grooves per inch). Lead-out in the second document reference is quoted as being 2-5 grooves per inch.

The run-in on RCA 2164 looks as if it’s something like 1/32 inch per revolution (i.e. 32 grooves per inch), Grooves per inch for this quoted in the second document reference is quoted as being 16-32 grooves per inch.

The small centre spindle hole looks like 0.288 inches (which I can’t equate to anything in fractions, not even if I go with 64ths - it’s between 18/64 inch and 19/64 inch, but it does almost agree with the table in the second reference, i.e. 0.286" + 0.001" -0.002". I wonder why this weird size was chosen?

PS Earlier I hadn't realised that the second document had a link to two diagrams. These are what I was looking for. Thank you.

[Valvepower]

Hello,

I recently located the NAB AUDIO RECORDING AND REPRODUCING STANDARDS FOR DISC RECORDING AND REPRODUCING.

From what I can make out the NAB standards are used by quite a few of the mastering and cutting studios.

The NAB test LP mentioned in the text is also used to set up the refence level for the cutting lathe.

Here is a link to the document on the net.....

http://www.richardhess.com/tape/hist...d_graphics.pdf

Hope this helps.
Terry

[af024]

Thank you Terry, more interesting stuff there.

It makes you realise the amount of work involved in defining what the standard should be.

Regards,

Andy

[Valvepower]

Hi Andy,

No problem glad to help.

There is a British Standard BS 1928:1965 Specification for processed disk records and reproducing equipment, which gives dimensional information.

I have copy somewhere, just got to find it

Regards
Terry

[af024]

Oooh that sounds interesting too Terry, thank you.

Regards,

Andy

[whyperion]

The small centre spindle hole looks like 0.288 inches

Presumably as in the UK 78 decks had that sized centre spindle hole, which must go back to the days of the Berliner single sided flat disc. In turn this depended on mechanical spring driven recording and playback devices, I guess the optimum size given other constraints

[af024]

Good point. I wonder what the spec of the centre spindles of record decks is?