Uncategorized

Published on April 15th, 2012 | by Alan Cross

29

Why is the Hole on a 45 RPM Record So Big?

Here is a fundamental question that every vinyl lover has asked:  why is the hole of a 7-inch single so big?

For the first fifty years of the turntable’s existence, the spindle on which you placed the record was a standard size:  approximately .283 inches.  That was also the size of the hole drilled into all records.

When Columbia Records introduced the 33 1/3 RPM long-playing album in 1948, they kept the hole in the center the same size.  However, Columbia’s archrival, RCA, was most annoyed at this new format.  Rather than license Columbia’s technology for their releases, RCA introduced their own new record, the 7-inch single that spun at 45 RPM and had a center hole that measured 1.5 inches in diameter.

Why would they do something like that?  Two reasons.

While the LP promised up to 22 minutes of uninterrupted music per side, RCA’s crowed that their 45s could be stacked on the special tall, fat spindle—about 6 inches high—that was exclusive to RCA-manufactured turntables.  Once a side of a 45 finished playing after five or six minutes, the tone arm moved away long enough for the next record to drop down onto the platter.  The tone arm then swung back into place and the music would continue.  With the ability to stack up to ten 45s on the RCA spindle, it was theoretically possible for the music to continue for a full hour without human intervention.

RCA wanted their new format to crush Columbia’s LPs, so they began selling turntables that could only play 45s.  The thinking was that once someone bought one of these turntables with the fat spindles, they were theoretically locked into buying music in that format from then on. It was just like the future VHS/Beta and Blu-ray/HD-Video wars.

But there was a more scientific reason for the larger hole.  When a new 45 dropped from the spindle onto the turntable, it was required to spin up from a dead stop to 45 RPM very quickly.  This torque tended to cause the small holes to go out-of-round very quickly, causing record to wobble as it spun. The larger hole allowed the sudden rotational force to be distributed over a longer path—pi x 1.5 = about 4.712 inches—reducing wear and allowing the hole to stay round longer. 

And while we’re on the topic, what do you call that plastic piece that snaps into the hole allowing it to be played on a regular turntable spindle?  Sorry to disappoint anyone looking for an exotic name.  It’s simply called a “45 rpm record adapter.”





About the Author

is an internationally known broadcaster, interviewer, writer, consultant, blogger and speaker. In his 30+ years in the music business, Alan has interviewed the biggest names in rock, from David Bowie and U2 to Pearl Jam and the Foo Fighters. He’s also known as a musicologist and documentarian through programs like The Ongoing History of New Music.


Related Posts


29 Responses to Why is the Hole on a 45 RPM Record So Big?

  1. Adam says:

    Almost all of my 7" singles don't have the large hole and play on normal turntables. Thank goodness.

  2. Greybeard says:

    http://en.wikipedia.org/wiki/45_rpm_adapter (and other sources) say it's also called a "spider".

    And just try to find anyone under the age of 30 who knows what one is!

  3. markosaar says:

    They're ninja stars damn it.

  4. Ronald Eason says:

    How else will you spin the record, that’s what is for place in the middle of the record for fitting put it on the record player and jam, but you got to be old school to know that, yeah man… Groovy!!!

  5. Ronald Eason says:

    It’s so big so that it doesn’t wabble and play even on the record player

  6. james wagner says:

    The 45 player had a large Spindle. Mine would hold five records.then up came the 78 rpms. I don’t have my ,45 player any more but I do have three turntable’s

  7. james wagner says:

    The turntables that I have will play 45 78s 33 rpms there is a switch for each.

  8. Mike says:

    Without the large hole in the 45 the Jukebox would probably have the same centre wear problem as the multi-changer player.

  9. John Jewel says:

    If the small diameter spindle hole was damaged by the torque of the dropped record I can imagine how many classic records were ruined by people fastening a penny on the stylus
    head instead of changing it out when the record skipped.

  10. Sherry Cutlip says:

    I want to buy a 45″record player with a 1+ drop-down spindle that will preclude the need for adapters in the middle of the recotds. Where, oh where, can I buy one? I bet there would be a large market for such a player with millions of people that don’t want to sit and insert 150 adapters into their 45’s.

  11. Steve says:

    Where are there some 7″ singles without a center?

    • Alan Cross says:

      I know of one: Gaye Bikers on Acid once released a hole-less record called “Drill Your Own Hole.”

      • markosaar says:

        Hah that’s awesome.

        I missed Gaye Bikers on Acid the first time around … became acquainted with them a few years ago because Mary Byker sings and plays in Graham Crabb’s new PWEI incarnation. (Really great group of musicians he’s found to carry on the name.)

  12. Pingback: Steve Hoffman Music Forums: Why is the Hole on a 45 RPM Record So Big? | RELAXING VIDEO

  13. midimagic says:

    The truth:

    – That hole wear claim is hogwash. The only thing that ever wore center holes was a certain kind of spindle with a rotating segment for dropping records.

    – The center spindle was made large so all of the record dropping parts fit inside it without using a side shelf or an overarm. The umbrella-type spindle had not yet been invented.

    • Dirk says:

      Thank you for making the comments I was going to make. People should do a little more research and not make assumptions when writing historical articles. The idea behind the 45 RPM record was to be lightweight, with both the records and the players less expensive, and absolutely bulletproof simple-to-use. Eliminating the shelf or over arm kept the players small, simple, and less expensive to produce.

  14. Sidchrome says:

    As a mechanical engineer I believe midimagic is 100% correct. The torque required for spinning the record comes from the friction between the face of the record and the platter. Here in Australia we never really saw the large holes in 45s as far as I can remember, but some brands had the ability to snap out the centre part to create the large hole if required. It was always a mystery to me why new turntables always came with a disk piece of 1.5″ diameter and about 1/4″ high. It was only when I was older that I realised that the piece was to play records with the large centre hole.

    • MidiMagic says:

      More history of the 45 RPM record:

      First, the history of why 78 rpm became the standard speed: Before 1928, each record manufacturer used a different speed to avoid patent infringement. But once the patents had all expired, there was no need. The (US) National Association of Broadcasters demanded one uniform speed so the DJs didn’t have to tune each record. Since Columbia was using 80 rpm and Victor was using 76, they settled on a compromise of 78. They also agreed on lateral recording.

      Next, RCA Victor wanted long playing records. They started making Vitrolac (vinyl) 33 rpm records (a speed used for voice radio transcripts) and turntables. But the records wore out after just a few plays.

      RCA tried to make the 45 system in 1939, including vinyl and the large hole. But they could not find a pickup that would not wear out the records quickly. Then World War II started and the idea was put on the shelf.

      In 1948, Columbia, along with Sonotone and Collaro, developed the LP system and pickups that could play vinyl records without wearing them out.

      RCA immediately pulled the 45 system out of mothballs and introduced it on 4/1/1949. They now had an available pickup.

      Blame Les Paul for the 45 speed. He ordered a recording lathe from a machinist with 78, 33, and another speed in between (he used speed changes to do some of his fast guitar tricks). That speed was 45. A record lathe manufacturer then bought the rights to his lathe and stated making them for studios, 45 speed and all. RCA bought some.

      The 45 would not have gained popularity if it weren’t for Wurlitzer. They switched their jukeboxes from 78 to 45. This forced record manufacturers to make 45s if they wanted jukebox play. The large hole made it easier to make a jukebox ply both sides.
      .
      45s made in the US have just the large hole, without punch-out adapters. I bought hundreds of spiders because I have two turntables that can take 12″ and 10″ 33s with 7″ 45s in the same stack.

      • Dirk says:

        Actually, it was Seeburg who developed the 45 RPM jukebox in conjunction with RCA. Wurlitzer did not develop a dedicated 45 machine until 1954. Seeburg’s machine was the 100 B introduced in 1949.

    • Allan says:

      MidiMagic, excellent response. I couldn’t imagine Jukeboxes operating successfully without the records larger centre hole. A slighly tapered ‘cone’ assures a rapid record load and quick positive centering.

  15. Allan says:

    I always thought that 16rpm was initially used for voice & voice broadcast transcripts. Sound for early movies was once synchronised to a record but I don’t know what rotational speed that was.
    An interesting thread…

  16. MidiMagic says:

    The original purpose of the 16 rpm record was the Chrysler HiWay-HiFi player.

    Audio Books started with 7″ 16.67 (the actual speed) large hole records, and then made all three sizes (7, 10, 12″) of 16 rpm with the 1.5 inch hole. Later they made 8.33 rpm records in the same form. They made an adaptor that fit on a record changer turntable to play the 8 rpm records with your 45 spindle and the speed set at 33. I borrowed a book and the adaptor from the library and was amused to see my Collaro Conquest dropping large hole 10″ 8 rpm records onto the adaptor turntable and playing them automatically.

    Seeburg made 7″ 16 rpm records with 2″ holes for their background music system.

    Warner Brothers Vitaphone was the sound-on-record movie system. The record was 16″ 33 rpm coarse groove. This was 25 years before the 16 rpm speed was first used.

  17. Wurlitzer adopted the 45 format for their jukeboxes. From that they could produce smaller units , the table side jukebox, which became Popular in diners and hamburger joints. The large hole was better for the jukeboxes, so that both sides of a record could be played. In the pre-rock ,78 era, jukebox activity were a primary indicator of a songs popularity. The 45 was a more flexible format, that could be used in jukeboxes and for retail sales as well. When Rock and roll hit in the mid fifties, the industry was ready for it. The technology was inline with the sea change in popular music.

    • Dirk says:

      You need to do a little research. Seeburg was the one who developed the first 45 RPM jukebox as the 100B and released it in 1949. Wurlitzer didn’t have a dedicated 45 mechanism until 1954, instead they had to try to make adapter kits for their old 78 machines with varying degrees of success. The size of the center hole has nothing to do with playability as the Seeburg 100A could play both sides of 78 records with a small hole as did several other manufacturers mechanisms. Even rock-ola and Wurlitzer that were using the Simplex mechanism were able to adapt it with a second tonearm to play the bottom side of the record. Am I used to mechanism that could flip the record to either the a side or the B side for their 78 machines. The size of the center hole was not an issue.
      The large hole was developed by RCA so they could put all of the changer mechanism parts inside the spindle, therefore negating the need for an overarm or shelf.

    • Dirk says:

      Oh, I forgot to note that the Seeburg 100A of 1948 could play both 10in and 12in records intermixed, all while using the small center hole. Again, the size of the center hole has nothing to do with jukebox and everything to do with RCA 45rpm changer.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Back to Top ↑