How to measure turntable speed

Discussion in 'Audio Hardware' started by cdgoldmine, Jul 12, 2019 at 9:12 PM.

  1. cdgoldmine

    cdgoldmine New Member Thread Starter

    Location:
    Middletown, NJ
    Been testing out turntables, and because I had a Technics with a strobe, I'm obsessed with checking the speed. My Technics started straying with the strobe and I could hear the difference.

    So I bought a tachometer to check the speed on the turntables I'm testing. Now the problem is what is the proper way to test the speed. For example, I was checking the speed with a record playing. If the speed is at 33.3 during the middle part of a record, the beginning part will be 33.2, then it will transition from 33.2 to 33.3 for the middle part of the record, then transition from 33.3 to 33.4 for the remaining third of the vinyl side. When the tonearm IS NOT on the record, the speed will run at 33.5.

    So I see others testing with their phone, which will put weight on the platter, or testing with a stroboscope, which won't have the tonearm on the record.

    So the question is what is the proper method to test turntable speed? With a record on or off the platter? With the tone arm on the vinyl or off the vinyl? Do you test with the album off and tone arm off and assume that the weight of the vinyl and tone arm are part of the calculation of the proper turntable speed?

    I'm going to copy the vinyl to my hard drive and compare a digital copy to the vinyl for proper speed. That will get me as close as possible I guess. But putting this out here for opinions. Thanks.
     
  2. ScottRiqui

    ScottRiqui Well-Known Member

    Location:
    Fort Worth, Texas
    It sounds like the readings you took with the record playing would be the most realistic and useful. And your readings say that the speed is only varying from 33.3 RPM by +/- 0.3% from the beginning of a side to the end, so I'd be pretty happy.
     
    All Down The Line likes this.
  3. cdgoldmine

    cdgoldmine New Member Thread Starter

    Location:
    Middletown, NJ
    I just copied side 1 of Please Please Me and tested I Saw Her Standing There to the 2009 remaster and it was pretty much in sync. I'll test out the last track on the side, Please Please Me, and one from the middle, and see how close they are. But I think the speed setting I have now will do.

    I'm testing a Music Hall mmf-1.5. It has a speed adjustment on the back of the turntable and I spent the day fudging around with that. Hopefully the speed won't stray too far from album to album because I did have to make adjustments from my original test, which was John Fogerty Centerfield.

    I noticed on my Technics that the strobe would shift with different musical passages. In other words, depending on how busy the music would get would alter the strobe pattern, or the position of the tone arm on the album. Also, the dead wax between tracks could alter the strobe.

    The testing mechanisms I'm seeing people use online can't give accurate readings compared to what I'm doing. If you're using a stroboscope, or an app on your phone, then the tone arm isn't going to be on the turntable.
     
  4. WestGrooving

    WestGrooving Forum Resident

    Location:
    California, U.S.A
    Personally, I'd like a record with a full side of a 3khz test tone. I'd play it alongside a Youtube 3khz test tone video and adjust the RPM setting on my Cruise Control 2.0 device until the oscillating sound was gone or minimal.
     
  5. cdgoldmine

    cdgoldmine New Member Thread Starter

    Location:
    Middletown, NJ
    I just tested track 7, Please Please Me, to the 2009 remaster and the drift was really bad. The speed on the tachometer was 33.3 and 33.4, so not much of a drift. But the oscillating sound was terrible. I Saw Her Standing There oscillated just a tiny bit, but was tolerable.
     
  6. McLover

    McLover Forum Resident

    Location:
    East TN
    Use a strobe disc with an incandescent lamp. The most accurate method. Test records vary from professional and laboratory accurate references to consumer grade rubbish.
     
  7. Guitarded

    Guitarded Forum Resident

    Location:
    Montana
    KAB Speed Strobe
     
    5-String and Helom like this.
  8. anorak2

    anorak2 Forum Resident

    Location:
    Berlin, Germany
    Download, print, punch a hole, put on turntable. Works best with fluorescent lighting - the old fashioned tubes, not the "energy saving" light bulb ones because they are Hertzed up a bit.

    [​IMG]

    Alternatively, get a copy of Kraftwerk's "Man Machine" :D.
     
    McLover likes this.
  9. anorak2

    anorak2 Forum Resident

    Location:
    Berlin, Germany
    PS two more thoughts:

    It is normal that the music plays slightly slow at the beginning of a record, correct in the middle bit, and slightly fast towards the end. This is a side-effect of how a conventional tonearm follows a curved path across the record surface, not a straight line. Only linear tonearms avoid this problem.

    [​IMG]


    I don't understand how you measured the speed; if it was by the music's pitch, then you should get that variation and there is nothing wrong. If you measured physical revolutions, you shouldn't because the rotation of the turntable is not affected and it should be constant regardless of the tonearm's position.


    Hmm, this relies on both master tape and cutting turntable running at the correct speed, and in the case of an analogue master the tape machine used during digitisation running at the correct speed. Three variables you have no control over, none of this is a given.
     
  10. Optimize

    Optimize Forum Resident

    Location:
    EU
    Hmm.
    I think that the best way to adjust the speed is to use a test record with a cut frequency. Playing that back and use a phone app that listening and expecting that frequency.
    You not only have a record on the platter you also have the drag from your stylus in the grove and therefore replicate exactly the same situation as when you listen on your albums.

    The ting is that the application also gives you a graph over the speed variation over time so you see the fluctuations I think it is called wow.

    But the sad thing I can not find the app on my phone or g-store and do not remember its name :(

    But on the other hand. Reflect little over how much the difference between 33.333 and 33.444.
    It is 0.111 part of a turn the record has traveled after a whole minute of spinning.

    A easier way to see it is that the circumference of 12" is 87.9646 cm
    87,9646×33,333333= 2932,1533040118 cm
    87,9646×33,444444= 2941,9271386824 cm
    2941,9271386824-2932,1533040118=9,7738346706 cm

    So after spinning for a whole minute with 0.111 to fast it has almost gone 10 cm to far.

    9,7738346706÷60=0,16289724451
    So each second it is traveling 1.6 mm to far with 0.111 rpm to fast rotation.

    But it is nice to know that it is as good as it can be.
     
  11. BrentB

    BrentB Forum Resident

    Location:
    Midwestern US
    Many old test records from the 60's and 70's had a speed indicators on the perimeter of the label. Easy to check while stylus is in the groove. Also some classical based labels had the markings. Audio Fidelity may have been one.
     
  12. t3chnobrat

    t3chnobrat Forum Resident

    Location:
    Florida
    In regards to the phone apps. I have two Technics too and had platter speed obsession when I set up my newest table. I was using the 'RPM' app on an Iphone XR and then I also downloaded 'Turntabulator'. It was interesting that the readings were consistently different between the two. I scooped up a Falcon PSU when one popped up for sale and installed that and remeasured and the readings from the apps were still different.. I was patiently waiting and SOTA turntables finally started selling the Roadrunner that they're licensing from Phoenix Engineering so I picked one up to pair with my Falcon. I tested both apps against the Roadrunner and Turntabulator was spot on in both quick mode and exact mode.. RPM was still inaccurate. So as far as apps go, Turntabulator seems to be the way to go.
     
  13. Helom

    Helom I'll take the monkey coffins

    Location:
    U.S.
    This. You want the SpeedStrobe. It allows measuring while the tonearm tracks the grooves.
     
    5-String likes this.
  14. cdgoldmine

    cdgoldmine New Member Thread Starter

    Location:
    Middletown, NJ
    Thanks to everyone for the advice. I spent the day testing out vinyl pressings from different eras at different weights and I think I have the speed settings set to the best I can do.

    Comparing my needle drops to digital copies wasn't an accurate measurement. There is going to be drift on the turntable when playing a side of vinyl. As I mentioned in my opening, the platter spins at 33.5 when the tone arm isn't down. The first third of the side will start at 33.2, then alternate between 33.2 and 33.3 for a bit, then lock in at 33.3 for the middle part of the side, then alternate a bit between 33.3 and 33.4 then close the side out at 33.4. I'm assuming this is normal, and comments above indicate that it is.

    As I mentioned, I'm using a digital Tachometer to measure the rotation of the platter. I really like this gadget. You put a reflective strip on the side of the platter, then point the laser at it and measures each rotation. It costs between $15-$20. Can't remember. Bought it off an online audio vendor. Can't remember offhand, but if anyone is interested I'll get the link out here.

    What are the chances of any platter rotating at 33.3 all the way through? Even spending big bucks.

    This is a Music Hall MMF-1.5 turntable with a factory installed Music Hall Melody cartridge. I haven't done vinyl in years, but have lots of bootlegs that might be worth doing, though I'm sure they've all been mastered better since. Not even sure if I want a turntable at this point, but I think I'm pleased with this one for now.
     
  15. SpeedMorris

    SpeedMorris Forum Resident

    Location:
    Iowa
    People have been saying very nice things about the sound of that table. It should support a nice cartridge should you go there. Don Lindich of the sound advice nrws blog loves the $100 Vessel A3SE with it.
     
  16. cdgoldmine

    cdgoldmine New Member Thread Starter

    Location:
    Middletown, NJ
    I wasn't able to find much on it, but what I found was positive so I took a shot. I tried the ProJect DC Carbon 1 with the Ortofon Red that came with it. The platter was uneven, so I would hear a bump every rotation. And it wasn't very forgiving to the condition of my vinyl. Pops and clicks were LOUD!! Tried a Rega Planar 1 and wasn't impressed, so trying the Music Hall now. Haven't decided how I feel about it yet, but no real negatives yet. It's a nice looking piece. Going to use it more for vinyl rips than listening, so once I A/B the rips to others I've done then I'll see. But it feels like a keeper.
     

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