Speed stability: Direct Drive vs belt

Discussion in 'Audio Hardware' started by DaleClark, Feb 11, 2019 at 5:48 AM.

  1. DaleClark

    DaleClark Forum Resident Thread Starter

    Location:
    Bexley, Ohio
    I'm seriously looking at purchasing a Technics 1200GR TT. I like the idea of pitch control. Many years ago, owning both DD and Belt driven turntables, I always felt the DD seemed more precise. Maybe due to the strobe platter edge.

    A couple of questions:

    1. how does belt wear effect speed accuracy? How long should a typical belt last?

    2. how does one hook an external speed control to a typical TT?

    3. Is it a myth that DD turntables are more speed stable?
     
  2. patient_ot

    patient_ot Forum Resident

    Location:
    USA
    A good DD table is more speed stable than any belt drive. Wow and flutter numbers for the best DD tables are very, very low.

    The better belt drives today (in the same price range as the GR) will only get down to .06 or .07 AFAIK.

    A good DD can get much lower than that, more like .0025.

    Re: your questions:

    1) Depends on the belt and the turntable. I've heard of people using belts for years and people having to change them once a year. Note that not everyone is constantly checking the speed on their TT, so some people may be using belts longer they they should.

    2) It varies depending the type of unit. Some merely have you plug the turntable's power cord into the unit, then plug the unit's power cord into the wall outlet. Not all BD turntables are compatible with speed controllers, and not every speed controller will work with every turntable. You have to do your research. Also keep in mind that some companies charge quite a bit for their speed controllers. For example, the Polytable controller is ~$700, and VPI charges ~$1,000 for their unit.

    3) No.
     
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  3. DaleClark

    DaleClark Forum Resident Thread Starter

    Location:
    Bexley, Ohio
    I think I will keep focusing on the Technics 1200/1210 GR. Looks like a winner all around. I like to visually see the speed stability with the strobe. Plus, I can have quick change headshells for different cartridges with minor TA adjustments (mono, 78, etc).
     
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  4. Of course it depends on many factors, including what "level" of TT you are comparing and how much you want to spend -- but ^^^^^ quote above hits the high points.
     
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  5. Raylinds

    Raylinds Forum Resident

    I am not disagreeing with your basic premise, but I do have a VPI Aries 3 that I modified to use 3 belts that measures .02 at 33 1/3 and .01 at 45 using the Feickert measurement software, but I am sure that there are DD that can better that. I recently got a vintage 70s Pioneer quartz lock DD. I will have to measure that with the software.
     
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  6. Warren Jarrett

    Warren Jarrett Audio Note (UK) dealer in SoCal/LA-OC

    Location:
    Fullerton, CA
    This is a controversial answer. So, more detail in the explanation is required.

    DD have their lowest W&F performance when there is no drag on the motor at all. And this is how their W&F specs are measured. But many have such low torque, that even the varying friction of a record's recorded information will cause an increase in speed instability. The so-called servo locks and digital displays of speed, do not reflect the temporary speed variations that our ears can hear.

    The really great DD turntables dont have this problem, such as Goldmunds and Brinkmans, etc.

    BD turntables, of course, also can be dragged down in speed, temporarily, by external friction, such as dusting off a record before play. But the motor's torque is so much greater, that simply the drag of a stylus against a record is not enough to cause any speed change at all.

    Also, if a BD is using an AC motor, the motor cannot run at any speed other than as designed, unless it starts cogging and totally misbehaving. So, when the platter does slow down, it is not the motor doing that, it is the belt slipping. All DD use a DC motor, which is the reason for their typically much lower torque. High torque DC motors are much more expensive than lower torque DC motors, and also more expensive than high torque AC motors. Since a DD has its motor shaft directly connected to the platter spindle, it has to be REALLY silent and have REALLY smooth speed variation. Whereas a BD can use a much less expensive high-torque DC motor, because vibrations and instabilities that would cause audible problems in a DD are damped by the belt.

    So, you can understand that this involves a complex set of circumstances, that a simple W&F spec does not accurately reflect, compared to our hearing.
     
    Last edited: Feb 11, 2019 at 11:09 AM
  7. costerdock

    costerdock Forum Resident

    Location:
    Prescott, AZ, USA
    You are not special in having this requirement. Most likely everyone here with a turntable has it and is very much satisfied with what they have. No one here would be happy with speed being noticeably changing even if it is barely noticeable.

    You want pitch control which the Technics clearly has.

    As far as speed stability my Technics is at the top and my VPI Classic is also known to be a performer(on par with master tape as per VPI.) I find both of them are spot on - no discernible differences in that area. Also note I’m on the original belt 2009 VPI.

    Belt or DD is up to you. If you like playing with the speed the the Technics will be pleasing and a good choice.
     
  8. patient_ot

    patient_ot Forum Resident

    Location:
    USA
    Those are very good numbers for a belt drive but this rig obviously costs far more than what OP is talking about. I did mention that caveat.

    What model is the Pioneer? Some DD tables are better than others with regard to motor performance. Also, if the turntable is 40+ years old it probably needs to be serviced and possibly have capacitors changed to perform at original factory spec.
     
  9. SteelyNJ

    SteelyNJ Forum Resident

    Location:
    New Jersey, USA
    When you ask about speed accuracy, are you referring to strict adherence to the intended speed (i.e., 33.33 rpm ±0.00%) or are you more concerned with speed stability, which can mean "drift," observable visually with a strobe, or short-term fluctuations which can be quantified in terms of wow & flutter measurements?

    A DD can have a low wow & flutter spec and still be somewhat imprecise. A quality belt drive with relatively low wow & flutter can be quite accurate, particularly if has variable pitch control and a strobe.

    I have a direct-drive Technics SL-1200 MK2 and a belt-drive Dual 510. Both are very capable performers. As far as I'm concerned, speed accuracy is not an issue with either. Regarding belt replacement, I bought the Dual new in 1976 or so and didn't change the belt until maybe 5 years ago...and that was only because I thought it was prudent, not because of any issues. I can't speak for other belt-drive turntables.
     
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  10. patient_ot

    patient_ot Forum Resident

    Location:
    USA
    If OP can scientifically prove to me (double blind and the works) that they can hear speed variation on a properly functioning, brand new 1200 GR, that is not due to pressing defects on a record or anything else that has nothing to do with the turntable itself, I will send OP a brand new audiophile record.
     
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  11. Mike from NYC

    Mike from NYC Forum Resident

    Location:
    Surprise, AZ
    The reason I sold my VPI and started using my old Kenwood 750 again as my so-called reference TT was because of speed issues I had w/the VPI Scoutmaster I had. The Kenwood is far better in wow and flutter.
     
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  12. Warren Jarrett

    Warren Jarrett Audio Note (UK) dealer in SoCal/LA-OC

    Location:
    Fullerton, CA
    I have never heard Wow & Flutter on any Technics TT. But I have on some of the cheap DD turntables, when I was shopping during the 70s. And sadly, I have heard W&F at shows, much more recently, with the Air Force 1, a VERY expensive Japanese Direct Drive turntable, that uses a servo to control speed. THAT was a shock to me.
     
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  13. Not Insane

    Not Insane Well-Known Member

    Location:
    Kentucky
    I have a Kenwood KD500, a Yamaha PF 50 and an Audio Technica AT LP120 usb. All three are dead on accurate and all three are also dead quiet. I have the AT for playing through headphones via my computer (I use the USB) while surfing and posting. I noticed, yesterday, that I was reefing on a goodwill find with my discwasher, really slowing down the motor, and it suddenly hit me that if it were a belt drive, I'd have to worry about stretching or breaking a belt.

    With DD, you don't even think about your drive system. No broken belts, no speed differences due to wrong belt dimensions, etc. And the point of my post is to point out that I'm experiencing this at all price points - at least, so far. You just play your records and listen to the music without a care regarding maintenance.
     
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  14. harby

    harby Forum Resident

    Location:
    Portland, OR, USA
    Wow and flutter is not measured on reputable classic turntables with an iphone app. It is measured with a test tone record and a wow and flutter meter, so specifications reflect playing music.

    [​IMG]
     
  15. patient_ot

    patient_ot Forum Resident

    Location:
    USA
    Both my Yamaha and JVC are "cheap" by high-end standards but have never given me speed trouble. I can't speak for some of the earlier direct drives with no quartz lock, that used pitch controls, as I have only heard them here and there and not extensively. I have heard w/f on cheap belt drives but it's not an issue with nicer, more expensive models. Not familiar with the Air Force TT but it sounds like something went wrong there. Perhaps they need to go back to their test equipment and see where they screwed up.
     
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  16. Not Insane

    Not Insane Well-Known Member

    Location:
    Kentucky
    When I pulled my KD500 out of storage back in 1999 (or so) it would not lock on to speed. I gave the speed knobs a few turns and it didn't really help. You could actually watch the strobe indicate it was on speed and then suddenly would drop significantly, then pick up too fast for a sec, then settle, then drop.

    What DID help was to just let it run for about 24 hours straight and de-oxing the speed controller knobs. It's been rock steady ever since.
     
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  17. patient_ot

    patient_ot Forum Resident

    Location:
    USA
    The issue with the phone apps is that they vary, and they rely on the phone's gyroscope which also varies. With something like this meter box, or recording a test tone record into software, you need to be 100% sure the record is well pressed and not off center. I have seen some newer test records that are horribly pressed and utterly useless.
     
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  18. patient_ot

    patient_ot Forum Resident

    Location:
    USA
    Yikes. Did you have an electronic speed controller on the VPI?
     
  19. David Fischer

    David Fischer Forum Resident

    Location:
    Pittsburgh, PA
    I don't think it is so easy to answer the OP because not all belt drives are equal, nor are direct drives. It really comes down to the engineering and quality of the drive mechanism. Both belt and direct drives have pluses and minuses, but the given the best belt drives in the world vs. the best direct drives, I would tend toward direct drive. I am debating between a VPI Avenger with belt drive vs their Direct Drive at some point, and Harry Weisfeld's additional insight has me leaning toward the direct drive.

    In Harry's words, it is not that perfect platter speed is the main issue. Harry stated that "being off by .01% means less than nothing, the only thing that matters in a turntable is microsecond to microsecond speed stability. If you want to read out your speed that is fine, that's your business and I would not take that away from you. But your reading something that has already happened. The trick to a real life sounding table, as we found out in the rim drive and then in spades with the direct drive, is the INSTANTANEOUS speed stability. By the time a belt has stretched and the system tells it to correct, it is already way to late, it has happened already! The trick to the best table sound is to drive an AC motor in real time with a clean perfect signal that is strong enough and quiet enough to not change motor speed... What is important and what isn't and I can tell you absolutely, 100%, the micro second to micro second speed swamps everything else. Most people have never heard the VPI Direct Drive but there is a reason that the basic model is in Class A+, the Titan and Vanquish DD wipe out the Class A+ table Fremer reviewed, it is this growth that comes from knowledge of what is wrong, what makes a piano sound like a piano, and how to fix it and make it sound real. Absolute speed is not in the top 5 items of this discussion."

    I am certainly no expert in this, but definitely food for thought.
     
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  20. McLover

    McLover Forum Resident

    Location:
    East TN
    The best DD turntables have the edge in speed stability, but the best belt drives are not far from a DD in speed stability. Even classics like the AR turntables, and the Empire models and Thorens are very accurate in good working order.
     
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  21. David Fischer

    David Fischer Forum Resident

    Location:
    Pittsburgh, PA
    Agreed. There is a lot to consider, and speed stability is just one of many. I've heard many comment on how low the noise floor is on the VPI direct drive, even in comparison to their best belt drives. Wish I could A/B them.
     
  22. Not Insane

    Not Insane Well-Known Member

    Location:
    Kentucky
    You bring up a key challenge to this site. It's like a car site where one user want's to know which is best, a used Honda or a used Mitsubishi. Then another want's to know if he should pull the trigger on a Bently Bentayga vs Continental GT.

    One post might as well be about horses and the other about cooking.

    My comments are always at the Honda/Toyota/BMW/Corvette level. ;) The exotics don't really exist to me, other than to look at.
     
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  23. costerdock

    costerdock Forum Resident

    Location:
    Prescott, AZ, USA
    There is no noise on my VPI Classic - I'm not sure how you best that. Same goes for the Technics. Try as hard as I can (headphones) - no noise. Good to know though that they get beyond no noise.
     
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  24. David Fischer

    David Fischer Forum Resident

    Location:
    Pittsburgh, PA
    Certainly creates some interesting discussion :)
     
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  25. Not Insane

    Not Insane Well-Known Member

    Location:
    Kentucky
    What about my cheapo at lp120 with zero noise, even with headphones? I may be missing something, but I always thought that, to actual human ears, direct drives do not create noise. Maybe they really, REALLY cheapened them up the last couple of decades with chinese made stuff, but my at LP120 is part of that batch and still, dead quiet. I don't thing it's even all that difficult for DD to attain that. It's just part of the way they are designed.
     
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