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Speed stability: Direct Drive vs belt

Discussion in 'Audio Hardware' started by DaleClark, Feb 11, 2019.

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  1. TheVinylAddict

    TheVinylAddict ___The Enforcer___

    I'd bet a donut with sprinkles you're probably right!
     
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  2. Big Blue

    Big Blue Forum Resident

    Location:
    Wisconsin
    I would guess that for most people (I don't have a statistic, but I am thinking it's a high percentage), anything under 0.1% is probably indiscernible in real listening. I think it gets more iffy between 0.1% and 0.2%, with some people being more sensitive than others, and I think I am one of those people. I should be happy with 0.08% for sure, though.
     
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  3. patient_ot

    patient_ot Senior Member

    Location:
    USA
    Key word: "some".

    DD technology got better throughout the 70s and into the early 80s. Technics has made further improvements in their design and motor construction today, based on decades of knowledge and experience.

    Even my 1978 JVC has a coreless motor, quartz lock, and does not cog.
     
  4. Helom

    Helom Forum member

    Location:
    U.S.
    My only point is that there are good and bad examples of both types - can't make a blanket statement that one is always better than the other. I don't believe I've heard a cogless DD table, but the DD's I have owned/heard sucked much of the magic out of vinyl, for whatever reason.
     
  5. patient_ot

    patient_ot Senior Member

    Location:
    USA
    Don't get me wrong, I'm not anti-belt drive. I'm anti-can't hold the right speed and can't meet 70s broadcast standards belt-drive. There are some great belt drives out there, but they don't come cheap. The ones I've looked at that I would consider buying would need outboard speed controllers (for my own satisfaction) which would add significantly to the cost. Look at what the speed controller costs for a Polytable, for example.
     
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  6. TheVinylAddict

    TheVinylAddict ___The Enforcer___

    Good point, and one reason I enjoy and use the Yamaha GT-2000L for all of my LP hand-cleaning duties! The GT-2000L uses the same motor as the GT-2000x, and both have an option to drive the 39lb gunmetal platter --- the stock platter on my GT-2000L is in the 15 - 20lb range. I could probably sit on the platter and it would still spin!!! If there's a TT, DD or otherwise, with more torque than the GT-2000L I don't know what it is! (didn't say it doesn't exist :) just that I don't know what it is!)
     
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  7. TheVinylAddict

    TheVinylAddict ___The Enforcer___

    Which, of course, begs the question "which DD's have you owned??" :winkgrin:
     
  8. seed_drill

    seed_drill Senior Member

    Location:
    Tryon, NC, USA
    I've got a Dual CS 5000. It actually has a quartz lock that prevents the arm from engaging until it's reached true speed. It's a great table when it works, but I'd never recommend it to someone now days, as it's finicky and parts are becoming unobtainium. You even have to use Dual belts. My experiment with generic led to the table not reaching true speed!
     
  9. Helom

    Helom Forum member

    Location:
    U.S.
    PLX-1000, MCS 6700, Pioneer PL55X, Pioneer PL-550 Technics SL-1900 and the AT-LP120, just the ones off the top of my head, I'm missing a couple. My friend has a modded SL-1200 mkII - same character applies.
     
  10. patient_ot

    patient_ot Senior Member

    Location:
    USA
    I think this must be fairly common with vintage belt-drive TTs. There was an issue where someone used a generic belt on a Pioneer table. The OP needed to buy a more accurate to OEM belt from Germany in order to get the right speed.
     
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  11. TheVinylAddict

    TheVinylAddict ___The Enforcer___

    Of that list, I can see where you might say that... they are good TT's, but not the upper end DD's.... I have some DD's (actually many :)) that include the Pioneer PL-70Lii, Kenwood KP-1100 / 9010, Yamaha GT-2000L, Denon DP-59L..... and a few SL-1200's. Trust me, these don't suck the life out of the music, and the SL-1200 is the level where the IMHO motor noise is less of an issue than lesser TT's

    The SL-1900 is a notorious "dud" in the SL line, the PLX-1000 is a Hanipan 1200 clone and although good has its shortcomings, the LP-120 IMHO is below the line of what I would recommend to anyone getting started --- I like to point folks to the AT LP-1240 instead (which is on par with the PLX-1000, both Hanipans, both with similar underlying specs). Just MHO, YMMV not all will agree with my assessment.

    Based on the TT's you listed, I now understand the justification for your statement!!
     
  12. Warren Jarrett

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

    Location:
    Fullerton, CA
    Thank you for your kind words about my posts. I hope they are thought provoking, even if they may not always be "technically correct" -- and often written with a certain amount of overconfidence, which is not "politically correct".

    But in this case, I am being technically correct, and you are slightly misinterpreting your observations. Have you ever seen a heavy platter driven by a DC motor? No, they always use a low mass, cast aluminum, plastic or thin glass platter. This is because DC motors don't have enough torque to start-up and get to speed anything high mass. And if the rotational speed slows down a bit, do to friction, they don't have enough torque to get the speed back up instantaneously. But AC motors do have enough torque, to start and keep-at-speed a very heavy platter. So with an AC motor and a very heavy platter, you can have the benefit of high rotational momentum (actually called moment of inertia) without any problem. What you have experienced, when a BD gets slow, is the belt slipping on the motor pulley, not the motor slowing down.

    As long as a BD does not slip its belt on the pulley, the platter runs exactly at the speed of local power frequency stepped-down by the ratio of pulley circumference and platter circumference. EXACTLY. A DC motor, which all DDs use, can vary in speed, depending on frictional load, by a brush and even by the changing friction of stylus/record contact. So the design requires a servo to monitor that platter's speed and constantly adjust as the speed goes up and down within the servo's design parameters. Again, the provided spec for Wow & Flutter is measured only with no load AT ALL, not even while playing a record.
     
    Last edited: Feb 11, 2019
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  13. avanti1960

    avanti1960 Forum Resident

    Location:
    Chicago metro, USA
    Some direct drive tables can sound like they are hesitating / hunting for proper speed.
    Many belt drive tables waver in pitch during sustained notes.
    Belt drive tables with the platter rim being driven by the motor pulley are multiple times more speed stable than tables using a smaller sub platter.
    The latest Technics direct drive technology makes for the most speed stable turntables I have ever heard and the impact to the sound is noticeable.
     
    BrentB likes this.
  14. bluesky

    bluesky Forum Resident

    Location:
    south florida, usa
    DD table = more stable speed.
     
  15. 5-String

    5-String μηδὲν ἄγαν

    Location:
    Sunshine State
    Yes I have seen many heavy platter turntables driven by a DC motor. They are made by Clearaudio and they have exceptional speed stability.
     
  16. Warren Jarrett

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

    Location:
    Fullerton, CA
    You are right about Clearaudio. I would guess that thier motors are very expensive, which is well covered by thier expensive TT prices.

    The Michel Gyrodec originally used a DC motor, but they found AC was better for thier very heavy platter.

    And Triangle Art originally used DC motors, but they found AC was better for their very heavy platters.
     
    5-String likes this.
  17. Helom

    Helom Forum member

    Location:
    U.S.
    The PLX is as good as any vintage 1200 (better even IMO) as is the PL-550.

    I haven't experienced the coreless motor type which I suspect does away with the weird sound I notice in other DD tables.

    Here's my question to the DD stalwarts: what is your reference for belt-drive sound quality?
     
    Last edited: Feb 11, 2019
  18. 56GoldTop

    56GoldTop Forum Resident

    Location:
    Nowhere, Ok
    I used to think that DD was the only way to go for speed stability... then Phoenix Engineering came out with the Eagle PSU and Roadrunner Tachometer. I'm still pissed about it's demise. Can't believe no other manufacturer to date, to my knowledge, has taken that ball and run with it. Salty. Salty. Salty. I was going to get one for my Thorens TD-150 MKII AB. There are a number of tables both classic and modern that could have had stellar performance with that combo. :mad:
     
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  19. Slick Willie

    Slick Willie Decisively Indecisive

    Location:
    sweet VA.
    Interesting...
     
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  20. Helom

    Helom Forum member

    Location:
    U.S.
    Vintage Thorens have excellent PRaT without motor controllers. I own a KAB Speedstrobe but have yet to use it on my Thorens. It sounds so good in terms of pace that I really don't care how accurate it is or isn't.

    Off the top of my head, Gem Dandy, SME, and Acoustic Signatire offer highly accurate controllers with adjustable pitch. I know there are others.
     
  21. TheVinylAddict

    TheVinylAddict ___The Enforcer___

    I used to own both belt and DD, these days I am "all DD" in my large "collection" (I like to call it that to convince myself I'm still sane) ---- but recently I am being tempted by a couple of VPIs, a couple of Linn / Thorens vintage belt drive...

    .... these "one or the other" threads are so limiting :) --- why not BOTH!
     
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  22. Helom

    Helom Forum member

    Location:
    U.S.
    Go with an SME, even if you have to buy used.
     
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  23. TheVinylAddict

    TheVinylAddict ___The Enforcer___

    My sentiments exactly.

    Let's agree to disagree then...... respectfully.

    PLX - I don't think any Hanipan compares to the build quality or performance of a 1200 -- they are called 1200 "knock-offs" for a reason. I owned a PLX-1000 for a short time, an AT-1240 for a long time (still in the stable - but stored now), and others --- the 1000 and 1240 were the best, and fairly close in build and performance --- but not in the same league as the 1200, which I have owned many and currently own three.

    PL-550 - better case on this table, but IMHO a rung down the ladder compared to the 1200.... I will admit I have never owned a PL-550, but have seen / heard one in use --- but you already said it sucked the life out of the vinyl... so... :)

    But again, it's all opinion and at the end of the day that and a dime won't buy us a cup of coffee anymore.... but there are probably a lot of folks that would disagree that a 1200 knock off exceeds the real deal!

    Cheers
     
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  24. The Dragon

    The Dragon Forum Resident

    Location:
    Madison, AL
    Yes, it does! I have heard these arguments before, but the truth is that any wow due to record eccentricity only adds to whatever wow is already being produced by the turntable. Theoretically, you would want the turntable to produce the least amount of wow possible so that the total produced while playing a record is the lowest possible.

    Also, people tend to overgeneralize when it comes to the direct drive systems. They are not all created equal and therefore not all will be superior to all belt drives. Regardless of the type of drive, you want a very speed-stable and well-isolated drive system. That said, I really do like the new Technics direct drives. They are high end performers. There are some fine belt drives too.
     
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  25. Davey

    Davey NP: Maarja Nuut - Hinged

    Location:
    SF Bay Area, USA
    The Phoenix system just keeps the long term average speed constant with a once per revolution correction integrated over time, nothing to do with speed stability in the same context as wow & flutter. There are many old and new belt drive tables with much higher frequency servo systems than the Phoenix controller, and some that don't really benefit from it, but I agree that it's a great accessory to have on the market for synchronous AC motor tables with no speed control, shame that it isn't available any more.
     
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