[neobop]

There are some things everyone can probably agree with, like the need to maintain steady speed, a platter that doesn't wobble, a rigid arm etc.  Most of the rest is a matter of opinion and those opinions tend to be based on experience and unwavering.  In the '60s or '70s B&O wrote a white paper on table design philosophy that touted low mass (everything).  Mainstream audiophilia pretty much rejected that approach, but some of those tables were half decent if set-up properly.

The point is, it's all relative.  Good and bad are relative terms like hot and cold it depends on what your used to, and expectations.  AR made 4 or 5 different tables over the years.  I think the XA(B) was one of the earliest, a simple table with a machined metal platter with a primitive looking arm.  It was probably better than most of the later AR offerings that could in no way compete with an HW-19, VPI's only table in the mid/late '80s until the TNT came out. 

Optimistic owner anecdotes and other credible (or non) bullshit might illustrate a point, but aren't what table design is about.  There's plenty to talk about though.  How about suspended vs no suspension, optimum platter weight, or conventional arm bearings vs unipivot?
neo   

[Wayner]

The one thing I think many fellow ACers that are into vinyl realize, is that there is one shit-load of information lying in those grooves. Unlike digital (for the most part), this invites "tweaking" especially for those that are more experienced, more advanced. They all know that if they tweaked just the right thing on their tables, another world of detail is opened up. Micro details that can elevate a listening experience to a new level of emotion and memories. I know those details are there and almost everyday I seek new ways to unleash them. It sometimes is thinking outside the box. Do the guys with PHDs have better sounding rigs? I don't think so. Are there tweakers out in the world that have reached or near reaching that vinyl nirvana? I'm sure there are.

We have several members among us that are chronic tweakers, some  have built their own tables, using parts from others, like Sonny and Bill and others. John TheChairGuy, was a mad tweaker, filling his cheapie JVC with plasticlay and putting a Longhorn on his Grado. Lots of guys are trying this or trying that, to see if it improves the performance, and then hence, the joy of vinyl.

As of late, I have discovered some recordings whose level of detail I did not think possible. Many times I'm caught in dis-belief. Is there a right way to do all of this? Probably. But we all have different systems, different ideas of what things should sound  like, and we pursue those ideas with a passion, in our own ways.

Oh vinyl, you are a drug, and we are all vinylphools.

Wayner

I just realized how much I miss John TheChairGuy.....

[neobop]

How do you determine the optimal platter mass?   With inexpensive tables it seems that heavier is better, but is there a point when lighter is better?

I think so.  It's relative to the drive system and its ability to overcome speed fluctuations because of stylus drag.  Remember Southerland Engineering video?  Near the end, the table slows down when the stylus is cued down.
http://www.youtube.com/watch?v=RF2XieUlzvk

So, you set the speed with the needle in the groove if you have provisions for doing that, but if the speed fluctuates that much when cueing the needle, what happens when there is a much heavier groove modulation and friction increases?   It can sound thick, deep and authoritative, but the timing and  tempo is increasingly lost as platter weight goes up and torque goes down.  Motor torque is deliberately kept low as a price/performance move.  Rumble, motor vibrations will be held to a minimum and the motor is less expensive.  If speed is set slightly fast, then it should be about right when the needle is down. 

Direct, rim or idler drive restricts the platter weight because of the limitations of the drive type.  They tend to overcome the speed fluctuation problem, but generally lack the authority of a massive platter.   
neo   

[dlaloum]

Another issue is that PLL direct drive systems used to lock into a Quartz signal, are dependent on the ineraction between torque of the motor and mass of the platter...

If the platter is too heavy, it will speed up insufficiently and require additional pushes - making the whole process uneven, and introducing the potential for the "jitter" than some SL1200 tweakers describe (mostly when talking about PSU mods for the technics tables)

Same problem if the platter is too light...

The intricacies of determining how much latitude a specific motor and control system has for additional mass is a mystery to me - I am aware of the issue and its potential impact, but do not have the theoretical understanding, let alone the relevant measurement tools to investigate and tweak this aspect....

I think this is a high risk area, where a lot of tweakers have gone down the path of using heavy TT weights - with potentially subtle negative effects. (and due to psycho acoustics, it can be VERY difficult to pin down subtle effects...)

I have added a small amount of mass to my Revox platter in the form of plasticine on the underside as a minor damping treatment, and I use a BIB Clamp rather than a massy (messy?) weight.

I do like the idea and sound of the stability provided by huge inertia, but have issues with the idea of a 200lb+ turntable..... it somehow just lacks elegance.

bye for now

David

[trackball02]

I really appreciate the great discussions on this post. Lots of food for thought. I'm a molecular biologist by training then went on the medical school. I can't contribute much except what I hear with my 2 ears. I recently installed the KAB Fluid damper on my Technics 1600 MK2 and with a Grado Reference Master (aligned with the protractor for the Technics 1200 provided by Wayner published on AC, thanks).




 
I filled the trough less then half way. There was a noticeable difference especially in the bass. More focused, tighter, cleaner with a darker background. My reference was the a new LP by Mayer Hawthorne "Where Does This Door Go" . Before the fluid damper, my set up had a difficult time accurately reproducing the bass lines...very unfocused fuzzy and distorted. At least for my system, I am quite pleased.

[dlaloum]

Nice setup - I note that you have damped the arm with O rings along its length...

How have you found that damping ? (noticeable?) - Was the number of damper rings on the arm determined by some test/theory or simply by overkill (you have quite a few of them there!)

The wood surround is nice too...

I have a SL1600mk2 waiting for my attention at some stage.... a KAB damper is in its future, but I am also thinking about other arm mods...

bye for now

David

[neobop]

Hi Trackball,
Wondering what viscosity silicone KAB recommends?
Did you have the rings before you installed the damping trough?
neo

[WireNut]

Hi Trackball02,

I like the o-ring tweak .  Gotta try that one

 

[trackball02]

I installed the neoprene O rings before and KAB Fluid Damper, and left them on. Here is another picture.



I'm not really sure the rings helped that much. I put them on at random. I was going to try the heat shrink tubing, but was not excited of heating up the wand. Now that the Fluid damper is installed, I'm going to experiment and take to O rings off, and see if there is any difference. They are easily reversible.

The silicon I used came as a syringe with the damper. Very gooey stuff. It flows very slowly out the syringe. I'm sure KAB can tell you the viscosity value.

[neobop]

Another issue is that PLL direct drive systems used to lock into a Quartz signal, are dependent on the ineraction between torque of the motor and mass of the platter...

If the platter is too heavy, it will speed up insufficiently and require additional pushes - making the whole process uneven, and introducing the potential for the "jitter" than some SL1200 tweakers describe (mostly when talking about PSU mods for the technics tables)

Same problem if the platter is too light...

The intricacies of determining how much latitude a specific motor and control system has for additional mass is a mystery to me - I am aware of the issue and its potential impact, but do not have the theoretical understanding, let alone the relevant measurement tools to investigate and tweak this aspect....

I think this is a high risk area, where a lot of tweakers have gone down the path of using heavy TT weights - with potentially subtle negative effects. (and due to psycho acoustics, it can be VERY difficult to pin down subtle effects...)

I have added a small amount of mass to my Revox platter in the form of plasticine on the underside as a minor damping treatment, and I use a BIB Clamp rather than a massy (messy?) weight.

I do like the idea and sound of the stability provided by huge inertia, but have issues with the idea of a 200lb+ turntable..... it somehow just lacks elegance.

bye for now

David

The 1200 might have a deliberately stronger or more aggressive servo correction because of the way the table is used - not your usual audiophile application.

I read most of the rest of the thread on VE and I think this John guy (jrlaudio) isn't really better informed than many of the posters on the thread.  I noticed he talked about DD vs belt and the theoretical disadvantage of electronic quartz servo control, but said nothing about a belt continually stretching and contracting.  Apparently he isn't overly sensitive to pitch variations like some people and suffers from the same wishful hearing as most others. 

Theoretically speaking there's a delay between the servo correction signal and the motor.  Some of the better belt drivers also have electronic speed correction, but if the belt is continually changing, even if only for a few microseconds, the system is even more compromised.  Like a servo woofer where cone motion is monitored and compensated for at the amp, this works really good and fast enough so the bass doesn't smear. 
neo

[Wayner]

First of all, lets set this straight about the Technics SL1200(MKII). It was not a "disco" table that found its way into the home, it was the other way around. I have 3 DD tables, and 5 belt drive tables and there is no detectable difference in PRAT or wow and flutter between any of them, and I  am very sensitive to speed issues.

I also wonder why people think that the record itself doesn't have flaws. Analog recordings were made on a reel to reel recorder, which certainly can have speed variations, then the multi-channel recording is recorded to another 2 channel reel to reel which can have more speed issues, then to a cutting machine to create the master lacquer. So before the music even turns into a vinyl record, it has many opportunities to become corrupt.

Wayner

[neobop]

First of all, lets set this straight about the Technics SL1200(MKII). It was not a "disco" table that found its way into the home, it was the other way around. I have 3 DD tables, and 5 belt drive tables and there is no detectable difference in PRAT or wow and flutter between any of them, and I  am very sensitive to speed issues.

I also wonder why people think that the record itself doesn't have flaws. Analog recordings were made on a reel to reel recorder, which certainly can have speed variations, then the multi-channel recording is recorded to another 2 channel reel to reel which can have more speed issues, then to a cutting machine to create the master lacquer. So before the music even turns into a vinyl record, it has many opportunities to become corrupt.

Wayner

Yes, the 1200 was originally released as a home (nonprofessional) table.  Because of its immunity to feedback and high torque motor it was adopted by pros - DJ and radio stations.  Maybe I stated it backwards, but I still think the high torque motor could contribute to the jitter that David alluded to with power supply mods.

Just because you can't hear any speed differences between all 8 of your tables, doesn't mean they're all the same.  I'll bet if you measured them with a test record/equipment, they'd all be somewhat different.  If a record is imperfect, is it a good idea to add to that imperfection?  Do you have perfect pitch or absolute pitch?  I'm sure there are people that can hear pitch variations with more sensitivity than either of us.  I can readily hear differences with different tables with acoustic music.  "Better", more expensive tables tend to have superior pitch stability and those differences diminish.
neo

[Wayner]

I agree that they all have a slight difference in sonics, however, that can't be solely pinpointed to one thing or another, but rather a combination of (bad) effects. I bet that if I did a blind A-B test with almost anyone, they could not tell the difference between a belt and DD table.

Also, not all DDs were built the same. The sins of one brand should not be thrust upon other makes that had different designs. Also, the Technics DD and in particular the SL1200MKII has had many upgrades since its introduction. Only about 3,100,000 were built and most still in use. That has to say something for the product.

I also think the mass of the platter, and inertia helps to "hide" any pulsations one might expect from a DD table, but you know what, a synchronous motor has the same pulses from it's poles. Tell me that doesn't travel thru the belt to the platter. Few decks have DC motors, and they are critical to voltage, needing a power supply, which converts AC to DC. Did they use a perfect bridge to make perfectly flat DC?

They all have their issues. Perhaps the world is ready again for a "wind-up" turntable.

Wayner

[neobop]

Blind A/B tests aren't much good for telling anything except obvious differences.  When you live and use something over a period of time, differences reveal themselves.  You'll hear a familiar record sound different and after awhile will be able to identify what that difference is.   Once you know what to listen for, those differences become more and more obvious.

Yes, I can hear pitch difference between many direct drive tables and belt drivers.  Like I said before, it depends on the individual tables and how well executed they are.  The Goldmund Reference is a belt drive table with a quartz servo controller.  It has a 35 lb platter,  a heavy duty belt, and a digital tachometer.  I can't say I heard speed/pitch problems with it or some other well designed tables.  On the other hand, the original TNT which has a similarly heavy platter (maybe not as heavy), I could hear that difference in an instant, not only in comparison with the Reference, but with just about any quartz direct driver. 
neo 

[neobop]

I found those interviews with Pierre Lurne more interesting than the VE thread.  Although the VE thread brought up a couple of aspects I hadn't considered, like the wow/flutter and arm/cart resonance thing, the Lurne interview in Stereophile talked about something I never heard of before:

http://www.stereophile.com/content/pierre-lurne-audiomecas-turntable-designer-page-2

"To determine the ellipsoid of inertia, you put an axis anywhere through the center of gravity of the system, and calculate the moment of inertia around this axis. You find the two points on your chosen axis, either side of the center of gravity, where the moments are equal. You then choose another axis through the center of gravity and find two more points. At the end of the process, these points trace out an ellipsoid in space around the center of gravity. This ellipsoid gives you an image of the effort in every direction applied to the system, so in the ideal case, if it takes the same effort to move a tonearm, a cartridge, a needle, in any direction, that's better than the contrary, where maybe it is easier to go up and down than to go right or left."

I guess this is like the path of least resistance for the stylus/cantilever dragging the arm across the record.  Lurne wound up making unipivots.  Besides the claimed single path for vibrations to be dissipated, unipivots have an inherent problem, azimuth.  As the stylus gets deflected off the groove walls, what keeps the cart from rocking side to side?  Gravity.  Low center of gravity and outriggers for stability, keep the cart steady.  This aspect can't be as stable as a conventional pivot arrangement, but maybe it doesn't have to.  Some "state of the art" arms are now unipivots. 
neo

[dlaloum]

There are a couple of other arrangements that achieve the same end - the string hung arms are one example, and unipivots can be stabilised magnetically - as done within the Revox linear tracking arm - although looking at its structure, most of the mass is below the pivot point - so it is using both low centre of gravity and micro-outrigger type setup (the mass doesn't extend far to each side!), as well as magnetic stabilisation.

And then you look at the Grado Longhorn mod - outrigger stabilisation - it seems to work well.

I would love to hear/read an article about how P.L. went from linear servo-tracking arms to unipivots and the logic behind those decisions.... Did he decide that there was something wrong with the earlier approach, or did he simply choose a different set of compromises?

[neobop]

David,
Have you seen any diagrams of string pivot arm mechanics?   That would be interesting.

I read another interview where Pierre said why he switched from linear arms to unipivots, but I have yet to find it.  If I remember correctly it had to do with the physics, ellipsoid of inertia or something like that.  Because the pivot is constantly moving it somehow screws up the needle/cantilever mojo?
How's that for a scientific explanation?   

I'll see if I can find the interview.  Meanwhile, anyone interested in a concise summary of his table design philosophy:
http://www.enjoythemusic.com/magazine/manufacture/0208/

neo

[*Scotty*]

There is an excellent listening test for for tonearm stability. It involves paying close attention to how the phono system images. If there is instability in the arm, you will hear the image appear to waver as though you were listening to the image through a moving stream of water, in much the same way the stones on the bottom appear to move when viewed through the ripples on the surface of the stream.
A good comparison can be also be made if you have the same music on CD or computer file format as you have on vinyl. While the two sound-stages may be somewhat different, the the CD version will not exhibit any wavering of the image, it will be rock stable.
Scotty

[dlaloum]

The brochure for his Audiomecca J1 turntable and SL5 arm is on VE at http://www.vinylengine.com/library/audiomeca-pierre-lurne/sl5.shtml

more interesting reading there....

Doesn't answer why he stopped making the SL5 though...

Also this article on TNT...
http://www.tnt-audio.com/sorgenti/belladonna1_e.html

[dlaloum]

From the TNT review of the Septum arm...

OK so if we apply this test to a tonearm we'll get an ellipsoid around the arm's centre of gravity - approximately around the pivot of the arm. Now project the ellipsoid forward to the stylus so an ellipse surrounds the stylus and you'll have a representation of all the forces acting on the stylus, and by the way, to the arm cartridge combination. See diagram.

The perfect arm would have the ellipse as a circle with the stylus tip in its centre. That means that the stylus will move equally easily up, down and left/right. Neutrality is complete.

If the ellipse is flat then the system is not neutral, it is easier for the stylus to go up and down than left to right. In this case the combination of the arm's effective mass and cartridge compliance will give various frequencies of resonance rather than one which is easier to control. This is the design weakness of all air-bearing parallel-tracking arms, the resistance to up and down movement will be much like a bearing tonearm, but side to side will be much more difficult as the totality of the arm must move - around 20 times more difficult than vertical movement. Depending on the eccentricity of the record (no record is perfectly centred) the arm movement can take any direction and speed each time adding a different resonance. At best such arms can be symmetrical, at worse just crazy - by that I mean that to have an ellipse so distorted with the stylus way off centre - it means that all movements are different, adding different resonances, different behaviours etc.

interesting!

Pierre Lurne also believes that the arm has 80% influence on the sound and the TT only 20%....