Vintage DD turntables. Are we living dangerously?

All these leather mats are designed to be used with heavy record weights.
Use of them without weights is not creating a solid bond and also allows the lightweight mats to move against the platter....

A heavy weight will only create a solid bond in the center label area of the record, maybe slightly further. I think a clamp would be as affective preventing movement of both record and mat.

A reflex or periphery clamp should be more affective coupling the music part of the record. I haven't yet located the felt washer.

I suspect a leather mat is a bad idea. The compliant surface under the record seems to be the problem. The record needs to be supported in such a way that allows no movement of the groove.

A heavy weight will only create a solid bond in the center label area of the record, maybe slightly further. I think a clamp would be as affective preventing movement of both record and mat.

It's intriguing that people would rather theorise or speculate when the cost of actually trying and listening can be so minimal...👀❓

Halcro,
How thick is your pigskin mat?
Do tell, your formula for success. How heavy is the weight?

How can someone duplicate your results if the methodology is unknown?
Is a weight more affective than a clamp, and is Mike Tyson your hero?

Regards,

Henry, Your point is well taken in general, but in this case I believe Fleib wrote only a few posts above your last one that he did purchase a leather mat and did try it, albeit his was made of deer hyde.

Fleib,
http://forum.audiogon.com/cgi-bin/fr.pl?eanlg&1317949815&openflup&355&4#355
I have a number of record weights ranging from 450Gm to 600Gm.
They all perform their task adequately....

Lew,
I appreciate that Fleib has a deerskin mat....
It was the lack of a record weight and his doubt about its benefit that I was referring to...

Halcro,
You assume too much. My Sota reflex clamp is > 200g, but more importantly, I can use as much down force as I like and easily clamp onto the spindle putting 600g pressure on the label.

I think you missed my point about applying pressure more evenly across the surface. I also think your results are due to the thinness of the mat, < 0.5mm.
Regards,

Fleib,
Speaking of assumptions.....I'm assuming that you don't actually own a periphery clamp as I do...❓
You are probably correct in that the use of one together with a centre clamp/weight applies pressure more evenly across the record/platter interface.
However I have found that the sound quality is deleteriously affected if the clamp is used with any pliable platter mat.
When used with a solid mat (metal, glass, plastic) or no mat at all....the peripheral ring does iron out the three seriously warped records I own whilst appearing to have little to no affect on the sound quality.
When used with a compressible mat however, like rubber, felt or leather...the peripheral clamp on my turntables, manages to suck the 'very life' and essence out of the reproduced sound...😱

I am not saying that thin suede mats (because I have found it critical to always have the 'cut' suede side rather than the tanned leather side facing upwards) are the answer to every platter on every turntable...👀
It didn't improve my Raven AC-2 when placed on the copper-faced platter nor did it improve the sound when placed on top of the Micro Seiki Cu-180 platter mat.
I think all these things are system-dependent but as I started this discussion topic within a Thread by saying.....the cost of trying these suede/leather platter mats is small enough (for the possible gains) to warrant experimentation....😎

Halcro,
Interesting observations about periphery clamps. When a vacuum system is over applied it has a similar deadening affect, at least to these ears. Using a reflex clamp in reflex mode can have the same affect, depending on what's under the record and the rest of the record player. A combination of an over-damped tonearm (SME V - too much silicon) and a physically stressed record will sound dead as a doornail. Combine this with a ponderous sounding belt drive and it's torturous.

The best I've had is a Goldmund DD platter w/Goldmund clamp used only to hold the record in place. There was also a Goldmund mat made of methacrylate. Sota had what they called a Supermat that seemed like a similar hardness and was slightly concave. This would help flatten a record and compensate for outer groove brightness if clamped hard enough, but one had to exercise restraint.

All this leads me to believe a Delrin type acrylic or possibly carbon, and an unstressed record is the best.
I'll give away the deerhide - better results with a hard rubber mat.
Regards,

Fleib, I own a SOTA reflex clamp. On my SP10 Mk3/Boston Audio Mat2, I just sit it on top of the label, and I do not activate the clamp. I figure it weighs about 200g, give or take, and that is "enough". For my L07D, I own the OEM peripheral ring and the center record weight (which is quite heavy). When I listened with both devices in place, the veritable life seemed to have been squeezed out of the music, like toothpaste out of a tube. After more experimentation, I use nothing at all on my L07D, no clamp, no weight, no ring. Love it to death. There are no rules for this I guess; it's very subjective.

Lew,
I think there are similarities here. Have you tried the peripheral ring with the Sota clamp?

Matching the mechanical impedance of the record seems like a good idea, but only if vibrations are not reflected back. I think that's why a 5mm carbon mat is more affective than 3mm.
Griffithds likes the Funk Firm mat that purports to do just that - prevent reflections from coming back to smear the sound.

Perhaps using a metal platter or mat is a better match for slightly stressed vinyl? I use neither, but considering your and Halcro's posts, it seems logical.

Think I'll try the Achromat next. Maybe I'll take some sheet lead to a machine shop and have a thin undermat made.

Regards,

Fleib, What I wonder about is whether the stainless steel platter sheet of the L07D becomes a negative, when the LP is pressed firmly against it, since by all rights you'd think that immobilizing the LP with a ring and a weight should be a good thing to do. I probably should play with other platter surfaces, but the L07D design does not make that so easy to do. However, I can try the ring plus the Sota clamp.

On another note, I just had my SP10 Mk3 updated a la Krebs. The preliminary results are surprising, in that I really did not think much could be done to make the Mk3 sound any more lively and coherent than it does/did prior to the upgrade. Now I may be a convert. More anon, when I have had more time to listen.

Lew,
The record/platter interface seems to have so many different factors, experimentation is required, but then we have to take into account things like the sound of a particular cartridge. Assumptions can also be a problem. What works for one record might not be so great for another?

It seems that reflexing or using a vacuum changes the natural resilience of the vinyl and the way the needle is reflected off the groove. These two approaches are often thought of as a positive, but at what point does it become negative, and what kind of surface is under the record? I think using a weight and periphery clamp does the same thing, perhaps more predictably than guessing how much force to use when reflexing a record.

Because a metal platter or mat is harder than vinyl, and the mechanical match up is the opposite of a compliant mat, I would think it would be easy to make erroneous assumptions. It would be mandatory to immobilize the record anyway so you could vary center clamp weight or amount of reflex. Are there metal platters w/vacuum? You could even add weight to a periphery clamp. I doubt if that would help, but you tell me.

A compliant mat is like damping. A thick rubber mat supplied with inexpensive tables is generally more forgiving, but overdamped, smeared, and with less resolution. A very thin compliant mat like some felt or Jico thin one, seem to be the right damping for a metal or glass platter. I had an LP12 years ago and I used it with the felt mat.

The Pierre Lurne' approach is to dissipate rather than dampen, with tonearm and platter. In this respect he's probably the most copied turntable designer. The problem with dissipating vibrations is, where do they go? A hard platter/mat should be efficient transmitting, but where do they get reflected and do they come back?

My approach just copies Lurne'. Lead is very good at slowing vibrations.

Regards,

Lew, does Krebs address the mat with his modification procedure? If not, does he have a recommendation?

Thanks

Pryso, No, the Krebs mod has to do with motor and PS. You are free to choose your own mat. Richard is around here somewhere; perhaps he can weigh in on the mat question.

Fleib, I really have to say that I am so content with the L07D "as is", that I don't worry about ring vs no ring or how heavy is the record clamp. I am either getting old or lazy or both. However, I have all the doodads here, should I be moved to try the ring and heavy center weight again. I should think that a vacuum mat where the surface is metallic would be a very tricky proposition, since it would be difficult, maybe impossible, to achieve a good seal between vinyl and metal. Thus there would be a constant low grade "leak" of air and possibly not only no vacuum effect but noise added as well.

SP10 Mk3 a la Krebs is getting better from the very good baseline.

Pryso
My upgrade concentrates on making the motor and speed sensor do what the designer intended them to do. As designed and as built are two entirely different things. All the Kings horses cannot put back together what is broken in the drive. The technique is applicable to any DD. The TT-101 would be a good candidate

Re mats. In earlier TTs that I built, I experiemnted with rubber, lead, chamois and acrylic. I gravitated towards acrylic. Then more than 20 years ago I purchased my SP10 MK3.
Didn't like the original rubber mat and couldn't use the chamois because of the platter lip. I found that the acrylic worked quite well. I didn't think of trying copper or SS.
But I felt that the platter itself was compromising things so I made a new one in a tri-laminate of acrylic, duralium and lead epoxy'd together.
This I liked a lot and is what I still use today with a SME reflex clamp.
Pictures available on my Krebs upgrade web site. The black triangular unit.
All that said, I have heard exceptional performance from MK3's with original platter and both SS and soft mats. These were both take no prisoner systems in the USA that are simply spectacular.
So today I would think twice about discarding the original platter and spend more time on the record / platter interface.
There are so many options and ultimately it seems to come down to personal preference.

Lew, that is what I remembered but wanted to be sure.

Richard, thanks for adding your comments.

I have had a few weeks now to assess the effects of the Krebs mods on my SP10 Mk3. I was kind of a reluctant dragon going into this endeavor, because I was very happy with the Mk3 "as is" (now "as was"). When listening to the Mk3, I did not really perceive the kind of issues or colorations that were supposed to be "fixed" by the Krebs approach. This is in contrast to my experience with the SP10 Mk2, now departed. I could easily hear the "gray"-ish coloration that Richard perceives to be caused by an over-active servo (for want of a better way to describe it), when listening to my Mk2. In any case, you have to hear a modified Mk3 in order to know what you were missing. Richard's work makes the Mk3 more open and musical sounding, more of what HP used to call "continuousness". Based on this experience, I would suggest that the Krebs mod is also a no-brainer for the much more common Mk2. The cost is modest (especially for the Mk2 mod) compared to the benefits. Thanks, Richard.

I encouraged Richard to consider developing a modestly priced modification for the SL1200 servo and motor, since there are thousands of them in every day use. Apparently, he is already at work on that.

Henry convinced me going for a 101. my unit will arrive in about 2 weeks and I hope it has not too many defects as it is "for repair". I got a lot of information from Henry (👍 many thanks) also preparing my service team which is ready to start 🔧. now I am collecting ideas what kind of armpods I should use? Henry's pods look very nice and stable. I 'd like bringing in at least four arms on the DD, also an EA-10 which has a huge counter weight below of the arm. Therefore I need space below of the armboard.

If you are soliciting opinions from anyone with an opinion, then here is mine. It is a great idea to have a massive arm pod, and Henry has done a fine job design ing and constructing his. I could never do as well. However, the arm pod should be firmly physically attached to the same structure that supports the turntable bearing, so that the two are as close to being one as is possible. The arm pod should not stand alone.

Take a look at the arm mount and the underside of a Kenwood L07D, if you want to get an idea of how this can be done.

Thanks Lewm. What is the disadvantage of stand alone armpods and why is it crucial that there is a connection between armpod and table? Does the physical connection bear any advantages?

Taking Henry's excellent implementation, would it help if the separate armpods are standing on a firm platform as well as the 101 or would you propose a touch to touch connection between armpods and table?

I have seen the Kenwood's realisation. Very well done!
Just imagine one would take a non-plinth integrated 101 how could you connect pods with the table?

Thuchan
What is the disadvantage of stand alone armpods and why is it crucial that there is a connection between armpod and table?

This subject was a bone of contention here previously with the Train
analogy front and center. I will leave it at that.

Thucan -
it is very simple.The stylus is measuring the groove. To accurately measure the groove the platter and arm board must maintain a constant relationship. They must be rigidly coupled via a close loop system to ensure there is no differential movement between the two. Imagine trying to measure the length of a piece of wood with the 0 point of the tape moving back and forth.

A similar case can be argued for having a rigid closed loop between the motor and platter. Physics tells us that where a platter/arm are not rigidly coupled to the motor drive, then there will be speed instability. Examples are
1) Where people put TT's on air platforms and the motor is on another table
2) The motor is mounted on a chassis and the platter/arm are mounted on a suspended suspended sub chassis.

Totem395,
you`re right. Maybe I was asking too much in general. I am not referring to the theoretical implications. Copernicus should blame me. I thought in the meantime there could be some more experiences from experimenting rather than describing why one belongs to the stand alone camp or related camp, no? Everyone is proposing only THE ONE SOLUTION?

Back to the practical side: I am experimenting with stand alone and related implementations. For my 100M I am just building a very massive stand alone pod and I`d like to find out if it really makes a difference when the pod is related to the Denon or not (in case I am suceeding doing so)?

For the 101 I am attracted by Henry`s pod design. Only my EA-10 will not fit into one of the pods due to its large counter screw.

Another idea is building a massive substructure for the 101, precisely drilling a 40 mm high and 400 x 400 mm massive aluminum bases (like with the MS RX 5000) and incorporate four related arm pillars at all four corners similar to the Micro Seiki`s ones. In the middle of the bases I could carve out a 5 mm deep recess taking up the Victor thus fixing the 101, not moving around from this position.

When done properly by using 30mm steel knobs and original 20mm MS bases I have no problem using cantilevered armboards. In this implementation the pods would be related. I am not decided yet. Any ideas?

If the table has a suspension it's necessary to have the arm move with the platter.

If there is no suspension the advantage of a subchassis (structure that connects arm pod to the main bearing) is convenience. The disadvantage is, vibrations are usually more easily transmitted from platter, and possibly motor, to the arm.

Maintaining a fixed relationship between arm pod and platter makes it easier to keep mounting distance accurate, especially when swapping arms. Armboards can be cut based on that fixed relationship.

thanks Fleib and Dover - very helpful indeed!
what do you think about the two implementation designs I mentioned above?

Thuchan,
Contemplating a DD non-suspended table, I disagree with Dover. In this case mass/weight is used to insure the platter is not a moving target, and the mounting surface for both arm pod and platter is potentially a superior "closed loop" system. You're simply using the mounting surface to close the loop. Using a plinth or subchassis to insure stable arm/platter relationship is convenient but might have greater potential for degradation.

In practice, I think good results are more dependent on implementation with either approach, and I wonder about a cantilevered armboard. Seems like a bad idea.
Regards,

Fleib,
why do you think a cantilevered approach is a bad thing in this case? cantilever armboards can work very well when implemented properly!

For example the Micro Seiki engineers were really ahead of their time and they did know why they used 30mm knobs to fix the armboards and 20mm high armboards of a matching material. When properly fixed to a well working MS table even I (and I bring about 100 kg on the scale) can stand on the armboard without bending - in case there is enough counter weight on the table 😂.

The technological ideas and impact they put into this lead to a worldwide success of their tables and still do, many try copying them but it seems to me the copy cats do not reach the original also regarding rebuild armboards. Maybe this is the reason why some audiophiles complain about cantilevered armboard approaches, no?

Would you propose using separate armpods free floating around the 101? or do you have other ideas? Thanks.

Dear Thuchan, Dover and I are occasionally at odds, whereas I almost always agree with Fleib. However, in this instance, I disagree with Fleib, and I could not have stated the case any better than did Dover in his initial response. Obviously, a rigid relationship between the tonearm pivot and the platter bearing is a sine qua non for a suspended table, but it is also for me a "must" even in the absence of a suspension, and Dover said why. Like Totem said, this subject has been discussed ad nauseam. By now, those who will ever be convinced one way or the other have been convinced, or not.

I do think that a massive arm pod, such as the ones built by Halcro, linked rigidly to a massive cylindrical plinth (rather than standing on its own) would be a great way to go. Best of both worlds, you could say. Or, you could make the shelf part of the system by bolting the arm pod AND the plinth to a suitable shelf material.

Lewm,
There's another side of this coin. A rigid coupling of the arm pivot and main bearing, has greater potential to degrade. DD motor vibrations will be more easily transmitted to the arm.

A strict relationship between arm and platter can be maintained with high mass pod and platter structure, mass coupled to, or rigidly fixed to the mounting surface. In this case pivot to main bearing distance is not compromised. With either approach success depends on implementation.
Regards,

Dover,
Your "rules" apply to belt drive tables and seem inappropriate here. How is a DD motor mounted on a separate platform? Using a plinth or subchassis does not necessarily maintain mounting distance better than separate pods.
Regards,

Dear Lewm,
that seems to be a brilliant idea: why not building a massive slate plinth, let the 101 sink in the middle and Henry`s pods at three other holes having rigid contact with the slate plinth. will draw a draft.

Thuchan,
I was thinking a cantilevered armboard would have greater potential to resonate, but maybe that too would depend on execution.

Free floating pods? I think the pods would have to be coupled in some way. If by free floating you mean mass coupled, that would be possible, but difficult to execute. If you eliminate the plinth/subchassis, then the mounting surface becomes the means of closing the loop. Pods could also be rigidly coupled.
Regards,

Dear Fleib,
okay - that makes sense! I could build up a round aluminum (or using other material!?) corpus in which the 101 sinks in keeping rigid contact. Three floating but rigidly coupled armbases -eventually not neccessarily flying in the air- keep contact with the corpus via two massive tubes like at the Feickert Triple. The armpods will carry a flexible upper level segment which can be exchanged like at Henry`s pods.
This upper level plate will also carry a flexible & fast changing system as it is implemented at the Firebird thus enabling using 12, 10 and 9 inch arms.

This design could fulfill the rigid contact requirements of arms, motor and platter. The main issue will be that the 101 keeps contact with that "kind of plinth" as you suggest.
regards

Thuchan,
A DD affords possibilities not available to BD and suspended, and when looking at the complete design I think you should also consider other aspects. Energy dissipation is of paramount importance.
J Carr tells us that only a very small percentage of cart mechanical energy is used by the generator. The rest goes into the cart body, headshell, then travels down the arm. Some of it will be absorbed (converted) by the mass of the counterweight and arm structure. Then it goes into the plinth/subchassis or is dissipated to the mounting base.

Just as a plinth can convert or transmit cart mechanical energy, it can transmit motor or acoustic energy to the arm. Doing away with plinth/chassis does not entirely free you from this consideration. A mounting base could potentially do the same.
Slate happens to be good at transmitting vibrations. I suspect its successful use in tables like Saskia, is due to its weight. That table weighs 200 lbs. but I don't know much else about its construction. Mass/weight tends to convert mechanical energy to heat. Which brings us to your 101 pod. Steel is much heavier than aluminum, almost 3X for the same volume, and brass is heavier yet. Lead is even heavier and is very good at slowing vibrations. In the past it was used in tables and speakers in combination with other materials.

Feickert Triple uses two steel(?) bars on each pod connecting them to the platter base. He also has some kind of anti-resonance circuit. Without his testing capability it might be better/easier without the connecting rods? You could plant the pods at locations convenient for different length arms and still use armboards.
Regards,

Fleib, What are "DD motor vibrations"? In any decent DD motor, the platter either is the rotor or is securely bolted to the rotor. The stator surrounds the spindle. Thus the only source of vibration is bearing friction, which can afflict any type drive system. Cogging is also an issue for all types of drive systems. I hate to go into this yet again, but in theory one wants the tonearm and the tt bearing to be subject to the exact same external forces so they can respond in unison, resonate in the same way at the same frequency, etc, which should result in minimal dissociation between them in terms of energy dissipation. Thus the stylus is least disturbed from doing its job of following the groove. I'm convinced that this is the best way to go. I am not upset if others do not agree. This IS only a hobby after all. Not that music is not seriously important to me. Another way to say this: "Do what you want".

Truthfully, Thuchan, I think that the major flaw in the much loved Micro Seiki turntables are those cantilevered tonearm mounts. They are much too flimsy to achieve what I am talking about above. Once again, look at an L07D for comparison.

Sorry, Fleib. After reading some of your most recent posts, I see that we are not that far apart in our thinking. Just a little bit apart.

I wonder where is Halcro to argue the other side?

I use gunmetal micro-seiki arm boards cantilevered off of a 20lb steel weight to hold my tonearm. The bottom of the weight is double stick taped to a wall mounted platform. The turntable is on brass cones which are double stick taped to the can, including a critical cone in the center of the can. The cones sit on brass disks which are double stick taped to the same platform as the tonearm pod. Nothing moves independently from anything else.

The ms gunmetal arm boards are massive and allow me to rotate them in order to set the geometry. I use the Feickert protractor. Everything stays in the correct geometry until I deliberately move it.

I can't envision a use for a connection Btwn TT and armpod. But to each their own.

On the subject of platter mats I just want to re-iterate that I am using a lead mat glued to an Achromat. I thought that Fleib or someone else was about to try the same thing and wonder how that worked for them?

Lew,
"I hate to go into this yet again, but in theory one wants the tonearm and the tt bearing to be subject to the exact same external forces so they can respond in unison, resonate in the same way at the same frequency, etc, which should result in minimal dissociation between them in terms of energy dissipation."

That's where we disagree. As you pointed out, motor vibrations might be minimal in a high quality DD, but having arm and platter/bearing subject to the same external forces is a potential problem IMO. What about sound pressure waves hitting the record and plinth? The cart/arm already has to deal with this and might have to deal with it again if it's transmitted from plinth/chassis back to the arm.

I completely agree with Dover concerning BD or suspended tables, but if a DD is firmly planted where is the movement, the moving target? If a platter wobbles, it will wobble regardless.
The goal of controlled energy dissipation is to get rid of cart vibrations and isolate the arm from other ones. I think this is more easily accomplished w/o a plinth/chassis. The final exit of all vibrations should be out the feet otherwise it's just damped, although that might be sufficient.

In the real world either approach can be great or disappointing depending on design, materials etc.
Regards,

I wonder where is Halcro to argue the other side?

I think Fleib is doing quite a competent job....
It is clear from previous discussions that opponents of the free-standing armpod will never change their firmly held beliefs....so I felt no need to futilely inflame the situation...😡
I have never argued against the need for maintaining a perfectly regulated dimension from spindle to tonearm pivot....after all, it is the basis of all pivoted arm geometry.
The opponents of separate armpods appear to maintain that only a rigid horizontal member (the stronger and more rigid the better) is capable of achieving this requirement...?
This is a rather limiting view as gravity is a more powerful force than anything invented by man.
With a suitably massive armpod on spikes or appropriate footers, gravity and friction will ensure the necessary and stable relationship between spindle and tonearm pivot is maintained.
In the case of the Kenwood L-07D with its extended ribbed metal casting, it is easy to appreciate (and calculate) the dimensional expansion and contraction which inevitably extends and contracts the tonearm pivot point from the spindle centre with every one centigrade degree of temperature change.
This is NOT a recipe for dimensional stability...😱

The famed Continuum turntables have their tonearm mounting pads totally disassociated from the spindle and platter bearing, being suspended by wires from the top plate and held from the bottom with magnetism.

As Fleib has rightly repeated....it is execution rather than dogma which ultimately determines the value of the methodology.

regarding cantilevered armboards it seems to me we should look deeper into aspects like how long is the cantilever, which forces are put on, which are the mass ratios and which is the source of the resulting energy of the scanning process? If we do so we clearly see why the cantilever beam plays no important role!

Lewm, MS boards are flimsy??? When have you been standing last time on an original Micro Seiki armboard? Or do have double my weight? :-)

Fleib, Dover`s rules do apply to all TTs - regardless of drive mechanism.

Despite the convincing conclusion that platter and tonearm bearing should ideally not interact in relative movements I have experienced that it depends on the way of execution, e.g. in the Continuum or with my Toyo stand.

when the Victor arrives and has been repaired I will look into it again. Thanks all having supported me here so far and exchanged ideas - very helpful indeed !!!

Aigenga,
I won't bore you with excuses. I have yet to make the mat. Since the lead I have is about 2mm thick I'm thinking of getting the 3mm Achromat.

If anyone wants to experiment with sheet lead it's not hard to source online, but the shipping will usually be more than the product. I found some at a roofing supply. I think they call it flashing. This is a piece about 3 feet sq. and it cost something like $70.
Don't think this is used much anymore. When I called, the guy said they had no sheet lead until he remembered flashing. Wear gloves.
Regards,

Tuchan,
In this case Halcro's table meets Dover's criteria for a closed loop. The loop is closed by the mounting base rather than a plinth or chassis.
Regards,

Lew, did you ever manage to get hold of a Reso-Mat?

Moonglum, No, I have not tried it, yet.
Halcro et al, I only re-stated the case for a rigid connection between tonearm and bearing for the benefit of anyone who is reading this thread for the first time. Such an individual (Thuchan in this case) ought to hear both sides of the question before deciding which direction to choose. Like Henry, I am past trying to convince anyone else who has already made up his mind. But Henry, with all due affection and respect, your analysis of the L07D is ludicrous, certainly compared to the risk for drift of alignment of a fully outboard arm pod. The L07D is a system, using several different metals (stainless steel, alu, brass) with different temperature coefficients of expansion, closely coupled with substantial fasteners and massive. The temperature of a typical listening room varies by a couple of degrees during the course of time. Of course, if you leave your tt in the freezer on off days or cryo-treat the entire unit, you may want to do a re-alignment.

Lew...and this assumes that the feet of an outboard arm pod are even non-flexible and the mounting surface is stable - both dimensionally and mechanically in phase(!) ;^)

The L07D is a system, using several different metals (stainless steel, alu, brass) with different temperature coefficients of expansion,

The basic frame of the L-07d shown in my attachment is cast aluminium which has twice the expansion co-efficient of steel.
For every centigrade degree change of room temperature (and unless your room is fully air-conditioned 24/7 the variation can easily be 5 degrees C)...there is clearly change in the distance between the spindle and tonearm pivot of several millimetres which is disastrous in the scale of vinyl groove information extraction.
Now please tell me Lew....what is the exact "drift of alignment" of my fully outboard armpods?

Henry, Come back to me with actual numbers to describe the possible change in mounting distance, given what you perceive to be the problem. My listening room varies in ambient temp by about 4 F degrees, from 68 to 72. According to my calculation, the fractional expansion of an alu bar (which this is not) would be .000052 (4 times 13*10^6, using the inches/F coefficient) over this 4 degree F span of temperatures. Further, the aluminum yoke embraces a stainless steel and brass pod (yes, a heavy and damped pod like yours, except it does not touch the shelf) that in turn embraces the vertical shaft of the tonearm in a clamping collet (not with a flimsy set screw). The alu is constrained from expanding and contracting by the bond between it and that pod plus the fact that it is also surrounded by the concrete-like material that constitutes the plinth itself. In other words, your critique of the L07D is off the mark, at best, and a sidebar to the central question. But let's stop here; I am OK with your belief structure; it has no effect on me whatever, and I am sure your music sounds just fine. This is all about splitting hairs anyway.

Dear Thuchan, I may be wrong in my assessment of the top line MS tonearm mounts; I have only ever seen them in photos. Possibly they are more rigid than they appear to be. If so, my apologies.