Henry,
"How does the cartridge know the mass of the platter....❓👀"
You mean "know" in the biblical sense? When cart suspension collapses?
I think you would agree that platter and mat, supporting surface, does make a difference. Some platters are designed to use w/o mat and your experimentation with mats indicates agreement.
IMO, these things can not be considered in isolation. Consider an extremely lightweight platter, would tend to be more easily affected by extraneous vibrations despite stability of supporting structure. What about sound pressure waves? Maximum thickness of a mat is 5-7mm? Just enough to turn the shortcomings of a light platter, to mush.
Before you get reactionary, I'm not saying your Victors have extremely light platters, but platter mass can make a difference IMO. Consider the older Goldmund Reference - servo belt drive w/35lb platter. TT101 might have better pitch stability, but better sound is a matter of opinion. I wonder what you'd think of a Reference with one of your arms mounted.
Regards, |
Richardkrebs,
The measured performance is inferior to actual performance?
Wow and flutter can only be measured with an arm/cart. Timeline measures or illustrates absolute speed. Henry has shown that absolute speed doesn't deviate when using 3 arms simultaneously on his Victor.
W/F is measured with a test record 3150Hz tone. Output is checked for deviation from that frequency.
I think Thigpen must be referring to low torque belt drives, in which case a gnat landing on the arm or platter might upset speed stability.
Regards, |
Dover,
"There is no such thing as absolute speed. Speed is relative."
That is incorrect. For a turntable, 33 1/3, 45 RPM is absolutely the correct speed.
How it's measured is another story.
"The timeline only measures the arrival of a single point on the platter at the same place at each time. It does not measure what happens in between."
That was my point, commonly referred to as absolute speed vs. wow and flutter.
"Analogue wow and flutter is similar to digital jitter. Testing of digital systems as regards temporal errors and the effect on sound quality has yielded the following -"
Analog wow and flutter is very different from digital jitter. Your analogy is a bad one. Because of the continuous nature of analog, very small amounts of W/F are much less noticeable. Not so with digital. Because the music is chopped up and regurgitated back to analog, any jitter is more prominent, noticeable. This is especially true with harmonics and tonality.
Playing records is harder, more expensive, and a PIA compared to digital. Then why the resurgence, because it's cool? I don't think so.
It's more fun because it sounds better.
Regards, |
RK,
Just as I thought. Thigpen says, "Since the advent of the belt drive turntable, wow and flutter has been purely a function of tonearm geometry, the phono cartridge compliance with the elastomeric damping, and surface irregularities in the LP."
He's measuring tables with no load (absolute speed) and comparing to W/F measurements with cantilever oscillation thrown in. Yes, the belt drive tables are often more susceptible to external forces presented by a pivoting arm. This is not to say DD/idlers are immune, but I think we've all heard what happens with low torque tables of any type, when the needle drops.
This sales pitch is misleading because he takes TT speed stability out of the picture and replaces it with arm geometry, although benefits might be true for those with low torque tables.
I haven't considered W/F as a function of arm damping, but I don't like low torque tables. The term oscillation implies an increase in magnitude, but that's interpretive.
Regards,
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Dover,
"Speed is never absolute. It is always measured from a point of reference. The planet is rotating, the measured speed on your platter is relative to the rotation of the planet - it cannot be absolute."
We're talking rotational speed not land/air/sea speed. It's as absolute as the timing of a minute.
Regards, |
RK,
"Look at the raw trace for the WE8000.
Start at the first lower min freq, just above 3130 hz. Other than the max at around 3164hz, count every sharp change in direction until immediately before the next min of around 3130 hz again.
I count 14. The platter changes speed 14 times during that single revolution."
A tone is a vibration, a sine wave, not a straight line on a scope. You have to compare to a "pure" tone generated for 3150Hz.
Regards, |
I wonder how accurate this is. The waveform peaks at +16Hz and bottoms at -20Hz. That's a spread of 36Hz, a little more than 1%.
A scope or a meter with a frequency counter could be used to check results.
Another fly in the ointment - Werner Ogries EE, has reported calibration errors in both HFN and Analog Productions test records. Not sure of all the gory details. |
Taking a break from applied technology, how about remedial physics?
What do MPH and RPM have in common?
Time is a dimension we have divided precisely, based upon, but not dependent upon, the movement of Earth around the Sun. Our division of time does not exactly agree with the rotation of Earth and has to be corrected at regular intervals. It could be divided arbitrarily, but the days and seasons might not agree with nature.
The Earth rotates in a counterclockwise (west to east) direction at approx. 1040 MPH at the equator. If you went to Brazil near the equator and drove a car 100 MPH west, you'd actually be going backwards at 940 MPH and wind up in the Atlantic ocean?
Rotational speed of an object on Earth is not dependent on the rotation of the planet. Either is land speed. As long as we have precise and agreed upon divisions of time and distance, the rotation of Earth could cease and we would still be able to apply our divisions of time. We would still be able to play a football game, do the dishes and take a walk, weather permitting.
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Halcro,
I don't know what test record you're using, but this software, app, or whatever, is giving an erroneous impression. The TT101 has W/F 0.02% WRMS, and speed deviation of zero w/up to 120g VTF.
That W/F is at the limit of conventional testing ability. With a DIN 45 465 test disc w/locked groove and centering, you can test to 0.06% unweighted wow, if you have the program.
Below is a link to Kevin (KAB) talking about positional updating tables vs. linear frequency generators. It's not what we're discussing, but might give some perspective:
http://www.kabusa.com/myth2.htm
Regards, |
I read on Karma that deer hide is better so I got a thin one (< 2mm) figuring a thick one would have too much give. Although it looks to be of uniform thickness results were similar to Downunder. Mild edge warps looked exaggerated and it seemed that repositioning the record didn't correct.
I tried this on top of 2mm SRM acrylic mat that's just a bit too hard IMO, but sounds better w/o the leather. Putting the suede side up seemed to help a bit, but not that much. |
Dover,
I don't doubt your results. They are what they are. It's the explanation that doesn't add up. The Goldmund platter is designed to match the mechanical impedance of the record with the surface adjacent to it. A steel or copper surface directly underneath the record is a different approach.
I don't blame science or lack of, for the vagaries of platters/mats. A mat is designed to work with an existing platter. As your results indicate (VTT1 & Verdier) there are too many variables to call this science.
I assume the Counterparts mat is the one Sota called Supermat (80's). It's different from Goldmund mat. The plastic formula is softer and I believe the Goldmund mat has no layer of lead.
As the names indicate acrylic and methacrylate are closely related. Delrin is DuPont's trade name for acetal homopolymer and like copolymers, can be formulated for differing hardness. Most platters/mats are probably made from copolymers and their exact formulation was/is a trade secret. The Goldmund mat seemed slightly harder than their platters, but this perception could possibly be influenced by thickness.
What then is the goal with an aluminum platter, to dampen the platter or match the record impedance? Perhaps both?
Regards, |
Dover,
Interesting impressions of spiked mats. I'll keep that in mind, although you repeat yourself. Once should be sufficient?
" their goal is to dump excess energy from the stylus/record interaction to ground as fast as possible."
Exactly how is that accomplished, by using a mat of dissimilar mechanical impedance of a record? That doesn't take vibrations to ground, a high percentage will reflect back to haunt the stylus.
This is from a 1987 interview of Pierre Lurne who worked for Goldmund and was responsible for the design of the Studietto table:
http://www.stereophile.com/interviews/pierre_lurne_audiomecas_turntable_designer/
"From the Minimum turntable in 1979, through the second turntable which I designed for Audioanalyse in 1981 and now to the Audiomeca J1, I used the same concept of mechanics. I'll begin with the platter. I agree with other designers that methacrylate is the best material for a mat, and the shape of the platter is the same as the Minimum, which is to say that it is a little concave: it slopes from the outer rim to the center at an angle of 0.30$d. I decided on this form from a statistical survey of a large collection of records. There are actually two sheets of methacrylate, either side of a solid, 8mm-thick piece of lead, giving a total mass of 8kg.
"This construction is something very special. If you know the velocities of vibration in methacrylic and in lead, you can calculate when the vibration is reflected back to the stylus. First, the vibration induced in the record from the stylus tracking the groove goes through the record into the methacrylate, then to the lead, and so on. Each time the vibration is transmitted from one material to another, there is reflection and transmission, and the time taken for each reflection to return to the stylus can be calculated. You need not have all these delayed signals reach the cartridge at the same time. You then get the same effect as with the acoustics of a room with square dimensions—one big resonance. This is no good, and in addition, when a large reflected vibration reaches the stylus, the tracking is instantaneously different. But if you take care of the spacing in time of these delayed reflections—do you understand the concept of the 'Gold Number?'—then neither the music nor the tracking is affected, not at the beginning of the record or at the end.
"We use lead because it almost behaves as a 'magic material.' It has high mass, it has good damping with low-Q resonances, and it has a very low speed of vibration. If vibrations enter the lead center of the platter, they leave considerably later, much lower in amplitude."
Regards, |
Dover,
Can't say I accept your anecdote about the Studio as being typical of performance. I've heard a few and your description of "lurching around" suggests a malfunction or improper set up. I no longer own a Goldmund so I have nothing to defend, as audiofools typically do. The Studio isn't an easy table to set up. Your description suggests lateral movement from the suspension and/or platter wobble. If the table had the T3 arm that could have been a source of the problem. I didn't use their arm. I had a Zeta.
The DJ comment was Pryso's. Actually, the 1200 came out in the early '70s and was a consumer deck as were all with the SL designation. It was adopted by both the broadcast industry as a cheap backup deck, and mostly by the dance music DJ's. This was a time before digital and using a record player at a dance was typical.
Technics was aware of their sales and the use of the 1200. They redesigned the deck in the late 70's specifically for DJ use. Still light enough for portability, yet ruggedized and practically shockproof. The SP25 and 1200MKII are the same deck. The SP25 is for console mounting or in a separate plinth and the 1200 is a DJ deck. That's the way it is. How do people think the 1200 got the way it is, by coincidence?
Regards, |
*since the availability of the Feikert Speed App I have regularly stated that the Data downloaded on its 'Chart Info' was imprecise and non-scientific as it was not possible to duplicate the results from test to test.*
Why do we give credence to this in a magazine? Stereophile is Amateur Hour, unprofessional and lacking expertise. Too much trouble for them to conduct a proper test?
Read the specs page on the VPI Direct and all it has is the price. |
Plinko, I wouldn't make too much of that. Look at the mean frequency. You got a better test record, that's most of it. This app is useless for sorting the great from the pack. Still, an excellent performance from your WTT. Regards, |
Plinko, How do I know? Your mean frequency is exactly 3150Hz. The VPI is 3154.5. I forget what the Victor is, but I remember it's not 3150. Have you seen the Victor with the Timeline? It spins at exactly 33 1/3 RPM with any load. How do we explain the deviation? Not to belittle your table, it did remarkably well, but look at the green line which is supposed to be net performance, and compare to Victor. I wouldn't take it too seriously though. This app is really for amusement purposes only. No self-respecting lab would touch it. Kind of feel sorry for Mikey Fremer. He tries, but fights an uphill battle with Stereophile. Regards, |
Dover, You're way out of line posting your belt drive BS on this thread. It doesn't matter how good it supposedly is, it's inappropriate. Like your bit about absolute speed and the rotation of the earth, it doesn't make sense. |
Richardkrebs, Why don't you just make stuff up like most manufacturers? People don't know what it means anyway. Imagine a turntable going from 70dB S/N to 90dB !! You could pretend to rewrite the laws of physics with some doubletalk about external acoustic compensation curves or some such nonsense. Wow and flutter - not a problem. Just buy a few crappy off-center test records (aren't they all?) and you could have before and after "proof" of upgrade effectiveness. Enlarge the hole in one of the records and carefully center it for your after sample. Regards, |
Dover, Seems I made a mistake. I gave you an opening to spout further, but I think you would have found the opportunity anyway. The problem is, I don't believe you, about the SQ of your table and how it relates to speed stability. It's not that I think you're being deceptive, it's your judgment I question. "As to the subject of the thread “ DD are we living dangerously” then all turntables are relevant. In order to assess this proposition one needs a reference." This makes as much sense as your absolute speed declaration. Looks like you teamed up with Raul who graced this forum after a long absence, to support you, and you returned the favor on the MM/MI thread? Doesn't matter. You ask for proof from Richardkrebs, yet offer subjectivity to support your claims. Where's your timeline, where's your sound bite? Cheerio, |
Raul, **Richar obviously don't take the " road " posted here:
" People don't know what it means anyway. Imagine a turntable going from 70dB S/N to 90dB !! You could pretend to rewrite the laws of physics with some doubletalk ..... "
that IMHO is almost an " insult " to the audio community but each one can gives its opinion in this " free world ".**
It seems my joke/sarcasm went over your head, but that's understandable given a previous post: **Lewm, just think this:
suppose that your unit, before the mods, was running on manufacturer specs. Example 92db on SN ratio: what if after the mods that " figure " gone down to 84db?** You were talking to Lew about Richard's mods. Before this post I would have guessed that everyone on this thread knows those S/N figures on a turntable are impossible. S/N ratio on a component like a preamp is referenced to an output voltage level. S/N on a turntable is a rumble figure and is limited by the dynamic range of a record. Maybe you'll tell us you meant something else, but that was the topic. I deleted an earlier post which I thought might be too harsh. Happy holidays,
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Halcro, One thing I've been meaning to ask you, do you know why your 101 sounds better without the metal cage around the motor unit? I don't have a plinth or stand alone design for my 81 yet so I can't try it, but I also can't come up with a reason why this should be so. Regards, |
Halcro, I wasn't sure exactly what I am doing with the TT81. I can get an old Victor plinth relatively cheap, but I've decided to copy your design, with changes of course. Other things have come up and it hasn't been to the tech yet, but it runs and I have a 100V converter. I'm thinking of making a pod out of Kenwood style composite - ground limestone with polyester resin. There's a ground screw on the bottom of the metal cage. I read somewhere that's it's necessary to use it. Any comment? Sorry my response took so long. Regards, |
Lew, It seems to me that w/o a suspension, the advantage of a chassis or plinth coupling the parts, is lost. Instead of the chassis being a rowboat it's the base supporting the structures. If vibrations are affecting the motor unit they are more likely to affect the arm, if coupled. The back and forth of vibration transmission would smear the sound. In reality, I think either approach can sound good with good parts and execution. Regards, |
Halcro, Thanks for the tip, I figured as much. Does your new design change the attachment of the motor unit to the base? I was thinking of bolting it on and using compressed sorbothane washers. It will be awhile before I can get it together. Right now I'm devising a scheme for the actual build. Regards, |
Lew, I think that would be near impossible and might be better without the coupling. Isolating the motor unit from the arm would eliminate vibrations shared one to the other. On the other hand, outside energy hitting the platter or plinth would be different from that hitting the arm (board). There would be similarities, but I'm not sure if shared vibrations is a positive thing. Would micro detail increase or decrease? In this case I see the value in the Halcro approach. I think it might be better, if executed well. Looking at the stock Victor plinth it seems like just a plywood laminate with a hole in the middle with 2 wood armboards. I think I can make a better plinth, but not sure I want to. Regards, |
Interesting. There are quite a few things to figure out and it would be easier to incorporate them in the initial build, then to add-on later. If I want to bolt the motor unit to the structure I should embed threaded inserts and have space beneath to accommodate the bolts. This Kenwood ARCB stuff will probably be like working with clay or epoxy putty. I should be able to add on layers. I know you can drill/cut it, although a little messy. Polyester resin is auto body patch material (Bondo), and I'll have to experiment with mixing and sculpting. Seems a whole lot easier to drop it in a plinth. I could build a better (than stock) plinth and I wonder if the pod approach is worth the extra trouble. I'd have to make arm pods as well. Still mulling this over, but pods are intriguing. I also have an old Sota Sapphire I don't use cause it can't keep proper speed. If I podify that w/new motor, I could have 2 set-ups and 4 or 6 arms and sell a few tables. Sounds like a plan. |
The AT155 has the same 490mH generator as the modern 440/120. I see the 440 replacement stylus went up another $50. For another $25 or so you can get a 150MLX stylus. This is a great combination with the 490mH motor, reminiscent of the 160ML. The Signet TK5Ea, 7Ea, 7LCa, all have 550mH generators. All the beryllium styli (7LCa) are extremely rare. If you're looking, there are models like 152LC/ML and Signet MR5.0 LC/ML. These have the same fitment. The 440MLa stylus has a bump at 16KHz - might be a perfect match for the 550mH motor, I don't know. All of that series will fit. BTW, AT has a new "B" version of the 440/120. The generator appears the same. Regards, |
Hi Timeltel, Good idea to check stock with Stereneedles before ordering. Someone said they were out of all styli with beryllium cantilevers, over a year ago. They are slow to update their site and someone said they had trouble getting a refund. I have an ATN140LC - sounds similar to a an ATN440ML and the generator is the same 490mH. The 140 is more compliant. If they have the ATN155LC, that would be a good buy. Regards, |
Halcro, Not sure if you heard, Jico has discontinued the SAS stylus. Apparently they can no longer source the diamonds. The SAS was identical to the microridge and looks the same as an AT microline. Don't know if anyone noticed, but AT has been phasing out the ML tip in favor of an LT. The source was probably Namiki. Jico has plans to reintroduce the SAS. Regards, |
Halcro, You were right about the Achromat, as least as far as I can tell. I seem to have worked out the bugs with the lead sub-mat. Sheet lead is hard to keep flat and acts like a spring if not secured. Carefully trimmed and secured to the platter this is hard to beat. I use a thin deer
hide on top. Taking the 81 in for recapping. Still going to try the Kenny resin compound type mixture. Regards, |
Halcro, It seems that it isn't as uneven as it looked. With a raised edge or 2 going around every rotation it looks like a warped LP. Lead isn't that malleable,. It's bendable but tends to stay where you leave it. Your fingers won't leave a depression. The tedious part is cutting to size and using a calipers-flattening and going back and forth. A machine shop should be able to make short work of it. You could cast it, but it seems like too much trouble? BTW, wear gloves. I think I forgot..... Haven't listened to the 81 yet. My tech has been super busy and it's just going out. I didn't buy a plinth..... I also want to recap my AHT and a couple more tables. Also, using a laser tach for speed check. It says 33.3 go figure. Regards, |
Not a good idea to be touching the lead, especially with little cuts on your fingers. Wear rubber gloves at the least. If you're cutting the lead with a tin snip you have to be careful of sharp edges etc. Laminating to AL makes no sense to me. Most of the platters are already AL We have approx. 6mm total thickness to work with. Depending on the table, motor torque etc. I want it all lead + leather. Contact cement is no good here. It's too thick and uneven. The top surface can be painted, varnished or whatever, but it's the interface with the platter that makes all the difference. Dizzy Gillespie for President. |
Lew, Now you tell me. The greatest cowboy hero of all time told me to eat lead. He missed me cause I was partially behind a tree, but I gave it a try. Can't say I liked it much. Didn't have a lot of taste, and caused tremors of the spirit and insomnia. Now that I think about it casting should be relatively easy. I thought Walker has a giant lead platter? Lurne' figured out the "ideal" platter which is 8mm lead sandwiched between black methacrylate. Black whole grain isn't gluten free, but once those tremors overtake, you become one with the universe and it matters not. The 8mm thickness in our miniverse is based on the reflection back of any vibration when it hits a boundary. Since we only have 6mm ...... You just need a different adhesive, Regards,
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Funny you should mention encapsulating. The AHT non-signature had encapsulated Vishay space shuttle resistors. Those babies didn't budge from being next to the sun to absolute zero. They are the plug-in resistors for gain and load and are right on the board along with a DC offset pot(s). You think nude Vishay are pricy? In the '90s they were $60/ea. wholesale. The piece was sold direct for $5.5K, kind of amazing. I was always suspicious of Dan's story about leaving. I figured he was working for the military, but who knows? |
Another week rolls by and no progress. Maybe I'll hook up with my Tech later today. One of the problems with coupling a mat - do you want a "permanent" solution like a Goldmund mat, or maybe introduce another material like copper, which might also need some coupling. Maybe there's an adhesive that will hold it in place which is easier to change out if you want to experiment? Here's the deal with the Kenny type AR compound. It's said to be ground limestone and polyester resin. That's kind of a general description. Polyester resin varies from auto body filler to driveway coating. They start calling the stuff resin. Apparently there are mucho variations. Maybe I should try Bondo first and call the table "Big Pink". I suspect a driveway coating type might be better. A 5 gal. bucket requires a hand truck, but you can get it already dyed. Ground limestone comes in a 50lb. (?) sack and is the stuff they use for lines on a football field. Okay, a little experimentation is in order here. I suspect this should be done in one pour. If you're working with cement or concrete you can build it up, like sculpting with clay. I think this is more like a casting. What proportions? Weigh the component parts and try it? It's not as straightforward as you might think. Meanwhile, I only have so much time before South Jersey is underwater and Front Street in Philly is beach front property. No joke. The rate of ocean rise is greatly underestimated. Maybe I'll move to the Rockies. I hear their water is extra poisonous due to the old mines filling up with water and heavy metals infiltrating the supply. Sounds like rock and roll to me. neo McFleibster |
Hi Richardkrebs, Cool platter. The speed sensor moves with the platter? Seems a little strange. Regards, |
Had an interesting conversation with my Tech yesterday. He's been fixing all kinds of stereo equipment for a long time. He's one guy I know who is actually older than me and wise in the ways of keeping equipment functional. He essentially said, if it's not broken don't fix it. I told him my TT81 was fully functional, but I wanted all the electrolytics replaced and the board(s) gone over for cracks, old solder etc. He said he could do that but electrolytic caps don't automatically go bad after 20 or 40 years. They might last 80 years, and could very well last longer than I. After discussing a couple of pieces I have waiting in the wings, so to speak, I've decided to take my tube amp to him. I can't get the bias adjusted on the left channel input board, although it sounds good. This amp was built by Dan Fanny and is 50/wpc, class A/B. It was originally my tweeter amp and can pass a perfect square wave at 1KHz. Rise time is about 2usec and it sounds like nothing at all. I'll start experimenting with anti-resonant material and let you know. |
I'd have to say I agree about replacing electrolytic caps. Maybe I'll practice soldering on boards, but for now I don't feel competent. My Tech was being a little facetious with the 80 year thing. I'm of retirement age and he's a little older so he was alluding to components outliving their owners. I didn't make that clear. The amp is a little tricky to adjust/fix. The input board has a pot for each channel, but figuring out what to balance is a little confusing. I sat down with a pin out of the tubes and remembered what Dan explained. It might not make sense to most techs/designers (don't know), but it works. That was originally my tweeter amp for a pair of Infinity Emit tweets located between 2 Acoustat panels driven by Dan's version of a servo amp. My room wasn't big enough for woofers. The system I copied was that of Dr. Marty Wax. He had a 30wpc Bernig for his tweets and big Rowland monoblocks for conventionally driven panels, but he had a pair of large Entec woofers. That system was the closest to live, I've heard. BTW, the panels were driven full range on the bottom with the woofers augmenting the bass. fleib |
The Sony TTS-8000 and PS-X9 have a great reputation. |
Fast_Mick, I think the Kenny 9010 has a metal chassis, same or similar to the Canadian 990?? Yes, coreless motor and nice performer, but you might want to keep or rebuild the plinth. I have a 770d - straight arm version with removable headshell like a Graham Robin. It has end of record arm lift. I'm not sure about the 9010 as to arm and auto functions. I've found that modifying the plinth can be a substantial improvement. For less than TOTL DDs, bracing the plinth and adding mass can make all the difference. BTW, I think the entire Sony PS-X series of tables has BSL motors. Some of these tables can be modified for very high performance. Regards, |
Hi Halcro, **The centrifugal force of a spinning platter must be resisted by enough ’mass’ to avoid movement.** Interesting point. Assuming the motor is still coupled with three rubber pads, it's not only the mass of the pod which resists motion, it's also the integrity of the coupling and mass of the motor unit insuring that resistance. I wonder if performance would improve if the motor unit was bolted onto the pod. Regards,
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**Thus it is a force vector that has a direction described by an arc opposite to the direction of the arc of turntable rotation.** What force vector is that? If the platter/motor moves it would be in the direction of rotation. There is no force vector opposite to direction of rotation. It's the motor unit coupling to the mass of the pod that resists movement. The mass of the motor is heavy enough to resist, otherwise Raul wouldn't have been able to listen to the table. Regards, |
Dover, Modern physics says centrifugal force is a misnomer. It's called
centripetal force. The Victor motor units are relatively heavy containing the transformer and all the electronics. One can spin the platter under power and it doesn't go anywhere. I haven't listened to the table (TT81) under these conditions. Regards, |
Halcro, I wonder if you would hear a difference if the motor unit was bolted on. I'm sure you're aware of the three bolt holes underneath the edge of the platter. This is how the motors were bolted to the CL-P2D plinth. It might be better with the rubber acting as a damper. Of course you could always use rubber washers in-between. If the washers were compressed there should be no movement? With a wooden plinth it's easy to install threaded inserts, but with a stone pod you'd probably have to drill a big enough hole and fill around the insert with epoxy? Regards, |
Dover, Although I don't attend carnivals I have no argument with that. The question here is, does the rotation of the platter have enough force to overcome the mass coupling of the motor unit? Evidence suggests, the weight of the motor unit is enough to resist movement depending on the coupling to the pod, but is there micro movement which might not be readily obvious? That brings up another question. If the motor unit is bolted to the pod, would it be better to damp the coupling with rubber washers? A compressed thin rubber washer might not allow movement and provide a degree of damping which Halcro now has? Regards, |
