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  »  New  The Foolishness of Analog People..  Late to the discussion but cannot resist...  Analog Playback Forum     56  585084  01-30-2006
  »  New  Micro RX 5000..  Alternative method...  Analog Playback Forum     9  69932  11-09-2008
  »  New  Micro RX5000: is that bearing spins normally?..  How many turns do the good bearing......  Analog Playback Forum     7  42866  02-03-2014
  »  New  Fetish of Micro's?..  Size of ceramic ball...  Analog Playback Forum     122  414473  10-29-2017
10-14-2015 Post does not mapped to Knowledge Tree
be
Copenhagen, Denmark
Posts 86
Joined on 02-12-2007
Post #: 21
Post ID: 22076
Reply to: 22060
Circumference force
fiogf49gjkf0d
I think I misunderstood what you meant by circumference force.
What I was thinking of is the frictional force exerted on the needle by the groove moving relative to it.
The needle experience no centripetal or centrifugal force since it is not rotating with the record.
01-22-2016 Post does not mapped to Knowledge Tree
Retrofunk
Dallas Via London
Posts 6
Joined on 01-23-2016
Post #: 22
Post ID: 22411
Reply to: 22028
Micro Seiki - CU180, SDP, Mirko Clone - experience
fiogf49gjkf0d
I have been following this site for many years and as a result my knowledge of Audio has dramatically increased and many times I have had a good laugh along the way. Anyway, I am unsure where to post this, but being a MS owner and user of the CU180 and also having Mirko's latest RX5000 clone and flywheel, I thought it appropriate to share my thoughts.

I agree with 'Wellington' the CU180 on the gun metal platter is a great combination. On Mirko's stainless steel platter, I did not notice a difference and retired the CU180 to my double stacked Lenco. However, one enhancement to Mirko's SS platter is the addition of the German 'SDP' - not a big fan of acronyms but in this instance since it stands for 'special decoupling platter', the former wins out! In my opinion (and we all have them), it's difficult to improve the RX500 be it a good clone or not, invariable it involves a healthy bank balance and diminishing returns. But in the case of the SDP, to my ears, there is a positive improvement; blackness and even enhanced bass. 

For those who have the MS HS 80 flywheel, be it original, the dutch or Mirko's clone, it's a bitch to set up and to keep constant speed. I am sure before the advent of iPhone's and the 'iRPM' or 'Turntabulator' app that people with with the flywheel were confident and boasted about the constant speed ....well i beg to differ. Having the flywheel for 4 months and trying 'threads' from everywhere and taking opinions from all the 'forums' on the web...I almost gave up. In my mind the one motor, no flywheel gave me a constant speed, measured via iPhone apps and lately the 'Phoenix Engineering Roadrunner Tach'. The flywheel turned into an expensive ornament. I thought i would it give it one more shot, I purchased 'new' old stock MS thread from Japan, and 'bobs your uncle' (i'm english, reside in the states, so i apologize if that got lost on a few' ....it worked!!! The secret aside from the thread is to set the flywheel the same distance as the motor and for adjustments move the motor NOT the flywheel, for months I was moving the flywheel. In the last 3 hours (much to the Mrs's horror) I have listened to Monk, Jarret, Laurie Anderson, Faust and now 'oil on canvas' by Japan.....pretty much perfect speed...and the flywheel is a happy camper. To those with the flywheel ...don't give up!!! 








Micro Seiki RX5000 handmade clone (double stacked), Micro Seiki Flywheel, Fidelity Research FR 64S, SME3009 S3, DynAudio C1, Merrill Audio Thor MonoBlocks, VAC Signature MKII, Keith Monk RCM, Denon Au 320 SUT, Technics SL1200 (KABUSA) Marantz 2330b
01-23-2016 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,159
Joined on 05-28-2004
Post #: 23
Post ID: 22412
Reply to: 22411
Flywheel
fiogf49gjkf0d
Retrofunk, beside the complexity to setting up and get the stability what interest me is if you detect any sonic differences that might be attributed to use of the flywheel?

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
01-23-2016 Post does not mapped to Knowledge Tree
Wellington


South Florida
Posts 38
Joined on 10-03-2011
Post #: 24
Post ID: 22413
Reply to: 22411
Motor type?
fiogf49gjkf0d
Retrofunk,
Interesting observations. With regard to the speed variations with the flywheel, I have to wonder about your motor. I don't recognize particular unit. Do you have the original RY-5500 motor that came with the RX-5000? The RY-5500 has a built-in tachometer to measure and maintain constant speed under varying loads (within limits of course). It should compensate for the load of the flywheel - it was designed to do so. Maybe your motor lacks the elaborate speed control of the RY-5500? Another RX-5000 user I know told me that he really never heard an improvement with his flywheel. That's not the final word of course, just another opinion. I had never pursued one because the price is so dear (although cheaper for a clone). Maybe if I find one in a garage sale for cheap, I will take the plunge Smile
I now have a bit more experience comparing the 49-pound stainless platter to the original gun metal platter. The stainless unit does seem more relaxed in a natural way. The midrange in particular is more vivid and seemingly has a lower noise floor. Not hugely so, but significantly enough. Bass is as solid as it gets. The CU-180 does make a slight improvement to my ears on top of the stainless platter too, but I agree with Retrofunk, not as much as with the gun metal platter. I think the best combination that I've experienced with my table is the stainless platter topped by by the CU-180 but with NO soft mats. I have used the ST-10 spindle weight and the variable-pressure SOTA reflex clamp with equally good results to hold the LP tight onto the the CU-180. This is important, because without a soft mat to take up voids, there could be tiny air gaps between LP and CU-180 that prevent resonance control and even allow buzzing. A weight will "smash" the record down into intimate contact. I have to make sure that the surfaces are clean to prevent pressing dirt into the LP. Tapping lightly on an LP surface when it is clamped onto the CU-180 and stainless platter is like tapping on a granite boulder. Dead and quiet. But certainly not dead sounding! The best sounding rig I've had in my 40+ years of audio affliction. I think I'm done with table machinations for a while.



______________
Brian
01-23-2016 Post does not mapped to Knowledge Tree
Retrofunk
Dallas Via London
Posts 6
Joined on 01-23-2016
Post #: 25
Post ID: 22415
Reply to: 22413
Motortype and Flywheel
fiogf49gjkf0d
Wellington, my motor has separate pots so that I can make adjustments on the the fly to the speed, having said that I do not know if it has a built-in Tach to maintain speed under load. I will follow up with Mirko. A friend has the RY-5500 and the clone flywheel and did not have nearly as much trouble getting them to work together. However, when I started this journey I did not have the luxury of space, as I had a Lenco in fairly close proximity and therefore could not benefit from leverage by having the distance from the table greater. Having done that and using the correct thread, all is good.
With regard to 'is there a sonic difference' when using the Flywheel, after the expense, the time and the PITA factor...'hell yeah' there's a difference! LOL. To be honest, if there is, I really don't hear it, but that could be my ears (48 years old) or that room is far from sonically complimentary to my system. Adding the CU 180 was a bit upgrade, then replacing that with the SS platter, again big upgrade, adding the 'SDP' atop the SS platter, again big improvement. Others will swear by an improvement the Flywheel adds, and to their ears I am sure it does. But I have to say the visual and geometric aspect of the set up is stunning.

Micro Seiki RX5000 handmade clone (double stacked), Micro Seiki Flywheel, Fidelity Research FR 64S, SME3009 S3, DynAudio C1, Merrill Audio Thor MonoBlocks, VAC Signature MKII, Keith Monk RCM, Denon Au 320 SUT, Technics SL1200 (KABUSA) Marantz 2330b
01-23-2016 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,658
Joined on 10-12-2006
Post #: 26
Post ID: 22416
Reply to: 22415
Rube Goldberg in Drag
fiogf49gjkf0d
This is interesting. Of course the last word is always net "sonic gains", whatever they are deemed to be. When I look at this I wonder if similar results might be gotten by applying measured "drag" to the platter/motor, like Spiral Groove (and a few others, I think) do it. And, in the end, given the relationship between the platter, the motor, the thread and the "flywheel", I wonder how this is so different from simply using a less powerful motor with the original TT, or using two or three motors, etc.? What is the "explanation"?

Best regards,
Paul S
01-23-2016 Post does not mapped to Knowledge Tree
Retrofunk
Dallas Via London
Posts 6
Joined on 01-23-2016
Post #: 27
Post ID: 22417
Reply to: 22416
Drag
fiogf49gjkf0d
Paul S, you raise a good point, throughout this whole process - in the back of my mind - I have been thinking surely, less drag, less torque, the motor not working as hard would be optimum. Using a roadrunner tach to report the RPM to 3 digits, currently the single motor option is more accurate. I am sure i can get the motor and flywheel to the same accuracy, but adding another variable just makes the 'tweaking' more time consuming. 

Micro Seiki RX5000 handmade clone (double stacked), Micro Seiki Flywheel, Fidelity Research FR 64S, SME3009 S3, DynAudio C1, Merrill Audio Thor MonoBlocks, VAC Signature MKII, Keith Monk RCM, Denon Au 320 SUT, Technics SL1200 (KABUSA) Marantz 2330b
01-23-2016 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,658
Joined on 10-12-2006
Post #: 28
Post ID: 22418
Reply to: 22417
Speed accuracy
fiogf49gjkf0d
It seems like you are saying that so loading the motor somehow makes it more accurate, so it sounds better. Is this the case? I thought the "most accurate" speed control was DD with a servo (that only "corrects" errors after the fact), as "measured" by a device that is slower than the correction circuit? I am trying, but I can't understand how the flywheel should help more than just dialing in the basic set-up, in light of the weight of that platter assembly, going in. Doesn't there "have to be" an "optimal" relationship between a particular motor and such a giant platter that it would obviate the extra "flywheel"? Perhaps it is just "too much motor", going in? Again, how do the promoters "justify" the device?


Best regards,
Paul S
01-23-2016 Post does not mapped to Knowledge Tree
Retrofunk
Dallas Via London
Posts 6
Joined on 01-23-2016
Post #: 29
Post ID: 22419
Reply to: 22418
Speed
fiogf49gjkf0d
actually I was saying the contrary should ideally be optimum, less is more. My experience so far is that the single motor works under less strain and provides a more accurate speed - as measured on may Roadrunner Tach. However, having shelled out for an expensive flywheel , I am going to continue to tweak its position and that of the motor to see if i can obtain as an accurate speed as the single motor. If starting from scratch and knowing what I know now, in hindsight I would likely just stick with the single motor and would not have ventured down the path of exploring the flywheel. Again, this is just my 2c, quite  a few people swear the addition of the flywheel adds something better, than without.


Micro Seiki RX5000 handmade clone (double stacked), Micro Seiki Flywheel, Fidelity Research FR 64S, SME3009 S3, DynAudio C1, Merrill Audio Thor MonoBlocks, VAC Signature MKII, Keith Monk RCM, Denon Au 320 SUT, Technics SL1200 (KABUSA) Marantz 2330b
01-23-2016 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,658
Joined on 10-12-2006
Post #: 30
Post ID: 22420
Reply to: 22419
Still Dying
fiogf49gjkf0d
to hear the "explanation". In the meantime, I would think you'd want to thoroughly optimize the system without the flywheel first, in order to establish a base line, then add the flywheel, all while keeping the isolated idea of "speed control" in perspective, of course. From what little you've said so far, it sounds like the guy who sticks a strong driver into a big horn then notes that "LF is more extended". As for the people who "swear" by the flywheel, I hope one or more of them will chime in with a coherent take. On other forums, mere mention of the MS TTs is like a drug, and their putative presence alone inspires slack-jawed reverence. Not so here, however, despite the Boss owns them, himself.

If it makes you feel any better, truth be told, I'm sure I have "wasted" a lot more than I've spent well playing with hi-fi.


Best regards,
Paul S
01-30-2016 Post does not mapped to Knowledge Tree
chaslieb
Posts 4
Joined on 01-30-2016
Post #: 31
Post ID: 22446
Reply to: 22419
From a physics perspective...
fiogf49gjkf0d
I don't understand why people are using the flywheel with the same thread coming off the motor to go around both the turntable platter and the flywheel.  I also don't get why the flywheel is supposed to be used with a slipping thread at all.  To make it simpler, if we look at the transmission of energy from the motor unit to the turntable platter like filling a bucket with water, the motor's goal is to keep the platter spinning at the same rate, which would in our terms mean keeping the water level the same in the bucket.  The drag of the bearing, drag of the stylus and friction of the thread or belt are all reducing the amount of energy stored by the rotating platter.  We can think of them as holes in the bucket.  

The thread used to transmit energy is designed to slip on the platter.  This clearly protects the motor from burning out, but also prevents speed variations in the motor from having an effect on the speed of the platter.  If there is a slight increase or decrease in speed, the thread will slip and not transmit these micro variations to the platter.  The same slippage which serves a purpose for a motor to platter, makes the thread a useless device to couple a flywheel to the turntable platter.  If we go back to the water example, a flywheel adds energy storage and should make our bucket larger so that the small holes draining energy, by the bearing or by the stylus drag, have even less effect on the water level.  In practice, the use of a thread to couple the flywheel to the turntable platter is like a small pipe attaching two buckets of water.  When the water level in one goes down it will take time for the other to level it off because the transmission of energy, like the transmission of water between the buckets is not instantaneous.  This can create an oscillation between the transmission and response between the motor, platter and flywheel and could be predicted to create speed instability.  This situation is worse than having no flywheel at all!  A solid coupling of energy, like simply stacking platters or an idler wheel between the platter and flywheel will ensure a tight coupling and instantaneous transmission of energy, like making a bigger bucket.  If a belt is to be used between the platter and flywheel, it must be a rigid belt, meaning that it will not stretch or contract.  Rubber is useless for this purpose.  It also must grip both the platter and flywheel and therefore a coating that gives it  such grip to avoid slippage is necessary.  from what items are out there, only a non stretching fabric or plastic belt with some sort of gripping coating should be considered.  Given the different job to be accomplished by the thread drive from the motor, which is meant to slip, and the tight coupling needed to make a flywheel effective it is amazing to see people who set up their turntables the exact opposite way; with the thread connecting the flywheel to the platter and the belt between the motor and platter.  Probably just as bad are those who use a single thread to connect the motor, turntable and flywheel.  

Looking at the microseiki.nl site I see that they say their flywheel should only be used with a thread.  Considering the implications based on the coupling issues, I cannot guess why.  Also, I see people say that the flywheel was meant to augment the air bearing and not the oil bearing.  Given that the air bearing should have less friction losses than the oil bearing, I don't understand this either.  It seems like the greatest benefit would not be to the air bearing which already has the advantage of less friction, but to the oil bearing that has more friction losses and therefore more to gain by added energy storage.  I have not heard the flywheel used with thread or belt in any system and this analysis is solely scientific, and has nothing to do with anyone's personal experience in their system.  However, in my way of thinking, math helps explain the subjective phenomena we perceive, so I put these thoughts out there to suggest a possible way to approach the use of the flywheel that may provide a benefit.
Charles
02-02-2016 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,159
Joined on 05-28-2004
Post #: 32
Post ID: 22454
Reply to: 22446
...generally is not wrong but...
fiogf49gjkf0d
Chaslieb, you generally is not wrong BUT all of those very rational theories have in my view any practical meaning only in context of TTs with conventional platters, means the platters of sane mass. As soon we enter of domain the platters let say over 70-100 pounds then any exterior torque forces, acute pulling from belt or anything else external influences become just irrelevant. Retrofunk admits that visual aspect of the flywheel is very attractive and no one denies it. He also confirms what I have been advocating for years: with heavy platter there is no sonic impact to sound. I did not use a flywheel but I used an additional platter of Micro 5000 as a flywheel. I used a reel-to-reel tape to run the platter that is ultimate slipping drive.
 
http://www.goodsoundclub.com/Playback/Site_images/MicroDual1.jpg 
 
I do not feel that there was any tangible sonic impact from the second platter. 
 
One more thing. We all for sure would like to have our platters to have a stable rotation. Now is the question: what deviation from the stability we do hear. If the platter goes on and off 0.1rotation per minute them is it auditable? Let me to rephrase it. If a platter has a stable constant deviation from 33.33, or whatever it shall be then how auditable is it?  If it does 32.1RPM then what do we hear? Download the brilliant RPM app to your smart phone and play with it. Yes, we feel a change in pitch but where it become practically significant? This is the questions that everyone should answer to themselves. 
 
Still, I would insist that majority of audio people out there who love to be proud that they spent a lot of money  for super-duper solutions to stabilized the speed have still no clue what they are taking. A case to proof my arrogance. Year back, I think it was 2006, the last year I went to CES, the Australian company Continuum was just a start up. They brought a first model of their TT and it was before they become “famous” and before a few US marketing whores puffed them up.  So, Continuum, facilitated a closed demo at night for industry folks, trying to win US distribution rights. The room was staffed with all possible reviewers, distributes, dealers, editors and I was looking at all of that collection of audio dirt and was envying to those Muslims suicide bombers… Anyhow, the Continuum guy was spinning Heifetz’s Bach partitas. After the very first notes that were way lower I was looking at a friend of my (who invited me to that session) and asking with my eye if it was for real. He was also look like he had a tooth pain. The rest of the industry Morons were siting there listening that crap with no apparent complain or reaction. I stopped the listening and informed that the platter speed is way off. The Continuum guy did not believe me (!!!) and insisted that it need to be measured (!!!). So, he did and of cause it was way slower. It is not a big deal the TT get broken. However, that image of that room filled up with all that golden-ears holders audio-writing idiots,  sitting there, looking at that turntable, listening the objectively faulty sound and having to brain to recognize what they are hearing is very much follow me each time I see them writing anything about analog sound reproduction. Well, whatever it worth the Continuum did what they wanted. At the show they were selling the TT for $10-15K with target retail price of $25-$30 but a few month after the show and after the Framer and the rest dirt engage the Continuum the price went to $150K or something like this. BTW, my satiate about the Continuum  was written in a memory of that event: 
 
http://www.goodsoundclub.com/Forums/ShowPost.aspx?PostID=1957  
 
The Cat
 

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
02-02-2016 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,658
Joined on 10-12-2006
Post #: 33
Post ID: 22455
Reply to: 22454
Rationale
fiogf49gjkf0d
How many decent hi-fi "demonstrations" have I heard? Not many, that's for sure, and it does seem like the more expensive the gear, and the more arcane and/or elaborate the "case" for the equipment, the bigger the problems when that gear is demonstrated. The endless double-talk seems to be enough for many, in and of itself, and some literally buy in to the prattle. Of those, some "communicate" with each other in a proscribed language that avoids the methodology and/or topics that would be relevant in order to actually try to make the best of the product in question. For some, it becomes a matter of "keeping up" with the latest tweak. In most cases, pride of ownership is literally advertised and worn like a badge of honor and/or entitlement. Like Forrest Gump's mother always told him, "Stupid is as stupid does." I don't give a shit how much mass a TT has if the guy who uses it is unmindful of it's audio potential in terms of advanced audio, and IMO this condition is only worsened if the guy is also unconcerned or otherwise totally distracted by background noise.


Paul S
02-02-2016 Post does not mapped to Knowledge Tree
Wellington


South Florida
Posts 38
Joined on 10-03-2011
Post #: 34
Post ID: 22456
Reply to: 22446
Slippage?
fiogf49gjkf0d
On the topic of string slippage: I don't think my string, the original one from MS by the way, slips at all once the platter is up to speed. It would slip on the motor pulley when first turned on, as the heavy platter must be gradually brought up to speed, unless you give the platter a spin by hand before turning on power, as I do. Once up to speed, "stiction" (static friction) holds the string in place on the pulley and the platter. This is easy to verify on the platter side because you can watch the platter and string up close and see that they are moving together. It harder to see what's happening on the pulley side, so I ran a test. In the course of rebuilding my motor electronics (mostly replacing all electrolytic caps preventively), I monitored voltages inside the complex drive electronics while putting the table through its paces. The tachometer provides feedback to an error amplifier and then to series-pass power transistor emitter followers that drive the motor windings. I put an oscilloscope probe on those points (and others) while varying the load on the motor. As expected, when the motor encounters more friction, the voltage jumps up to compensate, keeping speed constant. It's a very sensitive system. I watched this voltage on the scope while gently touching the platter. The voltage responded immediately. Even the tiniest touches on the rotating platter, that I dare say nobody would hear as pitch changes, were responded to, immediately. If the string were slipping, this response would not be so immediate nor so proportional. I ran another test. I adjusted the motor speed control to give a platter speed of exactly 33 1/3 rpm using a stroboscope, at my average string tension setting. I then watched the stroboscope as I slightly varied the string tension by pressing a shiny screwdriver shaft against the moving string midway between motor and platter. I also very slightly nudged the RY-5500 motor closer to, and then farther from the platter while monitoring the stroboscope. The speed remained constant. If the string were slipping, the motor's tachometer would not "know" what the platter's speed was and it wouldn't be able to correct it. Tiny friction changes and speed variations caused by motor cogging, stylus drag and external vibrations are simply not enough to break the stiction bond between the string and the motor pulley or the platter, as long as the string tension is properly set over a wide set of tensions. Slippage would make no engineering sense that I can see. It would make speed setting uncertain, and it would result in scraping noise as the stiction is overcome (like a violin bow scrapes on the strings). Plus it would cause excessive wear on the string and pulley! My Kevlar string is probably close to 40 years old and it looks almost new.
Of course there are many ways to set up this turntable and its string. Then most critical factor is string tension. The string has a tensile strength of 24.5kg (54 pounds), so that there is a wide range of string tensions possible between total slippage and the string breaking. MS had little to say about it in the RX-5000 manual. I've set my string's tension so that there is about a half-inch of deflection midway between motor and platter with a light sideways touch of the finger. Not very scientific, but it works. It's not so tight that it's putting a significant side load on the bearings, nor is it so loose that there is any slippage once the system is up to speed. Like many things with this amazing table, it is probably not very critical over a broad range.
Here is what MS had to say:

* Positioning the string>>

First, the installation location of the platter unit is determined and the unit is secured. The motor unit is then provisionally placed between 10 and 15 cm away. The string is then cut to a length enabling it to pass outside the pulley and the platter perimeter, and bound firmly. The end of the string projecting from the join is then cut off with scissors. After checking that the string has been positioned around the platter and pulley, the motor unit is gradually moved out and the string pulled taut. Make sure that you do not make the string too tight. Once the platter rotates, the inertia will have an effect and so there is no need for the string to be pulled too tight because the power is transmitted. However, if the platter is helped to rotate by hand when it first starts up, it will reach the rated speed smoothly.>>



______________
Brian
02-03-2016 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,159
Joined on 05-28-2004
Post #: 35
Post ID: 22457
Reply to: 22456
That is pretty much what I am saying.
fiogf49gjkf0d
Yes, Wellington, that is pretty much what I am saying: if a TT have heavy enough platter and the bearing done right then the any speed deviations of motor of belt are kind of irrelevant. I remember years back a Russian guy presented heavy mathematics to model TT interfaces. It was hard belt, loos belt, idle wheel, direct drive. He was trying to prove from mathematical model perspective that one interface is better than another. Interesting that all his calculations according to him make any sense only in context of TT with platters mass comparable to the driving force.  He insisted that if platter mass and the consequential moment of inertia is too large then there is negligible difference how the platter is driven. I do not insist that he is right but to me his theory completely makes sense.

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
02-03-2016 Post does not mapped to Knowledge Tree
Wellington


South Florida
Posts 38
Joined on 10-03-2011
Post #: 36
Post ID: 22458
Reply to: 22457
Diminishing Returns
fiogf49gjkf0d
Yes, the Law of Diminishing Returns must apply to platter inertia, as it does for so many other things.

______________
Brian
07-22-2017 Post does not mapped to Knowledge Tree
Wellington


South Florida
Posts 38
Joined on 10-03-2011
Post #: 37
Post ID: 23335
Reply to: 22458
One more thing...
Anyone contemplating buying a CU-180 should know that it must be dead flat. Even the slightest departure from being flat will negate the benefit of intimate contact across the entire surface of the platter.

How flat? Flat enough that the weight of the CU-180 alone is sufficient to overcome the normal microscopic deviations from perfect flatness in both the platter and CU-180. In other words any minute departures from perfect flatness caused by machining, too small to see, will be overcome by the draping flexure caused by its own weight.

How can I test for this? Two ways. Visibly sighting is not enough. If it is visibly bent it is already an expensive (and deadly) Frisbee. Put the CU-180 on the platter without a record and tap all around the playing surface region with finger tips or knuckles. Check around the whole circumference. Rotate the CU-180 relative to the platter in increments and tap again. Try the rotation around all 360 degrees. You should feel and hear a "granite mountain" at all times. If you hear any tapping or clicking sound or buzzing, any at all, the CU-180 is slightly bent. Reject it. I am assuming the use of a massive Micro Seiki platter here, and assuming that that platter is flat, which it will be unless it was dropped. Another test is to lay the CU-180 onto a heavy glass table or a granite countertop used as a truly flat reference plane. Try to see/hear if there is even the slightlest play. Repeat the tap test.

What could cause a non-flat CU-180? Being dropped, just once, even onto a carpeted floor. Or getting flexed in shipping with inadequate packing.

Can't I just bend it back? No. At least almost certainly not. Once bent it will be hard to get it back into true flatness and small voids will occur from stresses remaining in the alloy. Think of unfolding a paper clip into a "straight" wire. How straight is it? No amount of fidgeting with it can ever make it truly straight again.

Buying? I have seen a few CU-180s for sale that say "slightly bent". A 1% bend does not decrease value by only 1%; it decreases value by 100%. Think paper weight. Get assurances that a return is allowed.

But a vinyl record is never perfectly flat. True of course, but we have to get the interface, the constrained layer, between the platter and CU-180 correct first. Then we can use a record weight or clamp to mash the record flat (as flat as possible) directly onto the clean CU-180.

Isn't this a pain in the ass? Yes, it is. But if you want to hear what your Micro Seiki is truly capable of, it's worth seeking out a flat CU-180.




______________
Brian
07-23-2017 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006
Post #: 38
Post ID: 23336
Reply to: 23335
Why buying this at all?
Not a MS owner, but have been wondering why buying this 30+ yrs old mat at all with all the risks you describe?
Virtually any modern metal shop will be able to machine it and check the flatness down to microns. The price I guess would also be much lower than a "vintage" one. Just a thought.



Cheers,
Jarek
STACORE
07-23-2017 Post does not mapped to Knowledge Tree
Wellington


South Florida
Posts 38
Joined on 10-03-2011
Post #: 39
Post ID: 23337
Reply to: 23336
And I'm not trying to sell it!
It is entirely possible to buy a good flat CU-180. I have two from eBay there were correctly advertised as being flat. I have also seen them on eBay as being "slightly bent". Those you avoid.
But I agree that a replica is a real possibility. I never said that the CU-180 is the only possibility. It is the only one with which I can confidently report excellent results. In fact I have seen copper mat replicas on eBay. If an experienced machinist properly machines both sides, and expertly handles any annealing and post handling, a good flat "copper" mat should be the outcome. There is the question of duplicating the alloy of the original CU-180 mat. How much does that matter? I don't know.
Micro Seiki also made the heavier CU-500 mat which is quite rare now. I have not used one. There was another vintage manufacturer of copper mats. The name escapes me, but I want to say "Final Sounds."(?) I also recall seeing at least one recent manufacturer, mainly appealing to the Technics crowd who love the CU-180.

______________
Brian
08-23-2017 Post does not mapped to Knowledge Tree
measet
Posts 15
Joined on 08-15-2017
Post #: 40
Post ID: 23365
Reply to: 22028
Stainless steel platter for Micro RX-5000
Hi Wellington,


Also I'm thinking to make a stainless steel platter for my RX-5000.
As you have good experience with yours could you tell me the exact parameters of the new design (beveled insight edge, thicker deck part). The schematic would be the best.
I was looking for the 316L material, I found the needed diameter but all of them have a very small reaction to magnet what I think is slightly unfortunate close to the cartridge area. Have you experience with this isue?

Thanks a lot!
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