Yes, those old Japanese Toho cast iron plinths are an eye candy, they also made their own tonearm btw.
I remember that Toho in the 70's made wooden tonearms rods with different mass.
Technics SP10 MK3 Restoration
Just got my SP10 MK3 base (motor unit & controller) back from JP at FidelisAnalog.com
JP
is one of the most knowledgeable on the SP10 MK3 and is the one who
designed and manufactures the MN6042 Speed Control chip that keeps these
and other Technics turntable models still operating.
My SP10 MK3 came with the stock Technics SH-10B5 faux obsidian base.
It
has very low hours of use , no signs of wear at all on the bearing and
not a single blemish, other than some specs of dust and a couple spots
on the copper part of the platter that need cleaning.
but I would
like to have a 2 arm, constrained layer plinth built and have the motor
unit mounted 'naked'. I am presently searching somewhat 'affordable'
plinth builders and suggestions would be greatly appreciated.
The work that JP did to both the motor unit and the controller:
1. Pre-refurbishment measurement to baseline the performance of the unit and to see if there are any underlying issues.
2.
Cleaning of all PCBs to remove the factory conformal coating. At~40
years this coating tends to become hygroscopic which can cause stability
issues.
3. Physical inspection of all solder joints under an
inspection microscope. Many of the joints will exhibit annular
deformities which can lead to joint fractures down the road. These must
be cleared of the factory solder and re-soldered. There will also be
poor joints that need the same treatment. You can’t just reflow as the
solder alloys aren’t the same which can also cause joint failure down
the road.
4. Electrolytic cap replacement and rectifier diode replacement.
5.
Disassembly and cleaning of the motor. Bearing inspection and service
work. Proper Anderol 465 oil is used for reassembly. Motor is then
checked for any areas of bearing drag.
6. The brake solenoids typically needs cleaned, and band tension is adjusted.
7.
Stop/start and speed selection switches in the motor chassis are
measured for contact resistance. Too high of resistance is indicative of
a switch failure in the future. In the control unit I typically replace
all the tactile switches, and the start/stop switch if needed.
8. Relocation of the brake regulator transistor to the heatsink to prevent overheating of the board (factory design flaw).
9. MN6042 replacement installation.
10. PSU ripple check at all critical stages (10).
11. Course calibration is performed and post-refurb baseline measurements for FG spectrum, motor drive phases, etc. are taken.
12. After 48-hour run-in final calibrations and verification measurements are performed.
The basic service returns the unit to factory or better specifications (assuming no permanent bearing damage has occurred). This service is quite exhaustive and very different from the typical work I see of just swapping some caps out, checking some voltages, and adjusting phase tracking.
The advanced service adds on top of the basic service:
1. Replace all polyester capacitors.
2. Replace drive circuit metal oxide resistors.
3. Replace all voltage regulator ICs and update circuits.
4. Replacement of certain diodes.
Rick
72 responses Add your response
Just watched this with better view of OMA Cast Iron plinth, and to my surprise Jonathan (at 5:10) said that there is a CRYSTALLINE GRAPHITE in this grey iron formula. |
Just watched this with better view of OMA Cast Iron plinth, and to my surprise Jonathan (at 5:10) said that there is a CRYSTALLINE GRAPHITE in this grey iron formula. This is like mounting a bowl of jello on a 20 tonne rock. If you have ever seen the guts of a Technics SP10 you would know that the case is flimsy, and the motor mounts and stator mounts are almost as bad. The best thing you can do to a SP10 is remove and disassemble the motor, bearing and platter and re-engineer all the mechanical mounting points and pop into a rigid plinth as in the Kaneda mods and the original OMA Slate plinth. Seems to me the new OMA plinth is based around removing the time and cost of gutting the TT as in their earlier solution. The OMA plinth is just a fancy picture frame. Come on - you spend all that money to eliminate resonances and then use wood for the armband - of course each wood has a different sound - bit like buying an ice cream - what flavour would you like sir ? The rest of their presentation is like a Barnum and Bailey circus - Cant pronounce Technics correctly Claims the SP10R is significantly better than the SP10mk3 - LOL - of course the scarcity and age of SP10mk3’s would have nothing to do with their opinion ! You have to remember their market is lunatic billionaire New Yorkers who have never heard a decent stereo, but want something unique - in the looks department. Their mobile ring tone is probably bling bling. |
@pindac Checkout warrenjones SP10 appreciation thread on stereonet. There is some very interesting information on checking motor runout, platter runout, new platters - there are significant opportunities in checking tolerances and blueprinting the SP10 motor, bearing and platter as part of your build - big gains to be had. |
"Just watched this
with better view of OMA Cast Iron plinth, and to my surprise Jonathan
(at 5:10) said that there is a CRYSTALLINE GRAPHITE in this grey iron
formula."I think you need to do a quick read of the metallurgy of cast iron. Cast iron contains a high percentage of carbon, that's why when you machine the dam stuff you get so dirty. He is just trying to make it sound like something super special. Makes me laugh.That part of Pennsylvania has quite a few pattern shops and small foundry's, or at least whats left of them. If he worked with a small mom and pop pattern shop, than the cost of that pattern would not have been that expensive, it's a few days worth of work at most. Getting the grey iron casting poured is usually quoted on a per pound basis if you supply the patterns. Very cheap. The machine work is very straight forward, nothing fancy. What blows my mind is the 10K price tag he puts on those bases. If this was an industrial part it would be several hundred dollars per piece in small lot sizes. I wouldn't be surprised if I know the pattern shop and machine shop that he used. I used to service most of them.They would be shocked if they knew the end price of the finished product. It's such a simple piece to manufacture, very basic. BillWojo |
@dover has he started providing any meaningful measurements yet? The machine work does look rather nice, but I had to admit that I stopped paying much attention when he made the claim that the MK3 was digital. @billwojo I know one of the suppliers that makes the plinths is in to SP-10's, so I'd be surprised if they didn't know. |
I made slate plinths for several of my turntables, or I should say I had them made on a one by one basis, using Pennsylvania slate and a York, PA, Waterjet shop to cut the slabs. The total cost was always less than $500 per. Here we’re talking about cast iron, but the cost to build vs the retail price for audio products is known always to be wildly out of whack. You pay your money, or not. |
Claims the SP10R is significantly better than the SP10mk3 - LOL - of course the scarcity and age of SP10mk3’s would have nothing to do with their opinion ! I must admit he did not mention MK3, he said SP10. Turbtable drive in his old slate plinth on the right in his video is MK2 (not mk3) and SP10R is definitely better than mk2 @dover ? You have to remember their market is lunatic billionaire New Yorkers who have never heard a decent stereo, but want something unique - in the looks department. Their mobile ring tone is probably bling bling Yes and No. Steve Guttenberg interviewed one of his customer, it’s about new speakers (not turntables), but the guy is definitely not a lunatic and he owned so many different high-end speakers before he stopped on Jonathan’s (OMA) Fleetwood Deville high efficient speakers. Other people explained better who are the people behind Fleetwood Sound Company (OMA) in this topic. Not everyone is so skeptical, especially people who actually heard those. |
Cast iron contains a high percentage of carbon, that's why when you machine the dam stuff you get so dirty. He is just trying to make it sound like something super special. Makes me laugh. That part of Pennsylvania has quite a few pattern shops and small foundry's, or at least whats left of them. If he worked with a small mom and pop pattern shop, than the cost of that pattern would not have been that expensive, it's a few days worth of work at most. Getting the grey iron casting poured is usually quoted on a per pound basis if you supply the patterns. Very cheap. The machine work is very straight forward, nothing fancy. What blows my mind is the 10K price tag he puts on those bases. @billwojo business as usual, cast iron is even cheaper in Russia this is why I pay attention to cast iron plinths, but way before OMA made their own I discovered vintage TOHO cast iron plinths online. I don't have technics Sp10mkII anymore. But Toho plinth for Victor TT-101 is interesting (not so big and not so heavy). |
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That Toho plinth for the Victor is interesting but I don't like stand alone arm pods. I wish I still had my connections with my favorite pattern shop, they sadly changed owners. I'm sure that the past owner would have let me with his help build a cast iron plinth pattern to my liking. After that, drop it off to a local foundry and toss it up on the Bridgeport to finish. Would have been a fun project. BillWojo |
That Toho plinth for the Victor is interesting but I don't like stand alone arm pods. me too, you will find one Toho arm pod in this system |
Toho plinth - I discovered vintage TOHO cast iron plinths online. I don't have technics Sp10mkII anymore. But Toho plinth for Victor TT-101 is interesting (not so big and not so heavy). What happens when the cleaning lady, sorry - non binary cleaning supervisor, decides to clean under the arm pod and forgets to tell you they moved it. Answer - a year later you wonder why all your favourite records are mistracking. I subscribe to the loop rigidity principle - platter, bearing & arm mount must be absolutely rigidly locked together in position to measure the groove accurately. Arm pods in my view are only as good as what they sit on, and often will compromise loop rigidity |
@dover I subscribe to the loop rigidity principle - platter, bearing & arm mount must be absolutely rigidly locked together in position to measure the groove accurately. Arm pods in my view are only as good as what they sit on, and often will compromise loop rigidity. This is where my mentors in Turntable Design have guided me to. I stick with this Design Intent and see no reason to seek out an alternative method. Plinth Materials that have very stable properties in an environment are key to this. A plinth must have two properties in my view above any other: 1, It should not deform from its flatness across the different seasons and moisture levels being met in the air. 2, It should not expand in any dimension due to different moisture levels being met across the different seasons. If the Design for the Plinth is to have a materials which offers a Specific Intrinsic Damping Factor Measurement and offer the above properties then Densified Wood is looking likely to be the material to offer these properties. As for Stand Alone Tonearm Pods, much of my listening is carried out on other systems and one uses a Pod. I don't detect that any enjoyment of the music is lost, and it might need a very detailed analysis between the differing Tonearm Mounting Methods to produce an assessment of the Pro's / Con's where listening and perceived sound quality is the basis of the investigation. |
Pindac If by denified wood you mean panzerholz or lignostone then it is not stable. The stuff bends. You would need to anchor it to some other material or structure to prevent warping over time. I have seen some very expensive plinths that use panzerholz, and over time, you can see they are starting to come apart. |
I am familiar with Panzerholz used as a Single Board in 20mm and 32mm and I can safely say there is not any knowledge known to myself of it having any detrimental impaction on its properties in when solely chosen as the material for a Plinth. As a material used for plinths it is most likely to have reports on its usage that have close to a 12 Years History and I am not as yet with any recollection of seeing an information being offered informing of the material being unstable and not suitable for Plinth usage. I have discussed Panzerholz with a variety of Plinth Builders via Forums, Private Contact and Face to Face, I know some who have rejected it as a material for the Sonic Quality not being to their liking, but never for the deterioration of the material. During a recent search for a Product from the same producer, I learnt that Panzerholz is also used as the Cabinet Material on a High End Speaker Product. |