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note: this is a new reference.  The Shelter 501-II was replaced with a Denon DL-103R lomc cartridge.  Reason: The Shelter was producing some unwanted distortions and is now parked in its case.

Measure for Rumble and wow & flutter.

methodology: play test record on sp10mkII using a Graham 2.2 tonearm with a Denon DL 103R (with wood body/soundsmith ruby-LC cantilever-stylus) MC cartridge mounted.  The SP10mk2 is mounted into its "Test Mule" plinth.  The plinth stands on a Minus_K isolation platform as pictured above.  Signal chain: From the Graham, the phono cables plug into a step up transformer, then into the Hagerman Trumpet phono stage.  From the stage the signal is fed directly into a MasterLink 9600 hard drive recorder.  The Masterlink records the test record tracks and then burns a 24-96 hi-rez CD recording.  The plot spectrums seen below were developed in Audacity.  

 300hz_2.jpg (138728 bytes) 300hz tone @ +12db (HFN 001 test record)


Bass drum 3.jpg (141109 bytes) Bass Drum (Shure TTR-110 test record) (3rd drum hit)


Rumble_2.jpg (140387 bytes) Silent Groove (rumble test) (HFN 001 test record)

DSC_0319.jpg (74368 bytes) detail of the DL-103R lomc mounted in a Uwe Panzerholst wood body.  SoundSmith Ruby cantilever / Line Contact diamond stylus

DSC_0320.jpg (114588 bytes) 

DSC_0356.jpg (137653 bytes) cartridge close-up




Bearing Maintenance

hint: to view photo full size, click on the thumbnail

DSC_0211.jpg (142541 bytes) Looking at the thrust pad that is attached to the tip end of the bearing shaft.  From here it is not possible to determine how this thrust pad is attached.

DSC_0213.jpg (217807 bytes) But with some help from around the web, others indicate that the thrust pad is really just a cap that snaps over a knob end of the shaft.  Using a pocket knife, I very gently pressed the knife edge between the pad and shaft.  Very lightly.  And the cap lifted off with no resistance.

DSC_0214.jpg (149419 bytes) This is what I found beneath.  And a little bit of gunk left over from decades of operation.

DSC_0218.jpg (195124 bytes) Side view to see the shape of the "knob end".

DSC_0222.jpg (253988 bytes) Looking at the underside of the bearing cap.

It may be debatable if it is really necessary to replace this thrust cap with a new one, since it shows moderate wear at the thrust end.  (wear indicator = the size of indentation made from contact with the bearing ball that the cap thrusts against as the platter shaft spins)

I will look into having another wear cap made.  Perhaps I will make a small quantity and sell those at my cost to others needing a new thrust cap.

thrust pad sketch_lettersize.jpg (196428 bytes) Dimensional sketch of bearing thrust cap.

The first thrust cap is made.  Here at The Analog Dept. Date: 12/30/2013

below: determining accuracy of the machining.

DSC_0327.jpg (222955 bytes)  DSC_0328.jpg (232307 bytes) 

Above: checking pad thickness ( in inches ) This (analog) dial indicator only reads decimal inches.  Its' finest graduation is .0005".  slang: 5/10ths  or 5 ten-thousandths

Btw.  This record player was manufactured in Japan where the metric system is used for all dimensions.  Given that, and where possible, all dimensional references are in the metric system.  To convert from decimal inches to millimeters simply multiply the decimal inch value by 25.4.

DSC_0329.jpg (182743 bytes) DSC_0330.jpg (204742 bytes) 

Above: checking the outside diameter and then the length

DSC_0333.jpg (184425 bytes) DSC_0334.jpg (182171 bytes)

Above: First ..........setting the Mahr gage.  Then measuring the inside diameter of the thrust cap.  Note: The Mahr gage is in inches while the setting micrometer is reporting in millimeters.  Btw, the Mahr gage is very sensitive.  Its finest graduation is 50 millionths of an inch.  ( .00005" )  Zero on the dial is set to the nominal diameter.  Deviation is indicated either positive or negative from that nominal.  



DSC_0335.jpg (233323 bytes) DSC_0337.jpg (254791 bytes)

Above: visual examination of the new Torlon 4301 thrust cap next to the old standard Nylatron thrust cap.

The Fit

DSC_0341.jpg (144450 bytes) DSC_0342.jpg (142127 bytes) DSC_0343.jpg (164148 bytes)

Testing: Next

With Torlon 4301 thrust cap newly made and installed.

300hz tor4301.jpg (140938 bytes) 300 hz plus 12 db HFN 001

bassdrum__tor4301.jpg (152252 bytes) Bass Drum Shure TTR-110

rumble tor4301.jpg (151301 bytes) Silent Groove HFN 001

1 week after:

4301_1wk.jpg (156393 bytes) A very small dimple

The next three plots (same tracks and order as above) are measured 1 week after installation of the 4301 thrust cap. Date: 1/6/2014

300_4301_plus12_2.jpg (142236 bytes) 300 hz plus 12  HFN 001

Bass_drum4301_2.jpg (151946 bytes) Bass Drum Shure TTR-110

SG_4301_2.jpg (148068 bytes) Silent Groove HFN 001

2nd Thrust Cap: Torlon 4203  Date: 1/6/2014

DSC_0345.jpg (210648 bytes) DSC_0347.jpg (139556 bytes)

Above photos: Left: Torlon 4203 .......Right: Nylatron original equipment bearing

DSC_0352.jpg (121630 bytes) 4203 cap mounted.

4203 Test Record plots:

right after installation:  (1/06/2014)

300 hz plus 12 HFN 001

Bass Drum Shure TTR-110

SG_4203_1.jpg (148648 bytes) Silent Groove HFN 001

1 week after: ( 1/13/2014 )

DSC_0365.jpg (151495 bytes) after 1 week of normal play. Approximately 3 - 4 hours each day.

4203_300_2.jpg (141594 bytes) 300 hz plus 12 db  HFN 001

4203_bassdrum_2.jpg (148866 bytes) Bass Drum Shure TTR-110

SG_4203_2.jpg (146293 bytes) Silent Groove HFN 001

Black Delrin Thrust Cap

DSC_0361.jpg (258240 bytes) DSC_0363.jpg (229963 bytes)

Above photos: Delrin cap at left, original Nylatron cap at right.

DSC_0366.jpg (155424 bytes) DSC_0367.jpg (150566 bytes)

Above photos: New Delrin cap at assembly.  Left; partly on.......Right; seated on

Right After Installation:

Delrin_300_1.jpg (132662 bytes) 300 hz +12db.......HFN 001

Delrin_bassdrum_1.jpg (149860 bytes) bass drum......Shure TTR 110

SG_Delrin_1.jpg (135344 bytes) silent groove.......HFN 001

See anything different?

Only change = Delrin thrust cap

1 week after installation:


DSC_0404.jpg (120206 bytes) 1 week of normal play

Delrin 300 1wk.jpg (119699 bytes) 300 hz +12db .....HFN 001  

delrin bdrum 1wk.jpg (128668 bytes) bass drum------Shure TTR 110

Delrin SG 1wk.jpg (127489 bytes) silent groove.........HFN 001

SG delrin b4_aft.jpg (262804 bytes) silent groove side by side. Left; Delrin fresh install.  Right; Delrin 1 week after

comments:  Now after 1 week it appears that the Delrin thrust cap plots out just like the other cap materials.  The dimple size on the cap appears normal in comparison to the other materials.  But the question persists; why did the freshly installed Delrin cap plot out so much more quietly in the first place, and then what changed in the 1 week plot.

I can say that no part of my methodology, in these tests, has changed.  The only apparent difference between the before and after on the Delrin cap is the small evidence of wear at the thrust.  At this point I will refrain from speculating and just let the evidence lie, while continuing  these material tests.


MDS filled Nylon Thrust Cap


DSC_0401.jpg (244901 bytes) DSC_0403.jpg (193430 bytes)

Above photos: The new replacement Nylon cap on the left.  The original nylatron cap on the right.

DSC_0406.jpg (177338 bytes) DSC_0407.jpg (87332 bytes) DSC_0408.jpg (82336 bytes)

Note on machining nylon.  The material cuts cleaner with very, very sharp cutting edges ground with extreme rake angles.  Any further production of Nylon thrust caps will include greater attention to producing cleaner cuts than I have done on this first sample.

Test plots conducted just after assembly of the nylon thrust cap:

Nylon_300.jpg (141365 bytes) 300 hz +12db........HFN 001

Nylon_bdrum.jpg (149814 bytes) bass drum..........Shure TTR 110

Nylon_SG.jpg (146952 bytes) silent groove......HFN 001

Silent groove notes: appears to compare with all previous material test plots except to the fresh Delrin plot, which may be in error.


DSC_0452.jpg (172153 bytes) 1 week after installation.  Under normal use conditions.

Test tracks after 1 week of normal use

Nylon MDS 300_2.jpg (142589 bytes) 300 hz @ +12db.......HFN 001

Nylon MDS bdrum_2.jpg (147876 bytes) bass drum track........Shure TTR 110

Nylon MDS SG_2.jpg (148570 bytes) Silent Groove........HFN 001



Kevlar Filled Nylon

product name: Hydlar Z 

Material Manufactured by: Ensinger

DSC_0450.jpg (284323 bytes) DSC_0451.jpg (232369 bytes)

Above: Left: new replacement Hydlar Z thrust cap;  Right: original Nylatron thrust cap

DSC_0453.jpg (122125 bytes) DSC_0454.jpg (135890 bytes)

Above: Left. new replacement Hydlar Z thrust cap parked loose on the shaft knob end.  Right: Seated on.

Test Record plots with the new Kevlar filled Nylon thrust cap (Hydlar Z)

Hydlar_300.jpg (143631 bytes) 300 hz @ +12db.........HFN 001

Hydlar_bdrum.jpg (147359 bytes) bass drum ............ Shure TTR 110

Hydlar_SG.jpg (149690 bytes) silent groove ......... HFN 001

After 1 week (Hydlar Z)

hydlar_1wk.jpg (216027 bytes) 1 week Note the minimal wear.  Without magnification it is not possible to see any evidence of wear.

Hydlar_b4_after.jpg (154815 bytes) b4 and after

hydlar_inclusion.jpg (141789 bytes) note the inclusion of unknown material.  I can't say if this happened because of the machining process, or if the inclusion was within the material prior to the machining. Then consider that I have machined three caps from this same stock and neither of the other two have the inclusion.

Test plots 1 week out.

Hydlar_300.jpg (143631 bytes) 300 hz @ +12db.........HFN 001

Hydlar_bdrum.jpg (147359 bytes) bass drum ............ Shure TTR 110

Hydlar_SG.jpg (149690 bytes) silent groove ......... HFN 001

No difference noted.  Minimal 

Cap Material Summary:
At this point I've tried 6 different materials for the thrust cap job.  During this trial period I have observed some differences in the rate of wear between these materials over the 1 week test period that has been in use for each material.  The following reports the diameter of the wear spot on each cap within this report.

Instrument in use: a 10x Loupe with reticle manufactured by Peak (Japan).  This reticle is in decimal inches and resolves to .005 graduations.

(note: this symbol is gd&t for 'diameter'.)

4301_1wk.jpg (156393 bytes) Torlon 4301 at 1 week.  Wear: .025 inches

DSC_0365.jpg (151495 bytes) Torlon 4203 at 1 week.  Wear: .025 inches

DSC_0404.jpg (120206 bytes) Delrin at 1 week.  Wear: .035 inches

DSC_0452.jpg (172153 bytes) MDS filled nylon at 1 week. Wear: .040 inches

hydlar_1wk.jpg (216027 bytes) Kevlar filled nylon (Hydlar-Z) at 1 week.  Wear: ?imperceptible.  In different light and without magnification I can barely make out a shiny spot, but can not reliably 

for reference: 

DSC_0211.jpg (142541 bytes) original equipment thrust cap: I think the material is nylatron but will not bet on it. Period of use: 37 years.  Wear: .095 inches

Other notes: The test record report graphs were produced before and after the 1 week period on each cap material.  I saw no appreciably change between fresh and 1 week in this reporting.  Except for the Delrin results which I'm tempted to toss out as an unexplained anomaly and I doubt its validity.  Also it is useful to take note of the test record reporting on the original equipment 37 year old and well worn cap compared to any of these new materials.

Rumble_2.jpg (140387 bytes) OEM cap silent groove plot: 37 years of use

SG_4203_1.jpg (148648 bytes) Torlon 4203 silent groove plot: freshly installed.

Apart from the test record plots, listening sessions did not truly indicate any audible difference in sound quality between the above thrust cap materials.  In each case sound quality was as good as I'm used to hearing from this player.  Next step; the thrust bearing ball that the thrust cap spins on.  Will a difference in material and quality of this bearing ball make a measurable or audible difference?  

Thrust Balls:


Does it make sense to try different materials and grades of the bearing ball in the thrust end of the platter bearing?  Let's see if we can't prove it one way or another.

Ceramic: 9/32" SiN4 Ceramic grade 5  (sourced from Boca Bearing Company)

DSC_0479.jpg (196610 bytes) Prior to assembly, the ceramic ball is perched in the cup end of the thrust cap that will be used.  Looking close, the ball has a highly polished finish.  And also tiny bits of dust clinging tenaciously to its outer surface.  I wiped the ball with a chamoise several times to no effect.

DSC_0477.jpg (190685 bytes) Looking at the interior of a freshly made Torlon 4203 thrust cap.

DSC_0478.jpg (164194 bytes) Exterior detail.  The Torlon 4203 cuts fairly clean with commonly used lathe tool bits of carbide and high speed steel. A hand held metal file was used to apply edge breaks while the part was turning in the lathe. The part was cut complete in a single setup. Turning the OD.  Facing off the open end. Drilling with a center drill to open up for the boring bar, which was used to cut the ID for size and also used to cut the interior face to depth. To establish the length of the part, a parting off tool was used.  To finish it, a secondary operation was applied using a bench lap to lap the thrust face of this part into a smooth condition. This process has been used on all of the above thrust caps, including this one.


Replacing the plastic thrust cap at the tip end of the bearing shaft is somewhat simpler than replacing the bearing ball.  For the cap all one needs to do is leave the player upright and disassemble the platter from the motor unit, then remove another 'gazillion' machine screws an assortment of keepers and cover plates......and a platter brake assembly.  After than we can gingerly lift the rotor, the very valuable rotor, up out of its bearing housing. To understate it, Technics has their player securely buttoned up and held together tight.  

But to remove the bearing ball at the bottom of the bearing housing, one needs to hold the motor unit upside down safely and securely, then unscrew another gazillion machine screws to remove the bottom cover.  Having done that it exposes the main-board circuitry and the all important platter bearing thrust cup sticking up in the middle of it all.  But one needs be careful not to disturb the printed circuit boards and the small city of electronics parts attached to them. Or perhaps it is better to remove the printed circuit board prior to removing the bottom bearing thrust cup. The parts on this player are rare and valuable.  See elsewhere in this article ( Disassembly photos ) for some details on removing the platter bearing thrust cup.  It is held on by threads and a generous amount of thread sealer.  Care needs be taken.  Care and technique...if you want to avoid damage.


DSC_0486.jpg (117274 bytes) The bottom thrust cup once removed.

DSC_0485 copy.jpg (164807 bytes) Looking into the thrust cup.  Notice the threads, the spot face at its bottom and the prominent crater that indicates previous use.  The bearing ball holds a fixed position, does not turn and is held in firm contact with both this cap and the side walls of the bearing housing where it resides.  click the photo to view it full size.  Then notice two bits of annotation.  A number 1, indicating the spot face surface, and a number 2, indicating a wear spot where the bearing ball makes firm contact with the cup.

Let's measure the wear spot to see how deep the crater is:

DSC_0487.jpg (195287 bytes) A granite based drop indicator is used to measure the wall thickness at the cup bottom.  This shot shows the indicator almost set to zero. This was adjusted prior to making measurements to exact zero on the big dial.  Also take note of the smaller dial within the face of the indicator.  It is also set to zero. That smaller dial counts revolutions of the large needle.  One rev is .050 inches.

DSC_0488.jpg (191424 bytes) Checking the spot face area for thickness.  What's the reading? Reading the two dials I get .096 inches of wall thickness between the cup bottom and the spot faced surface.

DSC_0489.jpg (196764 bytes) Checking in the center of the wear crater. What's the reading?  Look at it two ways.  Compare this reading to the previous reading taken on the spot face surface to get a simple depth read.  Just subtract the smaller value (crater read) from the larger value (spot face read) to find depth of the crater. I get just a touch over .001" of depth in that crater.  Not very deep.  You can also figure wall thickness at the crater bottom simply by reading the dials.  For that I get .095 inches.  Isn't this fun.

While I've got the thing apart let's take a look at some other sizes.

DSC_0480.jpg (212916 bytes) I'm using a Mahr gage to find the size of the bearing housing ID.  I used the Mahr gage to scan up down and around within this housing.  The gage indicates a straight through bearing bore with no relief areas, that is straight and round.  Variation of the readings was less than .0002 inches.

DSC_0483.jpg (195641 bytes) Using a micrometer I'm gaging the diameter of the original equipment thrust bearing ball.  Guess what; the .2815 inch ball is closely size for size with the bearing housing inside diameter. This also works out to a fractional inch size; 9/32".  Go figure.  A Japanese manufacturer, where the metric system dominates, choses a 9/32 inch bearing size for their top of the line record player.  What this leaves us with is a bearing ball that is size for size with the bearing housing it must fit into.  A small amount of force is used to assemble and disassemble the ball from the housing each time.  That way the ball is not allowed to move, not even slightly, while doing its job at the bottom of the platter bearing.

DSC_0482.jpg (179338 bytes) Checking the new SiN4 Ceramic grade 5  bearing ball.  Funny, it checks .0013 inches larger in diameter than the oem ball.  And this is over the nominal 9/32" stated size for this bearing.  What it means is that if I use this bearing ball it will need to be pressed into the bottom end of the bearing housing.  Should I do that or should I find another ball?  As it turned out I just placed the ceramid ball on the opening end of the bearing housing, then screwed the bottom cup down over it to press the ball into position.  The required force did not seem excessive to my calibrated wrist as I wrenched the threaded cup down over its fitting.

Test Record Plots for the ceramic ball:

ceramic_300.jpg (140742 bytes) 300 hz @ +12 db.......HFN 001

ceramic_bdrum.jpg (146354 bytes) bass drum .......... Shure TTR110

ceramic_SG.jpg (145814 bytes) silent groove ............. HFN 001

As I review this group of test plots and compare against previous plots from the different materials while using the oem bearing ball, I see that there are some small differences in the measurements. In particular as I look at the silent groove plot exclusively I can find differences between them on the order of 2 to 3 db.  And that is all.  This is not significant.

After 1 week: 2/9/2014

DSC_0496.jpg (113831 bytes) after 1 week.  Wear spot measures .030 using a 10x magnifier with reticle.

Wear rate does not stand apart from the previous group when using the standard issue hardened steel bearing ball.

Test record spectrum plots after one week

ceramic300_4203_2.jpg (143270 bytes) 300 hz @ +12 db.......HFN 001

ceramicbdrum_4203_2.jpg (149475 bytes) bass drum .......... Shure TTR110

ceramic_SG_4203_2.jpg (147665 bytes) silent groove ............. HFN 001

Listening notes:

I heard no overt differences in this configuration than I had previously.  Perhaps, there were some subtleties to be appreciated.  Inner details seem nicely rendered.  I can't say that I did not notice this in any of the other cap/ball configurations.  Nonetheless, sound quality is as good as I have heard it over the duration of this bearing cap/ball test session.  As good as I've yet to hear out of this motor unit regardless of configuration.