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An O-ring idler wheel for the Thorens TD124, TD135, TD121 and TD184 From AudioSilente in Rome, Italy.

Review period: February 2017 to November 2017 

Price: $48.00


The wheel is nicely machined in aluminum.  Bushing is bronze. Comes with instructions and three spare O-rings.  As delivered, on the wheel is the black rubber O-ring.  In the bag are two red O-rings and one other black. The shiny red one is silicone, the others are rubber.  Presently I'm listening to the black rubber that was on the wheel as received. 

DSC_3391.jpg (274745 bytes) DSC_3392.jpg (215402 bytes) DSC_3393.jpg (316964 bytes) DSC_3394.jpg (195782 bytes)

 DSC_3395.jpg (231075 bytes) DSC_3399.jpg (223565 bytes) Left.  Two photos.  The Thorens idler wheel, then the Audiosilente O-ring wheel.

DSC_3403.jpg (213726 bytes) DSC_3402.jpg (175303 bytes)  The Audiosilente wheel out of the wrapper.

DSC_3400.jpg (190856 bytes)  Left: looking at the exposed TD124 chassis with platters off and directly at the idler wheel axle shaft, thrust washer and phenolic spacer washer beneath.  The phenolic spacers are used to adjust wheel height relative to the stepped pulley that drives it.


DSC_3409.jpg (210127 bytes)

Link to movie file of the wheel in action. (.mov file -- Quicktime movie)

Early notes:

Fit and finish appear excellent.
There was a need to adjust wheel height by using a different combination of phenolic spacers beneath the thrust washer.
Visually, the wheel appears to spin true in all axes.  The O-ring appears to be well seated within the wheel and spinning true.
SQ: most prominent difference: bass seems better defined and also more prominent.  Good sense of visceral thrust.  No loss of detail in the other sound frequencies.

Notes: 11/18/2017

To avoid reader confusion let me define some terms:

diameter.  all rings supplied have the same diameter so that they may fit over the same aluminum wheel
cross sectional thickness (which is also correctly described as a diameter of the cross-section)  
materials:  Red rubber, red silicone, black rubber, black silicone

I see two different cross sectional thickness'  in the supplied kit of rings.  The fat ones have a thickness of 3.5mm.  * The thin ones are 2.5mm.  The thin rings when fitted to the wheel will cause a smaller outside diameter at the rim than the thicker rings.  Because this is an idler wheel, different diameters at this part does not affect platter speed which is controlled by motor rpm, pulley diameters and the inside driven rim diameter at the platter.

footnote: the symbol is GD&T for 'diameter' and is used in drafting documents commonly seen in Aerospace manufacturing

At present I'm using the 'fatter' red silicone O-ring....and have been since May this year.  With the red ring I can confirm my earlier listening observations made while using the 'fat black' O-ring.  Speed from a cold start comes up to the mark on the strobe within the first revolution.  This was the case with the previously worn Thorens idler.  And it reflects on how well my motor and drive train refurbishments were carried out.  However, now with the the AudioSilente idler wheel, I have an apparent better sense of constant speed.  While this might have been achieved with other idler wheels, including new wheels available from Schopper in Switzerland, speed seems as consistently steady as I've ever heard on a TD124 in my listening room. 

About the noise floor and the new idler wheel.  I have not made any recordings so that I might use software to present Signal to Noise Ratio charts as evidence of my listening observations.  I thought it inappropriate since the previous idler wheel used on this particular player was worn and showing evidence of age (small crack lines in the rubber) and hardening of the rubber.  So these observations are based on my senses of hearing and sight.  That much said, the test deck, sn 13943 is a mk1 with mk1 configuration motor mounting grommets.  Initially I tried this wheel on the deck while the deck was equipped with new but standard rubber motor grommets.  Then I changed from using the rubber grommets to using some silicone grommets from Geltec in Japan.  With the Geltec grommets the deck ran quite obviously quieter than with rubber.  All the while using the Audiosilente idler wheel.  So....with this idler wheel and with the Geltec grommets in the deck while situated in a heavy slate plinth, the drive train noise is quite low and acceptable to me.  Perhaps an upgrade to the mkII grommet kit would improve drive train noise to even lower levels.  As it is, I'm happy.

With regard to making listening comparisons between the black rubber o-ring and the red silicone o-ring I can't say that there are any overt easily recognizable differences heard between the two.  Other words, listening is very good with either one.  Try them all, you decide.  I'm happy with the fat rings.  The smaller 2.5mm o-ring seems a but slim on cushion against the driving stepped pulley for my squinty, skeptical eyes.  That said I have yet to try the skinny rings but I might later.  You try them, you decide.

With regard to the machined wheel I can say that the idler wheel runs very true for concentricity and also true in terms of any apparent vertical run-out.  The video I produced earlier this year will serve as evidence of that.  The machining on this wheel is 'top tier' for accuracy of form, fit and function.  And the cosmetics are also top tier.  A classy product.

Link to movie file of the wheel in action. (.mov file -- Quicktime movie)

With this wheel I get; excellent bass, momentum and musical details high and low.  After changing motor grommets from rubber to silicone, drive train noise was reduced to expected levels.



Note: the Audiosilente website is in Italian language.  Speaks English.

Simone's email: [email protected]

also: [email protected]


-Steve (webmaster)