-edible zone-

  (click for full size)

-- Above: A Thorens TP16 in complete disassembly, and slightly damaged.  Can you find the damaged part?  Click above image for full size.

-- Date: 12-08-2010

-- Taking it apart completely: 

-- Recently another TD160C came my way. It had mostly good features to it but, unfortunately, it had a bent arm tube on its TP16 tone arm. In order to replace the arm tube it is necessary to disassemble the tone arm completely. This way we get to see all of the parts inside.

  TP16 pieces TP16 guts

  lower horizontal pivot lower pivot detail

  cone and cup 

-- The lower horizontal pivot bearing.  Cone and cup variety.  Cone is a ball race.  The cup is pressed onto the lower body barrel and consists of a circular array of steel bearing balls.  The cone can be seen as the conical ball race mounted on the shaft in the photo at left.

   Another view of the lower horizontal bearing cone.

  vertical pivots (hint: click thumbnail for full size image)

 vert pivot  left: one of the two vertical pivot bearings. Cone and cup design. The cup features 5 steel bearing balls in a race. Adjustment is by fine pitch threads on the cup and in the gimbal housing.

  vertical pivot   The vertical pivot cones are part of the same shaft, which is pressed into the cast housing

    Upper horizontal pivot brg. cone.  Showing some dust clinging to its bearing race.

 

____________________________________________________________horizontal pivot 

The next stage is to replace the bent arm tube with a straight one.

  arm tube assemblies The replacement arm tube prior to assembly of wires and coupler joint.

 

   

    There.  The replacement arm tube with tonearm wires and coupler joint assembled.  The old damaged arm tube can be seen above the new one.

  ____________________________________________________________________horizontal rule 

-- Further assembly details:

  (click for full size)

   The vertical pivot brg. cups have been flushed out with acetone to remove any dust/debris/residue.

   Vertical pivots installed.  Adjustment is prelimary.  Each cup screws in equal distance to fully engage the cones while locating the arm tube at the center of the gimbal.

   

    The vtf adjuster wheel requires the spring and detent ball to be assembled prior to fitting.

   With spring and detent ball in their socket.

   VTF adjuster wheel in place.  Note the very thin, almost invisible, cord that slots into the pocket within the wheel.  As the wheel is rotated, the cord tensions another spring within a tube above the counterweight.  It is a little tricky to install this cord correctly.  Sorry, no photos for this detail but if you have made it this far, I'm confident you'll figure it out as I did.

   VTF wheel with the upper horizontal bearing cone assembled.  The cone looked good under magnification.  Was cleaned in acetone.  Wiped dry with soft cloth and mounted.

   anti-skate magnet...above

   anti-skate magnet...underneath.  This is not a particularly strong magnet.  A refrigerator magnet exerts greater energy than this one.  It fits up beneath the under gimbal and is held in place by the steel tube that holds the lower horizontal pivot bearing cone.  The steel tube threads into the bottom of the inner gimbal and clamps the magnet solidly.

   The inner gimbal being assembled into the outer frame.  The tube extending out of the frame threads solid into the bottom of the inner gimbal.  The tube contains the lower horizontal bearing cone.  The aluminum housing, just to the side, contains the lower horizontal bearing cup.  The steel tube fits down into housing to engage the bearing cup.  Housing screws into bottom of the outer gimbal frame.

   With the housing partially assembled, but the upper horizontal bearing cup is not yet in place.

    With the upper horizontal bearing cup assembled. It threads into the outer gimbal frame to engage the upper horizontal pivot. Preliminary adjustment of the horizontal pivot bearings is to gingerly thread the upper cup until solid contact is made against the cone. Both upper and lower horizontal pivot bearing tension is adjusted by the upper cup. Free movement of the armtube is retained while the cups and cones are adjusted rather solidly. When finished, there is a decorative dust cap which snaps into place above this upper bearing cup adjuster.

   Preliminary check to view the partially assembled tonearm.

   Another view.

  __________________________________________________horizontal rule 

  TD160C 

-- In the box was this Grado Prestige Black. Used that for the test.

Alignment notes:The Thorens headshell jig is used to set overhang. Every TD160C came equipped with several accessories including the headshell alignment jig. Most, unfortunately, have been lost by their owners. I managed to keep mine. If you lack the headshell jig, overhang alignment for the TP16 is per Stevenson. So get a Stevensen based 2-point alignment protractor. Although it is sometimes possible to use a Baerwald protractor, (on this tonearm), but only if the distance between stylus and mounting holes on the cartridge you've got fitted is not too long. (Baerwald overhang lengths tend to be longer than Stevenson overhang lengths) Azimuth is set using a mirror and the headshell jig. VTA is set by leveling the arm tube to the platter. Adjustments made at the base mount using the two set screws to release /adjust height/ re-fasten. VTF is set by first balancing the arm to float slightly above record level with vtf ring set to zero, then adjusting the vtf ring to 2.0 grams of downforce. Antiskate was initially set to 2.0 grams, but later re-set during the hfnrr test record session to improve the scores on the bias tracks.

For more detailed information regarding tonearm and cartridge alignments see this link: here

For more detailed information on using the TP60 headshell alignment jig link: here

HFNRR Test Record session (HFN 001)

-- Side 1

  1. R/L was swapped, swapped again to correct

  2. phase=OK

  3. bal=ok

  4. bal -L=ok

  5. bal-R=ok

  6. clean

  7. clean

  8. clean

  9. buzz left

 -- Note:  tracks 6 through 9 (Bias tracks) are sometimes referred to as the 'torture tracks' because they measure tracking ability by providing a 300 hz tone with increasing decibel levels at each succeeding track. A clean pass means that the arm/cartridge was able to track through the band without buzzing at either channel. Tracks 8 and 9 are generally regarded as overkill in that there is likely no Lp track that will duplicate this level of amplitude. However these tracks are useful as a repeatable measure of how well a given arm and cartridge can negotiate them. In this case it appears that this relatively inexpensive tone arm and cartridge has scored very well. Very few tone arms/cartridges can pass cleanly through track 9. .......This indicates that the cleaning and adjustments made to the pivot bearings was successful.

-- side 2

  1. trackability = clean

  2. lateral arm/cart resonance test = 9 - 10 hz

  3. vertical arm/cart resonance test = 10 - 11 hz

  4. trackability = clean

  5. bal-R=ok

  6. clean

  7. equal by ear (azimuth check)

  8. unmodulated groove to evaluate residual system noise = quiet

  9. trackability = clean

 

-- Listening check

-- I put on Paul Simon, There Goes Rhymin' Simon. This Lp I am very familiar with and use it as a check for VTA setting. The limit here is the low priced Grado Black. This is their lowest priced offering. Even so, it re-produced the music on this Lp cleanly and with good ambiance. I have to admit, however, that this tone arm deserves a much better cartridge than the Grado Black. In the past I have listened to other TP16 (mk1) tone arms using much higher quality moving magnet cartridges to very good effect.

-- Conclusions:

-- The cleaning and adjustments made to the pivot bearings resulted in a tonearm that tracks difficult grooves very well. Frankly, I am surprised that it scored as well as it did on the hfnrr test record 'torture tracks'. All in all.....a success. Given this level of encouragement, it seems logical to consider the possibility of upgrading the standard tonearm wires of this tonearm to a higher quality wire. Silver perhaps. And then the RCA cables could be replaced with a high quality RCA jack plate with nice gold plate RCA jacks to accept the IC of your choice.

-- Additionally, I wonder how well this tonearm would handle low compliance MC cartridges known to energize arm tubes with needle talk. Would a Uwe bodied DL103R tend to rattle the pivot bearings on this tone arm, or would they handle the energy and allow the DL103R to sound like itself?