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back to 2078 index page

The tonearm in use: Fidelity Research model FR54

above image: the FR54 is put into place just to visualize its appearance on the TD124 chassis.  The armboard in the view has been previously cut to fit

a Rega tonearm and will not actually be used for this project.

DSC_5159.jpg (111320 bytes) hint: click on thumbnail to view image full size

Above photos: As received. A used Fidelity Research FR54 tonearm.

Pivot bearings work freely with no evidence of slop.  

Here is the data I have on the FR54:

Specifications:

Effective length: 245,0mm
Overhang: 15,0mm
Offset angle: 21,5
Effective mass: 16,0g
Cartridge weight range: 4,0g 16,0g
Tonearm height adjustment: 30,0mm 90,0mm
Mounting hole: 21,0mm
Null points: 59/120mm
Made in Japan.

Fitting the cartridge

DSC_5206.jpg (222944 bytes) The standard headshell weighs 9.9g

DSC_5207.jpg (268038 bytes) with a brass headweight: 14.5g (headweight weighs 4.6g)

**The counterweight weighs 122 grams**

The combined weight of the headshell, the headweight and the Uwe Panzerholz bodied DL-103R is ...... 27.8g  do a little arithmetic and we understand that the weight of the Uwe Panzerholz DL-103R is 13.3g.

DSC_5837.jpg (112942 bytes)

With this much information we can anticipate how much additional weight at the headshell end could be added before a heavier counterweight would be needed.

Cart weight range: 4.0 - 16.0g (rated by the mfr)
actual cartridge weight as pictured: 13.3g

If we substitute a heavier headshell how heavy can it be?

example: Sumiko HS12 headshell weighs 11.4g

The standard FR headshell weighs 10.0g. : difference = 1.4g 

This may be slightly more than the counterweight can balance, however, to achieve 2.5g vtf, the cw won't need to be positioned all the way back.  It may work.  Although we can still subtract the 4.6g brass headweight to achieve balance.

If the goal were to use the HS12 headshell, then it seems very likely that it will work in this instance...but the brass headweight may have to be eliminated.

A new armboard from Basswood* is cut and drilled.  Mounting distance from spindle center to pivot bearing center is 230mm. A special purpose gage is being used to double check the accuracy of the -spindle to pivot- distance (aka mounting distance).  A separate arc protractor will be used to set overhang and zenith.

DSC_5394.jpg (149515 bytes)

DSC_5395.jpg (165312 bytes)

Once we are satisfied with the quality of fit, and the quality of sound, the armboard will receive a multi-coat black lacquer paint job.

* Basswood is one of the materials used in acoustic guitar making for its quality of tone.

Armboard after finish coats:

DSC_5456.jpg (114702 bytes) DSC_5457.jpg (131833 bytes) multi-coat acrylic lacquer.....piano black.

 

Alignments: Overhang

DSC_5841.jpg (153400 bytes) Setting overhang and zenith angle with an arc protractor