A fortnight ago met up with fellow forumer mpw to see if a Denon DL103 cartridge can be made to work on his Technics SL 23 turntable. The effective mass of his arm is 12 grams. So at least in theory if there is enough counterweight mass, it should be possible to balance the 8.5 grams mass of the DL103. From the outset, I suspected that the counterweight mass will not suffice so I brought some extra weights with me to tie/attach to the counterweight. Turns out his arm does not have enough counterweight mass to properly balance the DL103. So the extra weights came in handy. After much misadventure including a broken headshell wire that had to be re-soldered, the combination played nicely, aided by the rubber band that held the extra weights to the counterweight. But it was obvious that larger mass was needed.
Also, a huge hum developed while we were fooling around with his setup. Much troubleshooting ensued. Finally it was decided we will try making a heavier counterweight for his arm, and change his tonearm cables and replace the 2-pin power connector. So I ended up bringing home his turntable and his LehmannAudio Blackcube II SE phono stage for the above work.
So for the first time in my life, I made use of the formula for a cylinder that one learns in high school.
Mass of Cylinder = Density of Material x Volume of Cylindrical body
= ?V
= ? x (?r^2h)
Here's the drawing of the "cylinder":
There are two cylindrical cutouts here - one for the counterweight stub, and the other for the grub screw that will tighten the counterweight to the stub. So these two cylindrical cutouts get subtracted from the actual mass. So mass
= ?(V - V1 - V2)
So I worked backwards with radius of the holes for stub and grub screw, as well as h already defined, with target weight of 168 grams (a la the super heavy Jelco counterweight), with only the outer radius kept as unknown.
This is the outcome:
I made one for my Origin Live tonearm as I need to use two counterweights to balance the DL103 when using a super heavy DIY headshell spacer.
Here they are side by side. The inner radius of the two designs differ as stubs are of different diameters, but target weight for both is same (168g):
After chrome plating (the right most weight):
The others are (L to R): stock counterweight of Technics SL 23 (106 g), stock counterweight of Origin Live Silver Mark IIIa (106 g), heavy counterweight of Silver Mark IIIa (136 g), and the new kid on the block (168 g).
Here it is mounted on the Technics SL 23 arm:
There is enough stub length for even heavier cartridges. There is about 10 mm length left on the stub after balancing a DL103 with a 9+ gram spacer, using a headshell borrowed from a Technics SL 1210. The spacer is needed for two purposes - for correct VTA and to increase effective mass of the tonearm for the low compliance cartridge.
Next step: to measure the resonance freq of the combination and calculate the new effective mass.
It is playing well and seems to be a bit more energetic.
Also, a huge hum developed while we were fooling around with his setup. Much troubleshooting ensued. Finally it was decided we will try making a heavier counterweight for his arm, and change his tonearm cables and replace the 2-pin power connector. So I ended up bringing home his turntable and his LehmannAudio Blackcube II SE phono stage for the above work.
So for the first time in my life, I made use of the formula for a cylinder that one learns in high school.
Mass of Cylinder = Density of Material x Volume of Cylindrical body
= ?V
= ? x (?r^2h)
Here's the drawing of the "cylinder":
There are two cylindrical cutouts here - one for the counterweight stub, and the other for the grub screw that will tighten the counterweight to the stub. So these two cylindrical cutouts get subtracted from the actual mass. So mass
= ?(V - V1 - V2)
So I worked backwards with radius of the holes for stub and grub screw, as well as h already defined, with target weight of 168 grams (a la the super heavy Jelco counterweight), with only the outer radius kept as unknown.
This is the outcome:
I made one for my Origin Live tonearm as I need to use two counterweights to balance the DL103 when using a super heavy DIY headshell spacer.
Here they are side by side. The inner radius of the two designs differ as stubs are of different diameters, but target weight for both is same (168g):
After chrome plating (the right most weight):
The others are (L to R): stock counterweight of Technics SL 23 (106 g), stock counterweight of Origin Live Silver Mark IIIa (106 g), heavy counterweight of Silver Mark IIIa (136 g), and the new kid on the block (168 g).
Here it is mounted on the Technics SL 23 arm:
There is enough stub length for even heavier cartridges. There is about 10 mm length left on the stub after balancing a DL103 with a 9+ gram spacer, using a headshell borrowed from a Technics SL 1210. The spacer is needed for two purposes - for correct VTA and to increase effective mass of the tonearm for the low compliance cartridge.
Next step: to measure the resonance freq of the combination and calculate the new effective mass.
It is playing well and seems to be a bit more energetic.
.
