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Adding Mass to a Technics Tonearm

Okay this looks better than the prototype from my original post. I've added 4.3 grams of additional mass to the Technics Tonearm using 1/2" lead tape. The tape is used in Golf and Tennis to add more swing weight to clubs an rackets. The mass in tonearm applications helps to resonance and phono cartridge compliance.

Technics Tonearm Additional Mass

For the prototype I used 3.8 grams of plumbers putty. The final is completely reversible using 24mm of adhesive lead tape. The tonearm is sporting an AT440mla at the moment and singing.

Tonearm Lead Tape Tags

1 comments:

psychedeligoat said...

What exactly are you trying to achieve here?

http://forum.audiogon.com/cgi-bin/fr.pl?eanlg&1248642631

07-27-09: Viridian
The relationship between the arm and the suspension of the cartridge can be modeled like a spring. The springier, more compliant, the suspension, the less mass is desired in the arm to bring the total resonance of the system to the optimal point. Likewise, if the suspension is stiffer, more mass is required in the arm to keep the total system resonance at an appropriate frequency.

Interestingly, the weight of the arm is not of importance. What is importance is the effective mass, which takes into account the distance that the mass is from the pivot point. An extra gram at the headshell increases effective mass much more than a gram near the pivot point.

If the resonance of the system is too high it can be excited by low freqency tones within the music. If it is too low, warps will cause the resonance to be excited.

In your example, yes a one ton arm and one ton counterweight could play a record, provided that the compliance of the cartridge was suffienciently low. This is kind of theoretical though.

Commercial arms vary from somewhere around 6-7 grams effective mass all of the way up to 30 grams or so. Most medium mass arms, like the Rega, Audioquest/Jelco, Technics, etc. fall into the 9-10 gram range.

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