Adding mass to a tonearm


I would like someone to explain to me why adding headshell weights doesn't really alter the mass of the tonearm that much when figuring cart vs tonearm compliance. I have a Denon DL-103r and I keep reading that's it's for high mass tonearms. I also hear that adding headshell weights doesn't really alter the mass. What gives?

I want to try a DIY on my Pioneer PL-530 turntable tonearm where I mask off the arm such that only the chrome arm on the headshell side is visible and spray it with Plastidip. This would seem to add mass and resonance control. If it doesn't work the I can just peel it off.  
last_lemming
Raul, and last_lemming, maybe I didn't make myself clear.  My suggestion to experiment with bits of clay to add mass was not meant as a permanent condition.  It was merely an easier way to find out if, and how much, added mass would improve the performance of the cartridge.  It went without saying if say a 2 or 3 gram increase was beneficial, then find a headshell that much heavier.

Otherwise, experimenting with a number of different headshells could get expensive and would be very time consuming, given consideration to mounting and alignment for each trial.  That was why I included the thought of "a more permanent solution".

I tend to agree with Pryso.  Look at the Technics EPA250 tonearm: The optional arm wands with lowest effective mass are all straight pipes with a tiny fixed headshell.  The arm wand with high-ish effective mass is an S-shaped pipe with provision for optional headshells.  This suggests that Technics realized the effect of pipe shape on eff mass. However, I also agree with Raul.  Adding mass to the headshell is not "the best" way to increase effective mass.  Changing the headshell for a heavier one would be the simplest alternative way to go but as Raul also said, this will also change the "sound" by a bit.  Another route is to add some mass evenly across the length of the arm wand, by wrapping it with tape or heat-shrink or whatever.  But ALL of these methods will possibly change the sound.
Hi, just wondering how you went with your experiment, as I am in the process of doing the same thing? I have a Grace 747 that I want to add some mass to, and want to use it with a Miyajima Kotetu/Spirit mono cartridge. These carts are extremely low compliance, and should be used with a high mass arm. I just want to save money and use what I already have, or I will have to buy an Audiomods series 5, which looks awesome.
Kombi, I think you can find the consensus of opinions by reading the above posts.  If you want to save money, of course you can just add mass to the headshell.  (There's no law of man or audio against doing that.) Raul and others mentioned the possible drawbacks of going that route, but it certainly "works", and it's certainly a cheap experiment. But first of all, I would listen to what you've got until you have a very firm grip on how it sounds and whether you really feel the need to do anything at all.  Then when and if you do decide you need higher effective mass, you will be able to sense whether adding mass takes you in the right direction.

I bought various screws for my Reed 3p tonearm to add weight, because most vintage MM cartridges i have are too light, still usable, but the counterweight of the toneam is too close to the pivot, so those 12mm cartridge mounting thumb screws are 1.51g each (about 3g for pair) and made of the gold plated brass (non magnetic). Available here in various size and weight. Recommended!