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
If you add a headshell weight to the tonearm it will change the resonance frequency of the tonearm and cartridge.
Adding weights to the headshell DOES increase the effective mass of the arm. Not just because of the weight itself, but also because to then balance the arm, the counterweight on the back end will need to be moved further from the arm's pivot, which also increases the arms effective moving mass.
it doesn't really alter the mass of the tonearm that much because of the pivot

Agree with bdp 24. Probably contra-intuitive but moving the

counterweight nearer to the pivot decreses the arm mass.

Adding weight to the headshell on the other side ''obviously''

increases the arm mass.

Even if you proceed with your experiment, you might just find that you don't have enough counterweight on the back of the arm. Headshell weights are usually for use with extremely light cartridges, but that isn't the case with 103R. 

I'd suggest trying the resonance test tracks on the HIFi News test record before and after any experiment. 

Also, a potential can of worms, but if you are planning this whole concept because of vinylengine calculator results "are you factoring in  the tendency for Asian, espec. Japanese, carts to establish their µm/mN compliance figure at 100Hz rather than the 10Hz typically used by the various on-line calcuators and formulas. Unfortunately many Asian manufacturers rarely publish that info. Euro carts generally use 10Hz.

I also understand, but am not an expert here, that there is no direct translation or conversion formula. The general rule I've read is to multiple the 100Hz compliance number by somewhere between 1.5 and 2.0, then use that result as part of the resonance frequency assessment. I use 1.75. Vinyl Engine gives the green light to resonance frequencies in the 8Hz to 11Hz range.". Cheers,
Spencer
As someone else wrote, adding mass to the headshell most certainly DOES increase the effective mass of the tonearm, by a factor roughly equal to the added mass, in grams. (As you move down the tonearm toward the pivot, the effect of adding mass at any point on effective mass lessens proportionately.)  Adding mass to the headshell will also cause you to need to move the counter-weight further back away from the pivot, in order to counter-balance the added mass and achieve the same VTF.  Doing that ALSO will increase the effective mass of the tonearm, by a factor equal to the square of the change in distance from the pivot to the center of mass of the CW, times the mass of the CW.  

From what I have been able to learn without owning a DL103 or 103R, there is almost no limit to the effective mass that those cartridges might "like".  One of my friends uses a home-made tonearm with his DL103 which appears to have an eff mass of nearly 50g! (Probably I am exaggerating, but it's mass-ive.)  I would suggest just experimenting with added mass at the headshell (and correspondingly re-balancing your tonearm) until you reach an effective mass that seems to be optimal for your cartridge. Then use a test LP to guesstimate the resonant frequency.
Dear @last_lemming:  I'm a little confused with your thread. First I seen you own the VPI TT, I don't know where the PL-530 could be the subject.

In the other side, which kind of problems already experienced with that Pionner TT and the 103R?

If what you want is to stay inside the 8hz-12hz  desirable resonance frequency you really need to know the real effective mass of your tonearm when the 103R is mounted and to take in count on that tonearm effective mass calculations the precise position where the tonearm counterweigth is " seated " because any minute changes in the counterweigth position affects those calculations. 

All depends what and why  you want to do that. Ask you before make anything.

Btw, you don't need to add weigth to the headshell you just need to change it for other with higher " natural " weigth.

Regards and enjoy the music,
R.
Raul -

 I have two systems, my "fun" system which has the pioneer Pl-530, and what I consider my "high end" system which has my VPI Prime.  I'm only talking about my  The system that has the Pioneer, which has the Denon PL-103r. The only reason I was asking about adding high is because I've read that the 80's turntables with "S" arms are lower mass and that the Denon likes a higher mass  tonearm.   I cannot find any specific literature about the Pioneers S arm and what it's effective mass is.  

While the Denon sounds really good right now in the system I was just wondering how much I was "leaving on the table" by not having a higher mass arm, this led me  wanting to experiment and see what I could achieve with higher mass tweaks. 
Dear @last_lemming : Ok. What you can do is to buy a higher weigth headshell and see what happen.

Now, when we change the headshell from with the cartridge is mounted for other diferent headshell it does not matters its weigth ( well it matters but... ) the changes in the " new " quality level performance comes not only from the weigth but from the new headshell build material, new headshell build shape and the new headshell wiresa/connectors. So, its not easy to say if the changes for the better or bad quality comes from the diferent weigth.

Regards and enjoy the music,
R.
First, I don't believe that "S" arms are necessarily lower mass.  That will be a function of the material the arm was formed from, how thick the walls, the length, and so on.  If fact for a given length, a straight arm with offset headshell will likely be lighter than an S arm with the same effective length when other factors are equal.

However, to experiment, you could take a small ball of Blu-tak or plumber's putty weighing a gram or two (use your VTF scale) and affix that to the headshell, rebalance the arm, and see if this offers any sonic/tracking improvement.  If so, keep adding weight until it becomes worse, then reduce it to the optimal.  If no improvement was observed, then forget about it.

Note if that does give an improvement you should be able to determine how much mass could be added for a more permanent solution.

Dear @pryso : """  Note if that does give an improvement you should be able to determine how much mass could be added for a more permanent solution."""

As I posted the " game " of "" adding mass " rigth at the headshell is not the best way to do it because when adding anything at the headshell you are changing the resonances colorations/distortions because the material used to increment the mass can works as a " damping " tool or the other way around depending on the kind of material used on it.

Regards and enjoy the music,
R.
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.