My SME M2 9 is quite light at 9.5g mass. It makes it edgy for some cartridges, esp those that are both light and low compliance (I'm thinking of a Lyra Delos which is not a perfect match as is). Ideally I'd like to add 7-10 grammes mass to the arm.
Reading around, the wisdom seems to swing from 'bung on a heavy headshell', to counterweight additions.
I think I can see that anything that causes the counterweight to be placed further back (like a heavy headshell would do) is not an ideal solution, so the added mass needs to be near the bearings...as near as possible. So? Behind the bearing assembly, (but is this in the right place, behind the balance point, to do any good)? Or maybe just in front of the bearing wrapped around the arm tube itself?
I have in mind cutting to size and weight some simple lead sheet (plumbers roofing repair type stuff) which has the obvious advantage of weight with little bulk, and the ability to stay in a shape (and hopefully, in place) once formed...I'll simply bend it around the arm tube.
All thoughts welcome. The present cartridge is also 'just' in the green OK resonance zone, so I'll try the final theory out on it and report back. Currently at 11Hz resonance, I can move it into the magic 'perfect 9Hz' zone by adding 8g.
Rockmiester I fear you are going down the wrong path.
If I understand correctly, your arm - cartridge combo is having trouble tracking certain records; they sound edgy. If this is so it is a case of
cartridge mistracking and has nothing to do with the LF arm-cartridge resonance. It is possible be that the arm tube is skewed, but that is highly unlikely. Many MCs are prone to mistracking, perhaps that is what you are hearing. I haven't used an MC for many years for this very reason. Bear in mind that when a cartridge mistracks, it damages the grooves. It would be helpful if you would give us the exact make and model of the cartridge(s) that is (are) giving you this problem. In the meantime, we can take a sample cartridge and do some sums to show you that added mass is not needed; indeed it is likely to be detrimental to the overall performance of the rig.
Let's pick the Ortofon Cadenza MC as an example. According to Ortofon's data sheet: C = 12 micro-m/mN and m = 10.7g = 11g (approx). Unfortunately ortofon do not specify whether this is lateral or vertical compliance, or an average, nor do they specify the frequency. Let's pretend it is vertical compliance, near the LF resonance for that is what matters. So we have effective m' = 21 g & C = 12 micro-m/mN. A bit of arithmetic gives a us an LF resonance frequency of approx. 10 Hz which is almost perfect! Your 11 Hz is even better, why would you wish to add mass to the arm to lower the LF resonance to the sub-10 Hz range where record-warps are worse?
A suggestion: Use a test record to check tracking and LF resonance. Only then will you be able to diagnose the actual problem.
Please play a badly warped record with your current rig. When going over sharp bumps, does the arm move up and down as it rides the bumps while the cartridge cantilever remains steady, or does the arm remain steady while the cantilever flexes to accommodate the bumps? Please report back and we can analyse further.
Edits:
P.S:- IIRC, an article published in the AES Journal back in the 1970s concluded that the optimum frequency for the LF resonance was around 12 Hz. It may have been by James Kogan of Shure.
P.P.S:- Poul Ladegaard of Bruel and Kjaer recommended even higher resonance frequencies. See:
http://www.laudioexperience.fr/wp-c...-Resonances-in-Turntables-AN17-233-1977-1.pdf