Phono Stage upgrade to complement Dohmann Helix One Mk 2

Effective mass of the tonearm will be related to the mass of the CW X (distance from center of mass of CW to pivot)-squared. So if you want to minimize EM then you’re nbest off with a heavier CW placed closer to the pivot.

@drbond, I can make mounting plates but I thought it was a counter weight you needed. The counter weight of the CB is in two pieces. The larger section unscrews from the top section through which the tonearms shaft passes. There are three different bottom sections. The arm comes with the intermediate section then there is a lighter one and a heavier one. Both @lewm  and @rauliruegas  are entirely correct. Depending on the mass of the cartridge and the VTF you want to choose the counterweight that gets you closest to the pivot. Personally, I think the arm should come with all three weights. Being able to make the weights allows me to tune the situation exactly. It is just basic machining and now that I have all the drills and taps required I can turn them out rapidly. Brass is easy to polish and get a mirror finish. The only problem is matching the color. Most people would never notice unless it was pointed out to them. 

I assume you got the arm from Dohmann with the table. I would contact them first to see if they have additional cartridge mounting plates. Get at least one of each so you can be prepared for any eventuality.

@mijostyn

As far as I can tell, the counter weights that I have work fine, but I haven’t tried anything else, so possibly brass counter weights would work better, or possibly worse. Is there a theoretical "best"?  (I, personally, would have no idea as to whether the brass would be better or worse than the "stock" counter weight, or how to calculate such measurements.)

Thanks.

@drbond , The stock counter weights are brass. It is a slightly different alloy from the stock I have access to. The counter weight should be within a centimeter of the bearing housing. If it is farther away you need a more massive weight. 

@mijostyn 

Sounds interesting, but I would think that it would be simplest to use a lighter cartridge mouting plate and move the counter weight forward based on that as opposed to adding a heavier counter weight, which would then affect the effective mass of the tonearm in a more difficult way.  

The Schroder CB manual says that the effective mass of the 11 inch tonearm is 17g.  However, it doesn't say at which distance from the bearing housing that calculation is based upon, but I guess it doesn't matter that much.  So, getting a heavier counter weight would allow me to place it closer to the pivot point, but then that would lower the effective mass of the tonearm, which would affect the interaction with the compliance of the cartidge.  I don't see how a tonearm with a lower effective mass is neccessarily better than a tonearm with a slightly higher effective mass.