Kuzma 4Point Owners: Try This!

[ShawnZH]

Very useful tips. Thanks Bazelio. I'll give it a try to my 2 4P 11inch, while I guess it would work better on a higher compliance cart. I mount a Lyra Atlas Lambda onto the 4P while the 18g effective mass actually is a bit too high considering the resonance match between cart compliance and arm eff. mass. The best eff mass for a cart like Atlas may be about 10g-13g if we follow the formula of resonance rate between 8hz/11hz. I don't know how much effective mass will be reduced after the removal of the 13.34g absolute mass but I guess it will take me closer to the ideal range.

I have another 4P 11inch mounted with Ortofon Anna Diamond (which somehow beomes my favorite recently). That might work better with the throughs and damping oil due to its low compliance and high cart mass (16g).

Thinking down the road, if we look at the 4P 9 inch, it might be an even better choice since it comes without the through design and being cheaper. The only compromise is the versatility of the VTA adjustment mechanism. But if anyone uses a Kuzma towner with VTA adjustment, that shouldn't be a concern. As for 9 inch VS 11 inch, or 12 inch, I find it is not always longer the better.

 

[bazelio]

Effective mass is minimally reduced. You'll notice the need to adjust VTF counter-weights somewhat after the change. So that'll give you an idea.

 

[Birdwatcher]

...but the need of changing VTF is not necessarily meaning, that the eff. mass has changed (or how far it has changed) and vice versa. These are completely different things.

As a long time user of 4Point 11” with original Lyra Atlas I have thought about to buy the long 14” 4Point for it (and for a DS Audio W2 Cartridge). But as I read here, you wouldn’t recommend it to do?
There are high recommendations on FR66 tonearms for different Lyra Cartridges as an excellent match. This tonearm has an even higher eff. mass without problems.
so what do you think?

 

[ShawnZH]

...but the need of changing VTF is not necessarily meaning, that the eff. mass has changed (or how far it has changed) and vice versa. These are completely different things.

As a long time user of 4Point 11” with original Lyra Atlas I have thought about to buy the long 14” 4Point for it (and for a DS Audio W2 Cartridge). But as I read here, you wouldn’t recommend it to do?
There are high recommendations on FR66 tonearms for different Lyra Cartridges as an excellent match. This tonearm has an even higher eff. mass without problems.
so what do you think?

FR66 is usually designed for low compliance carts while Lyra Atlas is a high compliance cart at 12 dyne @100hz and converting to almost 20 dyne@10hz. If you follow any cart/arm resonance calculation formula, the best match would be lower mass arms than 4P 11 inch. I ordered a 9 inch 4P with 13g eff mass and I’ll know better when I have it mounted side by side to the 11 inch. Will update once it comes.

 

[Ultrafast69]

I only played with the trough once and things sounded off, and moved the points out of the damping fluid. I get the troughs add mass but this is offset with the counter weights, regardless, its easy enough to try in the upcoming weeks, and see what it does, Bazelio thanks for sharing!

 

[sbo6]

To add some notes on this modification:
-the total mass removed is 13.34 grams
View attachment 71557
- the majority of the removed mass is located about the vertical pivot cups thus the center of gravity is reduced (to an already negative CG Tonearm)
- this mass of 13.34 grams was installed on the right side thus loading unequally the vertical cups
-the VTF after removal was reduced 0.4 grams.

therefore the removal of this mass led to a very noticeable sound improvement due to :

1. The effective mass of the Tonearm reduced; and made a better match with high compliance cartridges

2. The center of gravity lowered thus made the Tonearm less prone to vertical rise (because of the negative CG , the specific Tonearm tends to rise)

3. The moments of inertia reduced

4. The unequally loaded vertical cups are now loaded equally

5. The removal of the trough and paddles means less vibrating elements

p.s. Prior this modification, I spoke with Franc Kuzma , who didn’t find any negative

Looks like you removed both troughs, correct?

 

[Vienna]

yes that’s correct