The Korf Blog

The inside story: our research, development and opinions

10 August 2020
More About the New Tonearm
We're still catching up on our commitments, and thus the updates will remain a bit scarce for the time being.

I've hinted at a new tonearm prototype last month, and this generated a lot of excitement. Thank you very much for your letters of interest, they do mean a lot to me. The development of the tonearm is going forward, and I think I can share a bit more about our first "metal" prototype. Just keep in mind the eventual production version would have very little in common with it.

The arm is based on the monolithic flexure pivot we've explored before in one of our prototypes. This time, we're using a cantilevered configuration that allows for more rigidity. Zero stiction does wonders for tracking.

For the vertical bearings, we've chosen widely spaced ceramic bearings. They have very good starting torque, and putting them far apart minimizes rocking of the vertical axis.

The armwand is a seamless steel tube, and there are numerous tricks employed to maintain rigidity at the headshell connector and the counterweight stub.

We have opted for magnetic antiskating. It seems silly to spend all the money and effort on these fantastic bearings, only to ruin the stiction performance with pulleys, rods etc. With the modern magnets, it's possible to achieve linearity of antiskating force over the whole LP.


Measurements
The first tests look quite promising. We're very close to the performance of Prototype 5 from our first tonearm series. The well-defined peaks show that the rigidity has been preserved, and we've learned from the mistakes made with our first flexure prototypes.

There's obviously room for improvement, and I have still not made up my mind over what to do with that 690 Hz mode. It doesn't really show up in the listening tests, but I feel I must at least try a few configurations that would decrease its amplitude.
As for listening, it shows some promise. Enough to continue the development in this direction.

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