The Korf Blog

The inside story: our research, development and opinions

18 August 2017
Evaluation of Prototype 1
We have finally managed to obtain a satisfactory set of vibration data from our first prototype tonearm. Then it was time for some listening! How was it? Read on!

Our prototype number 1 is fitted with a thin-walled (0.2mm) aluminium armtube 9.7mm in diameter. It was factory hard anodized. For all previous and subsequent measurements we are using an Audio Technica AT7V cartridge. It has reasonably low compliance and thus generates more vibration than most other moving magnet-type cartridged. It is also quite pleasant to listen to, making subjective evaluation a bit easier.

Here is the result. For ease of comparison, I have left the resonance trace of SAEC 308L tonearm in light blue.
And what do we see?

It's not too bad, actually! Our mongrel arm with a simplest possible armtube measures slightly better than a very respected SAEC 308L. The main bending mode is well-dampened and is, in fact, lower than both counterweight resonance and bearing chatter.

Notable points: the prototype arm has just 1 bearing resonance peak, not the usual two. Probably because the bearings are so close together and are embedded into a massive center part. Also, we have managed to design a not so horrible headshell!

Subjective evaluation
Do we have beginner's luck? Would our prototype really sound as good as it measures? We have mounted the arm on our reference Micro Seiki RX 1500 and did some listening.

To sum it up: no, we didn't better (or even match) a SAEC. While the sound wasn't bad, problems were apparent. There was some sibilance on vocals and especially on cymbals. Generally, the high frequencies sounded a bit tinny and harsh. Compared to SAEC, there was noticeably less "body" to music and voices.

On the positive side, the stereo stage and its depth were adequate.

Result: ★★☆☆☆

This is one more reminder of the limitations of almost all measurements in audio. At the very best we can speak about correlation between the sound and the measurement.

Now we have established the baseline in both measurement and sonics. Unless something unexpected comes up, in the next blog posts I will report on how various arm tubes perform.
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