The Korf Blog

The inside story: our research,
development and opinions

2 May 2019
Headshell Performance — Sumiko HS-12
In this series of articles, we measure the performance of removeable tonearm headshells. Today, the subject is a Sumiko HS-12, an OEM version of a Jelco HS-25.

The headshell is made of magnesium alloy and weighs slightly more than 12 gram without wires or mounting screws. There's no fingerlift.

Jelco's bayonet mount is slightly different from the typical one. While usually the location pin is only protruding at the top, Jelco's is also sticking out at the bottom. This definitely improves the mechanical connection, but makes the headshell incompatible with some tonearms that only have the top slot.
The surface is anodized black, and it took a while to get reliable accelerometer attachment.

Visually, the Sumiko headshell is very similar to Nagaoka AL-703. I have expected it to have a broadly similar performance, but no. Look at the oscilloscope traces of IET measurements below — they can't be more different. Sumiko's is closer to SME 3009's than to Nagaoka's.
Sumiko HS-12
SME 3009
And the spectrogram difference with Nagaoka AL-703 is massive as well.
While the Sumiko has only 2 sharp peaks at 750 Hz and 2.2 kHz, Nagaoka rings all over the spectrum. But Nagaoka's resonances have a lot lower Q.

Below, for your reference, are the comparisons to Audio Technica AT-LH13 and SME 3009.
Isn't it interesting how similar, and yet different, the spectrograms of a Sumiko and an SME are? There's a lot more energy in these SME peaks (+10dB!), and they produce a lot more harmonics.
The waterfall plot is as expected. The main mode at 750 Hz rings for about 240 milliseconds. Interesting to compare this to another magnesium headshell: both have very little low frequency energy.

Here's the result of an IET measurement with a Technics EPC-U24 cartridge attached. We're comparing it to the Nagaoka again.

The result is a bit strange. Where has the 750 Hz main mode gone? Up to 2 kHz? We'll need to look closer into this, maybe do one more set of measurements.
Materials play a critical role in headshell performance
I was surprised by the measured performance of a Sumiko HS-12 headshell, and how different it is from a mechanically similar Nagaoka AL-703. Looks like materials do play a critical part in headshell performance. The similarity in low frequency spectrum between two very different magnesium headshells seem to prove this point.
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