The Korf Blog

The inside story: our research, development and opinions

10 April 2019
Headshell Performance — SAEC ULS-2X
In this series of articles, we measure the performance of removeable tonearm headshells. Today, the subject is an OEM version of SAEC's famous ULS-2X.

It was a standard SAEC headshell for more than a decade, and established a pattern for countless copies.

The headshell is stamped from a thin magnesium casting, and the thicker part of it has circular cutouts for even lower weight. The fingerlift is integral to the shell. ULS-2X tips the scales at about 9 grams without wires and mounting hardware.
The headshell is epoxy powder coated. It's probably the easiest surface to attach an accelerometer to.


Here's the trace of SAEC ULS-2X's IET measurement. For comparison's sake, I've included oscilloscope traces from the most and least rigid headshells so far: AT-LH13 and SME 3009. Even here it's visible that the SAEC keeps ringing... and ringing... and ringing.
SAEC ULS-2X
AT-LH13
SME 3009
Here are the spectrogram comparisons. First, with the "ringy" SME 3009:
Then, with the reasonably inert AT-LH13:
There are 2 very high Q peaks at approximately 380 and 850 Hz. The damping is completely absent, and the headshell continues to ring past the plot limit of 280 milliseconds.

How long will this ringing continue? I have changed the time axis on waterfall plot to show it:
More than half a second, believe it or not! This is our worst measured performance so far.

Here are the results of the IET measurement with a Technics EPC-U24 cartridge attached.

The main mode shifted down to about 220 Hz, but its amplitude and duration is unchanged.

I am surprised by how badly SAEC ULS-2X fared
I am a bit surprised by how badly SAEC ULS-2X fared.

While definitely not top of the line, it was widely considered an acceptable high quality headshell. That ringing for more than half a second tells otherwise.
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