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The Korf Blog

The inside story: our research,
development and opinions

10 June 2021
CB-A01 Ceramic Cartridge Spacer/Base
Wow, we went a whole month without a post! Not good, and I will do my best to write more.

This happened because we have been exceptionally busy. The new arm is finally taking production shape despite all the COVID-related disruptions. The headshells are selling so well that we have to redesign the assembly process. And, of course, the Paragon restoration is coming to an end, and we will share the results soon.

You might remember that we asked a question back in October — is a ceramic cartridge spacer/base something that might interest you? The answer was an overwhelming "yes", and here it is!

Our new cartridge spacer is called CB-A01. It's a white piece of alumina ceramics that looks quite similar to the AT633 that we measured before, sharing the same basic dimensions: 22.5x17x1.5mm.
The spacer comes in a credit-card sized reusable packaging. The insert holding the spacer is laser cut and protects it in transit and in storage.
Here is the CB-A01, mounted on our battered RB300 arm. And, of course, it looks a lot nicer under the Ortofon 2M Red:
Measurements
We're still using the same methodology we have described in the post about the typical tonearm resonance measurements. The accelerometer is attached to the top front of the headshell, and the vertically modulated 0 to 20 kHz sweep recording is played. The output from the accelerometer is conditioned, amplified and converted to g. We're keeping our tradition of using the Audio Technica AT7V cartridge for the vibration measurements.

Here's the comparison of the Korf CB-A01 spacer, the Audio Technica AT633, and the Rega RB300 without any spacers at all. The Korf spacer is made of the same material as the AT, has the same geometry and mass, so it should perform the same. Right?
Well, no. Surprisingly for me, our spacer performed differently. Arguably better, as the data suggests it's stiffer than the Audio Technica one. Why can that be?

The ceramic casting and cutting technologies have advanced quite far since the 1970s. Purity of alumina has increased. I think that today's casting techniques create the parts with less internal tension and stress.
Subjective Evaluation
I have very little to add to what I wrote when I measured (and listened to) the AT633 spacer:

"The improvement in bass is expected and very welcome. [...] Sibilance is not just diminished, it's completely removed. With the spacer in place, one can finally appreciate just how neutral the AT7V is. The imaging is also a lot better, and some depth can be felt."

To my ears, the Korf CB-A01 spacer sounds only a little bit different to the AT633. There's possibly some more smoothness and depth. But the character of the improvements remains the same.

CB-A01 gives a taste of what a more rigid tonearm sounds like
The price? €45 plus shipping. You can get it at our partners The Supersense. I expect the initial batch to sell out very quickly, but do not despair: more spacers are coming in a few weeks.

I am glad that you, my dear readers, pushed me to build this ceramic spacer. It's a small and relatively inexpensive part that gives a taste of what a more rigid tonearm sounds like.

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