The Korf Blog

The inside story: our research,
development and opinions

17 January 2018
Vibrational Energy of MC and MM Cartridges
We all know the task of a turntable cartridge is to convert vibrational energy into an electrical signal. Like all transducers, the cartridges aren't perfect, and most of the vibrational energy isn't converted. It has to go somewhere from the cartridge body, and that "somewhere" is a tonearm.

Accepted wisdom says MC cartridges with their lower compliance emit a lot more mechanical energy and thus are more difficult for tonearms to handle. Is that so? Let's find out!

In the MM corner
Here is the quintessential moving magnet design — a Shure M97xE. Lone survivor of a once large and proud family, it boasts very high compliance, low downforce (1 gram!) and very high theoretical tracking ability.

Sound quality-wise, it's been overtaken by younger brethen, and its rolled-off highs (hence the "x" in the name) are not to everyone's taste. Still, there's a lot of life in it and it remains a bestseller.
In the MC corner
Introduced in 1962 as one of the first professional stereo pickups, Denon DL-103 has seen it all. The fact that it's still made in its original configuration proves how good the early 60s design was. Unabashedly brutal, it has low compliance and needs 2.5 grams to track well.

When it comes to sound quality, "Flat Earth" audiophiles swear by it. Those with more modern tastes usually prefer its re-bodied incarnations. Unmodified, it's warm and lively, but perhaps not the last word in resolution.
Aaaaand fight! Our old trusty SAEC-308L arm is back in action. Hot wax on the headshells (and some on my finger — ouch!), accelerometer connected, recording software running... What's the outcome?
The difference is drastic to say the least. If we consider the noise floor, the main resonance of an armtube is almost twice as big with a DL-103 than with a Shure. And that's just the beginning.

Vibrations from M97xE weren't strong enough to excite armtube harmonics or a counterweight stub. They did leave some impression on the bearings, that rang at a typical SAEC 2 small peaks at 5 kHz or so. The headshell resonances didn't fit on the chart (they were largely higher than accelerometer's own resonant frequency), but they peaked at very reasonable 0.1 g.

DL-103 is, well, brutal. Anything that could ring, did. Interestingly, the bearings were so overpowered by vibration that we've got a single jagged peak at 6 kHz. And the poor cheap bent aluminium headshell screamed for mercy.

Audiophiles often say that DL-103 "needs" a heavy arm. Looking at the chart above, I am inclined to agee. A heavy rigid monster of an arm will perhaps be the best match. Dainty SAEC definitely doesn't need to apply.
So yes, the MC cartridges do dump a lot more vibrational energy into the tonearm. But is it purely a function of compliance, or does the construction of the cartridge play a part too? Next week, we'll add a third cartridge — a medium to low compliance MM — and see how it compares.

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