Benny Audio writes: “In my previous article, I focused on the construction of a phono cartridge, concentrating primarily on what I consider the most critical issue affecting cartridges—vibration. The more expensive the cartridge, the more attention is given to this issue. This is a straightforward conclusion drawn from analyzing descriptions of high-end designs.
Along the way, I received some criticism, and rightfully so. Feedback from cartridge manufacturers made me realize how little I actually know about them. The proper functioning of a phono cartridge is highly complex and is not solely about vibrations. This knowledge is held by designers, and it’s understandable that they do not readily disclose their solutions.
As a result, cartridges are often designed without much consideration for tonearms, as if the tonearm were not crucial in the process. Of course, the tonearm is supposed to ensure proper guidance of the cartridge, correct geometry, and so on, but we still do not fully understand its role.
Tonearm manufacturers also protect their know-how and rarely discuss how their tonearms work or why they function as they do (though a few key ones are more open). They may boast about having the best, reference-quality tonearm, but that’s about it. They let us focus on the visual aspects rather than the mechanics.
This creates a somewhat challenging relationship between tonearms and cartridges. Usually, this relationship is tested experimentally—pairing cartridge X with tonearm Y and then listening to the results. This is something I did myself when designing my first tonearms.
It turned out that sometimes the sound was unstable (I mentioned earlier that the tonearm has a significant impact on wow and flutter, measured with a test record), sometimes there were issues with the highs, sometimes with the lows, or the midrange was overly emphasized. All of this occurred with the same cartridge after only minor changes to the tonearm.
The conclusion is clear—the tonearm has a huge impact on the performance of the cartridge.
The question remains: what causes the same cartridge to perform so differently on tonearms that differ by only a few details?
It took me a while to uncover the truth, and, as usual, luck played a part. Early in my journey with turntables, I came across an article about the construction of the Audiomeca Septum tonearm (I refer you to the TNT portal, where you will find plenty of interesting articles). While pondering tonearms, I revisited this article, and suddenly, it all clicked.
You see, the cartridge operates through vibrations. Vibrations cause an elastic wave. This wave travels through the cartridge body and—pay attention—it moves to the headshell, from the headshell to the tonearm, and so on. It either transfers or it does not.
So, if the same cartridge performs differently on different tonearm configurations, it means that the energy transmitted by the cartridge to the tonearm is causing the issues.
If the wave passes into the tonearm and starts bouncing around, unable to find an outlet or greater mass to dissipate into, vibrations occur. If the frequency of these vibrations aligns with the next wave of energy at the same frequency, resonance is created. Once resonance occurs, it’s game over—the tonearm resonates and negatively impacts the cartridge, adding an extra vibration component to the stylus’s movement.
This is how you end up with problems in the highs, lows, or an overemphasis on the midrange. If we could design a tonearm that handles elastic waves across all audible frequencies (or those generated by the cartridge), we would have the ideal tonearm—one that does not interfere with the cartridge’s performance in any way.
This would solve the problem of tonearm-cartridge mismatches because such mismatches (aside from obvious mass compatibility, compliance, etc.) would no longer matter.
Now the question arises: how can we determine if a tonearm resonates and at what frequency? How do I know that the BennyAudio tonearm will perform well even before listening to it?
I will reveal that next time! For now, let’s keep things general—after all, this is “secret knowledge.”