Killing sibilance distortion - VPI & Jubilee

Goatwuss, which AK? I did we quick look and didn't see the title. Perhaps I missed it. If I have it I will play it and report what I hear.

I doubt that a tonearm's tracking ability has much effect on the distortion levels of sibilants.

Much more important is the way a particular tonearm/cartridge COMBINATION handles stray mechanical energies. (This is what Raul and others mean when they emphazize the importance of arm/cart matching. It's not resonance behavior at 8-11 Hz, it's how the combination handles loose energies at 100, 1,000 or 10KHz, and everywhere in between.)

Every cartridge allows some mix of energies at various frequencies to escape from the generator as mechanical energy, rather than converting them to an electrical signal (which is what it's supposed to do). Those stray energies may reflect off the headshell back into the cartridge, or travel into the headshell and end up lord knows where, maybe reflected back into the cart or elsewhere.

Any stray energies that get back into the cartridge will distort the sound. They're at similar frequencies to the new signal but they're time-delayed, out of phase and probably distorted in waveform shape and amplitude themselves.

At lower frequencies this sounds like mud. At higher frequencies it sounds like fingernails on slate.

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I don't actually own that AK record, but if someone wanted to mail me one, help me find the software and tell me how to get the signal to a desktop PC that's three rooms away, I'd be happy to post a recording. Might be fun (or embarassing, who knows!).

Narrod - I actually posted the link at Music Direct on my last entry there. It is a double LP set called "So Long So Wrong," and this is the last track on side 2 of the first record called "Find my way back to your heart"

Hello Goatwuss,
I'm glad that you 've come to that conclusion. As with what we corresponded through email, if we have carefully set up the combo (put together with educated guess of which might mate well with what) and it doesn't work after readjusting all the known parameters (VTA, VTF, Anti-skating, Azimuth..etc), time to move on and try different combo. I used to think that with more upscale cartridges, they HAVE TO track and sound much better than the cheaper ones (given that they all are possible good match for the arm). Boy ..was I wrong and the AT33PTG I recommended is a living proof, at least in the tracking part.
If this combo doesnt work out well, dont kill yourself over it with nano adjustment..the issue just wont go away. Try different cartridges or arms. It's all synergy.

Best,
Hoa.

By the way, I dont think you are too sensitive with distorted sibilance. It's unacceptable and it annoys the heck out of me too.

Hi Doug:

I agree with the overall theme of your post, but regarding the technical details of the "escape of energies at various frequencies from the generator as mechanical energy, rather than being converting into electrical signals", please allow me to clarify and expand.

Most cartridges are capable of converting the movements of the coils into electrical energy - it isn't an "either/or" choice between electrical or mechanical energy.

What actually happens is that while the mechanical energy from the stylus is fully able to drive the coils to generate electrical energy, the mechanical energy doesn't stop there, and keeps going deeper into the cartridge structure. The dampers behind the coils are designed to linearize mechanical resonances of the cantilever/core/coils so that the conversion of mechanical into electrical energy doesn't have any significant frequency-domain errors, but they are not powerful enough to completely burn off the mechanical energy that remains after the electrical conversion process has completed. I typically refer to this as "depleted energy", in the sense of depleted uranium (the stuff has finished its job, but what's left over is still strong enough to create plenty of problems).

The net result is the equivalent of a mechanical echo chamber inside the cartridge - where previous mechanical energy can reflect back and alter how the electrical generation of new signals.

The greater the number of mechanical interfaces in a cartridge, the more likely it is that complex internal reflections will occur, and the more complex those reflections they are, the more it is likely that they will sound not like echos or harmonic distortion, which is acceptable to the ear. but inharmonic or subharmonic distortion, which isn't. Many cartridges that I have looked at contain multiple such interfaces, such as between center yoke and rear yoke, between rear yoke and cartridge body, and sometimes there will even be an inner body and an outer body.

Designing the entire cartridge structure that follows after the coils and dampers as a stiff mechanical diode is a good way to minimize reflections and stop the coils from being corrupted by echo distortion, but since it doesn't alter the total amount of mechanical energy (only redistributes it away from the cartridge), the problem gets transferred to the tonearm. And depending on how well the tonearm is designed, dumping as much mechanical energy as possible into the tonearm (which is what the cartridge wants for optimal performance) may cause various sections of the tonearm to ring, with audible consequences. Pioneer published some articles on the issue of tonearm vibration handling in the 1980s, and came up with a solution that they called a Dynamic Resonance Adapter (DRA).

Whether the tonearm uses DRA technology or other techniques like laminated construction, energy-absorbent stuffing in the armtube, rigid materials that exhibit high internal loss factor et al, the tonearm headshell, armtube and bearing structures should be designed with substantial vibration-handling abilities in mind.

cheers and hth, jonathan carr