Killing sibilance distortion - VPI & Jubilee


Hello,

Along with what others have posted in the recent past, I also have a long running case of nasty distortion on sibilants with my vinyl playback. It is worse in the inner grooves.

To build on some other recent threads about this topic, I ordered a MFSL that is supposed to be a good test for mistracking. I have made a recording clip of my playback playing some of the last track on Side 2.

I have the recording on this link:

Playback Recording

If you take a look at that, we can all be on the same page with what exactly is going on.

The setup is a VPI Scoutmaster table, JMW9 sig arm, Ortofon Jubilee cartridge. The table is leveled on a Salamander Archetype rack. VTA is set with the arm parallel. VTF is set to 2.4g. Alignment is setup with the MINT arc protractor, 10x magnification. The VPI mechanical Anti-Skate is being used, with the lighter rubber washers. Azimuth is level by means of the "VPI straw trick" (a straw in a groove on the headshell).

Is there anyone that can point me in the right direction to fix that sibilance distortion you're hearing on the recording?

I've tried quite a few things, including different cartridges, and VTF, VTA and antiskate settings, but the sibilance is always there.

Here are some photos of my setup:

Cartridge Closeup

Aligning with the MINT

Thanks for reading
by Goatwuss
goatwuss

Showing 1 response by jcarr

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