Audiofun
You raise a valid point in asking what my upgrade actually entails. Prospective customers need this information. You also accuse me of "straw man arguments", something I cannot let slide.
Hopefully I can address both of your points at once.
My upgrade consists of 5 separate but, in some,cases interrelated procedures, on the SP and now other motors. We are talking here about the SP10 motors so, I will confine this discussion to them.
The areas worked on are:
. Motor stator chassis
. Bearing support
. Stator
. Commutation
. Speed sensing
Taking these one at a time:
I first addressed the motor chassis. In spite of the millions of R&D dollars spent, in my view, Technics did not pay particular attention to the loop between platter and arm. This in the form of rigidity and resonance control.
One only need to look at the LO 7d to see how this should be done.
My upgrade improves this situation by helping to control resonances in the motor chassis. In standard form it is quite resonant and flexible.
This change produces an immediate and unambiguous improvement.
I then cast my attention to the bearing. Not actually the bearing itself which is quite good, but not up to the standard of the inverted bearing used in the P3. Again loop rigidity is compromised by the "as built" structure. My upgrade significantly improves this situation. Again this is clearly and unambiguously audible.
Now I started work on the stator. This is where things became most confusing. I made changes that I was sure would be an improvement, but in fact it was actually different and not necessarily better. Pulling apart the motor numerous times over many years in order to solve this mystery led only to frustration. The changes were reversed and reinstalled too many times to count. The stator with the changes in place was electro-mechanically stiffer, but I did not like the effect. The greyness or "Jitter" that I refer to on my web site was even more apparent.
The breakthrough came late in 2011, early 2012 when I turned my attention to the commutation and speed measuring mechanisms. Again with reference to the LO 7d and motors in the JVC line up, I consider the the Technics SPs to be inferior. Even in comparison to their own SL-1200.
As I'm sure you know, precise commutation is mandatory if the goal is low torque ripple. Within the standard architecture the commutation can be made more accurate.
Lastly I worked on the speed measuring mechanism. Again it will be appreciated that accurate speed measurements are a prerequisite to accurate dynamic speed control. As built, I do not consider the SPs to be particularly great in this area and we are perusing greatness. IMO, even the humble motor used in the DD Goldmund studio has a superior speed measuring mechanism. But the SP can be significantly improved.
Working on the last two areas now showed, without doubt, that the stator changes were indeed positive. A motor with the high torque to moment of inertia ratio that exists in the MK3 can easily get itself into trouble if it's controller is not feeding it the correct, corrective signal.
Do I have the resources to objectively measure the effect of these changes. No, but as I said earlier, we do not listen to measurements.
So why bother with the SP10 at all if it has so many compromises? I believe that the motor must exercise absolute control over the platter. While others advocate low torque high inertia drives, my preference is for high torque high inertia. The MK 3 is definitely in the latter camp. It's DRIVE is addictive.
There are a number of materials used in my upgrade, most of them man made. The organic material used is the same as that employed by Duelund in some of their products. Once dry it is stable and enduring.
This brings me to your initial posting on the subject.
As you know, I am endeavouring to contact your friend who owns the MK3.
I stand by my work and that of my agents. If it transpires that it is indeed my upgrade, clearly something has gone terribly wrong and I will do my best to make it right. If it is not my work, I will still try to help him out as, hopefully I can bring some knowledge to the situation.
Cheers.
