Hi
@dover - hope you've been well.
So you believe the frequency generator, speed and phase control circuits meet current state of the art performance do you, even though the SP10 uses 70’s chips and we now have chips capable of switching at a trillionth of a second, and computer power millions of times faster today ??
If indeed the SP10mk3 controller is as crude as described in their advertising - then basically it is correcting instantaneously any speed deviations calculated using data generated from those 70’s chips.
It is no different to digital jitter in my view. The advertising implies there is no smoothing of the error correction.
This implies, as did your previous comment, algorithms, prediction, data, computational error, etc. In other words, computing.
The SP-10MK3 uses analog PLL speed control. Computing in the sense you conveyed is simply not relevant here, and as such your claimed deficiencies are also not relevant.
I note that Technics again claim in their advertising that the higher platter mass of the mk3 ( 10kg ) is key in generating a more stable FG used in the speed and phase control circuits.
By comparison the Victor 101 calculates the error over a period of time and feeds the correction in over a period of time to "smooth" the correction.
FG is the speed proportional feedback from the motor, so I don't understand what you mean by 'more stable', as frequency stability of the FG is directly proportional to speed stability.
The platter mass is a low pass filter, hence 'smoothing'. Not to say that low mass platters are drastically inferior - it's a system where the components are designed to work with each other.
The 101 is also analog PLL controlled. The lighter platter works well with the low torque of the coreless motor, and the PLL is tuned for such. There's no 'calculating' error over time or applying correction over time, aside from the bandwidth, gain, and filtering of the system, as with any PLL implementation.
Also as you would know the L07D relies on platter mass for stability, the error correction only kicks in when the speed deviation is beyond quite a wide range.
I know that's been claimed on L-07D.com, and I also know it's a false statement, or at least a very confused one:
"The PLL system plays backup, only being activated when platter speed varies by +/- 3.7% at 33.33 rpm or +/- 5.0% at 45 rpm. Within that range, PLL is maintained and the controller makes no speed corrections. Motor speed is regulated by a quartz crystal (vibrating at
5.5296 MHz)
to precisely 33.33 or 45 rpm with zero tolerance."
The first sentence says PLL plays backup within the range yet the second sentence says PLL is maintained within the range. Can't have it both ways. It's just another analog PLL motor control circuit, though with a couple of unique features.
It is clear that Technics, Victor and Kenwood, 3 of the supposed best direct drive TT’s from the 70’s, had 3 quite different views on how best to implement speed control of the platter.
They must have had 3 disparate views on how speed control circuits affect sound quality.
They all put a different spin on analog PLL motor control, but they're not necessarily that different. They clearly couldn't implement motor control the same way due to IP, and they'd presumably want to achieve real and/or marketable differentiation.
Since I believe you own all three decks - I would be curious to know if you believe they each have a sonic signature.
You tell me how to eliminate all variables such that only the motor control implementation is different and I'll tell you if I think there's a sonic signature between them.
