10-13-11: Halcro:
"Doesn't it seem odd....if a coreless DC motor produces no cogging and sounds so 'fluid', relaxed and unfazed.....that a manufacturer would be foolish to even contemplate an alternative design?"
You look at the release of the models chronologically, then you realize all coreless motor models came out in latter days. Once they went coreless, they stayed coreless. This is the same trend in other brands such as Kenwood, Yamaha, Pioneer, Sony, Sansui, etc...
As far as I remember, the only two major brands stubbornly stayed with non-coreless motor was Denon who kept using their induction motor through out and Technics.
Pioneer's top of the line model was the P3 and latter P3a (linear motor). It was not coreless motor but it was too popular in the market place and too developed to change such flagship model. But in the models below that, they did switch to coreless motor. One example is the PL-50L, core motor, and the latter PL-50L II, coreless motor.
Looking at it historically, the trend in DD design is that by 1975 just about every table is quartz locked ( the "QL" in JVC models) and 1977 point on to early 80's, many Japanese manufacturers switched to coreless and stayed that way until CD took over the world.
One physical feature of a typical coreless motor is that they shape like a pancake usually flatter than their core siblings. It's because a coreless motor has no iron core to wrap around and they shape like a series of air coils in speaker crossover and the rotor is right on top of the coils.
I cannot scientifically confirm coreless motor is responsible for the fluidly smooth sound compare to other motor genres but from my own experience every DD table I heard using coreless motor has that sonic character. The first time I heard this smoothness was from a cheap Pioneer PL-300. It was outperforming its earlier more expensive siblings that got me curious about its motor structure. Playing records of violin solo gives a good idea of its smooth character.
03-26-14: Banquo363:
"There appears to be some disagreement regarding whether the tt 81 has a coreless motor or not. The vintage knob asserts that it does, but 'caligari' on this thread says he's positive that it does not."
Nowhere in the text of VintageKnobs.com mentions that the TT81 is a coreless motor. It says "the motor of both versions is a high torque 12-pole 24-slot DC-brushless." A brushless motor is NOT the same as a coreless motor.
After some research, the motors of TT71 and TT81 might be similar but they have different model numbers. TT71 uses M932A motor and TT81 uses M922A motor, according to their service manuals. The TT101 uses a M926 motor, by the way.
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