Direct drive/rim drive/idler drive vs. belt drive?

Lew

The DP80 uses an iron core stator.

The distinction between Denon's "3 phase AC outer rotor motor" and Technics "Brushless DC with integral magnet platter" is largely semantic.

The Technics motor is a 3 phase outer rotor motor which includes a circuit in the motor which generates 3 AC waveforms due to the motion of the rotor. These waveforms are necessarily synchronous with the rotor. The waveforms are then amplified to a level determined by the PLL controlled servo loop and fed back to the motor drive coils. The PLL is fed by Technics famous frequency generator circuit.

Without access to the Denons circuit details I cannot say exactly how the Denon generates the frequency required to run its motor but I can say that it also employs a PLL controlled servo loop to slave the coil drive to a motion dependent signal, this time generated by a magnetic signal recorded on the platter (a primitive version of a rotary encoder). The loop presumably also controls the voltage of the drive amplifiers - if it did not the level of cogging would render the motor useless.

From a practical point of view the only difference would be in the fidelity of the drive waveform. The forward drive voltage in the Techics motors I've seen is fairly ugly, the engineers relied on the high speed of the FG servo to smooth the rotation. Denon's encoder is a lot slower so they would have to have a cleaner waveform to start with. They are both neat solutions to the central problem, neither appears to me to be inherently inferior to the other.

Mark Kelly

Thanks, Mark. That's a lot more information than I can glean from the Denon literature from that era. And the schematic is beyond my comprehension. Others, including Technics as you note, have spoken of the Technics SP10 motor as being of the DC type. Now I see that this is a distinction without a major difference.

Dear Lewm: +++++ " reveal the nature of these especially good tt mats. " +++++

that mat/pad with our build blend material is only the tip of the iceberg in relation with build materials and its importance in TT- tonearms - cartridges and maybe some other items. The mat is only one kind of use in the audio world.

No, the material that Ralph describe is different from the one we own, between other things ours has a lower weight due to the blend material used.

IMHO I think that the real importance of that build material subject is that we are starting to talk about when one or two years ago we did not heard nothing on this build factor.

Sooner or latter the TT and tonearm designers/manufacturer ( mainly ) must take " the bull by its horns " if they want to offer better quality performance products to we the customers.

I posted several times that we deserve the very poor non-evolution audio products we have because we the customers never ask for more: sometimes because a very poor know-how, sometimes because we don't care about and sometimes because we are thinking like 30 years ago ( with no evolution attitude. ). Of course there are some exceptions on both sides: builders and customers.

Here in this thread we have a precise example of that " old thinking " way: where Quiddity try to expose and sustain with numbers a few subjects/factors the next post to it say something like this: " if we go for the numbers a Yamaha will be better than a Lamm unit ".

Well I say that almost any audio " stage/performance " can be numbers related ( here and now ) if we know what to measure, where and how to measure, when to measure and with which tools/instruments we must to measure.

Lew, we are talking in this thread ( like in many other ones. ) of products designed 30-40 years ago that are competitive with today designs: turntables, tonearms and cartridges, with almost no evolution in the audio industry, why is that? I ask, who has the culprit? manufacturers or customers, I think both but mainly the customers that are manipulated by the " professional " ( some corrupted with intention and some " corrupted " by non know-how. ) magazine reviewers and that are ( the customers ) the ones that buy those very poor audio design items, yes we deserve what we have!

I think there are a lot of talent out there for design and build a lot better audio products in any single link of the audio chain but unfortunately we customers don't give to them any " sign " that motivate them to be better than what they are showing today, we are proud with what we have.

Anyway, continue with the thread subject.

Regards and enjoy the music,
Raul.

My experience with coreless motor is not limited to just the Pioneer as I have several turntables here that exhibit this silky smooth quality. The Pioneer is better to illustrate the distinctive quality of coreless motors even in an inexpensive model. I believe the later Pioneer models, the "L2" series of turntable, such as PL-50L and PL-70L all converted L2 to use coreless motor with the same specs, all employing their trademark feature "Stable Hanging Rotor" SHR, basically a fancy way of saying an inverted bearing. Anyway, I realize many top or almost top of the line models from various brands used coreless motors such as Kenwood L-07D, Sony PS-X9, JVC TT101, Yamaha GT-2000, PX-1, Pioneer PL-70LII, Sansui XP-99, et al. I owned neither so obviously I am drooling here. I am not saying only coreless motors are good. It's just that whenever I detect this kind of smooth sound, invariably it's a turntable with a coreless motor. JVC have some core motor tables approach the smoothness I crave for - I haven't listened to my SP10 for a while now. That's why I reserve the core motored tables for tape-driving purpose as the tape smooths out the tiny bit of cogging or whatever you call it for the passive platter.

Raul, I admire your forward thinking. Keep up the good fight. Yes, sometimes audiophiles got what they deserve, un-innovative products.

After chiding someone on VA over miunderstanding servo loops I should correct an error in my description of the Denon.

Where I said "it also employs a PLL controlled servo loop to slave the coil drive to a motion dependent signal...." I should have said "it also employs a servo loop which adjusts the coil drive, using a motion dependent signal...."

The master is the quartz reference.

Mark Kelly