Direct drive vs belt vs rim vs idler arm

Dear Tony,
Thanks for all your feedback and interest.
Surprisingly.......Ketchup and Richardkrebs who requested the testing I provided due to their keen interest.......have gone silent?

Halcro
Thanks again for doing these tests they are most interesting.
I did reply almost as soon as you posted. But it seems that I have suffered from moderator silencing
I did note the dampening influence of the second tonearm on the DD but it is interesting this doesn't seem to be reflected in the filtered results which showed no change. Have I interpreted the data correctly?
Also have you made any significant changes to the platters inertia from original?

Many thanks

Dover.
To answer your questions.

The servo does not know if you are going to play Mahler or Beethoven before the fact, but it does know very quickly when you do. The feedback is very fast. In much the same way that we do not know where a tennis player is going to hit the ball, yet we can follow its path smoothly without over or undershoot. This is the essence of properly designed closed loop control.

The no measurable speed change comment due to stylus drag was for the SP10MK3 and was taken from their specs. The power supply current draw observation was for the Goldmund and was a clear indication that stylus drag is real and significant. It does not, I agree, quantify its magnitude but it must be big since its effect was present even at treble frequencies. It does however give us a realtime picture. ( exluding propegation delay of the servo electronics, if you want to be precise ) I have not said that there is no measurable speed change with the Goldmund.

Loop rigidity and plinth energy dissipation. Of course these things effect attack, deacy et el. So does room treatment.

You didnt use the time line for the tests. My mistake.

The Goldmund and the LO7D are two completely different machines in concept and execution. The LO7D being an all out assult on the art of DD, TT design. The Goldmund was built to a price point using a badge engineered motor. While this motor does what it was designed to do, these price constraints show. Wrapping feedback around a motor does not elevate it above its core performance.

Peace.

Halcro.
Thanks for the test results. I agree with Tonywinsc, your dedication is impressive.

Halcro, I am interested in your response re "platter inertia", which is to say, are you using an aftermarket platter mat that adds significant mass?

Would be interesting to look at the audio output waveform, to see whether those notches in the peaks are also present there. One could just put a 'scope on the output of the phono stage. 1000Hz is a good frequency to look at.

Now that we are adding a touch of real data to the discussion, things become more interesting and cordial. Thanks, Henry et al.

Halcro,

Thanks a lot! I was actually waiting to respond until I had some time to really study your results so I wouldn't ask any stupid questions, but all I have done so far was to take a quick look. So, a stupid question.

Is the app capable of outputting frequency versus time data instead of a graph? It might be interesting to see changes over very small units of time. When I requested the test, I thought it might be useful in seeing micro speed changes, but I'm not sure if that will be possible. What do you think?

the DD table seems to like a little more load perhaps

Does your DD table have an oil filled bearing well? If it actually does like a little more load on it, it might be possible to improve its speed stability by using a higher viscosity oil. This is getting interesting!