Turnable database with TimeLine

Dinster,
I have the Feikert App and the 10" Test record to go with it and have done repeated testing on both my tables using my iPad and posting the relevant print-outs.

The important thing about scientific or objective testing...is 'repeatability'.
In other words....every time you or I proceed to test exactly the same thing....we should achieve exactly the same result?

With the Feikert App.....I achieved different results every single time I repeated exactly the same tests?
In some cases...the results even showed the Raven AC-2 giving better results than the Victor TT-101? :-)
The test record itself was a major part of the problem.....
Due to the fact that it contains a modulated groove of exactly 3150Hz....it is essential that the record hole is dead-centre.
This is simply unachievable to the degree necessary to avoid variations from that constant test tone.

With the Timeline......every test result is repeatable....

TT-101/3 ARMS
For the record.....not 3/8" shift :-)

01-08-14: Richardkrebs
HF Dover
Phase lag is a result of drag, not a cause of it.

Yes, phase lag COULD be a result of stylus drag, but not necessarily exclusively.

As a matter of courtesy, I would ask you to address me correctly as "Dover" which is my name on this forum.

A DC Motor is a simple device. The speed is proportional to voltage input and load. If the load increases then the speed will drop and current will increase. My Sota tt has a simple power supply and DC motor. It has a trim pot for fine tuning speed; but speed will vary as load changes. (A tt with closed loop controller for a DC motor would vary voltage to maintain speed under varying load conditions.) Using the iPhone app I can adjust the speed to within 0.02%- about an order of magnitude off compared to Peter's SME deck. Also, speed drifts on my tt as it warms up so I must let it run for 15-20 minutes before fine tuning the speed. I know the higher end Sota tt's have much more sophisticated motor controllers. I would like to know how they perform in comparison.
Synchronous AC Motors are based on frequency. The rotor of an synchronous AC motor is always following the rotating magnetic field. That is phase lag or slip as Richard mentioned. As the load on an synchronous AC motor increases, phase lag increases. Current draw in the motor will increase which increases torque in order to bring the phase lag back to near zero. The frequency source for a synchronous AC motor can come from the 60Hz AC line or from a seperate frequency generator. Voltage will not change speed on a synchronous AC motor but it will change the amount of torque available to minimize phase lag. (More voltage means more current draw is available.) A closed loop synchronous AC motor controller must vary frequency to adjust speed.

Halcro, My test record that I use for the iPhone app is also flawed. The record hole is off-center so I filed the hole open a bit and I must center it as best as I can on the platter. I get differing Wow&Flutter measurements (between 0.06% down to 002% filtered readings) depending on how well I center the record. My record also has a slight warp and at around 12 seconds into the track the frequency shifts due to this warp. So my overall measurements look better when I start the recording past that warp. I did screen saves on sevaral measurement trials using the iPhone app and finally saw this pattern of speed or frequency shift at the same point every time.