Direct drive vs belt vs rim vs idler arm

I am now using laser tach to determine my platter speed and stability. IMO, it is the most accurate way to gauge the speed on the platter. Accurate to 1/1000 th of a rpm. Only $200.00. It should be placed on a tripod for the most accurate measurement. Monarch PLT 200.

http://www.omnicontrols.com/detail.aspx?ID=3720

An accuracy of 1/1000 rpm is 0.003%. This is only as good as most high end tt's. It needs to be an order of magnitude better than that. It will be good for dialing in speed, but not for examining Wow&Flutter. If it is off 0.003%, then the platter will gain/loose 1/3 of rotation per 10,000; assuming all else is constant. I'd call that good. Why doesn't anyone talk about the iPhone app? It at least plots speed over time for you.

The original Timeline flashes once every 1.8 seconds (1 revolution). The latest version, which is at least about a year old, flashes eight times every 1.8 seconds.

Tonywinsc,
I don't know how much faith I have in the accuracy of an iphone microphone!

Peterayer,

A distance for sure is important, I have been doing this very easily for a while now and if the table isn't close to a wall I just use 2 light rulers and tape them to the back of the table stand along with a pce of paper between the two with a pce of painters and a dark line on such so it's very easy to view between so it's under 2 ft

All the tables I have tested, no worry about waiting for 20 minutes either. Most failed within a few rotations even after using the TimeLine to actually try and set the speed accuratly. I found most tables were not capable to be set for accurate speed.

Using the strob, numerous tables that were used and then rechecked with the TimeLine proved the TimeLine is a more accurate devise and all these tables failed within 10 or so rotations either too slow or too fast and that was with no stylus even on the record.

This has really left me scratching my head.

I have an FFT analyzer app on my iPhone. I used a B&K calibrated 1000Hz test tone and the FFT plot was dead on. It is about the frequency counter tied to the internal clock. I don't know the accuracy, but I figure it must be within the range of the timeline- quartz crystal clocks inside their processors.