Eminent Technology ET-2 Tonearm Owners

Dover

The "included angle" has nothing to do with VTA

Cutterhead angles are a minefield as they varied historically over the years and different cutting lathes were set up with different cutting angles. There was a standardisation of sorts in the 60's but bear in mind the US settled on 15 degrees +-5 degrees and the Europeans settled on 20 degrees +-5 degrees.
The actual cutting angle used would also depend on how the engineer sets the equipment up and that is unpredictable. Springback is a common problem when cutting and this will alter depending on the composition and quality of the lacquers used ( they are soft ).

Temperature is a big factor and if the lacquers have been stored at room temperature, as opposed to the recommended cool room temperatures, then often engineers would alter the cutting angle to get a clean cut due to the changing properties of the lacquers at different temperatures.

first statement is true on its own.

but in the data that you provided especially the last sentence - "engineers would alter the cutting angle to get a clean cut due to the changing properties of the lacquers at different temperatures"

With the ET2 VTA system angle changes can be corrected without affecting VTF and alignment - see previous post. this is also documented in the manual. This is what I was referring to.

Dover when you say

Increasing the room temperature by 5 degrees F or approx 3 degrees C will lower the tracking angle by approx 1 degree.

Lets say we have a situation where the room is left alone to go up in temperature. So the sound will become more warm and full bodied - less treble brightness - as you have lowered the tracking angle ?

Is this because of warmer plastic (record) ?

Can this explain why the music can sweeter (warmer) toward the end of a session?

Ct0517..
Increasing the room temperature by 5 degrees F ( 3 C ) is enough to soften the rubber suspension in the cartridge and drop the VTA by 1 degree.
I would assume by the time you have finished a session you will have softened up the suspension and this may explain some of what you hear.
Where you live it is quite easy to experiment - start with a cold room and warm it up, or put a lamp over the cartridge so the heat is localised. You will hear quite a difference - as the cartridge reaches optimum temperature the sound opens up and becomes more natural, as you overheat the cartridge the sound will literally go gluggy. What I have experienced is some cartridges mistrack on a seasonal basis (winter vs summer) here in NZ even though the temperature swings are not large, eg the Shelters. The Benz's generally spec out the optimum temperature and humidity ranges in their cartridge packaging.

Dover - in the winter the OTL's are enough to keep my room at the temp it started at - heating vents closed. The last couple summer months with the door/windows closed in my basement room the temp will go up 1 degree every hour. The OTL's are like two 50 inch plasma tv's as far as heat out put goes. With the door or window open this drops by half - 1 degree every two hours.

The last couple summer months with the door/windows closed in my basement room the temp will go up 1 degree every hour.

forgot to mention this is with the AC turned off. with it on having your room in the basement pays off. cold air sinks down from rest of the house.

Just got mine up and running! This is a very big change from the stock Classic arm. Took some time to find a compressor and build a surge tank, but well worth it.

Tim