What angle should I set the VTA on my VPI turntable?


I can't believe after all these years, I am asking such a basic "analogue 101" question, but here it goes. I own a VPI turntable that has a "VTA on the fly" knob.  I thought the best VTA setting was for the arm to be 100% parallel to the record surface.  

However, based on some research, I am not so sure that is correct way to set the arm to achieve optimal VTA and correlatively, optimal SRA.  Not sure, ... but I think I have to raise the pivot side of the arm.

Any advice would be appreciated. 

Thanks.     
bifwynne
One thing a lot of these comments have in common is what I consider extremely large or gross adjustments. This is fine if all you want is to be somewhere in the ball park.   

But for that you don't need a USB microscope, or even a bubble level. All you need is a piece of paper with parallel lines. Hold it on the platter, adjust the arm tube parallel, call it good. None of these other things are gonna get you any better, because from here it must be done by ear.  

Sure you can use those other methods. Just don't kid yourself they are any better. For the simple reason the fine-tuning of VTA is orders of magnitude smaller than anything you can see even with a USB microscope.  

VTA differences I have heard are as small as 1 mark on a VTA dial, like the one on the VPI. On my Graham these were about 1-2mm apart. The Graham VTA adjuster is about 24 threads per inch. It has been a while so I forget but it seems there were something like 30 of these marks all the way around. 30x24=720 so one mark is 1/720th of an inch. Pretty close to one one thousandth. Origin Live thread pitch is finer and looks more like 32tpi. Also the wheel is a lot larger. This probably explains why with Graham I was often times interpolating while with OL the larger marks spaced farther apart were fine. In both cases we wind up somewhere around 1/500th to 1/750th of an inch. 

This is vertical at the pivot point. Do your geometry if you want to work out how many arc seconds that is at the stylus. Go ahead, knock yourself out. As for me I am happy to rest assured it is less than you will ever be able to measure with any USB microscope. You just won't see it. But I sure can hear it.  

Probably a lot think this is crazy. Fine with me. Not the point. I am as always the last one to argue with anyone says they can't hear any difference, don't care, etc.  Just want to be real clear exactly what I am talking about when I say I do.     

If your VTA is off by as little as .01", then however good you think your imaging is, presence, extension, definition and detail, if it is even this much off you can make it better with a few micro VTA adjustments.   

This is why they put those tiny little marks on VTA adjusters. This is what you paid for when you bought that expensive arm. Use it or lose it.
Kleos (and every Lyra I've owned) should start with arm tube level and parallel with record surface with stylus playing.  Then turn the VTA adjustment knob one full turn up and listen.  Then back to level and listen, then one full turn down and listen.  Return to parallel with record surface and listen.  Whatever sounds best, adjust to that position.  Then use that as a starting point to repeat the process.  

At some point, moving the arm pivot up or down one full turn will degrade the balance, timing and imaging.  That means you've gone too far and should start heading in the opposite direction.  

Just as a reminder, tracking force may change slightly with VTA changes.  Check the rest of the alignment during the testing to make sure VTA changes haven't change them.  
remember to use your protractor after raising/lowering the arm....the cartridge will need to be moved forward/backward.
millercarbon, then you need to adjust your VTA with each record as they are all a little different and you think you can hear it. Knock yourself out.
Read the number off the dial, write it down on the record sleeve, done. Next time you can dial it back precisely where it was, fast and simple as reset the dial.

Sounds like a lot of work and that puts a lot of guys off. But, how many hours, weeks, months of working and saving did it take to get the thing in the first place? Ever wonder why it is people pay hundreds of dollars for some guy to come tune their table and say it was well worth it? Ever wonder what it was they did that was so magical? This is it.
Needless to say this will not be worth it if you are unable to hear the improvement. But then how did you manage to set it in the first place?