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In the Forum: Analog Playback
In the Thread: USB microscope for setting VTA
Post Subject: TheoriesPosted by mem916 on: 10/23/2013
Hi Romy,

I have a couple of theories as to why I wasn't able to get to the "VTA sweatspot" before I tried the microscope method. 

The first is that my "baseline"  (using the ice skate tool that wally sold me) was so far off that the range I was working in just didn't make much difference on the record I was playing.  What I noticed back then was that some records sounded great, others had some distortion that I was not sure about.  Was it VTA? Was it VTF? Was it a bad pressing?  Naturally I set VTF first (2.0g).  But nothing I did around this "baseline" setting for VTA made much difference.  So I gave up.  By the way now these same records sound fine after using the microscope to set to 92 degrees.  I do also adjust for thickness of the record.  It is about 1/2 turn between a "thin" record and a "thick" record.

Another theory is that changing amplifiers (I now am using VTL Wotans with my Soundlabs) and then also changing the output tubes (to vintage Tung Sols) has allowed me to hear the changes that VTA makes.  Whereas the previous attempt (without the microscope) these changes were buried in the higher noise floor of my system back then.

I can do some simple tests now to see if my first theory is correct or not.  For example I can take my VTA back "way out of whack" and see if I hear a half-turn difference in either direction from that "bad baseline" now.

As for changing VTF now:  If I add 0.2g to the VTF I would also have to set up the microscope again and see what it did to the VTA. Say it changed to 90 deg due to the added weight on the cartridge then I could re-adjust VTA to get back to 92deg.  Then I could listen to it both ways and decide which sounds better.  Perhaps 2.2g VTF requires a different VTA to sound best?  I don't know.

There is a third theory of course:  This is all in my head and having the microscope and adjusting to 92 degrees makes me feel better so I think it sounds
better.  I don't like this theory at all.  Wink


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