Using Adjust+ for VTA

Re: Using Adjust+ for VTA

Postby Brf » Mon Jul 15, 2019 7:24 am

Golear wrote:I don't think Brf meant Pivot-to-Spindle distance. That would remain constant because the mechanism that adjusts the RTH will not move the tonearm's position and just move the bearing assembly in a vertical plane. (Or at least, one hopes so.)

I think Brf meant Pivot-to-Stylus distance when measured in the horizontal plane - this will be affected by the angle of the tonearm with respect to horizontal. I think a change in Pivot-to-Stylus distance will affect the cartridge alignment, as well as VTF. (And a change in VTF will likely have its own small effect on the SRA/VTA.)


Golear, you are correct, S2P was an incorrect term. Adjusting the VTA tower will affect the stylus overhang alignment. If one uses an arc protractor or the VPI jig and aligns the stylus tip perfectly, any subsequent adjustment to the VTA tower will affect the stylus's position.

My original post has been edited for accuracy
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Re: Using Adjust+ for VTA

Postby Dorian » Tue Jul 16, 2019 11:49 am

This is all very interesting and begs the question if there is a correct order of steps for cart setup? It seems that every adjustment affects every adjustment, so really it’s just a best efforts exercise. Right?
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Re: Using Adjust+ for VTA

Postby Golear » Tue Jul 16, 2019 7:44 pm

I agree - best efforts. Careful and correct set-up will make a difference, but there's no need to lose sleep and you can take your time getting there. For example, if, after a lot of listening, you find that your system sounds better with a 0.01 increase in VTF, then you might also check the alignment. May be. The difference may be so slight that, in practice, other errors like eccentric LP may swamp it.

I suggest:
1. Set VTF
2. Set alignment
3. Set anti-skate
4. Set azimuth
When doing all this, adjust RTH so that the top of the tone arm is parallel to the platter. Then when you play LPs, adjust RTH until the top of the tonearm is parallel to the platter, and then make final adjustment by ear. I find that I only have to make a 1/4 to 1/2 turn correction (usually higher RTH). With practice and some tools, it takes about 10 seconds.

If your system is off, you'll hear it. And you can experiment by intentionally setting them up wrongly. So then you'll be able to tell it's the VTF, alignment, azimuth, anti-skate or RTH that is off.
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Re: Using Adjust+ for VTA

Postby Dorian » Thu Jul 18, 2019 5:15 pm

That the order I currently do things in too Golear. I did another setup yesterday and it sounds great. One question - what is RTH? I think you mean VTA?
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Re: Using Adjust+ for VTA

Postby Golear » Thu Jul 18, 2019 11:16 pm

Just look back at my post in this thread, made on Jul 10. Shorthand for "adjusting VTA/SRA, azimuth, overhang and VTF, all at once".
It might catch on, it might not. :-)
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Re: Using Adjust+ for VTA

Postby Mr_Putty » Fri Jul 19, 2019 1:07 am

RTH
Record thickness height
Real thickness horizontal (plane)
Other?
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Re: Using Adjust+ for VTA

Postby Dorian » Fri Jul 19, 2019 8:26 am

Relative Tonearm Height. Makes sense.
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Re: Using Adjust+ for VTA

Postby Votan » Tue Jul 30, 2019 10:32 am

Brf wrote:Adjusting the VPI Vta tower (pivot height) affects the stylus as follows:

Azimuth (AZM): due to the tonearm offset

Stylus Rack Angle (SRA): sin(θ) = Opposite / Hypotenuse

Tonearm overhang : Pythagorean Theorem


1. I would add that in VPI unipivots, a change in the VTA also affects the VTF, as Golear mentioned and also it has been extensively explored on an older topic.
2. So the "philosopher's" question arises: Does it make sense for VPI (for Unipivots in particular) to have VTA towers for adjustments on the fly? (not to mention Golear's earlier attempt to achieve remote VTA switching from listening position!!! :o ).
Something that, in addition, significantly raises the cost, adversely affects the very rigid supporting of the arm, as well unnecessarily increases the path of (tonearm-cart energy's) mechanical grounding (not to mention side problems, such as the dial slop observed in almost all VTA towers), comparing to the very simple but very rigid tonearm base (sonically superior IMHO) of say Prime Scout with only a single VTA adjustment knob and a VTA locking screw.
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Re: Using Adjust+ for VTA

Postby Golear » Tue Jul 30, 2019 9:57 pm

Votan wrote:2. So the "philosopher's" question arises: Does it make sense for VPI (for Unipivots in particular) to have VTA towers for adjustments on the fly? (not to mention Golear's earlier attempt to achieve remote VTA switching from listening position!!! :o ).
Something that, in addition, significantly raises the cost, adversely affects the very rigid supporting of the arm, as well unnecessarily increases the path of (tonearm-cart energy's) mechanical grounding (not to mention side problems, such as the dial slop observed in almost all VTA towers), comparing to the very simple but very rigid tonearm base (sonically superior IMHO) of say Prime Scout with only a single VTA adjustment knob and a VTA locking screw.


It's not just unipivots. Any arm with an offset will change the azimuth when you change the VTA. Only the linear tracking arms are immune to this.*

It wasn't an attempt. My remote control knob turner works, and it works great. You are right that there were many known unknowns and no doubt a few unknown unknowns. I figured I'd try it and see what happens, because there are no math formulae for this and one can't do a thought experiment.

My first concern was whether the tonearm would pick up the sound of the motor. Happily, it's below the level of the music. So there's nothing dangerous going through the amp and speakers. And nothing to affect the enjoyment of the music.

The second concern was whether performance of the arm would be adversely affected. Of course, I had to disconnect the two bolts that locked the platform. So did this have a huge and terrible effect on the sound? What about other performance areas? There's more force acting on the knob. Fortunately, together with the 2 dimes under the LP weight, I get wonderful soundstage and can see into the back of the soundstage. (The platform responded well to some tape. VPI may wish to consider making the platform like the plinth of the Prime, or we can experiment with tape. And the gears lock, so the knob does not unwind because of vibrations during playback. So I didn't miss the two bolts.)

As for slop, there's a technique for this. Machinists who work at high tolerances have to deal with this, too. My technique, which I borrowed from them, is to lower the VTA below I need. Then reverse direction of turn, which means going through the slop, and then raising the arm slowly up to where I need it to be. If you operate the VTA control in a consistent direction, you won't have to worry about slop. And my laser system comes in handy, so I can do this for each LP in about 10 seconds. I actually set it slightly lower than where I want it to be. Then I play, and then adjust every so lightly upwards from my listening position, until bliss.

Is it better to adjust the VTA or leave it locked? I know I prefer to adjust the VTA for each LP. I'm ok with a Rega RB-300 not having a VTA adjustment because of the modest cartridges that will be used on them. But at our elevated levels, I have to have it.

The proof was when I got my neighbor to listen to my system. I set everything up and played an LP, with the VTA intentionally too low. As the music played, I adjusted it slightly upwards until I heard it hit the sweet spot. My neighbour (who knows nothing about hifi and claims to be slightly deaf) turned to me and said, "The bass is better!"

In the end, is it something to obsess about? Certainly not. I have a $2000 cartridge, and I can say there's a lot to be had by adjusting the VTA. If you have an Atlas, I'm guessing there's more to be had.

*One correction: the Thales linear tracking arm is by azimuth, so they don't allow for VTA adjustment on the fly. To me, that's a key limitation of a brilliant design.
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Re: Using Adjust+ for VTA

Postby Votan » Wed Jul 31, 2019 5:39 am

Hi Golear,
Without having to controvert your own findings, in my own setup, rigid and completely solid base (dogleg) of the unipivot's pivot needle has a much more positive effect on the sound (whole spectrum) than continuous VTA readjustments for each individual LP, let alone with disconnected the two bolts that should lock and stabilize the platform during playback.
I have even found that just inserting a stainless steel screw (of proper length for a given VTA) as a support (the bottom of which rests on tt's plinth and the top firmly supports the dogleg just below the pivot needle) supports and mechanically grounds even better the dogleg with clearly audible improvement in sound, than just having the two mounting bolts securely tighten.
In general, I can devote tens of hours, and/or days to the most meticulous setup of my tt and for all my analog chain, and after that also to spend so much more time in acoustical evaluations until I finally feel my heart fluttering with satisfaction and engagement for the sonic result.
But once I do that, and for long periods of time I can't and I don't want to think about setup issues every time I put my needle on a disk for amusement, instead of letting the music drag me along its magical paths. And even if at such moments the (inevitable to many, including me) audiophile nervosa appears for some extra refinement in the setup, all it can do is irrevocably spoil the magic of the moment.
My point is (even a bit cliche) that life is too short and music too much and also, with so many known and unknown variables in tt's setup, audiophilia (as many other things in life) maybe should be the art of compromising, otherwise we may chasing our shade....
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