Setting RTH for each LP

Setting RTH for each LP

Postby Golear » Tue Jan 14, 2020 2:32 am

I'd like to kick off a discussion about adjusting VTA/SRA, or, as I call it, RTH.

I had no idea RTH would be such a controversial subject. If you think it's inaudible, or not important, or undesirable to adjust it, read no further. I won't get mad. Please leave out the Ad Hominem attacks - they're so boring.

Raising/lowering the height of the bearing will affect the VTF, azimuth, alignment, anti-skate as well as VTA/SRA. In short, everything. This was why I suggest using a new term: RTH, which stands for Relative Tonearm Height. This is a measure of the height of the bearing, with respect to a reference point. We can choose any reference point we like - as long as it is NOT affected by the thickness of the LP. I suggest thinking about RTH as the height of the bearing from the plinth.

Setting RTH is probably more important for a cartridge with an exotic stylus profile than, say, a one with a spherical stylus. In other words, the more expensive the cartridge, the more important RTH will be. And while one hears differences in the bass, I also hear difference in the height of the musicians in the soundstage. The kick drum is not smushed into the floor, or floating above the floor. When there's a violin, we get a sense of the height of the musician.

Many tonearms do not have a way to adjust the RTH. I think Linn is against it. Some have a way to adjust it, but it's difficult (eg Thales). A small number of arms allow for RTH to be adjusted easily. I was attracted to VPI products because one could set the RTH so easily, and while the LP was playing. OMG!

I make the adjustment in two stages.

Stage 1: put the stylus on the LP, then raise/lower the RTH until the top of the cartridge is parallel to the LP. There are many ways to do this. There are gauges made of clear plastic, some arms have a bubble level incorporated into the arm, and Clearaudio makes a very small bubble level that can be placed on the head shell.

(Some cartridges want to be slightly nose down, or nose up. No problem - just find a way to reproduce that angle for each LP. If you use the Clearaudio bubble, then the bubble won't be exactly centered in the circle.)

As explained in an earlier post, I turn "down" the knob so that the RTH is too low. Then I turn "up" the knob, in stages until the head shell is parallel. Do not reverse direction on the knob. This will account for the play in the gear and is what machinists do on lathes.

Stage 2 is making a fine adjustment. This is done by ear, because:
a. There's no standard thickness for an LP.
b. There is no standard depth of the groove in an LP.
c. The cutting angle can vary.
(Because of this, you can't use a micrometer to measure the thickness of the LP, or some other way of measuring the thickness of the LP. And one cannot use a USB microscope because one cannot see the stylus in the groove.)

For Stage 2, I had to get up, make a small adjustment, then go back, listen for a bit longer, then adjust again. And again. And so on. As Votan correctly pointed out, this was such a pain. Late one night, while listening to my system at a healthy volume, and a Jack Daniel's by my side, I emailed HW.

Me: "Hi Harry, how about a remote control VTA adjuster?"
HW: "I want one too! Where can I get one?"
Me: "There isn't one, I want VPI to make it."
HW: "Oh, you want me to do all the work?"

We exchanged a few emails and HW said that VPI would consider something in the future, as they were quite busy. I didn't hear back, but I can see just how busy they were. They were working on the lower-end turntables, the McIntosh turntable, the 40DD, the gimbal arm, the FatBoy, the Dual Pivot. I decided to make one myself. How hard can it be to make a remote control knob turner? Not very. It was great fun. And I could get many of the parts off the shelf, mainly from the robot building community. I did have help from a master machinist in making one critical part - so it wasn't all off the shelf.

So now, for Stage 2, I sit in my chair, and move the control up, in 1 or 2 second bursts. Usually, I just need a few throws of the switch. (I don't obsess about it.). It turns out that doing Stage 1 is a major aid, and Stage 2 is icing on the cake. One can easily get substantial benefit by just doing Stage 1. But Stage 2 bring out the magic. It does mean that there is no lock out the arm via the two side bolts. But like someone else on this forum, I could not hear a benefit from them. I got a better benefit by putting electrical tape to damp vibrations on the platform (as previously reported).

If anyone is thinking of making one, do please bear in mind that the knob moves in the vertical plane as it is turned. So the assembly that holds the motor must allow for this. You may wish to consider a spline. It might need to be custom-made. I went with a different design. I was also concerned about whether the motor noise would be picked up by the arm and cartridge and amplified into the speakers. I'm glad to report that, while the motor is (quietly) audible when it runs, it does not set off a resonance or feedback. And it's also masked by the music so in practical terms, it's inaudible. Kudos to VPI for their arm! It's a DC motor, used in robotics, geared down to 1 rpm, so I can look at the second hand of a watch or a clock and get a sense of how much the knob has turned. The motor holds position when it is not powered, so the knob doesn't wind down of its own accord from vibrations going through the arm. (So may be I really don't need the side bolts.) It's fed by an old-school regulated DC power supply, pure analog, and there's a very long wire between my turntable and the control box. Fortunately, there's no chance of tripping over the wire in my room. The control box sits on my armrest and I feel like Captain Kirk on the Enterprise (NCC 1701).

(You can also make a wireless one from a garage door opener/winch kit, though that adds digital into the set-up.)

Here's a video of how Clearaudio adjusts the RTH on their arm:
https://www.youtube.com/watch?v=ForESvXDOro
Go to about 16:00 if you don't want to watch the whole thing. I had no idea that bubble levels came in such a small size. Of course, they do weigh something, and could depress the cantilever ever so slightly. But it will be a consistent depress, and so an allowance can be made for this when centering the bubble in the circle. This seems to be a lot easier than using a plastic gauge.

This may be all you need for Stage 1!
https://elusivedisc.com/clearaudio-mini-bubble-level/

With practice, adjusting the RTH can take just a few seconds, and I believe it's a major upgrade, at no extra cost.

Here's another idea. VPI supplies a metal rod to set the azimuth. How about adding another channel that is 90 degrees to the existing one so that the rod can be placed the other way, so that the end points to the bearing. The angle of the arm can then be seen more clearly, when setting RTH via plastic gauges (for Stage 1).

Adjusting the RTH is kinda sorta incompatible with the Votan Greatest Mod for All VPI Turntables. You can still incorporate Votan's mod, if there's a way to make it adjustable. Shouldn't be hard. And it's only going to add a few more seconds. But you will have one more thing to do.

PS: What's next for my remote control VTA adjuster? How about doing Stage 1 automatically? Stay tuned!
Last edited by Golear on Tue Jan 14, 2020 4:08 pm, edited 1 time in total.
Golear
Senior Member
 
Posts: 479
Joined: Wed Nov 30, 2016 4:51 pm

Re: Setting RTH for each LP

Postby thegage » Tue Jan 14, 2020 12:07 pm

One thing that is rarely mentioned about VTA on the fly is that most implementations also change the effective length of the tonearm at the same time. (A few tonearms, such as the old Eminent Technology ET2, do not.) Admittedly a couple of turns of the VTA knob result in little change in effective length, but the change is still there. Given how many owners obsess over precise alignment, it seems worthwhile to consider additionally this contribution to a change in perceived sound.
TNT 2, Classic platter, Periphery Ring, Stillpoints LPI, VPI Fatboy 12 Gimbal, Hana ML, Moon 310LP, PrimaLuna ProLogue Premium pre, PrimaLuna DiaLogue Premium HP amp, Golden Ear Triton 2+, Martin Logan Depth
thegage
Senior Member
 
Posts: 474
Joined: Wed Sep 17, 2014 9:41 am

Re: Setting RTH for each LP

Postby Golear » Tue Jan 14, 2020 1:17 pm

Good point about alignment.

Just thought of this:
1. Make the Stage 1 and Stage 2 adjustments.
2. Measure the RTH. Use something like this to measure the height of the top of the knob with respect to the plinth:
https://www.ebay.com/itm/LCD-Digital-He ... 2792608850 or this:
https://www.ebay.com/itm/Digital-Dial-I ... 3791041790
3. Write that down on a piece of paper and keep it with the LP.
4. When we want to play that LP again, check the value on the paper, and set the RTH to that exact value.

And hey presto! we should get the right RTH again. So may be we don't need a Remote Control VTA adjuster! I guess Votan wasn't too far off the mark when he thought of measuring the thickness of an LP with a micrometer and writing that down. But the groove depth and cutting angle must be taken into account. So one has to go through Stage 1 and Stage 2.

(Of course, without the remote control adjuster, Stage 2 will have to be done the old-fashioned way. And we'll need a motor, etc. if we want to do it automatically.)

PS: The Mongoose arm from AnalogArtizan cost $25,000, in 2018:
http://www.enjoythemusic.com/superiorau ... Review.htm
Last edited by Golear on Tue Jan 14, 2020 4:36 pm, edited 1 time in total.
Golear
Senior Member
 
Posts: 479
Joined: Wed Nov 30, 2016 4:51 pm

Re: Setting RTH for each LP

Postby Brf » Tue Jan 14, 2020 4:07 pm

Golear, I agree with everything you wrote, but the question for me is...do I want to do this for each and every album?

I use a very similar VTA/SRA setting procedure as you with the following exceptions. I use my most common album thickness (160g) and set the sra/vta to 92 degrees and then adjust by ear. I really don't subscribe to the level tonearm wand or the use of a bubble level due for the simple fact the way the stylus is affixed to the cantilever is not consistent nor uniform from sample to sample. After I tune to ear, I will remeasure the sra using a usb scope only to satisfy my curiosity.

With respect to comments made that a change in sra will affect overhang, azimuth, vtf are all true from an empirical standpoint, but these changes must be kept in perspective. I would assume sra changes made from album to album do not deviate that significantly from the baseline sra setting, therefore, we looking a fractions, or fraction of fractions of one degree or mm.

Maybe my perspective would change if I had a remote controlled vta tower....who knows. It obviously works for you, and in my book, you don't need any further justification for it use.
User avatar
Brf
Site Admin
 
Posts: 4541
Joined: Tue Aug 26, 2014 9:23 am

Re: Setting RTH for each LP

Postby Golear » Tue Jan 14, 2020 4:15 pm

Hi Brf,

It's a personal choice, yes. And yes, while something might be true from a strictly geometric point of view (e.g. effect of RTH on effective length) in practice, it can be a non-issue. And I'd also agree that each cartridge can be different so having the top of the cartridge level with the LP is a starting point.

I think you're using a 12-inch arm, am I right? Perhaps longer arms are not as affected by changes in LP thickness, groove depth and cutting angle as shorter arms.

Oh yes, one more thing. One may want to add two electrical limit switches, so that the motor cuts off short of the two extremes of knob rotation. An alternative is to couple the motor to the knob loosely, so that when the knob reaches it's limit, the motor spindle will slip against the knob, with minimal stress to the knob. You just have to set the level of tightness by feel.
Last edited by Golear on Tue Jan 14, 2020 4:38 pm, edited 1 time in total.
Golear
Senior Member
 
Posts: 479
Joined: Wed Nov 30, 2016 4:51 pm

Re: Setting RTH for each LP

Postby Brf » Tue Jan 14, 2020 4:36 pm

Golear wrote:Hi Brf,

It's a personal choice, yes. And yes, while something might be true from a strictly geometric point of view (e.g. effect of RTH on effective length) in practice, it can be a non-issue. And I'd also agree that each cartridge can be different so having the top of the cartridge level with the LP is a starting point.

I think you're using a 12-inch arm, am I right? Perhaps longer arms are not as affected by changes in LP thickness, groove depth and cutting angle as shorter arms.


Yes, I use 12" tonearms but they present different challenges when compared to shorter arms. It's like playing pool on a 12 foot table as oppose to a 8 foot table where slight alignment errors are magnified. Also, I agree with you that geometric errors as result of a change in sra can be a non-issue.
User avatar
Brf
Site Admin
 
Posts: 4541
Joined: Tue Aug 26, 2014 9:23 am

Re: Setting RTH for each LP

Postby Shep » Wed Jan 15, 2020 2:16 pm

This article represents my approach to VTA/SRA adjustment for each record and offers what seems to me, a reasoned approach to the subject...
https://www.tnt-audio.com/sorgenti/vta_e.html

On the other hand, I'm in the "If it sounds better to you, it's OK by me" camp. However, I don't hear the improvements described when making minor/miniscule changes to SRA, so am comfortable using the "set it and forget it" approach.

Lastly, existing terminology/acronyms are more than sufficient to describe & discuss the subject. Introducing a new term (RTH) adds no value.
Prime Signature Rosewood; Fatboy Gimbal; Ortofon Windfeld Ti; B.M.C. MCCI Phono Pre
User avatar
Shep
Member
 
Posts: 29
Joined: Wed Nov 30, 2016 8:47 am
Location: Rome, GA.

Re: Setting RTH for each LP

Postby Johnny » Wed Jan 15, 2020 2:29 pm

I am more in the set if forget camp also.

Golear, how many turns of the VTA tower knob are we talking about? Once you find a baseline, are we looking at ± 1 turns?

Have you posted a pix of your modified VTYA tower in the past? If not, can we see a pix?
Johnny
Senior Member
 
Posts: 624
Joined: Mon Sep 29, 2014 7:26 am

Re: Setting RTH for each LP

Postby Golear » Wed Jan 15, 2020 10:55 pm

I think the max. for me is one and a half turns. I do more than that, to take the play into account, as well as to intentionally move the RTH much lower, then raise it to where it needs to be. So I can't really say how many absolute turns are made.

Here's the pic I posted before:
viewtopic.php?f=7&t=9923&hilit=remote+control+VTA&start=10

So... yeah..... sure.... it's not the best looking thing in hi-fi. But this was a proof of concept - and it needed to (first) do no harm to the music reproduction, and then do some good. And I needed a lot of adjustability and accessibility in every part. A friend urged me to get a designer, spiff up the looks, clean up the wiring, etc. But I got busy. And it does the job.

(There is one other part that I can't reveal at this time. I promise to show it when it's ready.)
Golear
Senior Member
 
Posts: 479
Joined: Wed Nov 30, 2016 4:51 pm

Re: Setting RTH for each LP

Postby edw » Tue Mar 10, 2020 12:03 am

User avatar
edw
Senior Member
 
Posts: 346
Joined: Sat Mar 12, 2016 9:02 pm
Location: NY/NJ

Next

Return to Support Forum

Who is online

Users browsing this forum: Google [Bot] and 5 guests

cron

x