My Views and Procedures for Adjusting VTA

[karma]

ZYX really doesn't really have anything in common sonically with the Genesis cartridge line. The ZYX has the ability to draw you into the music that eludes (d) the Genesis cartridges.

HI Myles,
But what about the Sigma cartridges? They were a definite step up from the Genesis.

Sparky

 

[bblue]

HI Bill,

Thanks for the info.

Other than periodic releveling, I never mess with my set up once it is set.

8.5 PSI is a value I don't recognize. What pump are you using? If it's a Wisa, I measured 7.5 PSI. I don't think that this difference is significant.

Right, anything above 3psi is supposed to be satisfactory.

I'm using two Wisa 200's in parallel and out of phase from one another. That significantly reduces the 60Hz 'puffing' that one does by itself. Then a 2' long 4" dia PVC pipe filled with cotton balls as the final smoother (about 1.3 gallons) before the final filter and airline to the arm which is about 30' away. The 8.5 psi is what I end up with at the end.

How does the zyx compare to yout Ortofon's? I have never heard either. But I have had experience with designer of zyx. He designed the Monster cartridges which I used for years. First, I had the Alpha Genesis 1000 (two of these) and then the Sigma Genesis 2000 (two of these). I still have a 2000 mounted on my ET2.5 on my Sota Nova. I think it is just an outstanding cartridge. I would expect the zyx to have the basic signature of the 2000 but probably better.

It isn't similar response curve-wise, but it is as far as the sound stage and ease at which it tracks. It's a very nice listen with lots of detail. I have an Alpha II that other than a weakened suspension still sounds pretty amazing. The A90 has much more realistic presentation and sounds to me, more accurate to the source. I don't think it's as good a tracker as the Zyx, or perhaps I just haven't gotten things set quite right yet. It seems to have trouble with high velocity center channel or mono modulation of vocals, percussion, anything that really pushes the lateral modulation. Yet it performs well on the conventional tracking torture tests. My current thinking is that I don't yet have arm mass set quite right for it. Or it could simply be that it needs a little more than than the recommended VTF. Still playing with that from time to time.

On my ET2.5 mounted on my Oracle Delphi V, I have a Lyra Skala. It's definitely the best cartridge I have owned. It's also the most expensive.

Yeah, funny how that works.

You want some fun for a week end? Try getting all the air leaks fixed when you are using 27 PSI as I am. They are fixed but it took some creative thinking.

No, but thanks. I have more than enough fun going on!

Are you running the newer 2.5 manifold, or the standard one with just more pressure? If the latter, why? What is it gaining you?

--Bill

 

[MylesBAstor]

HI Myles,
But what about the Sigma cartridges? They were a definite step up from the Genesis.

Sparky

Personally I thought the Alpha 2 was the best of the line. After that, they just seemed to have tipped up upper octaves.

 

[karma]

Right, anything above 3psi is supposed to be satisfactory.

.................
Are you running the newer 2.5 manifold, or the standard one with just more pressure? If the latter, why? What is it gaining you?

--Bill

Hi Bill,
I found that the original aquarium pump provided 2.5 PSI. It worked well. But, I wanted more, more , more!!

Two Wisa's explains the pressure discrepancy. It sounds like a good air system.

Yes, the 2.5 manifold is used on both arms. My original arm was the ET2 but it has been upgraded. Is yours a 2.5?

My second arm was purchased as an ET2.5. It came with the carbon fiber wand.

One of the reasons I started this thread was to try to clear up the VTA by ear issue. So, I must ask you what you specifically listen for. Try to be as specific as possible.

Sparky

 

[karma]

Personally I thought the Alpha 2 was the best of the line. After that, they just seemed to have tipped up upper octaves.

HI Myles,
Well we run into a disagreement. I felt the Sigma was significantly better than the Alpha 2. This could be accounted for by a simple difference of tastes. The system choices we have made seem to indicate this. My particular aim is resolution and detail. Yours may be a bit more subtle.

Sparky

 

[bblue]

HI Myles,
Well we run into a disagreement. I felt the Sigma was significantly better than the Alpha 2. This could be accounted for by a simple difference of tastes. The system choices we have made seem to indicate this. My particular aim is resolution and detail. Yours may be a bit more subtle.

It may be simply a difference of resistive loading between the two series.

--Bill

 

[bblue]

Hi Bill,
I found that the original aquarium pump provided 2.5 PSI. It worked well. But, I wanted more, more , more!!

Two Wisa's explains the pressure discrepancy. It sounds like a good air system.

It seems to work well.

Yes, the 2.5 manifold is used on both arms. My original arm was the ET2 but it has been upgraded. Is yours a 2.5?

No, a standard 2, but with the extra gauges. I ordered a CF wand and a Magnesium arm with it, then ordered another CF and acquired one of the earlier aluminum wands

My second arm was purchased as an ET2.5. It came with the carbon fiber wand.

One of the reasons I started this thread was to try to clear up the VTA by ear issue. So, I must ask you what you specifically listen for. Try to be as specific as possible.

I'll try. It seems like I wrote up a similar explanation somewhere else here, but I don't recall which thread it was in.

In general, I have found two 'levels' to identify. The 'outer' level happens as a change of character of the bass. It goes from very lean (pivot too high) to muddy (pivot too low). Inside that transition which is about .01 in size (according to the fine scale ET gauge, IIRC), sometimes a little broader.

Usually within that range or at one 'edge' is where the critical area for HF detail and resolution occurs. You go very slowly through that range listening for balance of detail. If you're too high, percussive HF events, acoustic guitar strums, etc., will take on an overly bright attack to them. If you're too low, generally speaking, those same things will be kind of cluttered and interfering with each other. Right in the middle is a point where everything sounds balanced and in perspective with each other, and the entire sound stage opens up. Just how broad that area is depends on the specific type of stylus and how much contact height in the groove it commands.

Things like VTF, incorrect overhang, azimuth slightly off (tilt), zenith (cart rotation), and leveling for neutral arm float, all will affect how this is perceived and the degree of improvement you'll experience.

I think that about covers it. Hope you find it useful! If you have any adds or observations, I'd like to hear them.

--Bill

 

[karma]

HI Bill,
Manifolds,
Why don't you get the 2.5 manifold? Your pressure is what it is designed for.

Resistive Loading
I seriously doubt that resistive loading is responsible for the difference of opinions Myles and I have. But, it is a good idea to explore.

The one exception is if the resistive loading is set to extremes. For example, some folks load their low output MC's with 47K ohms. I have found this does add an edge to the sound that I do not like.

Since my preamp allows loading to be adjusted from a front panel switch from 47k to 1 ohm, I have experimented extensively on many LOMC's cartridges. Except at the extremes, I have found them to be quite insensitive to loading. I have settled on 100 ohms as a good value for most cartridges. 1 ohm seems deaden the sound and 47K sounds too sharp caused, I think, by insufficient magnetic damping.

VTA
Thanks for your description. I think you are making it much too hard. Remember, all we are trying to do is match the stylus to the groove. The best way to determine the match is at high frequencies. This is the only case where small changes to VTA can be determined to be correct. Please reread my description.

The reason that mid and low frequencies are not useful is the very small changes necessary to get the high frequencies right are such a small percentage of the lower frequency modulation wavelengths that they are essentially not a factor. Think it out and you will understand.

Your technique reminds me of most other descriptions I have read. I reject them. VTA is not a tuning technique . It is very specific to a physical relationship, the stylus and the modulated groove. Once the high frequency groove/stylus relationship is established, all other sonic factors follow naturally.

Sparky

 

[bblue]

HI Bill,
Manifolds,
Why don't you get the 2.5 manifold? Your pressure is what it is designed for.

What do you believe the higher pressure gains you?

Actually, I was originally going to get the 2.5. But in conversing with Bruce at ET, it came up that I would be using a special wand to play 78's. His opinion was that with the fast lateral travel of 78's that the 2 would be a better fit. I never could get him to describe what exactly the higher pressure of the 2.5 improved.

Resistive Loading
I seriously doubt that resistive loading is responsible for the difference of opinions Myles and I have. But, it is a good idea to explore.

The one exception is if the resistive loading is set to extremes. For example, some folks load their low output MC's with 47K ohms. I have found this does add an edge to the sound that I do not like.

Likewise. It's a transformer type 'ringing' that certainly does not enhance the clarity of sound. That said, I can't say I've actually tried 47k on an A90. Maybe it's different in behavior than others.

Since my preamp allows loading to be adjusted from a front panel switch from 47k to 1 ohm, I have experimented extensively on many LOMC's cartridges. Except at the extremes, I have found them to be quite insensitive to loading. I have settled on 100 ohms as a good value for most cartridges. 1 ohm seems deaden the sound and 47K sounds too sharp caused, I think, by insufficient magnetic damping.

I find just the opposite. The sound of MC cartridge at 50 ohms is decidedly different than at 71.5 ohms (my next highest step) or 100 ohms. Each step upward increases the effective HF amplitude output of the cartridge. I adjust those values so that playback response of the tonearm is consistsent with other high quality sources in my studio. When I then measure its frequency response with a test record it is usually right on 'flat'.

VTA
Thanks for your description. I think you are making it much too hard. Remember, all we are trying to do is match the stylus to the groove. The best way to determine the match is at high frequencies. This is the only case where small changes to VTA can be determined to be correct. Please reread my description.

The reason that mid and low frequencies are not useful is the very small changes necessary to get the high frequencies right are such a small percentage of the lower frequency modulation wavelengths that they are essentially not a factor. Think it out and you will understand.

Your technique reminds me of most other descriptions I have read. I reject them. VTA is not a tuning technique . It is very specific to a physical relationship, the stylus and the modulated groove. Once the high frequency groove/stylus relationship is established, all other sonic factors follow naturally.

If you think it out, and perhaps even try it you might see my point.

Trying to find one .001-.002" area in a scale of over 300 such divisions is rather like trying to find a needle in a haystack, and very time consuming. However, the low frequency shift is much broader and quite easy to find in one or two quick passes over the range of adjustment. By doing that, you have identified the specific area where the finer point will be found, thereby saving time and frustration. Plus it can be done on just about any record.

--Bill

 

[karma]

HI Biil,
But it is a needle in a haystack. It's the nature of the beast. The challenge is to find it. Your method will not give the precision that is needed. It's not as time consuming as you think especially after you have done it a couple of times. The objective of my procedure is to find the needle without fail. Please, think about the problem and understand the need for an exact groove to stylus fit and the precision required to accomplish this objective.

I can tell you, you have not found the needle which is what I was afraid of.

The higher pressure gives a stiffer air bearing. Sonically, the entire presentation solidifies. This is especially true of the image. Bass, thought to be a weak point of the arm, becomes a strong point. The sound stage gains more specific qualities where each instrument can be placed with certainty and the walls and dimensions of the venue become more than abstractions. And the primary image becomes holographic. Other than that, not much.

Sparky

 

[bblue]

HI Biil,
But it is a needle in a haystack. It's the nature of the beast. The challenge is to find it. Your method will not give the precision that is needed. It's not as time consuming as you think especially after you have done it a couple of times. The objective of my procedure is to find the needle without fail. Please, think about the problem and understand the need for an exact groove to stylus fit and the precision required to accomplish this objective.

I can tell you, you have not found the needle which is what I was afraid of.

Yeah, right.

The higher pressure gives a stiffer air bearing. Sonically, the entire presentation solidifies. This is especially true of the image. Bass, thought to be a weak point of the arm, becomes a strong point. The sound stage gains more specific qualities where each instrument can be placed with certainty and the walls and dimensions of the venue become more than abstractions. And the primary image becomes holographic. Other than that, not much.

Well that's pretty significant. I was originally suspicious of the pressure being responsible for soft bass and discussed it with Bruce @ ET. He said no it would not cause that unless pressure was very low, and that the *apparent* reduction of bass was actually more accurate to the source compared to a pivoted arm, which tends to build up bass due to the summation of vertical and lateral arm resonances. The ET arms don't sum those resonance points and therefore paint a much cleaner clearer representation of the original.

Still I have reservations about that taken entirely at face value. Your description is exactly what I would expect from a stiffer pressure. The question is, though, at what point (psi) does it become significant, and above what point (on each manifold type) is further increase irrelevant.

Separately, I found that the biggest factor controlling apparent bass on my arm was the correct matching of mass loading between the arm and cartridge. The manual is not at all clear in that regard, and seems to gloss over the significance of matching the two.

--Bill

 

[karma]

Still I have reservations about that taken entirely at face value. Your description is exactly what I would expect from a stiffer pressure. The question is, though, at what point (psi) does it become significant, and above what point (on each manifold type) is further increase irrelevant.

Separately, I found that the biggest factor controlling apparent bass on my arm was the correct matching of mass loading between the arm and cartridge. The manual is not at all clear in that regard, and seems to gloss over the significance of matching the two.

--Bill

HI Bill,
I have only run higher pressures with the high pressure manifold even when I had the Wisa.

I found that pressure changes over 25 PSI could not be detected. I run the air system at 27 PSI.

Sparky

 

[DonH50]

Any thoughts on how the stylus shape impacts VTA?

 

[karma]

Any thoughts on how the stylus shape impacts VTA?

HI Don (again!),
By the time I developed the procedure described here I had been using fine line contact styli for years. So, anything I say is conjecture. I have never tried the procedure with elliptical styli.

The alternative shapes are pretty much limited to conical and the various forms of elliptical. Conical is not worth considering. Elliptical, however, could be in the conversation. I basically think that the smaller the small radius is, the finer is the resolution of the procedure. But, a good elliptical will still fit into the highest frequencies of the groove modulation which is the key to the procedure. So, I suspect the procedure would work well for elliptical. I don't think the sweet spot would be the same. It seems to me the sweet spot would be wider and not as definitive (not as deep), similar to the results I get from pivoted tone arms.

As for correctness of the VTA, I think it is always correct for it to be right. It's just that elliptical is probably more forgiving but also, does not give as ultimately good results. I'm, as I'm sure you are too, in the fine line contact camp.

Sparky

 

[DonH50]

Thanks Sparky. I know we (myself, another tech, some friends) tested conical, elliptical, hyper-elliptical, and fine-line styli and my memory of the results matches your conjecture. That was long ago and I do not really recall the details. We were assessing VTA and anti-skate on a variety of arms including an air-bearing linear, electromechanical linear, a modified SME (to make it easier to adjust VTA), my Unitrac, and a couple of others I do not recall. We used three or four turntables and rotated arms and cartridges. Testing used test records and a few musical selections (I know the Sheffield drum record was one, not sure the others); we used test instruments and listening tests. The main cartridge was a Grace, I think, as we could get all four stylus topologies with the same body. We used a few other cartridges (one was a Stanton IIRC, and another a middle of the line Shure) but very few companies offered different stylus tips on the same body so our selection was limited. It took about two - three months to do all the testing and catalog the results. The results were published but not in the AES Journal; Audio, I think or maybe Audio Amateur. I was listed as co-author but in fact did almost none of the actual writing; I was a kid and mainly the lab rat.

One interesting conclusion, based on measurements more than listening, was that it was indeed easier to find the sweet spot using HF test signals. However, most everybody agreed that, outside that very small point of perfection, it was much faster and easier for most people to hear what happened in the midbass; we had to train people to listen for a pure HF signal (we actually used two-tone testing for much of the study). We did find test tones worked much better than music for dialing it in, and IMD was one of the best indicators both by measurement and ears.

Measurements showed a narrow sweet spot; ears were more forgiving. Going from very thick to very thin LPs back-to-back we could see differences in measurements; listening tests were much less conclusive. The only times we got clear recognition was with a two-table setup that we could quickly switch between; even from very thick to very thin records most people could not tell which was "perfect" with a minute or two gap between trials while we switched records and replayed the test. Shure had a hand in making the test recordings on thick and thin blanks; a Shure VP lived in KC at the time.

 

[karma]

HI Don,
What exactly were you measuring and what was your instrumentation? Yours is a very interesting experiment.

Sparky

 

[DonH50]

Thinking back it may have been crosstalk, not IMD... In any event, the test record had two-tone signals in each channel plus single tones in each channel (the better to tack vertical/horizontal modulation). Test equipment was a 'scope and audio analyzer to measure THD/IMD/SNR and a spectrum analyzer (HP, I think). With a slightly different tone in each channel we looked for the "wrong" tone in the other channel. We also did two-tone tests in each channel and both to check IMD.

 

[ack]

Setting VTA/SRA by ear

Based on some recent email discussions, I wanted to revive this thread a bit... I have read numerous claims on the net how to best set VTA/SRA by ear, and the one that's been floating around on audiogon for quite a while now is listening for harmonics either leading or trailing the fundamental, as an indication of SRA being off in either direction. I think this is entirely misleading: the very definition of a harmonic is that it cannot possibly exist w/o its fundamental, so for it to lead or trail its fundamental is meaningless to me.

There are some very informative posts in this thread, primarily #7 from Myles (pointing to ET2 arm's manual), and #35/#37 from DonH50. After reviewing this thread again and other articles on the net, I wanted to point out the following:

SRA affects Intermodulation Distortion (IMD), and is thus optimally set with an oscilloscope and/or spectrum analyzer and two test tones in a test track - and Don says up above that they were best able to do that with test tones; but who really has one of those analyzers and what exactly is the SRA angle of any test record used with it to be used as a reference point? These issues render such advanced methods useless for us mere mortals. So listening tests and USB microscopes is what's left. Microscopes have been discussed elsewhere here and TAS has an excellent article on its site and current issue by Mr. Jennings; so what about adjusting by ear?

The ET2 manual includes IMD tests in pages 51-54; moreover, Fremer says the following at http://www.analogplanet.com/content...icroscope-set-92-degree-stylus-rake-angle-sra

The more accurately the playback stylus replicates the cutter stylus angle, the less IM (Intermodulation Distortion) is produced, resulting in smoother yet far more detailed sound. Setting SRA by “ear” usually meant going from brighter, harder sound when set too high, to duller, thicker and less focused sound when set too low.

IMD as a function of VTA/SRA goes back decades; I found this article very interesting as well http://www.hi-fiworld.co.uk/vinyl-lp/37-technology/73-vertical-tracking-angle.html

Because the practical subjective consequence of vertical tracking angle errors on sound reproduction are really of most significance I don't intend to dwell too long upon measurement technicalities, but a few consequences of incorrect vertical tracking angle are presented for illustrative purposes. Classic in measurement terms is the waveform to be seen in Fig 5. The upper trace alternately shows rounded and sharp peaks of significant second harmonic distortion and the spectrum below shows the harmonic structure. From the same disc can be seen significant intermodulation distortion in Fig 6 due to this cause. Lower trace shows two signals, one of 4kHz and one of 200Hz from the disc; above can be seen the 4kHz component filtered out. The change in level is due to presence of distortion sidebands from amplitude modulation which, in more straightforward terms, means that the 4kHz tone is now accompanied by other tones of significant level that weren't there in the first place and wouldn't be there either but for a vertical tracking angle of just over 30°.

See also post #19 here http://forums.stevehoffman.tv/threads/how-to-set-vta-from-first-principles.151366/

The definition of IMD is (from wikipedia) is:

Intermodulation or intermodulation distortion (IMD) is the amplitude modulation of signals containing two or more different frequencies in a system with nonlinearities. The intermodulation between each frequency component will form additional signals at frequencies that are not just at harmonic frequencies (integer multiples) of either, but also at the sum and difference frequencies of the original frequencies and at multiples of those sum and difference frequencies.
​

​

The key here is, additional harmonics at the "sum" and "difference" of the fundamentals - basically, IMD introduces EXTRA unwanted harmonics beyond those occurring naturally.

This is why the Analog Productions Test LP http://www.analogueproductions.com/index.cfm?do=detail&Title_ID=35532 (and others like it, e.g. the CBS and DIN test discs referenced in the articles I quoted) have a special track for VTA/SRA:

Track 9 VTA adjust
This is an IEC intermodulation distortion (IMD) test signal; 60Hz & 4kHz 4:1 ratio.
Using an IMD tester, adjust VTA by raising or lowering the tonearm for minimum distortion.
​

​

Notice, it includes just two frequencies so that one can see the extra sum and difference harmonics on a scope or spectrum analyzer, and make sure they are minimized or eliminated. But again, who has such equipment and no one knows the SRA of those test record (thus even these types of tests are not meaningful enough).

Therefore, to me, the bottom line is that we should be listening for the minimum amount of intermodulation distortion - minimal or no additional unwanted harmonics - when adjusting VTA/SRA, and hopefully for every LP if we can.

 

[mbskeam]

If I can ask, what Test LP's do you guy use?

 

[ack]

I use the Analog Productions