My Views and Procedures for Adjusting VTA

PeterA

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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.

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.

Here is one of the posts to which I think Ack is referring. It appears originally in my system thread here on WBF, though there are additional references to this on Audiogon:



Hello Frank, I spent a month experimenting with VTA settings and found that proper SRA is essential to getting the most enjoyment out of vinyl. To my surprise, it has little to do with LP thickness. I did these experiments while I was also experimenting with loading and gain options on my old Pass XOno. I had thought loading and VTA would effect the sound in similar ways, namely tonal balance. I was very wrong.

SRA has everything to do with the timing of a note. If the VTA is too low, the fundamental and the harmonics are slightly separated in time. The note is stretched and sounds unnatural. If the VTA is too high, the harmonics overlap and obscure the fundamental of a note, softening transients and hiding details. When the SRA matches the original cutting angle of the LP groove, the notes sound more natural and the timing relationship between the fundamental and the harmonics is correct. Transient, sustain, decay.

To this end, I now adjust the VTA of my SME V-12 arm within a 4mm range. I use the SME supplied paper protractor which has a mm scale on the end. I measure from the top of the armboard to the bottom of the arm rest support, both of which are flat. The average measurement is 17mm. Some records are as high as 19 and some as low as 15, but the majority are between 16 and 18. I find the correct setting for each LP when I play it and then write it down on a sticky note which I keep between the cover and the outer sleeve for easy reference for the next time I play it.

I did this demo on a fellow member's (ACK'S) system with two of my LPs. He was really surprised at how much the sound changed and how much more natural the music sounded. In another experiment, this gentleman asked me to shut my eyes and tell him when the VTA sounded best as he adjusted it up and down on his VPI table/arm. When I said stop, he measured and told me that the setting was extremely close to the theoretical 92 degrees that he had previously calculated. I think that was a coincidence for that particular LP because I have found that the same thickness records have different ideal SRAs. 92 is just a close compromise and if you don't have a way to do the math or capability to see the stylus, how do you know what the angle is? It is much more accurate to set it by ear. You just have to train yourself to know what to listen for.

It has taken some practice, but it now only takes me about 15-20 seconds to adjust the VTA before I play the LP. Sometimes I will play a few Philips LPs in the evening for example which have the same setting, so I don't need to adjust anything for that session, but usually, I make 2-4 changes an evening. It is well worth it, IMO.

LPs that used to sound a bit flat or lacked detail and natural tone now sound much better. Dynamics improved also, but mostly, it is the quality of the notes which sound much more natural when the SRA is correct. Incidentally, a 1 mm VTA height change on a 12" arm is less than 1/4 degree of SRA change. This is audible on my system and has contributed greatly to my listening enjoyment. I dare say it is about as significant an improvement as going from the XOno to the XP-25. And some of the sonic improvements are similar, ie better spacial layering, more tonal density, and more accurate timbre.

And the best part is that this improvement in sonics was free for a change.




This method of adjusting SRA/VTA was taught to me by an audiophile friend named Doug Deacon. He posts frequently on Audiogon in the analog forum. I think he wrote somewhere that he learned what to listen for while adjusting SRA from Frank Schroder. The "fellow member" to whom I refer above is Ack. We performed this demonstration on his system and got positive results.

I don't claim that it is the only way to adjust SRA, nor the best way. Nor do I think everyone should adjust SRA for each LP with a different original cutting angle. However, I have found that precise SRA can improve the sonics of one's system and that this is the method that works best for me. It is relatively quick and does not involve the use of any testing gear besides one's ears. The problem that I see by using a test LP is that we do not know what angle the original cutting head was set at, nor is the thickness of the test LP the same as that of the rest of one's LP collection. Ack's recommendation to use an LP may work great for that LP, but as I have found, the important thing is to try to match the SRA of one's stylus with that of the cutting head originally used to cut the lacquer. Because there was no standard, that angle varies, so setting the stylus to match one test LP may not give one the best results for the rest of the LPs in his collection.

Regarding the timing relationship of the fundamental of a note and its harmonics: This makes intuitive sense to me and it is what I think I hear when listening to something like a piano key or cymbal being struck. It is more difficult for me to hear with a bowed string, but I have learned to hear that also. When the timing relationship between the fundamental and harmonics of a note is correct, the note sounds more natural with increased clarity, dynamics and correct timbre.

As Ack mentions, there is a lot of misleading information on the net. I hope that I am not contributing to it by sharing with others the method that I learned for adjusting SRA.
 

ack

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Thanks Peter; after careful listening, I eventually undid the adjustment during the demo. Frankly, as it stands right now, it feels like both you and I were wrong, at least in the context of what I hear now. As it stands, SRA right now has gone entirely in the opposite direction: while you thought raising the arm even further resulted in an optimal setting (and what I had calculated), I have gone WAY down, further lower that I had originally set it. Will be thinking about what we heard (or thought we heard) some more. As it stands, the alleged timing between fundamentals and harmonics still makes no sense to me, audibly or from an engineering/physics perspective. Adjusting for lowest possible IMD does and is in line with all articles I referenced.
 

PeterA

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Thanks Peter; after careful listening, I eventually undid the adjustment during the demo. Frankly, as it stands right now, it feels like both you and I were wrong, at least in the context of what I hear now. As it stands, SRA right now has gone entirely in the opposite direction: while you thought raising the arm even further resulted in an optimal setting (and what I had calculated), I have gone WAY down, further lower that I had originally set it. Will be thinking about what we heard (or thought we heard) some more. As it stands, the alleged timing between fundamentals and harmonics still makes no sense to me, audibly or from an engineering/physics perspective. Adjusting for lowest possible IMD does and is in line with all articles I referenced.

Ack, I think we listened to my copy of Vivaldi's Concerto for two Mandolins on Erato for that SRA demo. And perhaps a second LP. The SRA we set was optimized for that/those two LPs only. Are your comments based on listening to your copy of that LP? If so, then perhaps it has something to do with all of the modifications you have done to your cables and to your phono stage. It could also be the effect of your new amps in the system, though I don't see how that would effect the timing of the notes. It was not the same system I heard the first time and sounded very different, so I would expect you to have to make some adjustments.

Based on the last time I heard your system, I would think that lowering the SRA would help. I think I mentioned to you that I heard high frequency distortion from the records you played and a blunting of transients. You mentioned this on piano and drum. Perhaps that was the harmonics obscuring the fundamental or excessive IMD referenced in your links. I would think that lowering your arm quite a bit would help that condition.

What does the Analog Productions test LP tell you? And have you been adjusting SRA for different LPs or have you settled on one angle? The advantage of your arm is that it is fairly easy to adjust VTA. What do you mean by "WAY down"? Four mm is about one degree in SRA for your arm.
 

ack

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I remained skeptical about your demo that day, even though I didn't show it. As mentioned to you privately, I will play along, then think about it, in case I am missing something. I don't think I was. I lowered it back to what I had the next day. Then even lower the last two weeks, after careful audition having had the amps fully broken in. The difference between where we set it during the demo (+9.25mm) and where it sits now (+6mm) is too huge for us to claim that it was just your LPs that needed a higher SRA setting - every LP I have tried now benefits from the lower offset. What I think may have happened back then is that, because of the darker sound of the 360s, we were falsely looking for more high frequency content. With the 400s now and their exceptional ability to render treble, perhaps I now hear the distortions much more clearly... perhaps.

My careful auditions recently started with the LP on the bottom - I thought I would do an acid test with very high dynamic content, and what better than a soprano, and in this case, two sopranos. At the setting I had it and more so at the setting you demoed, shrilling is quite evident - shoot the speakers please; lowering SRA fixed it. That's how excessive IMD will sound. Then verified the same with strings, RR's The Age Of Swing's hi hats and cymbals, and a lot of other content. I do agree that during the 400's audition there was some bothersome high frequency content at times; it was probably a combination of SRA and the amps breaking in; I don't think the XP-25 and MIT MA-X mods have anything to do with this, other than remove veils exposing IMD distortion in the cartridge set-up - but that's just a guess.

Regarding the Analog Productions LP, I should clarify that I only use it to verify speed with the 1kHz tones and set azimuth, nothing else. Setting SRA is meaningless with that LP exactly because they don't disclose the cutting SRA, so there is no reference; and I don't have a spectrum analyzer (though I could easily get one).

 

PeterA

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Here is the link to another thread which discusses how to adjust SRA:

http://forum.audiogon.com/cgi-bin/fr.pl?eanlg&1413345890&openfrom&13&4#13

I have included an excerpt that describes one method. It may be at odds with what is written above in this WBF thread, but I have found it to be very helpful when adjusting SRA in my own system. I don't have test equipment and I don't think using a test LP will help much for the LPs in one's collection if they were produced using different cutting angles. This is the method that works best for me:


I listen to 90% classical myself, with a particular interest in period instrument performances. About 4,000 LPs, perhaps a third from musicians like Hogwood, Harnoncourt, etc. I'd take exception to a suggestion that such recordings aren't sensitive to SRA adjustments. In fact, I find that good recordings of certain natural (not amplified) instruments are more revealing of SRA changes than any other type.

We probably have records in common, but rather than provide a list I'll address your comment that you find this difficult by describing what to listen for. From this, we can deduce what type of instruments are most revealing of SRA changes and why.

There are two schools of thought on what sonic changes an SRA adjustment typically makes. Those with less experience and/or less revealing equipment often describe a change in treble/bass balance, rather like a tone control rolling off one end or the other. Raising the arm strengthens treble, lowering it strengthens bass. I used to play a (stock) Shelter 901. The above is exactly what I heard with that cartridge.

When I moved to more revealing cartridges, I began to hear something different from SRA changes. It was more subtle and more closely related to reproducing the sound of real instruments. A stock Shelter 501II would probably not reveal this, but that OC retip will make all the difference. (Great move, BTW.) A line contact type stylus is needed to reproduce what I'm about to describe.

Frank Schroeder (the tonearm designer/builder) described the sound of SRA change to me very succinctly. He said, "Listen for the timing between a fundamental and its harmonics."

Whaaaaaat?

Imagine a plucked string like an acoustic guitar or harpsichord, or a struck piano string or cymbal tap. The first sound that reaches your ears is the fundamental. Following immediately after that are various harmonics generated off that fundamental. If you listen attentively to a live instrument, you'll be aware of time lags between the various sounds that make up one "note".

Raising tonearm height causes the harmonics to occur too early relative to the fundamental. Lowering tonearm height causes an unnatural time lag after the fundamental before the harmonics arrive. The difference may be nanoseconds, but getting SRA just right "pops" all these facets of a note into temporal (NOT spatial) focus. The instruments sound more real.

The easiest instruments to hear this on are those with a crisp attack followed by a naturally decaying bloom of harmonics. I named a few examples above. Instruments with a soft attack and/or a long sustain, like pipe organ or recorder (or electric guitar), are difficult or impossible to adjust SRA with.

Considering the above, I'm sure you can pick recordings from your own collection that would be suitable.

P.S.
For any given record, the window for optimal SRA is EXTREMELY TINY. Raising or lowering the arm outside of that zone typically makes almost no sonic difference at all. This may be why you're having trouble getting your ears around it. Move your arm more than a half turn of the adjustment dial and you'll zip right through the sweet zone without even knowing it. So, start with the top surface of the cartridge level. Then tweak up or down in TINY movements from there.

P.P.S
For this to be really audible, VTF should be dialled in first, by ear. Anti-skating, if you use any, should be as minimal as possible, consistent with clean tracking.
 

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