Do You Have a Favorite Disk to Set VTA/SRA?

Melm,

Thanks for coming back. ;-)

Your tonearm, like my TriPlanar, offers quick, repeatable height adjustment on the fly. The good news: it's easy to adjust. The bad news: it's easy to adjust! Welcome to the risk of joining the, err... lunatic fringe.

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.

Doug- your way of describing the differences is helpful. The difference in timing between the fundamental and the harmonics/decay is consistent, i think, with the grosser difference in 'thin' v 'thick' sounding. I agree that the window seems to be tiny, in that there is a 'just right' spot (just as I think most records have a 'natural volume' where they tend to sound best in a given room). But, when I had Lyra cartridges- I guess very revealing at least at the upper rungs of their ladder- i found them incredibly sensitive to VTA. Not so much with the Airtights which I've been running for a long while.

New generation tonearms should have VTA and other adjustments with remote control, so you don't have to leave a sweet spot.

Here is another discussion about setting VTA on Whatsbestforum: post #38 is
quite interesting.

http://www.whatsbestforum.com/showthread.php?5656-My-Views-and-
Procedures-for-Adjusting-VTA&p=277738&viewfull=1#post277738

The methods may be similar, but it seems that the language used to describe
what to listen for is different.

Peter,

Thanks for posting a link to that discussion, which I hadn't seen. Post #38 seems problematic in two ways:

1. He "doesn't get" how the timing between fundamental and its harmonics can change. If we were discussing the original sound itself, neither would I. But we're not.

The sound source of interest is no longer a trumpet or guitar. It's a modulated piece of plastic. We're extracting sound by tracing those modulations with a stylus. All manner of mechanical inaccuracies, including SRA deviations, can and do alter the original sound in ways that could never happen when listening to live music.

Have you ever heard a live musician and said to yourself, "He needs to be playing with higher VTF, or less antiskating?" Of course not. The poster is suggesting that recorded and reproduced sound must have the same characteristics as live sound, which is patently untrue.

If the SRA of the playback stylus differs from that of the cutting stylus, the contact surfaces of the playback stylus will encounter groove modulations "out of synch" with what the cutting engineer intended. This, to my ears, alters the perceived sound as Whart and I have described.

2. His recommendation to set SRA by minimizing IM distortion using a test record is 100% correct; provided that, all you ever intend to play is that test record. As soon as you change records, however, the validity of that "perfect" result goes out the window.

With respect to the unknown poster, his method is that of someone who prefers the certainty of numeric measurements, even when those measurements have no applicability to the real world problem - which is how to adjust SRA for the particular record I'm about to play.