2008 RMAF – – – all things analog.


I have two questions/comments on the 2008 RMAF below.

1) First thing…

Who’s Going?

I’m going for my second consecutive year. I enjoyed last year a great deal. I had wonderful discussions with analog types like Thom Mackris, Alvin Lloyd, Jeff Cantalono/Thomas Woschnik, and Frank Schroeder. I had time with my own LPs on all of their tables as well as quite a few others. I’m looking forward to this coming year as well.

If you are going to the 2008 RMAF, I’d like to know so I can meet some of you out in Denver.

2) Second thing…

Any suggested Table, Cartridge, Arms to pay particular attention to?

Again, If you are going to the 2008 RMAF, I’d like to know so I can meet some of you out in Denver.

Dre
dre_j
There's a lot to catch up on in this thread, and I'll do my best to be brief and yet thorough ... well ... maybe not brief ...

Speed Errors.

There are various types which correlate to the magnitude and distribution of the error. Chris alluded to this in the stylus drag discussion. At the lowest level is IM distortion discussed in my post above, and loosely equivalent to digital jitter in the sense that we don't hear this as pitch change or wavering but rather as a combination of harshness, a paradoxically rolled off top end, and bleached out harmonics in the mid-bass. As we work our way to longer time domains, we begin to hear timing errors - like the band isn't completely on the beat. Increasing the time domain further, we begin to hear shifts in imaging and pitch until we reach a point where nausea sets in for some of us. It's important to make these distinctions when we talk about speed.

Selection of Music.

I agree in general that acoustic music is critical to understanding what's going on, but this focus on period instruments is more a point of familiarity and reference for our friends on this list than anything else. It provides one (and I emphasize one) means of triangulating on the truth.

For an alternate, equally valid reality, listen to Bill Monroe, Doc Watson, Mark Knopfler, Neil Young, acoustic Jorma Kaukonen, John Fahey, Cal Tjader, Charles Mingus, Kathleen Battle, Talking Heads, Scissor Sisters, etc. and they'll all tell you something equally important about what's going on with your rig.

One of my favorite torture tests is to play a capable soprano going full tilt. Dense music has its place as well, and in this category, you can learn as much from Heavy Metal (even though I don't like it) as you can from full scale romantic pieces.

Rock 'n roll and other electronic music presents a challenge to understanding what's going on, but well recorded rock can also tell you things that you can't hear with acoustic music. You have to be watchful however. Listen to Neil Young playing his beat up Fender Tweed Deluxe, and if you know the sound of those amps and their harmonic overtones, it's unmistakable when a system gets this right.

Period music (Academy of Ancient Music) will tell you about subtlety, nuance and such. Other genres will tell you something different. When we had our Saturday night after hours session at the Audiofest, Palasr brought an AC controller which we listened to (designed by the same fellow who's working with Win on the Saskia controller as well as with us). Well, we're still hunting down a 3-phase motor, and the 2-phase we were driving was relatively crude sounding compared with our legacy controller.

If you listened only to pop and rock, this crudeness would have been lost on you, as bass lines had nice punch to them. A shift to acoustic music told the rest of the story however. Drej and Palasr will agree, I'm sure. One of the main dangers of trying to reach a conclusion when listening to electric music is that the distortions in the recording process can be masked by electronic distortions in your system.

In my humble opinion, a system needs to do it all, and if you limit yourself while you're evaluating, you may well be limiting your ultimate outcome. So, if you listen only to period instruments, should you also invite Jazzdoc over with his Scissors Sisters records. The reverse would be true as well - don't listen only to electric.

Ultimately, you're making choices, but listening to all different sorts of music at a minimum will expose you to different worlds, and the fellow who tells me that Woody Guthrie doesn't have a story to tell me and that all of the valid music was composed by white guys who died a hundred years ago is equally self-limiting as is the reverse. Ultimately, even if you listen to music written by dead white guys, you can still learn a lot that's relevant to you by listening to modern music occasionally.

Cheers,
Thom @ Galibier
Back in 2002 Audio Asylum correspondent Klaus discovered a letter in a 1967 issue of the Journal of the Audio Engineering Society where RCA reported some measurements they had made of speed variations caused by stylus drag. Using a metal master, the RCA engineers measured a 0.078% speed change when playing a silent groove and a 0.079% speed change with a modulated groove. The speed change was even lower on a vinyl record, 70% of that measured with the metal disc. Since the difference between playing a modulated and a silent groove on a metal master was 0.001% (0.079% - 0.078%), and a vinyl record reduced that difference to 70%, the real speed change caused by a modulated groove would be .7 x .001% or 0.0007%. That's 2/10000 of an RPM for a 33 1/3 RPM LP. I really doubt that anyone can hear the difference between 33.3333 RPM and 33.3331 RPM. In any case that speed change caused by stylus drag would seem to be buried beneath the wow and flutter of even the most stable turntables.

Of course those measurements are over 40 years old now and I suppose that today's much better stylii might have even lower drag and speed change. It would be nice to have contemporary measurements of the phenomenon but until someone repeats the RCA experiments stylus drag would seem to be inconsequential.
Robdoorack,

Interesting stuff, but not necessarily conclusive of anything. Read the posts by Teres and Thom Mackris just above (well, some of Thom's anyway!). Depending on the time span over which "speed" is measured, the effects of stylus drag may produce no measured difference at all, yet may still be audible.

Consider this analogy:

A. You decide to time me running laps around a track, but the seat you chose to observe from can only see the start/finish line. It has no view of what's in between.

B. You observe that I pass the start/finish line precisely once each minute, so you conclude (correctly, from your perspective) that I'm travelling at a steady 4 minutes/mile clip (assuming a 1/4 mile track).

C. What you don't know, because your chosen vantage point doesn't let you see it, is that half the circumference of the track is actually a foot deep pool of water. This slows me down to 8 minutes/mile speed, but I make it up by blazing through the dry half of the circuit at 2 minutes/mile speed.

D. Your limited resolution of measurement (you can only see and measure in whole laps) leads you to the false conclusion that I'm running at a steady pace. The reality is that my speed is varying all over the place. Only the long term average is steady.

E. A turntable with a motor/drive system that allows deceleration due to drag, but then re-accelerates to faster than average speed when the drag is removed, could easily maintain a perfect AVERAGE speed of 33 1/3 rpm, while producing audible or even horrible sonic speed changes that a once-per-revolution measurement would never detect. A longer period of measurement would be proportionately less likely to detect them.

So, the experiment quoted was vaguely interesting, but proves virtually nothing. The human ear is vastly more capable of detecting short term speed changes than the crude experiment you described.

Doug

P.S. If anyone ever observes me running 4 minute miles, please let me know!
Robdoorack, Thanks for the interesting data. The measurable deviation cited was more than I would have expected. As Doug points out the measurement time period is very significant. Most people are not able to detect relatively large errors in average speed. For the majority of us the threshold is more than 0.1% and nobody can detect a 0.0007% error. However short term deviations are a different matter. It is well documented that digital jitter of 10 picoseconds is audible. That's a short term deviation of 0.000000001%, one billionth of a percent! So it should not surprise us that a short term analog speed deviation 10,000 times greater would be audible.
Wow some interesting reading. The speed issue has been with us from the beginning of vinyl playback right. We all have accepted the fact cause were here. I am in constant adjustment between lps. Observation done with a KAB strobe on top of my center weight as I am able to check when playing a lp. I am tuned to hear pitch changes and thats the reason for the constant checking and tweaking. All of the reasons are known for this yet there is no drive system that will remove our drag problem that i am aware of.

In the end though the sound of vinyl play back is so far superior to digital that i can live with the drag in my hearing. IMO

No pun intended ha.