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Why are records still warped?

This is more of a grouse than anything because I know the molding process won't ever be perfect. Still, here we are in the 21st century in the midst of a vinyl revival. Artists get it and are trying to satisfy us geeks with tasty pressings.

Cases in point are Bennett & Gaga's "Cheek to Cheek" and Lennox' "Nostalgia." Ordered both of them in (live in the sticks so no local source) and one dished, the other warped. Neither are unplayable, but both conditions are audible. Disappointing to say the least on such outstanding efforts.

The same week they arrived, I got copies of Hampton's "Silver Vibes" (mono) and Mendes' "Look Around" used at a swap meet. Perfectly flat with outstanding fidelity, especially considering their age.

Many of my "not" Golden-era pressings from the mid-70s through late-80s also lived up to expectations when I got them home. Many more did not, and that's why I ended up jumping on the CD bandwagon with a Sony CDP-101 in 1983.

In 2015, my digital playback deck is about 1000% better, CDs are better, SACDs are even better still, HD downloads can be superb, but still none of them best vinyl at its best. Unless it's warped.

We have the technology, know better and can better control the process. So, what is up with the warp thing? Is it laziness, budget or what?!?
effischer
ketchup
698 posts
 
TTW, it's not just the movement of the suspension system that causes a change in SRA when playing a warped record. Even if the suspension didn't move at all, SRA would change as a cart tracked a warped record since the record surface is not horizontal as with a flat record, but angled one way as the cartridge goes up the hill and angled the other way as the cartridge goes down the hill. The tonearm angle also changes when going up the hill and down the hill which adds more changes in SRA. So, all three things add up and change SRA when tracking warps: The angle of the record surface, the angle of the tonearm, and the angle of the stylus as the suspension deals with the warps (there is more force on the styles/suspension when going up the hill and less force on the stylus/suspension when going down the hill).
moonglum
619 posts
 
...Not to mention dynamic changes in VTF as it rides the warp (depending on the arm) ;^)

Funny thing is, although we can easily detect small, consistent changes of VTA, our ears seem to ignore them more when dealing with warped discs...
(Or perhaps it's just subconscious "denial" ;^)
ketchup
698 posts
 
Moonglum,

Your "dynamic changes in VTF" are what TTW and I referred to as suspension movement... I think! Maybe you're talking about something different, such as the platter slowing down as the stylus goes up the hill due to an increase in friction between the stylus and the LP due to an apparent increase in tracking force and the platter speeding up as the stylus goes down the hill due to a decrease in friction due to a reduction in apparent tracking force. I don't know what you meant, I'm just thinking of other ways that warps can mess up the sound.
moonglum
619 posts
 
Dear Ketchup,
Although I'm not a mechanical engineer it's an effect that relates to the mechanics of the tonearm design and the position/height of the pivot relative to the stylus? An analogy I use to help me guess which way the force increases is what happens when a tonearm is balanced.

If you balance the arm then briefly push the "stylus end" downwards the arm will react with a restorative force which eventually restores the arm upwards back into a balanced horizontal position. (i.e. analogous to less VTF).
By the same token if you lifted the "stylus end" then released it would fall due to a similar restorative force, eventually settling in the manner of a damped oscillation. (Otherwise the arm would defy gravity and stay exactly where you released it?)

(I believe) the behaviour is the opposite of what you'd expect if you viewed a declined or inclined tonearm playing an LP? Typically, warps encourage increased rather than decreased VTF.

Qualified M/Eng's might volunteer to offer their insights. ;^)
Cheers,
moonglum
619 posts
 
..To elaborate further you can use the VTA calculation/rule-of-thumb promoted by MF & others to work out roughly how much of an increase will occur due to the height of the warp...

(As a rough "guesstimate" you could be looking at a few hundredths of a gram or more, so in theory it could push the suspension slightly beyond the cart's Specification)

Hope this helps.
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