How much do warps effect pitch?

[rito25]

My piano teacher says he can hear the change of pitch of a record warp. Outta curiosity how much change of pitch would something like a 1 mm warp or less be? What about something like 4 mm warp?
I never hear warps by the way.
I can't seem to find much info on this online, maybe you guys can help?

 

[mcdan]

Depends on how bad the warp is, tracing weight, and total mass of the tone arm and pickup. The effect is called "warp wow". Low mass arrangements tend to be less noticeable. Hope this helps.
Dan

 

[ev13wt]

Get a vinyl with a test tone that is constant, warp it with one sided heat and play it.

If the tone changes you can also hear warp.

 

[Dan ʕ•ᴥ•ʔ]

Warps don't bother me as much as records that were pressed off-center. That sort of wow irritates the hell out of me.

 

[Mark W.]

It would be completely variable depending on how stretched the groove was. An alernating warp would be the worst. A slight gradual swelling would be the least.

 

[rito25]

Does the wow and flutter of the turntable effect how noticeable warps are?

 

[JonL]

I think it depends a lot on the music. Fast music with lots of instruments you probably won't hear it. Slow music with a single piano or guitar (acoustic) you probably will. I don't understand why the turntable would have an effect. To me, the change in pitch is related to the local change in speed or change in groove length caused by the warp. Actually, without thinking about it too much, it seems that these would be very compensatory effects... Anyway, here's a crappy video I took a while back. I took it with my ancient still camera so the quality sucks and it's very short but I can't hear the very severe warp on this music.

http://www.youtube.com/watch?v=BYT8haIz8_o

(BTW, anyone know how to actually embed the video in the post?)

 

[tvphobic]

If you make a diagram, you can calculate the pitch shift of a warp (if you measure it or pick an arbitrary 'height') You will note that it's a function of the length of the arm. With a typical 282mm arm, it's not such a big deal, but warp is a serious problem for the Souther and Clearaudio fully mechanical linear arm because the actual tangential arm is so short, if using them it's great to have vacuum hold-down.

 

[thedelihaus]

Does the wow and flutter of the turntable effect how noticeable warps are?

Torque (or lack thereof) might.


I own a few record clamps- clamps, not weights- and they help greatly with flattening dished or warped records.

Also, watch for subsonic activity at the woofers- sometimes also caused by warpage.

Makes the woofers "boogie" like St. Vitus unless you have a subsonic filter engaged.

 

[Karma16]

HI,

My vacuum turntable (Sota Nova) eliminates almost all warps. Thus, I rarely hear warp wow. This also means I am very sensitive to it and can't stand it.

Sparky

 

[thedelihaus]

HI,

My vacuum turntable (Sota Nova) eliminates almost all warps. Thus, I rarely hear warp wow. This also means I am very sensitive to it and can't stand it.

Sparky

I imagine that the vacuum method is the best for curing warps. T'was highly regarded from various manufacturers.

Didja know....

JVC offered a vacuum model?:yes:

 

[rito25]

Warps I don't hear. Just trying to figure out how much a change in pitch it would be for someone to hear a warp.