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How best to eliminate LP warps

I own about 2500 LPs, and I like to think they're flat.  Furthermore, I espoused the view that warped LPs ought to be discarded.  But lately I have found 2 or 3 of my LPs that do have warps but sound too good and are too precious for the music recorded on them to throw away.  So I am in the market for ideas on how to remove warps.  I am aware that there was a device on the market that looked like a large waffle maker, to be used for warp removal.  I think Furutech made it, but I never see it advertised these days.  I am also aware of the DIY method of placing an LP between two glass plates and heating the ensemble.  The question there would be how hot and for how long?  Any suggestions are welcome, especially opinions on the efficacy of the Furutech.  Thanks.  Please no comments on vacuum hold down; I think it's a great idea but none of my five turntables has that feature.

lewm
terry9
2,348 posts
 

@optimize @jw944ts 

Mistracking and wow are only part of the problem. If you want to get the most from your vinyl, you have to set all TT parameters pretty accurately. That includes stylus azimuth.

A dished LP will significantly mess up your azimuth adjustment consistently for the whole record. A warped LP will severely mess up your azimuth every 1.8 seconds.

My DIY air bearing tonearm / Koetsu setup is sensitive to small azimuth changes - 6 minutes of arc from perpendicular is clearly audible. The effect manifests itself as a loss of beauty tending towards grating coarseness. It's not better when it comes and goes.

A 1 mm dish over the 150mm from edge to spindle is 1/150 of a radian, or 23 minutes of arc. Warp similar. 

My reflex clamp reduces most imperfections to nil, which works for me. YMMV

terry9
2,348 posts
 

By 'most imperfections' I meant dishes and warps.

lewm OP
13,163 posts
 

Terry, you wrote, "My DIY air bearing tonearm / Koetsu setup is sensitive to small azimuth changes - 6 minutes of arc from perpendicular is clearly audible".  That's remarkable because it infers that your Koetsu is perfectly constructed internally.  If perfect 90 degrees of azimuth yields audibly superior results even in comparison to a few minutes of arc off 90 degrees, then that would be the case.  There is a good case to be made for setting azimuth at 90 degrees notwithstanding electrical measurements of the results, but it usually means a slight compromise in crosstalk perfection, because most cartridges are not perfectly constructed. But your general point that warps throw off azimuth as well as speed is well taken. 

mijostyn's avatar
mijostyn
8,570 posts
 

@lewm , you hit on it. It depends on what is playing at the time. You can hear the warps on prolonged steady notes with quieter backgrounds. I think solo piano is the worst. The violin note on The Lark's Ascending would do it.  

edcyn
1,876 posts
 

All the vicissitudes that plague the LP are part of the reason I'm just not as fanatical about the format as I used to be. It doesn't hurt that Hi-Def (and even CD quality) streaming can sound really, truly good through my system as it is currently constituted.

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