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

Hi Folks,

Here's a guy 😉 who made some modifications to be able to use a VPI Periphery Ring clamp on a platter it wasn't designed for. Together with a center clamp, best warp solution I am aware of - and reduces LP surface resonance reactions from lower compliance, more significant VTF carts.

Cheers, John

https://www.audiocircle.com/index.php?topic=124081.msg1307306#msg1307306

petgo, I guess the only clue an end user would have that a cartridge is internally misaligned would be if he attempts to set azimuth electrically (equal crosstalk in each channel) and this result requires tilting the cartridge in either direction from a 90 degree orientation of the stylus tip to the groove walls. By that criterion, most cartridges are not perfect, but they are not far off, either.

I have used the Vinyl Flat for several years.  Initially I would borrow from a friend that has one about 10+ years old.  I believe that pouch only had low and high.  I would use the high, regardless, for about 3 hours and worked well.  I eventually decided to get my own and the high setting for 3 hours melted the grooves.  It was pretty wild and thankfully nothing special.  I went to medium for about 2 hours and eventually found the sweet spot of medium for 3.5 hours.  

My experience is that this works well for new vinyl.  Any of my collection of older vinyl I have not had any success.  I don't have as much of a problem with older vinyl so there's that.  

Pressing plants basically suck for new vinyl as it can be so awful right out of the sleeve on new releases.  I used to return them to amazon but got tired of the fight as the replacement was often the same.  Now on new vinyl if it is warped at all, it goes right in the Vinyl Flat for the 3.5 hours and is all good.

I recently bought a second copy of the Cardas test LP. I’ve been using it for years to warm up cartridges that either need break in or have been out of use for long periods, which happens when you own 5 turntables and 2 systems. Anyway, the new copy was very badly warped right out of the sleeve. I of course immediately returned it to MICHAEL PERCY audio, and he replaced it immediately, no questions asked. Still, it is surprising to me that Cardas could let such a thing go out the door as a test LP, of all things.

I have thousands of 45 RPM records. I got 2 1/4 inch thick pieces of glass made with the center cut out for the label. I put the 45 between the glass, taped the glass together, and sat it on top of light bulb. (about 6" from bulb) I would give it 30 minutes and take it off and let it cool. It only failed a few times on the very thin reproduction 45 records. It should work on an LP.

In my audio system I have a Sota vacuum turntable and must say it works great. Basis make one that work great also.