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.


Yeh adjusting azimuth something that takes some time to realize how many factors there is..

For example you can dive into the rabbit hole and use for example a azimuth fozgometer or like I did with a digital oscilloscope.

There is many ways/methods to adjust one and each parameter..

Ok here is the kicker if you use one of the tools mentioned above with a calibration LP disc (just a good one of those are pretty pricey in my book) you adjust it perfectly to that individual disc.


But how is a calibration LP disc manufactured? Yes you guessed it. it is manufactured as a LP is usually done. Hopefully with some more care in the setup of the lathe that includes setup of azimuth with the sapphire cutting needles on the lathe that will cut into the lacquer.


So more precise you have just adjusted your azimuth to match the azimuth that the sapphire cutting needle HAD during the initial production of the mold for your specific calibration LP disc..


If you get different manufacturers/labels of calibration LP discs they will not be perfect if you measure those. 


Why.. yes you guessed it there is still some small variance in azimuth setup from sapphire cutting needles setups from lathe to lathe and time to another time.

My approach is when knowing that is to set it perfectly straight like mijostyn have explained.

The reason is to not adjust it after a/one specific lathe cutting occasion, only.

The second reason is that all of the different albums we own has its own lathe azimuth adjustment when they're cut. So the idea is that with a straight setup you will on average over the whole collection be OK. And not be better on some and then worse on some of the others..

In assumption that the cartridge manufacturer has mounted the diamond, canteliver and so on straight..


But the super best way is to get azimuth as good as possible is using one of the tools mentioned and getting different calibration LP discs from of different manufacturers and labels and take a average then maybe you are still little better on it on average.. and probably adjusted also for deviation from the cartridge manufacturer..


Anyway that is nothing that anyone is doing maybe one individual on 2 billion people may or can do that. 🤣


But adjusting VTA/SRA is a different story and has physical properties during cutting. And depending on your stylus shape and so on there is more or less ideal ways to make that adjustment.


"You simply adjust azimuth until the hourglass stands up perfectly straight. It hardly takes any practice once you get the set up down."

It seems to me that the adjusting eye or lens needs to be perfectly normal to the cantilever, which means simultaneously adjusting two right angles. I doubt if anyone can do that without an adjustable, stable platform, repeated accurate measurements, and statistical analysis.

Whereas anyone can listen to a dozen challenging, flat, LP’s and set for the ’best’ sound and take measurements. Then throw away the two top and bottom measurements, and set to the mean or the median as indicated. At least, anyone with accurately calibrated azimuth-on-the-fly and a statistical background.


Actually, this whole discussion leads me to the conclusion that we are chasing a ghost. As @optimize notes, there are irregularities in LP manufacturing, whereas we are treating the LP as identical precision instruments that just need to be set up via the cartridge.

Instead, we should be looking for a tonearm that can be easily and finely adjusted on the fly to suit each LP as it is played. Preferably, the tonearm should have a precise measuring system built into it’s adjustment mechanism, so that these numbers can be noted on the record sleeve, and the adjustment made in two or three seconds prior to each play.

And, of course, we should remove warps and dishes from the equation, coming back to Lewm's point.

All of this discussion about azimuth involving USB microscopes, test disks, oscilloscopes, Fozgometers, hour glasses, adjustment for each disk and such leaves me LOL. Better to put more faith in one’s hearing.

Assuming you have easy adjustment for azimuth, and if your stylus is symmetrically placed, adjust roughly for level by matching your cartridge parallel to its reflection on a disk. It doesn’t take much of an eye too get very close. Use a flashlight and/or thin mirror if that helps. If the stylus is a bit crooked, use a mirror and do the best you can to have the stylus as vertical as possible.

Then put on your disk with the best, widest, soundstage in your collection. Listen carefully as you adjust azimuth just a bit, first one way than the other. If the soundstage widens, continue slowly in that direction. If it doesn’t widen you’re done. If it does widen continue in that direction to the max soundstage.

it's scary to see your expensive cartridge and stylus on a badly warped record.