LP condition - how warped is too warped?

[Telleadict]

Hello

Firstly appologies if this would be better in "Vintage Audio" but the threads there all seem to be "hardware" related.

I have been given three random LPs that I will probably pass on to a charity shop etc but have tried to see what sort of condition they're in.

One looks rather like a soup bowl it appears to be about 5mm out of flat if laid on a table-top. I guess this one's for the bin or can it be flattened out somehow?

The others looked OK so I tried them on the turntable. They seem to play OK but there is visible "up-and-down" movement looking at the edge as they spin. I have tried to measure the movement with a rule and it seems to be about 2mm, is this acceptable or should these be scrapped too?

Last thing. As a "rule of thumb" am I right in thinking that general wear shows first as high notes, eg. brass or vocals, sounding "flat"?

Thanks for any tips.

Will

[Audio1950]

I've flattened many LPs by sandwiching them between two pieces of stout chipboard with a pile of dinner plates on top, and putting them in a very low setting in the oven for about an hour. I've only melted one!

Barry

[af024]

Hello Will,

These are only my thoughts, but if they play without skipping or grounding the cartridge, and there is nothing annoying to hear as the arm rides the highs and lows, then keep them and enjoy them.

I guess it's not just about how much is rised and falls by, but what the rate of change is - especially going from highs to lows as this can leave the stylus in mid air. A considerable rate of change in the other direction can ground the stylus and even cause high stylus pressure groove damage.

Also, it's worth saying that some players are much more tolerant than others when it comes to warped records. My personal hate is a record that's not been pressed concentrically (as I do seem to be particularly sensitive to wow), but I digress ..

A gradual 5mm rise/fall on a 33.333rpm doesn't sound particularly horrendous to me. I've seen warps like you wouldn't believe and some decks still hanging onto the groove throughout despite it all. Mind you, I don't suppose something like a Lenco GL75 would hang on to it (nice though they are, the arm does tend to stay in mid air following a moderate high to low transition. I'm sure that same is true for some others too).

Of course high stylus pressure damage tends to produce a shushhh sound.

I don't know whether this helps you or not Will.

Regards,

Andy

[Nickthedentist]

Originally Posted by af024

A gradual 5mm rise/fall on a 33.333rpm doesn't sound particularly horrendous to me.

It's a very personal thing. On sustained notes, particularly with classical works, I find that this kind of wow makes the music completely un-listenable to

[paulsherwin]

I agree with Nick.

Vinyl records had all sorts of mechanical problems which the modern proponents of analogue vinyl seem to ignore, but which we were heartily glad to see the back of when CDs arrived in 1983.

Significant warping will result in horrible wow effects long before the record becomes unplayable, and this seemed to happen to records mysteriously no matter how carefully you tried to store them. Off centre stampings were also very common and resulted in easily audible effects.

Record wear is most audible on volume peaks at the centre of the record, but this is also where a stylus will tend to produce compliance distortion even with a new record and it can be difficult to separate the two effects.

[ben]

What are the records? If they're anything halfway decent or sought after, don't ditch them as they may have value despite the defects.

On the other hand, if we're talking about the likes of, say, Jim Reeves, Perry Como, Mrs Mills, Mantovani, Barry Manilow or Christmas albums, you can safely go and play frisbee! You always see tons of that stuff in every charity shop, nobody seems to buy them in any condition.

[PWH]

A twist on an earlier theme is to put the record between 2 sheets of flat glass and put the sandwich in the sun. Watch. As soon as the vinyl heats up you will see the record flatten. Pick the lot up run indoors an allow to cool. Leave it too long and you will have a mess but I suppose if the record was unplayable, you have nothing to lose..

[Radio Wrangler]

I made myself a marking and punching jig for fixing badly eccentric records. I stuck a paper label over the hole and used the jig at to mark two radii at roughly right-angles to find the centre, then the punch knocked out a larger hole and I could lay it with a collar slipped over the turntable spindle. It sort of worked, but it assumed the outside of the record was more concentric with the grooves than the hole was.

I had intended to do a second version where I could spin the record and adjust the offset of the axis until the grooves could be seen to run true, and find where the new hole should be. I never did it, the CD arrived and fixed a lot of irritations like these.

Ben either forgot Max Bygraves, or else we've just found out his secret taste in music...

David

[broadgage]

Some years ago, I read of a system to extract the programe content from badly warped LP records.

Basically the record was played at a much reduced speed and the result recorded on tape running at a similarly reduced speed.
The much reduced speed meant that the stylus would neither bounce out of the track, nor exert excessive downwards force.
The circuitry employed would have to be suitably sensitive to frequencies below the normal audio range.
Playing the tape back at normal speed gave near normal reproduction.
Presumably a similar principle could be applied digitaly these days ?

Alternatively, as suggested by others, gently pressing the record flat whilst being subjected to very gentle heat should work.

[Telleadict]

Hello

Thanks for the response.

The worst example is a Frank Sinatra title that seems to strougle to reach 99p on Ebay so it would probably be a good canditate for experiments in flattening if I have the inclination.

As for the others, it sounds as though if they play OK, which they seem to, it's nothing to worry about.

thanks again.

Will

[Boom]

Originally Posted by broadgage

Basically the record was played at a much reduced speed and the result recorded on tape running at a similarly reduced speed.

It's easier on a computer to play the record at 16RPM and adjust the computer playback speed to suit.

[yesnaby]

Hello,

When I worked in London I had a friend in the office who was often buying several classical LPs at a time from a shop around the corner. One day he took back 3 of them to be exchanged as they were 'warped'. He was informed that he was 'not the type of customer that we want'. I never found out whether or not he was successful.

Michael

[ben]

Originally Posted by Telleadict

Hello

Thanks for the response.

The worst example is a Frank Sinatra title

Quite a coincidence. I was going to mention this earlier in fact. I have a Sinatra LP, 'Sinatra and company', a great album of Brazilian /bossa classics arranged by Eumir Deodato. It has the worst edge warp (not just on the vertical plane up/down, but also horizontally distorted - in/out movement too).

The only deck that can track it in my whole collection of over 30 machines is the Garrard 2025Tc/Sonotone 9TA.The combination of very low mass arm, high compliance cart and spring (rather than counterweight) downforce is what I put it down to.

With severe warps like that I suppose the only other way slowing it down and re-recording, as broadgage said a few posts back.

[Billy T]

Originally Posted by PWH

A twist on an earlier theme is to put the record between 2 sheets of flat glass and put the sandwich in the sun. Watch. As soon as the vinyl heats up you will see the record flatten. Pick the lot up run indoors an allow to cool. Leave it too long and you will have a mess but I suppose if the record was unplayable, you have nothing to lose..

There is a snag to that method that limits its effectiveness.

Most LPs have a raised rim around the centre island and a raised outer rim. I assume that this was intended to keep the playing area from damage during record drops on auto-changers. The centre island is usually the thickest section, so when clamped between plate glass as you suggest, I had found that some residual warping would always remain.

To counter this, I had suitably sized holes cut in the middle of two squares of plate glass so that only the outer rim of the record was clamped flat. Then I applied controlled heating from an infrared lamp and after heating from both sides then cooling, the records came out flat as.

Our antipodean sun might be a bit hotter than yours, but it is much easier to do this inside with contolled heat, and if you are really keen you can use an infrared laser thermometer to monitor for optimum temperature. Four of those really big metal document clamps will hold the glass plates together and keep them square so you could even heat from both sides at once to equalise stress, but I never found that to be necessary.

Cheers

Billy

[Radio Wrangler]

What is lost by playing a record slowly is some of the bass response. The whole audio spectrum is scaled downwards in frequency, and the lower limit o recovery imposed by the arm beginning to move to track the groove still applies. There is a low-frequency resonance set by the effective total mass as seen at the cartridge and the compliance of the stylus cantilever pivot of the cartridge.

There's a similar low freq limitation in tape machines set by the length of the pole pieces in contact with the tape. It's not as well known as the effect of the length of the gap on the HF response.

The thing is to minimise the moment of inertia of the arm, or put another way, the effective mass seen at the cartridge. In this respect a heavy large diameter but short counterweight close to the pivot, is superior to a lighter weight further out. Moment of inertia is proportional to mass and to radius squared. Twice the mass at half the distance from the pivot does the same balancing job, but has half the moment of inertia.

Of course the headshell and cartridge are even further from the pivot, so weight saving here has a particularly significant effect.

I have a turntable with an arm only about 6 inches long, very light in construction and not even a headshell. The cartridge is ultra-light and of very high compliance. Downforce comes from a calibrated spring. It is an excellent tracker of undulations, but eccentric holes makes its servo work a bit.

David

[julie_m]

What you want is a DJ-type turntable -- they're designed to cope with all sorts of abuse while keeping the stylus riding snugly in the groove at all times.

[Phil G4SPZ]

Coincidentally, when I built a disco deck console in the 1970s we used the 2025/9TAHC combination for exactly the reasons Ben mentioned in his earlier post. Most DJ consoles used SP25 decks, which were a lot more sophisticated, but an accidental nudge from a dancer would send the stylus skating across the record. The 2025s were virtually immune to this. I still use one!

Back on topic, the limiting value of "acceptable" warp to me is whether or not audible wow is present.