vinyl coefficient of friction

[gpapag]

If cavitation takes place during wet play, bubbles collapse at the vicinity of the diamond, thus the subsequent pressure waves will shock the tip and wet playback will be very noisy.
I haven’t read any report that wet play is noisy

George

 

[Hiten]

After wet playing if the dry playing is found noisier, one of the reason may be the microscopic dust must have been dislodged while playing wet, it then sticks to the groove walls which increases friction when played dry, if we reference it to earlier wet playing. Just Guessing though.
Real wet playing vinyl
Regards

 

[billshurv]

Let me check my Xerxes. If memory serves they used to claim a 20 minute run down time, which I never tested.

 

[SY]

If cavitation takes place during wet play, bubbles collapse at the vicinity of the diamond, thus the subsequent pressure waves will shock the tip and wet playback will be very noisy.

Good point! So I'm still at the mystery part, what causes this phenomenon?

Or could the "noise" from cavitation be sufficiently high in frequency as to not be heard or perhaps not be reproduced by the (bandwidth-limited) cartridge?

 

[lcsaszar]

Wet playing is just a kind of lubrication like at slide bearings. Dust particles will not stick to the groove wall where the stylus would pop over them causing a clicking noise, but they float in the water and the stylus will divert them away like the bow of a ship.

 

[billshurv]

So how do you explain wet played records being noisy when then dry played?

 

[lcsaszar]

Floating contamination gets dried onto the groove wall. This contamination comes from all over the surface (not only from the groove), but at the end all will be deposit onto the groove wall, because it is the last place where the water evaporates from. Just speculating...

 

[gpapag]

Good point!

It wasn’t a very good point. At least I failed to think of the high frequency spectrum effect and the LP nature of the cartridge

Or could the "noise" from cavitation be sufficiently high in frequency as to not be heard or perhaps not be reproduced by the (bandwidth-limited) cartridge?

I quote from:
'Fundamentals of Cavitation' Jean-Pierre Franc, Jean-Marie Michel. KLUWER ACADEMIC PUBLISHERS 2004


"The noise emitted by a collapsing bubble is very rich in high harmonics whose frequency exceeds some hundreds of kHz.
...
For bubbles oscillating at their natural frequency, the wavelength is generally of the order of the millimetre. For example, the natural frequency of a bubble of mean radius R0 = 10um under atmospheric pressure is f 0=ω/2π=340kHz and the corresponding wavelength is about 4 mm
...
Generally speaking, in real flows, cavitation noise is due to the succession, at a high rate, of elementary collapses of all kinds of vapor structures such as bubbles or cavitating vortices. For a fixed value of the cavitation parameter sv, the noise level generally increases with the flow velocity.
...
The duration of the final stage of bubble or cavitating vortex collapse, which is important in the erosion process, is of the order of one microsecond."

So I'm still at the mystery part, what causes this phenomenon?

My vote goes to a low tech explanation like the one by lcsaszar

Floating contamination gets dried onto the groove wall.

In the end, the use of a microscope will reveal the truth of the above scenario or cavitation damage at groove walls, no?


George

 

[Hiten]

...or while wet playing micro dust floats in the liquid which when vinyl is dry settles at the bottom of the groove and stylus picks up this as noise. When wet played again micro dust floats again.

 

[billshurv]

...or while wet playing micro dust floats in the liquid which when vinyl is dry settles at the bottom of the groove and stylus picks up this as noise. When wet played again micro dust floats again.

We could test that by wetting a record, vac cleaning it then measuring noise. wet play and then vac again then play again.

 

[luckythedog]

...or while wet playing micro dust floats in the liquid which when vinyl is dry settles at the bottom of the groove and stylus picks up this as noise. When wet played again micro dust floats again.

There's no need for any dust to obtain crackle-pop noise. All that is necessary is that the vinyl friction surface alters, such that friction increases. For an explanation and demonstration of crackle-pop noise without the need for dust see posts #16 and #20 on this thread.

In my own tests of wet-dry playback, within reason I have eliminated contamination with debris as a cause of dry playback noise after wet playback. I'm pretty sure the cause simply involves changes to the vinyl friction surface, but I do not know why that happens.

 

[luckythedog]

I quote from:
'Fundamentals of Cavitation' Jean-Pierre Franc, Jean-Marie Michel. KLUWER ACADEMIC PUBLISHERS 2004


"The noise emitted by a collapsing bubble is very rich in high harmonics whose frequency exceeds some hundreds of kHz.
...
For bubbles oscillating at their natural frequency, the wavelength is generally of the order of the millimetre. For example, the natural frequency of a bubble of mean radius R0 = 10um under atmospheric pressure is f 0=ω/2π=340kHz and the corresponding wavelength is about 4 mm
...
Generally speaking, in real flows, cavitation noise is due to the succession, at a high rate, of elementary collapses of all kinds of vapor structures such as bubbles or cavitating vortices. For a fixed value of the cavitation parameter sv, the noise level generally increases with the flow velocity.
...
The duration of the final stage of bubble or cavitating vortex collapse, which is important in the erosion process, is of the order of one microsecond."

Thank you George, that is interesting.

Any given point on the (dry) vinyl surface is in contact with the stylus for c 2uS. The effective length of the contact region is perhaps ~1um at any instant. This doesn't seem to tally well, but doesn't rule out I think.

I might expect the 'sound' of a single cavitation event to resemble an impulse - a sudden short event as the vortex collapses - as such I think it should have normal full spectrum audioband content. The author suggests harmonics extend into 100's of kHz, which seems plausible, but doesn't preclude audioband harmonics of course. I think 'oscillating' bubbles is a different phenomenum from collapse, so the 340kHz content is only part of the deal.

For example, cavitation in a boiling kettle has a characteristic broad spectrum audioband sound, many random near simultaneous events make it up. Nothing like that shows up in wet playback measurements or audio tests IME.......

But I really don't know, and cavitation remains on the suspects list IMO, perhaps with an alibi or two ?

Yes, good microscopy should reveal the truth of the nature of changes to the vinyl surface, which may not be 'damage' in the mechanical sense.

 

[jplesset]

Perhaps a test? Take an album, play it and measure noise.
Wet-play one or two bands.
Do not play other bands, but have them wet.
dry, and compare noise. Does wet or wet play sound different?

Perhaps we can eliminate one suspect.

 

[scott wurcer]

Experiments get expensive, I just noticed my complete collection of RCA STR series test records goes for $1000+ on Ebay.

 

[jplesset]

OK, so pick up something at a thrift shop you don't really care about. Cheap.

I would, but I gave up wet playing in the late 1950s...

 

[Hiten]

Thanks luckythedog.
-
Just curious. How much friction generated surface noise is in dB ? There was also mention of noise, clicks and pops on ELP turntable in other thread. Does static play any role in friction generated noise ? In wet play there would be no static I guess. Some links relevant to the thread...
Drylon Lubricant will this work on vinyls ?
Some closeup of vinyl grooves
LAST preservative which claims to protect the groove
Transfer of atoms of materials Interesting findings.
Regards.

 

[luckythedog]

Thanks luckythedog.
-
Just curious. How much friction generated surface noise is in dB ?

In post #43 you can see measured noise floor improvement (in an already quiet test record) is c 10 - 15dB. For a noisy record it can be far more than this, perhaps more than 30dB for the noise floor. But it is the audible elimination of the crackle-pop, having a random and very peaky profile which is the main benefit, but the overall improvement is typically profound even on already 'quiet' records. Again, I'm not advocating, just observing and pointing out.

 

[luckythedog]

Optical microscopy is beyond its limit of resolution to see fine detail in the vinyl wall, and there are few robust accessible SEM images of clean vinyl walls where the aim is to show its texture. But here is good one where detail is visible and colour contrasted to enhance it. Not only can we see the groove wall texture, but we can see what appears to be features of contact.

Edit: I'm unclear of the copyright for this image, so here's a link to a public page with it's preview which is also very clear:

http://tedkinsman.photoshelter.com/image/I0000AByRMtLBbf0

In case the link here doesn't work for some reason the page is tedkinsman.photoshelter.com/image/I0000AByRMtLBbf0 just add http:// in front.

Interesting ?

 

[SY]

Drylon Lubricant will this work on vinyls ?

A classic case of DON'T.

 

[Hiten]

Thanks SY and luckythedog.
That picture is surely interesting. Different texture area does look like contact area. Plateau (The surface between two grooves) is interesting too. Comparatively it looks smooth. Angle of light ? (Or in case of electron microscope scanning angle ?) Also interesting would be how much badly recorded music noise gets transferred to the grooves. Though various shapes of stylus are preferred I wonder if a conical stylus is a good compromise between surface noise and little more hifi frequency response.