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Investigating if ultrasound is harming LPs

Description

Take a piece of a LP and US clean it.

With a precision weight scale. Taking the weight before and after the ultrasound cleaning. To determine IF any material is removed from the LP or not with the ultrasound usage.

 

Material 

The things that are needed for the test setup:

  • US DIY 6L cleaner. With 180 watt at 40 kHz.
  • Weight scale 2 decimals of a gram and max 5g capacity.
  • A piece of a real LP record 

 

Method

First I selected a LP and tried to cut out a piece that is as close to 5 grams. To get the maximum size as possible that the scale can support. Tried to get a piece that includes lead-in to lead-out. To especially get some of the "glossy" part of those.

 

I used the US cleaning to do an initial cleaning of the record ~5g piece.

 

When I was not interested in weight loss due to dirt coming off. I need to start with a clean piece that is just the LP material and nothing else. When the goal is to determine if the ultrasound is removing any material or not. 

 

For the US bath I used a little bit of heat 30°C and reverse osmosis RO water (more or less the same as distilled water). And some wetting agent.

When we want the scrubbing bubbles being able to work into the groove. The piece of the LP will hang in the water like a record is and not lay down in the bottom of the US bath tub. 

 

I will run the US machine timer set to 30 min. That in practice a LP is less than half of its area at any time in the bath. That means more than half of the LP area is not in the bath when the record is revolving during a normal cleaning session. So in practice by having this piece submerged and US cleaned effectively for 30 min is like someone is spinning and cleaning in the US bath for more than one hour ! So it is more correct to see this 30 min as over an hour of US cleaning if it were a whole spinning LP. 

 

For the weight scale I make sure that the LP piece is clean and dry. And I try several times to rule out deviation between measurements, if any. Method where I learned to put the piece of LP on the exact same place on the scale plus I for each measurement looked that it went back to 0.00 g when I picked up the piece. I also reseted by pressing tare and looking again so I got 0.00 before putting the piece on the scale to get a new reading. 

 

Calculation example if we have a 5 g piece and 1% of its material were removed. Then that 1% should weight 0.05 grams and 0.5% should be 0.025 gram. That is what I see no issues to detect on the weight scale when the repetition accuracy is greater than 0.025!

 

So this method should be able to detect if less than 0.5% of the LP were removed by the scrubbing bubbles by the ultrasound and it's usage of it. 

But I was not expecting what happened below..

 

1st try Results

The start weight of the cleaned LP piece:

  1. 5.01 gram
  2. 5.01 gram
  3. 5.01 gram
  4. 5.01 gram
  5. 5.00 gram
  6. 5.00 gram
  7. 5.01 gram
  8. 5.01 gram

Average: 5.0075 grams.


 

After US bath "cleaning" first weight session:

  1. 5.02 gram
  2. 5.02 gram
  3. 5.02 gram
  4. 5.01 gram
  5. 5.01 gram
  6. 5.01 gram
  7. 5.01 gram
  8. 5.01 gram

Average: 5.01375 grams.

 

Hmm here is something fishy business going on between the weight sessions..

 

After the first US bath "cleaning" second weight session:

  1. 5.02 gram
  2. 5.02 gram
  3. 5.02 gram
  4. 5.02 gram
  5. 5.02 gram
  6. 5.02 gram
  7. 5.02 gram
  8. 5.02 gram

Average: 5.02 grams.

 

So there is something going on between weighting sessions..

I have taken those two weighting sessions and the average of the 2 x 8 measurements is 5.016875 grams.

 

Second try cleaning 

Now I am repeating the 30 min (one hour see above) Ultrasound treatment/"cleaning" for a second time.

 

And will weigh it also in two sessions and see what we get.

After 2nd US bath "cleaning" first weight session:

  1. 5.02 gram
  2. 5.02 gram
  3. 5.02 gram
  4. 5.02 gram
  5. 5.01 gram
  6. 5.01 gram
  7. 5.01 gram
  8. 5.01 gram

Average: 5.015 gram

 

After 2nd US bath "cleaning" second weight session:

  1. 5.01 gram
  2. 5.01 gram
  3. 5.01 gram
  4. 5.01 gram
  5. 5.01 gram
  6. 5.01 gram
  7. 5.00 gram
  8. 5.01 gram

Average: 5.00875 gram

 

So after a second US cleaning round and having the 16 measurements from the first US cleaning round.

Average from the two measurement sessions is after the 2nd US "cleaning": 5.011875 grams.

 

Conclusion

Is that there might be some deviation between measurement sessions of some reason that I can't explain:

  • Maybe it would average out if I took more than 8 measurements.
  • I should take more than only 8 measurements before the first UC cleaning session, which is why I later doubled them.
  • And I felt that I got better and better in my measurements routine. So the later measurements are more stable and have higher repetition accuracy than the first ones had.

I could leave the first iteration out from this post, but I wanted you all to see the whole process and not manipulate the findings.

 

Of the conclusions above I feel and believe mathematically with more samples that the second round is the one to look at and dismiss the first round.

 

Before I did the second US "cleaning" the average weight of the 16 measurements were:

  • 5.016875

After the second US "cleaning" the average weight of those 16 measurements were:

  • 5.011875

5.011875/5.016875 = 0.999003363647

 

Almost 0.1% (0.0996636352%) less weight after the second US cleaning.

 

That can be one of two things or little bit of both also:

  1. Measurement deviation before and after measurements. And more repetitions and measurements could be done. But I will stop here.
  2. That actually a VERY tiny part is removed of the LP by US

 

It is up to you guys to decide what you believe the data means. 

 

But remember it is a rather powerful US with 180W and in practice a very long US cleaning session as explained above.

 

Another note in the method of what I observed was that the little LP part were moving around in the bath when it were only hanging in a string. Usually a record is more firm and stable when the scrubbing bubbles are acting on its surface. If that makes any difference for the outcome but worthy of a note.

​​​​​(I got images on all the things and measurements 40 (!) But this forum is making it hard for me to attach them here)

​​​​​

optimize

Showing 9 responses by lewm

lewm
12,456 posts
 

Ijgerens, I didn’t get to see your first post until after I wrote mine. I thought it was excellent.

lewm
12,456 posts
 

Then there is me, who doesn't even own a US RCM and does not even care if US can damage an LP.  But for the umpteenth time, the question put forth by the OP was about a METHOD to determine whether US RCMs can damage an LP.  Not per se whether US does in fact damage an LP. 

lewm
12,456 posts
 

Pindac, If you can bear to read all the posts on this thread (and I don't blame you if you cannot bear it), I invite you to look for mine back up near the beginning, where I suggested that one proper way to make the assessment is to use test LPs with specific pure tones encoded on them or it, say 100Hz, 1000Hz, 10kHz (all 3 frequencies on the same surface of the same test LP).  Since we would expect HF to be affected by excessive US cleaning, ahead of any effect on lower frequencies, you could play the test LP tones into a storage oscilloscope, to measure both amplitude and accuracy of the frequencies produced, before vs after cleaning, using same cartridge, tonearm, TT..  Yes, this is an oversimplified desription of the experiment I would endorse; I do realize that the US parameters, perhaps the buffer, the temperature, and many other factors could affect the results, and proper controls would be needed.  But basically, any eroding of the signal voltage amplitude or alteration of frequency of the 10kHz band in comparison to the 100Hz or 1kHz bands encoded on the very same LP would be meaningful to the degree that the lower frequency bands would have been exposed to the exact same conditions as the HF bands on that test LP.

lewm
12,456 posts
 

Cleeds, if you want to know whether your US RCM can damage your LPs, then you have to design an experiment to answer THAT question on the physical level. If you want to know whether you can hear a problem, then just listen. Aural memory is so poor that you’re likely to hear what you want to hear. OK with me but just be aware of the bias issue.

lewm
12,456 posts
 

No objection to any of your finer points.  But you posit all good reasons why the weigh method is not the right approach, on which we agree.

lewm
12,456 posts
 

How bad can the damage be? Good question. But I thought the question was how to detect damage, not whether it’s bad (or noticeable) or not. Whether it's noticeable in your test of course would be a function of the listener’s acuity as well as the degree of any damage. Besides, I did not say that I know the damage could not be detected by a listening test; you said that you could not detect damage based on apparently one experiment with one LP using one machine under conditions that you typically use for cleaning (I am guessing). I think you would admit that your study was not exhaustive.  In my opinion, to address the issue you'd want to do it scientifically to get an objective result, not a subjective one.

lewm
12,456 posts
 

Like I said above, but which gleaned no attention at all, if you want to find out whether US cleaning can damage the encoded music signal on an LP, the way to go is to look directly at the signal on an LP before vs after US cleaning, not the weight of the LP before vs after cleaning. With respect for your diligence, it is misguided, because your method is faulty to begin with. Which is to say that if you conclusively find no difference in weight, it does not mean necessarily that no damage was done to the music signal. And you cannot even hope to detect such damage with a listening test, as someone else seems to claim. You need the proper electronic tools and the capacity to collect the data for comparison (e.g., an oscilloscope with storage function, a test LP with pure tones recorded on it in stereo, and probably other devices I have not thought of).

lewm
12,456 posts
 

effischer. No problems with what you wrote, except this: "Very few consumer devices are capable of tolerances better than 0.1 gram. This presumes the device is tared (validated) using a known standard traceable to an accredited, recognized standard (NIST in the US or NPL in the UK are examples)." While what you say about taring is probably correct, in this case, since we only want to know whether there is a change in weight, all we care about is the repeatability and the sensitivity of the scale and other elements of the weigh procedure. One other point, my Ortofon DS3 reads out to 3 decimal places (as do many other digital VTF gauges); i therefore would think that, best case scenario, it is accurate to 2 decimal places, at least.

In general, if US cleaning clips the HF response of the signal encoded on the LP (which is what some audiophiles fear), I would guess the weight of vinyl removed to achieve that damage would be infinitesimal. Better way to do this is to start with an LP that has test tones on it, say 1000Hz, 10kHz, 20kHz. Document its frequency content electronically, say with a storage oscilloscope, US clean it, then play it again comparing the data recorded before vs after. The relative levels of the various frequencies, before vs after, would constitute a nice additional internal control. (For example, compare the 1kHz signal amplitude to 10kHz and 20kHz signal amplitudes, before vs after. If US is harming the HF response, you would expect the 10kHz and/or the 20kHz signal amplitudes would be decreased after cleaning by more than any effect on the 1khz amplitude.)

lewm
12,456 posts
 

You want to hold the vinyl rigidly during the cleaning, to mimic the situation with an actual LP. Otherwise the US energy is dissipated kinetically as the 5g piece of vinyl is tossed about. Some energy is lost that might otherwise hypothetically be effective in grinding the vinyl.

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