Vacuum Record Cleaner Rreplacement

@oberoniaomnia 

Reference? Amount of delta T? Duration? Pressure yes, and that leads to bubble formation. Bubbles are NOT due to heat, but due to pressure change. Easy to demonstrate by taking room temperature water, start pulling vacuum. Soon enough it "boils" but not because of temperature but pressure. Particularly with water's high heat capacity, I'm skeptical about any temperature effect due to US. Not a physicist for sure. I have run US for half an hour at room temperature (for SEM specimen preps), and there is no perceptible temperature change after that amount of time.

When I mentioned localized heat, I am referring to the heat generated by the collapsing bubbles on a micro scale. The energy released during the collapse of a single cavitation bubble can be quite substantial (several thousand degrees C), and when numerous bubbles collapse simultaneously, it can lead to a significant increase in the local (micro scale) temperature.  Just do an online search and you can find many articles discussing this. Here is a good review article:

"A correlation between cavitation bubble temperature, sonoluminescence and interfacial chemistry – A minireview"  published in the journal Ultrasonics Sonochemistry (Volume 85, May 2022) by Nor Saadah M. Yusof, Muthupandian Ashokkumar, and colleagues

Interesting re that U-shape curve. Reference? Scale? Whether U shape has maximum at 100 and minimum at 99 or 10 makes a difference, and determines whether it matters in practical applications. And, it will also depend on the specific compound, so assessment of a variety of them to see common pattern and variance will be important for proper consideration.

This effect is common knowledge in the scientific community. This effect is often used in industrial applications to minimize the amount of surfactant required. The degree of change in the CMC as a function of temperature  is dependent on the particular surfactant and the difference can be as large as a factor of 2. Many references only have an abstract unless you have a subscription. Here is one reference where you can read the whole article without a subscription.

Chen, Li-Jen. “Temperature Dependence of Critical Micelle Concentration of Polyoxyethylenated Non-Ionic Surfactants.” Colloids and Surfaces A: Physicochemical and Engineering Aspects, Elsevier BV, 1998.

To provide info regarding some of this discussion:

Here is a very basic handout on the science of soap - ScienceofSoap.pdf.  CMC is the surfactant concentration when the surface tension of the water decreases no further and the surfactant begins to produce micelles - geometric structures and it's the micelles that provide the detergency.  Each type of surfactant, such as anionic and nonionic has different functions.  Nonionic is known for its ability to solubilize oils which is why you will see these in cosmetics, they are used to blend the essential oils.  Anionics are the backbone of the dish detergents such a Dawn but their CMC is much higher than nonionic and use requires much high concentrations.   The rule of thumb for using surfactants for detergency is to use at least 2-3X the CMC.

While UT cleaning can easily exceed that of vacuum-RCM using standard record cleaning products, consider that vacuum-RCM is nothing more than machine assisted (drying) manual cleaning.  Pre-clean with a good brush, good technique with a neutral-pH anionic detergent such as Alconox Liquinox used at 1.0%, rinsed, final clean with 0.5% nonionic surfactant only, rinse, dry will achieve very close to UT.  

As far a decrease in CMC with temperature - this article shows it for the Polysorbate family Effect of Temperature on the Critical Micelle Concentration and Micellization Thermodynamic of Nonionic Surfactants: Polyoxyethylene Sorbitan Fatty Acid Esters and between room temperature 25C and 35C is not that much.  The benefit for UT cleaning is that at the operating temp 35C a CMC concentration at 25C heated to 35C may add some detergency depending on the specific micelle development, but its marginal at best. 

High powered tabletop UT tanks like the Elmasonic P-series will heat the water in use.  A common small tank is the Elmasonic P60H P-series-P60H-brochure.pdf.  I have worked with people using the P60H (and larger P120H) and for those doing serial type cleaning we install a recirculated pump filter-radiator to cool the tank.  The reason you do not see it with the inexpensive Chinese units is that they are not very powerful.  Although they may be advertised at 160-180W (three 60W transducers) that is very optimistic.  People have measured the power draw (UT only) with a watt meter and measure about 110W.  The Elmasonic P-series can damage a record - I have seen visible evidence; but it was at >40C, very slow (<0.4-rpm) and duration about 20-min.  

As far as the "theoretical" temperatures developed during the cavitation-implosion event - that is shown in this computer simulation video - Inertial collapse of a single bubble near a solid surface - Bing video.  However, the implosion energy is dependent on the UT frequency and the tank power.  These are some of the basic design rules for UT tanks.
-The power to produce cavitation is proportional to the kHz, so a 120kHz UT needs more power than a 40kHz.
-For ultrasonic tanks, the bubble diameter is inversely proportional to the kHz, so a 40 kHz UT produces a large bubble than a 120kHz UT.
-The cavitation intensity is proportional to the bubble diameter and the tank power (watts/L) but there is a maximum power above which no addition cavitation intensity is obtained.
-The number of cavitation bubbles produced is proportional to kHz, so a 120kHz produces more bubbles than a 40kHz, but smaller bubbles.
-The smaller the tank volume, the more power that is required. It has to do with the ratio of the tank volume to its interior surface area.
-For lower kHz units (<60kHz), if the tank bath flow rate (from filtering or spinning) >50% of the tank volume per minute, cavitation intensity decreases.

Hope this adds to the conversation.

@richardbrand 

I recently purchased two LP albums from the store at Sade's website. Both sides of both LPs have a very loud swooshing sound that is in sync with the table rotation. I could even hear it when she was singing!

I sent both of them back, asking them to listen.  I received a full refund. 

I just don't understand how companies can sell products with these defects. Don't they listen to their own LPs? Do they think the listener won't notice or is too naive to hear it for what it is?

@antinn 

Thanks Neil

I for one find this level of discussion very helpful indeed when sorting through the weeds!

May I just add that, according to the paper I referenced earlier, the size of the bubbles produced is also affected by temperature

@kevemaher 

Don't they listen to their own LPs?

That's a fascinating idea!

Frankly, I am horrified when a record store offers to play my new record to check for defects .  Doing so would immediately turn it into a second hand item in my view!

Most likely they would use a DJ-style deck with an unknown amount of stylus wear.  If played through loudspeakers, they would risk emptying the store of customers (Mahler is not for everyone, after all).  The noise floor of the store may exceed the defect level and most headphones are not that revealing.

I have no objection to manufacturers sampling their output, provided the samples are not sold as new.  Sampling can show overall trends - like the wear on masters - but obviously cannot detect every faulty record.

In reality, I think manufacturers expect a return rate and factor that into the cost of doing business.  What they don't seem to factor in is reputational damage.  But apparently most records are bought by people who have no means of playing them anyway.  Of the six sets (12 disks) of Mahler 2 sold by my record store, only one set has been returned so far.

Deutsche Grammophon (DG) in Europe seem to have a new tactic to reducing returns.  They don't supply in the first place.

I am still waiting for Rachmaninov Piano Concertos ordered in January, and recently released Paganini ordered a month ago, all from Presto Classical.

Presto are particularly responsive and helpful.  The have refunded my money on defective records from DG's sister company Decca after asking for photographs of the damage.  In one case, it was obvious from a line of detritus caused by abrasion from Decca's new, glossy, thick, carboard inner sleeves.  In another case, it would probably have needed an electron microscope, which requires destruction of the record.  Presto asked me to destroy the record after getting my refund which seems reasonable especially as I bought the CD in the same purchase.  Never had to return a CD ...