New Hobby Ultrasonic Record Cleaning

@ antinn
Thanks for your concern.  Perhaps there is little to be gained and a lot to be lost by not going from 5% to 3% isopropanol.  I'll think I'll make that change. It's also cheaper.  Thank you.

@escscott482  I noticed that your link has the machine running at 40Khz oscillation rate.   The Kirmuss states that it is unsafe and doesn't work well to use smaller bubbles at Degritter's 120KHz rate.  Kirmuss uses a "70 KHz resonance to a standard 35 KHz sonic" rate.  I think AudioDesk uses 70KHz.  Who's correct?  I can afford $1,000 or $2,000 system but I tend to like the Kirmuss for safety and ease of use (I have 25,000 LPs and 7,000 78s, 12" and 10" records).  I have been using Disc Doctor with a VPI 16.5 (latter for 30 years-works perfectly as upgraded but doesn't clean every record like new, pops and clicks often remain on records previously played while dirty or with a dirty stylus by prior owners).  

https://kirmussaudio.com/safety-first/  35KHz is the recommended maximum frequency (size of bubbles/wave/timing of cavitation at the record surface) with a maximum temperature of 95F degrees.  Anyone contradict this analysis?   

@ fleschler
"Not 45, not 80, not 90 kHz. NEVER 120 kHz or higher. All are proven to damage records over time."  I have never seen any data that can confirm this and I think it is likely hyperbole.  None of the other ultrasonic manufacturers would be in business if this is the case.  I read a post on another forum of someone who ultrasonically cleaned a record repeatedly over a hundred times and found no macroscopic or sonic detriment.  One guys experience and may not be valid.  On the other hand, I can categorically refute "AVOID HOME MADE SYSTEMS WHERE TEMPERATURES EXCEED 95°F, (35°C) as these WARP RECORDS and affect groove integrity."  This is easy since warping is grossly macroscopic and easily detected.  I have cleaned over 1000 lps, some repeatedly, with a bath temp between 40-45 degrees centigrade.  I have never had one change in the flatness of lps.  Period.  His statements, in my opinion, are sometimes self serving and may not be factual.  The warping issue at the temperatures described is pure fallacy.

The Kirmuss statements on ultrasonic frequency are pure nonsense.  The science of ultrasonic cleaning is well understood and well documented such as detailed in this book -  Particle Adhesion and Removal | Wiley Online Books.  Fundamentally the lower the frequency the larger the bubble that is created. So, a 40kHz unit will produce bubbles in the size of about 75 microns. These are not going to get into the record groove. The Degritter 120kHz will produce bubbles about 20 microns and these can get into the groove. But, the larger bubble produces more energy when it collapses (cavitation) so there is fluid agitation around the collapsing event that can provide cleaning. How violent the bubble collapse is determined by the amount of power provided by the transducers. So, a low power 40kHz unit may be safe for soft metal (jewelry) while a 40kHz high power unit (used to clean carburetors) may not. The higher kHz smaller bubble by their size are limited to how violent they can collapse - so a high powered 120kHz unit has less potential for damage than a high power 40 kHz. So, fundamentally, if you follow the logic - the lower frequency units (40 kHz) are good for larger soil surfaces and particles while the higher frequency units (80-132kHz) are better at removing smaller particles.