Ultrasonic cleaning with kirmuss and loss of high frequency details.

From my own reading, the consensus seems to be that it doesn’t do what your claiming. I have not noticed this phenomenon myself. I have noticed increased detail retrival. Although, one can argue there is no smoke without fire. However, every set-up is different. Perhaps try again with a record you do not care about. Quasi-scientific analysis needs multiple tests to confirm the hypothesis. One test is to stop the rotation, and let the ultrasonic burn away at the submerged part for 20 mins. Playback should not have a modulation of a frequency change every half cycle.

I have the same machine. I don’t do what they do. All I do (for brand new or never cleaned records) is to manual wash and vac with a traditional machine then throw it in for a 5 min cycle. Then rinse clean and vac dry. Works well and it unlocks an amazing amount of detail. Mostly spatial information. No detectable loss in high frequencies. For previously cleaned records, I just throw it in for a 5min cycle, then rinse and vac dry. 

There is a sort of "scientific" way to ask this question, if you have an oscilloscope or a very high quality AC voltmeter and the requisite test LP.  Play some of the pure tone high frequency bands on the test LP, record the amplitude of the AC voltages thus generated, which is easiest to do with a 'scope, and then wash the test LP one or more times in your machine.  Then re-test at the same frequencies.  It would be helpful also to have a second duplicate test LP that serves as a negative control, i.e., don't wash it in between the test procedures.  But since this is pseudo-science, I guess the negative control LP is not mandatory.

I too have read the warnings about loss of hf with US cleaning.  Seems to me it would depend upon the operating frequency and intensity of the US generator.  In other words, I feel very confident that if the US generator were powerful enough and if it operated at "the wrong" frequency (whatever that is), then an LP could be damaged.  Most manufacturers assure us that their particular machine is completely safe.

Just wondering if ear protection when using the US cleaner might help?