Ultrasonic cleaning with kirmuss and loss of high frequency details.

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?

I have cleaned thousands of records with my US setup. What I hear is a reduction in high frequency content - but it is the hf NOISE which is gone. Like the hf tizz which is characteristic of low quality capacitors or resistors.

The US cleaning thread has lots of such information, like the test which I did to detect US damage. I didn't find any.

Hemoncdoc, I always use ear protection near an US machine.

It might be subtly irritating to be around the US machine when it is in operation (via bone conduction and other ways we sense ultra high frequencies), but can your hearing be damaged by frequencies that are so far above the range of audibility?  The frequencies are an octave or more above 20kHz, are they not? It's an interesting question.

What I was trying to say to the issue of damaging LPs is that there are dozens of machines on the market.  They vary quite a bit as to the frequency at which they operate and to the energy imparted into the bath.  No manufacturer wants to be associated with a product that does damage, but human error can be a b**ch, so caution is merited, IMO.  A third factor that theoretically could contribute to a damaging effect and which is not under the control of the manufacturer is length of time in the bath.