Those stating they hear a loss of HF content after US cleaning are very much in the minority among users. US cleaning has become almost mainstream in the audiophile community. At present, there is enough data of results spread across machine types, cleaning formulas, cleaning processes etc that if there were inherent problems with US cleaning we would have already discarded US cleaning, much as the community has embraced, investigated and ultimately discarded other tweaks. Harry Wessfield (VPI Owner) fully investigated the possibility of reduced HF content from US cleaning, and concluded the process is safe.
I set up a DIY US cleaner using a Chinese US tank, Vinyl Stack, and Rushton's cleaning formula. I pre-clean using a Spin Clean to remove large debris and most surface debris. I vac dry to remove any fluid or water residue. US cleaning is performed at 35' c, 0.3 RPM / 15 min, or 5 full revolutions in 15 min. My results are repeatable. I experience a significant reduction in background noise- often to a level below the noise floor of the rest of my system. MUCH better reproduction of transient response, "air", ambiance cues, and brass/string overtones. I also hear a virtual elimination of low level "shooooshhh-woooosh" noise. I theorize that a microscopic layer of debris is bonded to the walls of the grooves. The layer is just enough to blunt the leading edges of very fine groove modulations that contain all of the low level and background information I mentioned earlier. US cleaning removes this layer, exposing additional information to be reproduced. I think it is very possible, and very likely that before cleaning, this layer of grunge can be heard as HF distortion and may be perceived as additional HF extension. Removal of the layer, and removal of the grunge would remove any related distortion, and this may be what is heard by those who believe US cleaning reduces HF content.
I set up a DIY US cleaner using a Chinese US tank, Vinyl Stack, and Rushton's cleaning formula. I pre-clean using a Spin Clean to remove large debris and most surface debris. I vac dry to remove any fluid or water residue. US cleaning is performed at 35' c, 0.3 RPM / 15 min, or 5 full revolutions in 15 min. My results are repeatable. I experience a significant reduction in background noise- often to a level below the noise floor of the rest of my system. MUCH better reproduction of transient response, "air", ambiance cues, and brass/string overtones. I also hear a virtual elimination of low level "shooooshhh-woooosh" noise. I theorize that a microscopic layer of debris is bonded to the walls of the grooves. The layer is just enough to blunt the leading edges of very fine groove modulations that contain all of the low level and background information I mentioned earlier. US cleaning removes this layer, exposing additional information to be reproduced. I think it is very possible, and very likely that before cleaning, this layer of grunge can be heard as HF distortion and may be perceived as additional HF extension. Removal of the layer, and removal of the grunge would remove any related distortion, and this may be what is heard by those who believe US cleaning reduces HF content.