Recorded Cleaning Machnies

I'll add a few things. First, I started using an ultrasonic machine to clean records when the Audio Desk original model came out. I found that it did a nice job on well preserved and new records but if you buy older copies, or have copies with a questionable cleaning history, you need to use a manual cleaning method (combined with vacuum) to clean some deeply contaminated records effectively-- that ultrasonic alone won't do it despite the convenience, lack of physical contact with the groove surface, etc. 

I also found that a lot of the problems with "used" records probably resulted from previous "bad" cleanings- sprays, wipes, etc. This form of contamination is essentially the residue of cleaning agents that were not effectively removed from the record. 

Third, and think Neil addresses this, the number of records in a given bath, spacing, location of transducers and the ultrasonic machine's power in relation to the bath size all factor in to  effectiveness of the ultrasonic process; there is some science to this and its also understandable when you consider how cavitation works: waves creating imploding bubbles. The implosions are what cleans.

A machine that does ten records at a time is not necessarily going to clean more effectively than one that only does a single or double LP at a time; it could be less effective, though it sounds more convenient. This can all be calculated.

You also have to consider whether you are going to use chemistry; it will enhance the cavitation effect by reducing the surface tension of the bath water, but you also have to remove the chemical residue once done. This takes us full circle to my comment about past bad cleanings. 

I'm sure Neil (@antinn) can correct anything I mistook above; I don't have the science or engineering chops but arrived at a lot of these conclusions through experimentation. And, I'm happy to say that I published Neil's book, Precision Aqueous Cleaning of Vinyl Records, and in the course of doing so, learned a hell of a lot about why certain things work and others are less effective or cause problems. 

@antinn Thanks, Neil.

@gano - the answer is that proportion of older copies that have been contaminated. Visually, you may not see this. I was buying a considerable number of "rare" records and in some cases, particular pressings,  that were either not often seen for sale (even before the Great Disappearance™) or quickly went up to astronomical pricing. Therefore, I tried like the devil to get them to a high playing state. (Though in a few cases, I did wind up with multiple copies to get one that was a good, quiet player). 

I’d say there is a direct correlation between how many old pressings you buy and how often you have to resort to more rigorous manual cleaning. In some cases, I bought records that were never played, just bounced around among dealers, some of whom didn’t know what they had. Those days are over and I’ve slowed down considerably on buying, given grade and price inflation. Some are simply not on the market given the limited number of original pressings that were made, private label or obscure things that never succeeded in the market place at the time of release. There is no good answer to your question. Every record here gets cleaned before it gets played, including new records which for me, is a small fraction of what I have. But I vary how I approach each and also use a Furutech DF-2 flattener-- once you are sensitive to warped records, you’ll see how many are; I won’t flatten something that tracks properly but if the record is out of round, there’s not much you can do. Perhaps digitize it and rely on that-- I know that goes against the grain of the analog purists (of which I was once one), but I don’t want to risk my cantilever, especially on a linear arm where you can see the arm "hunting" on an out of round copy. 

PS: FWIW, if I had to choose between a vacuum machine and an ultrasonic, I'd opt for my Monks Omni, which is not a casual purchase. But, thankfully, I don't have to make that choice; I use both methods and they are synergistic in a real sense. 

@gano- one of the nice things about Neil's book is that in the course of explaining what is going on in the process of cleaning a record, he offers methods to do this without using a machine. It will require you to buy some chemicals and inexpensive apparatus but it is a thorough explanation, and you can, if you take the time to digest it, explore and determine the best approach for you. I'm a big believer in a rinse step, due to the residue issues discussed above.