Phono-pre: subsonic filter on or off ?

Bob,

"Sub" prefix denotes "under" or "below" when attached to a word. "Sonic" means having to do with, or using, sound waves. So "subsonic" can describe something that is below sound waves, meaning you cannot hear it. Granted, "sonic" is also an adjective used to describe something that has to do with the rate at which sound travels under another meaning, and "subsonic" generally means under the speed of sound. However, before we let semantics get too much in the way, let's use common sense, shall we? Do you really think subsonic filters are designed to cut off the frequencies that travel below the speed of sound rather than frequencies that cannot be heard by the human ear but produce inaudible rumble? C'mon, you can't be serious! I don't know how fast sound waves of 20 Hz or less travel, but I do know it is generally accepted that 20 Hz is the lower limit of the human hearing. Rumble filters such as KAB are designed to suppress sound waves of frequencies under 20 Hz, meaning they suppress sound waves that cannot be heard by the human ear, but are still reproduced by the amp and the speaker and cause the woofer pumping. Not the dictionary, but the common sense in the design goal dictates it.

Sorry Bob, but I think you're missing the point as you're getting too hung up on semantics rather than the design purpose. The point is that subsonic filters are designed to suppress low frequencies that are not audible to the human ear, and are not concerned with the speed of the sound waves, despite the arguably semantically incorrect nomenclature. So if you want to be the Thesaurus police (and as I explained in my previous post, an argument can be made you're wrong about that too), go ahead, but the Marakenetz's point is correct.
Btw, KAB does use the word "subsonic" when describing the filter. I took a quick look and saw the reference at least thrice on their website.

http://www.kabusa.com/rf1.htm

And who the hell is Will Rogers?

Bob,
You're probably right. I did notice, however, that the use of the term "subsonic" is actually quite pervasive in audio nomenclature when discussing rumble-related issues (I did a search on the internet for "subsonic filter"). It often seems to be used interchangeably with "infrasonic," which I agree is a more correct term. I wonder if the use originated together with the term "sub"/"subwoofer" and then caught on.