Phono-pre: subsonic filter on or off ?

Ptm,
I've never seen rumble filter adjustable. It's mostly oriented on sub-sonic frequencies of a large amplitude. Hence the alternate name is SUBSONIC filter.
SUB-SONIC means UNDER-AUDIABLE.

Actually, subsonic means 'under the speed of sound'. The proper term is Infrasonic. We don't say sub-red for infra red do we?

Also, Carver produced an infrasonic filter that automatically adjusted its cutoff properties to the low frequency content of the recording and the turntable's inherent rumble or lack of.
Salut, Bob P.

INFRA -- SUB
ULTRA -- SUPER

are synonims
as well as SUBSONIC or INFRASONIC.
Technically you can say SUB RED but it's not common.

Not only Carver produced the infrasonic dynamic filter. I've seen that in works of many different electronics designers adn Carver probably not the first implementing this circuit.

Marakanetz, Infra and Sub are NOT synonymous. neither are Ultra and Super.

Ever heard of super violet? SUB-Sonic has always been used for the speed of an object being lower than the speed of sound and never for UNDER-AUDIABLE, whatever that is. If you meant audio or audible, then that is not synonymous with sonic either. Sonic has to do with sound, not audibility.

Infra and ultra have always been associated with frequency, low and high, of vibration, sound and light, among others.

Perhaps this is a second language thing.

respectfully, Bob p.

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.