What was the fairly purvasive "rumble filter" for on many pre amps, integrated and receivers from the phono dominated era? I have been concerned about this since I have a subwoofer that has no effective lower frequency cut off, volume just trails off gradually at lower frequencies. While this is an asset on digital recordings, The low frequency energy (sounds like a rumble) is so loud on certain records in my collection that it intrudes on the music. This occurs on warped albums and some other recordings with no obvious physical defect. No rumble filter on my current amp. Have been thinking that cartridge/arm matching may be more critically important in this case. Is dawn of more low frequency capable systems brought on by digital sources making this compliance issue more noticeable and problematic for analog reproduction?
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