KAB RF1 Sobsonic Ruble Filter - Worked but feels like I lost some sound quality

fiesta, You wrote, "The KAB filter you have has a -3dB point of 20Hz.!!! Of course, using that filter will remove a lot of the music and dynamics. Get a GOOD subsonic filter. You want something like -3dB at 8Hz. or lower. With a slope of 24dB/octave or greater. Digital filters of 48dB/octave or greater are available nowadays."

I have to disagree with you at least in the statement that a -3db point at 20 Hz will remove "a lot of music and dynamics".  First of all, very few systems produce 20Hz in the first place and when they are capable of producing 20Hz, the signal is already at least -3db down using 1kHz as the zero db reference. Second, do you know the slope of the KAB filter? I do not, but if it cuts in at 20Hz, the slope has to be very steep to do any good in removing subsonic frequencies.  (For you to say it is -3db down at 20Hz tells us only that 20Hz is the inflection point of the filter; it does not tell us the slope.) And since many testify to its effectiveness, I would guess it must have a slope in the range of 18 to 24db, at least. And no filter comes with a free lunch, including digital ones.

I still think the problem here (loss of SQ at upper frequencies) is using a filter into a filter.

@lewm …using a filter into a filter.

That doesn’t “sound” good 😉

Yeah the problem is using a filter with a filter. It gets some really strange results. I tried again to use the KAB by itself but I can see the cone moving frantically, although in tiny movements.

@dman777 you worry too much. Rather than buying more equipment, buy solid component racks and treat your room. That will give you the best ROI 

I experienced this with stereo REL 9i's. Help from

REL, Grado, Paul McGowan and Rogue Audio was to no avail despite their kind guidance in trying to find the cause. Kevin at KAB sold me this filter and it stopped my RELs.from hitting the stops. I lost the below 20hz pressure which does effect the sound somewhat but it was that or forget vinyl.

BTW, same songs on CD, no problems. Speculation was subsonic sound caught during cutting the shellac master, even possibly the cutting machinery. No way to test this hypothesis, however.