Buy High Pass Filter or KAB RF1?

Craigert,  Based on one of your posts here, do you seriously plan to put the filter between the phono cables and the phono input of your preamplifier?  If so, that's a no-no, if you care at all about SQ.  If you're bi-amplifying the speakers, do you use an electronic crossover?  And do you have separate amps for bass and treble?  If so, put the filter at the output of the crossover that feeds the bass amplifier. Whatever your set-up, I suggest you avoid putting the active rumble filter directly across the very low voltage output of the cartridge.

Lew,

Thanks for the tip. The ultimate goal is to buy the Atoll phono preamp and put the KAB on the back side of it before it goes into a line level input of the Marantz.

i have a 5 channel amp that feeds my front two speakers and my sub has its own built in amp. 
The crossovers in the front two speakers are built into the speakers and the crossover that controls the sub is in the Marantz. 
There is only one line feeding the sub so I’m not sure how I would connect this just to the sub.

Do I need to wait until I receive the outboard preamp or is there a way to Connect in the meantime? 

There is only one line feeding the sub so I’m not sure how I would connect this just to the sub.

Does the problem still occur when the sub is not operating? If so connecting the filter just to the sub won’t help very much, of course.

If the problem only occurs when the sub is operating, though, you could connect the filter between the Marantz and the sub, with a y-cable connecting the bass signal provided by the Marantz to both inputs of the filter, and with just one of the outputs of the filter connected to the sub.

The reason for the y-cable is that I see in the instructions for the filter, which I found online, that there is an "important note" saying that it should never be used with only one of its two channels connected, and "if you must do that" a y-cable should be used to connect the input signal to both inputs. I’m guessing the reason for that might have to do with the possibility that noise occurring in an unused channel as a consequence of having its input unterminated may couple into the channel that is being used. If so, a shorting plug on the unused input could be used as an alternative to a y-cable.

In any event, I agree with Lew that the filter should absolutely not be connected to the output of the cartridge. There are several reasons for that. Just to cite a couple: The hum & noise produced by the filter is specified as "> -85 db ref 1 volt." Since the 5 mv rated output of the cartridge is 46 db less than 1 volt it would mean that hum and noise produced by the filter could be as little as 85 minus 46 = 39 db below the rated output of the cartridge, which would be unlistenable. Also the unspecified and unknown input impedance of the filter stands a good chance of being too low to provide reasonable results when used with a moving magnet cartridge.

Regards,
-- Al

Guys,
I may have figured it out and I would like to get your opinion. The P3 mass is 11 g. My Nagoaka MP-110 cartridge is 6.5 g with only a 6 for dynamic compliance. Using an online calculator this puts the resonant frequency at a 15-16 Hz!I believe it’s supposed to be around 10 Hz correct?
Do you agree this is most likely my problem?

Great insight on the y connector Al!

Also, I cancelled the order for the KAB because I now think it’s a cartridge incompatibility issue with my light tonearm since the dynamic compliance of the cartridge is a mere 6 causing the cartridge resonance to be 15-16 Hz.

It looks like I will be on the hunt for a new cartridge first.