Unsolvable Woofer Pumping (Phono only)


I'm at a loss for trying to find the source of my "woofer pumping."  It's most noteworthy when playing something that is mostly/all treble, and the woofers of my Focal Aria 906s are going nuts (inaudibly, of course).  Turntable is a Debut Carbon with Ortofon 2M Blue.

Initially I was told it's an isolation problem, so I better isolated my TT, even put it right on the concrete floor to test!  Next I thought maybe a problem with the TT itself, so tried a couple others, no change.  So I figured it must be acoustic feedback, as with the TT stopped and stylus on a record, I could produce woofer pumping by tapping on certain parts of my stand...but it is also not this! I turned off my amplifier and recorded from the pre-out to a Tascam digital recorder and played that back afterwards and the pumping STILL happened! So I tried an Schiit Mani phono stage, no change in woofer pumping...I was sure it had to be my pre-amp...

So a local audiophile came over with a couple of pre-amps and we tried those.  The only time the problem went away was when the subsonic filter that one had was engaged.  So, I've ordered some Harrison Labs "FMODs" (20Hz high pass) to see if they will help.  If they do, I may order a KAB RF1 one day...but don't want to spend that much if I don't have to.
Any other ideas on what could cause this?!

tl;dr: Woofer pumping not caused by isolation, acoustic feedback, phono/preamp or a compliance issue...what's happening?!

branden_8091
No. A speaker with extended bass response would not help. Most cabinets are ported in one way or another and therefore don’t exert much control over the woofer motion. However such designs in my opinion offer a natural sounding bass response. What you’d want is an acoustic suspension type, with a closed box.  The closed box exerts some back pressure on the woofer cone which inhibits the phenomenon you are observing. But in my opinion such types are less natural sounding in the base. That’s just my opinion. By the way, there are several Inexpensive subwoofers on the market that would cost you less money than replacing your entire speaker system. And I agree with others it would help your problem. Many such subwoofers, in order to remain small in physical size, do use some form of acoustic suspension cabinet. That alone would help.
Might be due to cartridge/tone arm mismatch. Some damping of the tone arm might help also. Something to research I think. I had a similar problem with a tone arm with a well for oil to damp tone arm vertical movement which went dry. There used to be add on devices to accomplish the same thing. Good luck.
newbee, Good point.  But the cure of damping might worsen the disease.  Damping would add mass to the tonearm, and that would drive the resonant frequency downward.  Resonant frequency is inversely proportional to effective mass.  Oil damping, as you mention, might help if it could be applied to the OP's tonearm.
Branden, the woofers in any speaker including subwoofers will still dance to the rumble but with a larger driver in a sealed cabinet it will be much less noticeable at moderate volumes anyway. All records have some rumble built in. You may notice that some records are worse than others.
You would have to have a damaged turntable or an old idler wheel drive for it to rumble that bad. For all of us the only way to keep our main speakers clean is to divert everything under about 100 Hz to subwoofers.
For those of us with two way or one way loudspeakers this is actually critically important even if you do not use a turntable as low bass will Doppler distort everything else the woofer or speaker is trying to reproduce. For those who do not know what Doppler distortion is just have a friend drive by you at 40 MPH leaning on the horn. As the car passes you the horn will change tone. It will go from high to low. That is exactly what is happening when the woofer is flapping back and forth at low frequencies. 

@mijostyn Very interesting.  I don't have any equipment to drive a subwoofer yet, just good old fashion two channel stuff.  A subwoofer will be something to look into in the future possibly!
@lewm I'm just itching to audition some speakers now! Ha ha. I was more asking if a more full range speaker would be about equal to adding a subwoofer now? I'm currently not able to have a subwoofer...and still my heart prefers old fashion two channel setups.