Why are my woofers pumping?

@o_holter 

Raul's suggestion that the cantilever suspension is failing could be an explanation, but the problem I have with that is the cartridge must be pretty new so this seems really unlikely.

I looked at the specs of the ARC used in the review; it cuts off at 10Hz. Your preamp, if still the Io, is only specced to 20Hz (at which point its within 0.25db, suggesting that it can go down considerably further). So its an unknown as to whether that's an influence. Your amps are full power to 1 Hz. I use similar amps in my system at home, but I don't get the woofer pumping, although that was a problem when using the SME5 and has not come back while using the Triplanar (which I see was used in the article you linked, so this problem may not have shown up).

A filter will introduce phase shift, and in a full range system such as yours, will be audible as less bass impact. So its probably best to solve this with elegance rather than brute force.

@o_holter Does this happen when the woofer and other equipment is not in the sun?

Same problem on 3 different Turntables. As a last resort, I bought a KAB rumble filter which I run via the tape loop. I do not notice any less bass and my system really swings. The filter even uses audiophile parts in it. New it was 179.00 but I saw one on here a couple of weeks ago for around 100.00 That, is a good deal. Regardless at what others will tell you, in my system it did not cut the quality of the bass or the deep bass. I can rattle the windows playing vinyl if I want.  The sun has absolutely nothing to do with it.

These mismatches exist and you’ll never figure out why, nor will you ever fix it. Just enjoy the music. SME V is arguably the best tonearm in the world ever made. And Lyra makes superb high end MC cartridges, even if I’m not the biggest fan.

Rumble filters not only ruin the bass, but suck the life out of the entire system.