Woofer pumping possibly due to tube amp when playing vinyl


I am moving this issue  to this forum because of what I discovered this weekend.

I’ve been trying to figure out why I have woofer pumping when I play vinyl, and for the last two weeks I’ve been messing with my vinyl rig trying to figure out what is causing the issue.  The woofer pumping seems to be more prevalent with the vertical up-and-down movements of the tonearm regardless of which turntable is being played. It appears it happens more at the outer edge of the record then the inner grooves.  I assume this is because record is more warped at the outer edges. The woofer pumping happens even in quite passages, so it’s not noise induced vibration affecting the turntable. 

 I have used two different turntables to try to figure this out, one is a pioneer PL 530, and the other is a VPI prime. both with different carts. Also, I have verified that all the carts being used on these turntables work well together with their respective arms.

However, it is not the turntable or cartridges. 

Things I can say for certain, it is not the turntable because I switched turntables with different cartridges to confirm this, and I still get the woofer pumping.  It is not a phono preamp because I’ve switched several phono preamp‘s, solid state and tube, and I still get the woofer pumping. It appears it is the tube amp that may be at cause. It’s the only component left of the chain. 
I have a Audio Research  Classic 60 amp. I got the amp used but it came with a new set of power tubes I don’t recall if I changed the four smaller driver tubes,  I also change the four large capacitors to new capacitors and biased the amp. 
The interesting thing is, with the TT’s I tried, it is the right channel that pumps more than the left channel, regardless of the variety of different cartridges tried, all aligned with AS Smartractor.

To be certain it was limited to vinyl playback, I plugged in a CD player and I do not get the woofer pumping at all. So I have a couple theories (1) the TT is just transferring subsonic frequencies from the records, ALL records I play do this.  Please remember, this is from the two different turntables being used, one a VPI prime belt driven, and the other a pioneer PL 510 Direct DrIve,  or (2) there’s some weird thing going on at the amp that I cannot explain. 
My question is, if there is something going on with the amp could it be a tube issue, or capacitor issue, or a biasing issue.  If so what is the most likely culprit.  Or I guess something else altogether. 
In the end I’m rather tired of chasing this ghost, and I would rather not use a subsonic filter if possible. If I do have to use a subsonic filter I want the most transparent one if such a thing exists. I’ve heard mixed results about the KAB unit. 
last_lemming
last_lemming, as you noted your equipment is fine and doing exactly what it was designed to do. You can either just  stick with digital, get a subwoofer (big drivers move less) with a high pass filter on your speakers or get a subsonic filter. The best subsonic filters are digital and part of a room control system which means you would have to digitize your turntable. You can also just stick a cap of the right size on your speakers, a very low frequency high pass filter. 
But compatibility isn’t the issue. The same equipment and rack in another room doesn’t cause pumping.  
@last_lemming 

This is an important clue! This means its clearly mechanical feedback between the woofers and the turntable.
Last Lemming, Millercarbon is correct; unfortunately, it is the turntables' interaction with the listening space. I had a similar experience with my turntable a few years ago. It was an Oracle Delphi Mk II with an SME V arm and Benz Ruby 2 cartridge. The entire setup was placed on a Target TT-1 wall mount turntable rack, mounted into the studs of an exterior wall. Oracle Audio pioneered the record clamp back in 1981. I installed everything myself, with much help from Wally Malewicz. After an exhaustive trial and error process similar to what you did, and contacting Oracle several times, it was discovered that the SME V requires a different suspension spring configuration than those typically shipped with the standard tune-up kit Oracle sells to keep the Delphi operating to spec. Once the correct springs were placed in the correct suspension towers and properly tuned, ZERO woofer pumping.

The woofer pumping occurs from acoustic feedback, resulting from the turntable suspension not being properly tuned for your combination of tonearm/cartridge, and/or your room’s resonant frequency. I know that the VPI is a "suspensionless" design; however the feet are made of different resins and polymers designed to filter out unwanted frequencies, but just aren’t doing a complete job of it. The Pioneer is even less equipped to do so. I have since upgraded to the Delphi Mk V in African Black granite, which has a platter mat made of vinyl resin concavely ground so that when the record is clamped it does exactly what the design of Millercarbon’s rig does, presses the record so that is is flat across the playing surface. You will NEVER get the same result from a record weight alone. You can achieve a similar result by utilizing a weight AND the peripheral ring clamp on the VPI; they are deigned to be used together. One other thing that may help, get yourself a shelf for the turntable to sit on that is decoupled from, instead of mass loaded to, the environment. Again, note Miller’s setup. The Black Diamond Racing Shelf for the Source is an outstanding device, albeit expensive. I am using a Z-Slab from Zoethecus (unfortuantely defunked) on top of a 1" African Black Granite slab in the TT-1 instead of the stock shelf. Yes, that’s a whopping 105 lb mounted to the wall. The Z-Slab/Oracle Mk V is supported by weight appropriate discs from Grand Prix Audio, and this has resulted in dead silence, from a turntable sitting 4’-5’ on the side wall from a F-13 Fathom sub and M-L Ascent i speakers in a 14’x11’ room.

Good luck with your journey. I hope that this will give you some direction in resolving this problem. I KNOW how frustrating it can be, but with perseverence, when it is resolved it will be SO worth it. Almost everything I play now is on vinyl even though I have similarly spent on digital for not only this one, but the other systems around the house. EVERY room has its’ own music system; it’s good for what ails ya!
Sorry guys.  It’s NOT THE TT’s. All three do it on all different rack types. There is no way you get the exact same results on three different TT’s, sorry, that’s not the case here. 
Is not induced by the music. It happens on quiet passages. No music to cause pumping. 
I believe it’s EMI or similar. 
That being the case how can I track that down. 
Remember in one room the same TT and racks reproduce pumping and in the other, with all three TT and in the same rack I don’t get the pumping. Again, on quiet passages. It’s not a physical manifestation, it’s electrical. 
But thank you for your responses. 
What I'd like to know is-members who have their table setup dialed in,  no rumble filter and use sub(s).

By the reports of some, you can actually play any LP, CRANK the volume, and you have ZERO woofer pump?