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. 

Showing 36 responses by last_lemming

No fireplace in the room where the pumping occurred, but ironically in the room that does have a fireplace it doesn’t pump. 

not sure I understand the question but the 4 surfaces I have directly coupled the TT to are:

concrete floorRigid stereo rack
heavy wood cabinet
on carpet

all of these surfaces produced the pumping exactly the same with 3 different TT’s and 5 carts. Also all these TT’s were moved around the room having the pumping issue and the pumping remained the same. 

In the other room where I don’t have pumping none of the 3 TT’s pump. 
So frustrating!
If I had to guess, I’d say 2-3 oscillations a second. Though the amount it moves in and out each time varies. 
The issue with ditching the mat is static electric. 
Well it’s not the music making the woofers pump since the pumping happens in the quiet passages as well. 

it has happened on all carts on both TT’s. 

Grado Sonata 3 (new)
Nagaoka MP200 (<200 hrs)
Nagaoka MP500 (<300 hrs)
Soundsmith Carmen II (<300 hrs)

they have all been aligned Using the AS Smartactor which takes error out unless you can’t read and follow basic direction. 
Also, both TT’s causre the pumping time be exactly the sameAnd at the same volume, even though one is DD the other belt driven, one light aluminum platter with stock rubber mat the other a 25 lbs aluminum platter with deer hide mat. I’ve sat them in the floor (concrete) to eliminate vibration as an issue, no change there either. 
In fact only thing the two TT’s have in common is the alignment. Could this be a cause?
I moved both TT’s - all over the place.  Not change at all and that’s spiked through to the concrete floor. 


I can’t discount your thoughts about the clamp, but how would this affect the outer edge of the record where there is no clamp. 
I use a heavy record weight - which I know you say is no good - but it firmly holds the record onto the deer hide mat. 
I’ve also tried several matts to no avail. 
You’re definitely right about one thing, it’s not the amp, I just pulled out my old CJ MF2100, and I get it there too. So there goes that theory. 


Thanks for your input, while the pioneer is a traditional gimbal arm the VPI is pivot.  As you probably know there are no bearings per se, to be sure I checked the pivot point and the cup, both are free of debris or burring.  I also have the second pivot point for the VPI and I even disconnected it to be sure, but the pumping happened in both cases with and without the second pivot point to the same degree.
yes it still does.  Not only that I turned off every circuit breaker in the house other than the one it was plugged into in another room and it still did it
This only happens when the vinyl is playing. 
It does the same thing on 3 different TT’s with 3 different carts, all carts are known to work with the TT’s, so a mismatch is highly highly unlikely at this point. 
Dekay- I did hook up another amp, my CJ MF2100, still the woofers pumped. 

I have considered this but the nearest appliance is a gas range opposite Side of the wall. 
If there is a phone app I’ll certainly give it a try. Got nothing to lose. 
One thing I don’t understand is the speakers go down to 32hz, but sub-Sonics can be far lower, so how do the speakers reproduce below there operable range with such amplitude as to move the woofer in and out 1/4” or more, when my strongest bass note I can get when turned up only moves the woofer 1/16”. 
I can also tell you the clamp isn’t the solution. I’ve got the VPI clamp that is dished on the underside and comes with a washer, but unless your clamp goes all the way to the edge of the lead in grooves, It ain’t gonna flatten those slight rises (Bumps) in some records right at the edge  I don’t care if you tighten it down with the force of Superman, it won’t flatten those types. 
A perimeter ring would help but they are pricey and kinda look like a PIA to use. But maybe that’s better than using a subsonic filter. 
If I thought there wouldn’t be a degradation in sound I’d use one. But anything that I’ve ever added to the chain that claims no degradation always does. 
Thanks for the responses

to answer some questions:

no sub is in use

my preamp does have mono but didn’t affect the pumping

I will try different speakers to see how that goes. 
Yes I did. No change. 
Also I got the perimeter ring in. Nice piece, keeps the record very flat, but didn’t really change anything. 
I guess it’s a KAB unit unfortunately. 
Well. I literally tried everything there is to try. Nothing worked . . .

. . . except the KAB unit. It does affect the sound, but I need more time to figure out exactly what has changed. 
But the GD woofer pumping is DONE!

Thanks. But compatibility isn’t the issue. The same equipment and rack in another room doesn’t cause pumping.  

It’s not about better equipment. My equipment is just fine and many people have the Same gear without any issues. 
I meant ALL my TT’s do it with ALL carts - exactly the same. What are the chances of duplicating the issue between to different TT’s and different carts. 
Also the carts compliance works with the arms, so there is no mismatch to be concerned here.

What,  I’m saying it’s VERY unlikely linked to an issue with the TT itself, but has to do with the subsonics coming off the record that both TT’s are picking up.

Well other than a clamp that works wonders, I’m not sure what is left for me to try. 

Here is a list of things most things I’ve done:

different cartsHead shell weightsAdjusted tracking force
different count wts
different antiskate
checked leads
different mats
different TT’s - in various locations
different phono pre
different pre Amps
checked different inputs on preamp
different amps
moving TT to concrete floor
Different cables
lifted motor off table so only belt spun platter

not sure what to check next. 
I would have thought that two different turntables without we skipped two different results but it doesn’t

I thought the same about antiskate.  I tried hi, low and off, nothing changed it. But I am using the same alignment and it is unique to the AS Smartactor.  It’s for better inner groove resolution. 
I will try a more standard alignment and see what happens. 
Thanks for all the input, here are some of the responses to some of the questions:

The platter is dead level I’ve checked it out digitally and with a old fashion bubble level
I’m pretty sure it’s not the phono preamp, I tried a Dynavector mkiii phono pre and an an Audio Research PH3se phono pre, it does it on both.
I have a Parasound JC3+ in another system, so I might try hooking that up as well to see if it happens.


i have those pads too, and tried them. No change. 
All my carts I have tried fall within the correct EM range. 
Some of the carts are suggested by VPI themselves. 
Thanks for your input guys. 
I just tried the mono switch on the preamp and it did somewhat reduce the pumping. About 30% less excursion as a best guess. 
I did relocate to a concrete floor to a completely different part of the room no avail.  
The carts I have tried. 
Grado Sonata 3 - new
Nagaoka MP500
Nagaoka MP300
Soundsmith Carmen II

And now I tried it with a third TT and cart. A Technics 1200 GR with an AT33sa (MC cart) and the pumping still goes on. And this time the TT was carpet, so no way vibration traveling through the walls or floor. Also, this same turntable and phono pre does NOT cause pumping on my other system. Again, not the TT. 
I also switched in my Parasound JC3+ Phono pre on this system and the pumping still continues. So not the phono pre. 

Also please remember I get the pumping on the lead in track with NO music, so vibration through sound is not the culprit either.  
In fact after 3 turntables with different carts and positions and surfaces within the room it’s defiantly NOT any of the 3 turntables.  
For kicks I plugged in another speaker on the right channel, unplugged the left channel, and moved The speaker all around the room to see if reverberation was the culprit, but nothing changed, The woofer consistently pumped. 
So it’s not the speakers or the sound coming from the speakers causing feedback and pumping. 
I also pugged the whole system into various other electrical outlets In the house just to check if it’s the electricity, that did nothing to help. 
The only thing that appears to be constant is the pumping is worse at the beginning of the record vs the middle. 

Yes the KAB is an option, but I want it to be my very last, but only after every other variable has been looked at. While I know some say it’s transparent, others have said otherwise.
To be clear the rack has not been constant. Anything but. The TT’s have been on concrete, carpet , rack, on and off maple block, with and without bear claws, different locations in the room, with and without record clamps, and all this tried with three different turntables, two amps, two preamps, three phono amps, different speaker cables, various IC’s, and even different power cables and outlets.  

It’s something with the room. I can’t figure what, but I’ve basically changed all components out, so what’s left is the room, and it’s not room interactions, because I hooked up a speaker with a very long speaker cable and ran the speaker outside the room the equipmentIs in, and it still pumped.  
It’s driving me nuts!  I don’t want to add a KAB to fix a problem that is not caused by the equipment.   

definitely don’t agree with the “need a better table than the ones listed” comment. All 3 of these tables have been in another system with No issues.  

Today I brought my other system in the same room as the offending system. Mind you the other system with same record doesn’t pump the woofers. But in this room, guess what, pumps the woofers. 

And, oh, when I bring the original offending TT and cart to the room with no issues, guess what, NO pumping. 

And don’t forget. I get pumping in the quiet passages in all things I’ve tried. 
So now a total of 3 tone arms, 5 carts, 3 surfaces to place TT on, 3 phono preamps, 3 amps, 3 preamps, 3 different outlets through out the house, 3 sets of speakers, 2 different alignment styles, and untold number of combinations of the above not to mention all manner of alignment adjustment have brought zero differences in the amount of woofer excursion, accept for when the mono switch was thrown, which did lower it about 30% (best guess). 

Here is what I do know. 
1. It happens with any turntable in this room regardless of all things done above to alleviate it. 
2. CDs don’t cause any pumping. 
3. The pumping isn’t caused by speakers resonating the TT, since it happens on quiet passages and at lower volume levels. 

4. regardless of placement In room or surface: concrete, rack or carpet I still get pumping. 
5. None of equipment, including any of three TT’s, amp pump in the other room. 
So what does this mean? Well, there must be some type of EMI or similar coming from something in the walls or in this area of the house interfering with the TT set up. Though the only thing I can think of if the oven/range on the opposite side of the wall.

I might be at the KAB point, unless I can figure out what’s the root cause.  

Big greg

thats not the system that pumps, that one is the one in the “other room”. I don’t have pics in the Woofer pumping room. 
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. 

I know it’s the TT per se, but it seems like some sort of interference is ramping up the pumping, because it doesn’t pump in the other room in the same set up - TT, cart, rack.

to you comments:

1. I have bought the ring. Hasn’t arrived yet
2. I have bear claws on a maple shade wood block, with the original prime feet secured to the wood block.  I have removed all these feet and tried various racks and also a concrete floor and carpet. Pumping is exactly the same in this particular room. Even on quiet passages. 
3. The TT is FURTHEST away from the right speaker where the pumping is worse. BTW the right speaker pumps more on all three TTs with 5 different carts and 3 different alignment methods. The pumping is exactly the same in all the different configurations. 4.  I did download a vibration program, but it must not be sensitive enough since the line is perfectly flat even on the most sensitive setting. 
I agree it has to do with the TT, but something is going on in one room that is not happening in the other and it has nothing to do with room or rack resonance. I’ve always had a weird hum coming from the electrical line in that room that I’ve always thought was a ground loop issues, but what if it is something else?
The only thing I can thing of is maybe there is some kind of electromagnetic interference that might be interacting with ll the different TT’s cart’s magnets. 
I do have a preifereal ring coming in, so we will see what happens there. 
There is but it’s about 8 feet away. 
Oddly enough it’s only 2 feet away from the system that doesn’t pump. 
There is probably nothing you can suggest that I haven’t already tried on 3 different TT’s and ended up with the same result. 

not the front end, I’ve eliminated those as variables. Since they are all fine in one room but not the other. 

I don’t have a EQ to do what you say.