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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
atmasphere's avatar
atmasphere
11,969 posts
 
@last_lemming 

Since a number of things have been tried on the 'table, I am starting to suspect the phono section might be playing a role. What kind is it?

The fact that its a problem with the turntable and not the CD player rules out the line stage and amplifier entirely.


So it is either the preamp or the turntable, and
the chances of duplicating the issue between to different TT’s and different carts.
-is actually a lot higher than you apparently suspect! BTW woofer pumping has nothing at all to do with whether circuitry is tube or solid state.


I agree that ditching the deer hide platter pad is a good idea. A proper platter pad will damp ringing in the platter and also vibration in the LP itself; deer hide will help with neither. I would think that the deer hide will be really tricky to maintain a uniform thickness- that might actually be the problem right there.

larry5729's avatar
larry5729
1,009 posts
 
Millercarbon, your system must cost a fortune.  I can't believe you are satisfied with listening to music in that kind of environment.  I like to incorporate listening into a beautiful room such as a family room so when I have company they can enjoy the music as well.  However, I am sure your system must sound incredible.  I noticed you have speaker wire stands.  What do they do and can you really hear the difference.  Looking at your system, there must be a lot of wealthy people in this group.  However, it is nice to learn from those who have invested a lot of money into their systems to achieve near perfect sound.  They must have near perfect ears to hear the difference or they have dialed in the sound that best maximizes their hearing.  What might sound perfect to one person must not necessarily sound good to another.  Nothing wrong with dialing in the sound best suited for your hearing because it is who is listening and who is investing this kind of money that matters.  I often think about this realtor who sends me listings of homes being sold in my area over the past 3 years.  He has sent me over 1,000 listings and I have yet to see one room with a pair of speakers standing.  I cannot believe people have a $5,000 piece of furniture with a wide screen TV and are willing to listen to the TV speakers.  I think 70% of the experience when watching to a movie is sound.  I also can't believe they don't like music.  Nothing nice than to have people over for cocktails and listen to music in the background.  I think most people are allergic to music are simply think music is noise.
baylinor's avatar
baylinor
1,444 posts
 
I use a TTW audio outer ring extreme V2, made in Canada. Extremely efficient and much less expensive than the VPI outer ring. That being said, once again, I don't believe that's your problem since I have never experienced the woofer pumping you describe before I got my outer ring even so I played some seriously warped vinyl.
baylinor's avatar
baylinor
1,444 posts
 
Unless you play your vinyl at 120 db :)
audiorusty
287 posts
 
I had a woofer pumping issue when playing vinyl a couple of years ago. The first thing I did was make sure the TT was as level as I could get it which helped a little bit. The other thing I did was place the TT on some anti-vibration pads like these https://www.amazon.com/PneumaticPlus-Anti-Vibration-Rubber-isolation/dp/B00HZS0CH6/ref=sxts_sxwds-bi...and the issue for me at least was eliminated. 
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