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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
jengelmann's avatar
jengelmann
58 posts
 
I would recheck your cart alignment method. Likely you used the same on both TTs.  If more predominant on one channel, it may be trying to ride harder to one side. 
The other thing that comes to mind is the anti-skate setting if so equipped. 
last_lemming OP
639 posts
 
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. 
millercarbon's avatar
millercarbon
12,531 posts
 
paulgardner-
@millercarbon Can I ask where you got a carbon fiber outer ring clamp? I need one! 
Everyone does! Took mine to CES one year, compared with a bunch of em, its a great clamp. DJ Casser must have been impressed, he copied it, and so his stolen from me copy is as far as I know the only one on the market. Mine being DIY and a one-off. Its made from some BDR Shelf material that was left over after making the Miller Carbon turntable. https://systems.audiogon.com/systems/8367

DJ died about a dozen years ago, his heirs seem to be keeping the company alive but its not like it was. Far as I know BDR is only sold through Music Direct. I would call and ask if they can make you a record clamp. It will cost a lot. It will be worth it. Only clamp I know better than mine. Better made, better sound. He stole the design but give the man credit, he also perfected it. 

If they can't do that the next best would be order one of the Round Things with the threads going all the way through. Make sure your spindle is threaded to use this. Otherwise you need a collet type clamp. Which let me know, it can still be done its just more work. But a Round Thing, you can see them in my System pics, they are round and almost the right size. A little small but still better than every other clamp on the market. Then either dish it out like I did, or get an O-ring the right size to go around the perimeter so it pushes the record down from the outside area of the label. Then put a washer, or a small O-ring, near the spindle. That is the key. To push the record down from the center to the outside edge of the label, so when its clamped down the outer edge of the record contacts the platter first. 

This works just amazingly well. I really don't know what's wrong with the people here. They're talking about anti-skate, and every single crazy thing a guy could possibly imagine that can have nothing to do with it, while stubbornly refusing to see the one thing that will. Ignore the herd. Get a clamp. You will see.
atmasphere's avatar
atmasphere
11,841 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
1,008 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.
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