There is but it’s about 8 feet away.
Oddly enough it’s only 2 feet away from the system that doesn’t pump.
Oddly enough it’s only 2 feet away from the system that doesn’t pump.
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.
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.
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You might have a power problem. I saw a situation once where a tube power amplifier drew enough power that when the preamp was on the phono, it was possible for the amp to drain the AC line so far that the preamp started to shut down. That caused it to put out a pulse which caused the amp to shut down a bit- then the line voltage recovered, the preamp made another pulse as a result and the cycle continued- woofers pumping. You could stop it by turning the volume down. It would only do it with the tube amp that had greater draw and only when on the phono input (which has more gain and so is more sensitive to issues with voltage regulation). If all the gear works in another room (and hooked up to each other the same way) then I would look into this. It might be as simple as a bad connection on the back of an AC outlet or in the breaker box. A digital voltage meter set on the AC voltage scale and plugged into an outlet on the same line might reveal this problem unless its associated with a particular outlet. |
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gibsonian Rumble filter is simple and easy, no big deal. Get one and move on. They’re in most all phono pre’s, for a reason.A rumble filter is a Band-Aid. While they are common on older receivers and lower-end equipment, you’ll find they are much less likely to be included on better gear, where the manufacturers expect the user to be using a properly setup quality turntable. For example, the phono stage I use is spec’d to be within ± .2dB at 10hZ and down just 2dB at .3hZ. My speakers are relatively flat in-room to below 25hZ. No woofer flapping, no rumble filter needed. |
^^ +1 My phono section has bandwidth to 2Hz and no worries about woofer pumping- my system is flat to 20Hz and the woofers are calm unless there are bass notes. The KAB knocks out low frequencies and part of the reason it sounds different is not only more amplifier power but also phase shift. IMO/IME its better to get a handle on this rather than place a bandaid on the problem. The result will be better sound. @last_lemming If you had to describe the woofer pumping, how fast was it? |
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@last_lemming did you ever figure out what was causing the woofer pumping? I'm having a similar issue that is not responding to the usual solutions. |
When my woofer was crazy pumping (moved heavy curtains behind my speakers) it was due to my Pass Labs phono stage. Changed back to my tubed Manly phono stage it it stopped about 80%. I then changed to a T+A phono stage (inserted inside my T+A HV integrated and it solved the problem 100%. Can play extremely loud, no thumping. The T+A phono stage also outperforms the Pass and the Manly. |
Welcome to the (very 20th century) world of imperfect records and turntables. Noise and distortion is par for the course. People spend fortunes on turntables and good pressings to avoid that. That’s just one reason why digital streaming rules in the 21th century. But gosh darn those imperfect ol records are just too darn much fun to dabble with to ever give them up totally once you have them. The joys of analog home hifi! |
