rumble issues - see old thread update

Audiotomb, I responded to this on the other thread. I run the Triplanar and ZYX and have used a variety of speakers, a good number of them ported. In addition, our preamp has phono bandwidth flat to 2 Hz.

We get no pumping. IOW the bandwidth the of the preamp is not an issue; if a low frequency rolloff fixes the problem then you have a set up problem.

Remember how I commented about using different weights? With the Triplanar you can use a lighter weight further from the arm, thus increasing the effective mass, or a heavier one that is closer to the bearings, thus reducing the effective mass.

The other possibility is that all your LPs are really badly warped, but I don't buy that.

You could also have a low frequency resonance in the room that is interacting with the phono. I don't recall you mentioning the stand that the table is on- that can have a **huge** effect. We use a Sound Anchors stand that is custom built to accommodate our equipment platforms, one of which is beneath the 'table (which has no suspension). The stand is perched on a set of Aurios Pro bearings. On this set up the 'table is immune to any playback volume- I do not get pumping even at sound pressures of +105db.

"NOT UNUSUAL AT ALL WITH PORTED SPEAKERS"? where do people get this stuff? My ported speakers don't rumble at all. EVER! just clean, tight, powerfull bottom end and only when the vinyl calls for it. not even on "warped, as few as I have, albums.

I "got" this stuff from my own experience with ported speakers and preamps that don't roll off. I have sat a watched Doug's speakers do the dance. I have seen just about ever other ported speaker do this with analog. You have a different experience. I won't say anymore about this because I can't say anything nice at the moment.

Koegz,

All ported speaker cones oscillate when air inside the chamber is energized at the port frequency. When air is compressed at the port waves flow back into the cabinet at that frequency. Something inside has to move and the easiest thing to move is the cone.

Dan is correct, mine do oscillate (though never to the point of audible breakup or distortion, as the OP is experiencing).

There could be many reasons why you haven't seen yours oscillate and I'm glad you haven't. Your speaker ports are certainly tuned lower than mine. Your phono stage may have a built in rolloff or filter. Your line stage or amp may not go low enough. You may not have noticed. But this doesn't change the fact that they will oscillate if excited at the port frequency.

Want proof? Try YELLING into the ports at their tuned frequency. ;-)

Yes, woofer pumping with vinyl and ported speakers is a very common problem. As Doug has alluded to above, the problem may be more severe depending on the frequency at which the ports are tuned.

While a tonearm/cartridge mismatch is certainly going to create a problem, I'm always amazed at the number of posts in these threads on woofer pumping that absolutely insist it is a setup problem.

IME it is absolutely possible to have a perfect match in terms of cartridge/tonearm, along with a well setup properly isolated table and system and still have problems with woofer pumping with ported speakers.

I have a great deal of respect for Ralph (Atmasphere) and perhaps my amplification is just not up to the job and that is why I've experienced problems with woofer pumping with vinyl. But frankly, I doubt that. I'm comfortable with someone saying they have absolutely no woofer pumping with vinyl and ported speakers but feel that they may just have a little bit of luck going for them too.

When you look at reports of woofer pumping from audiophiles here and on other audio sites they are almost always coming from someone with ported speakers.

Sometimes, in the real vinyl world, unless I suppose you want to change speakers (or possibly amplification-not so sure about that one) you just have to bite the bullet and employ a high quality subsonic filter.

Those who continually denigrate a subsonic as a band-aid solution and negatively affecting sound quality are, in my experience, off base. My system is clearly not in the same league as some posters here, but does consist of a vinyl front end and phono preamp with a retail list price approaching $6,500 with the table mounted on a high quality wall mount with a custom shelf. No tonearm/cartridge mismatch issues. Without a decent subsonic filter (I've used the KAB, which is an excellent product, and my Aqvox phono preamp has a very high quality switchable subsonic filter), I have woofer pumping.

In may case, the subsonic is not in the least degrading of sound quality. In fact, I'd argue it improves sound quality. Now if I had no woofer pumping, it might be a different story, but I do and replacing my speakers or amplification is not a cost effective or justifiable solution for me. A decent subsonic filter is.