rumble issues - see old thread update

HI Dan

Richard Gray - my local tech and designer thought it probably is tone arm compliance - needing a little more weight

we will see where it goes from there

thanks

Hi Tom,

As you know we use the same arm, cartridge and preamp. With 8-10 different UNIverses on our arm we've never had such issues with any music, at any volume up to window shattering.

Based on that experience I question the tonearm/compliance theory (assuming your cartridge has the SB option). You can test by trying a different counterweight, positioned to give you the same VTF. That will change the eff. mass slightly, which would alter the behavior if eff. mass were the culprit. Seems doubtful to me, as I said, but it can't hurt to try.

We get only minor woofer pumping on obviously warped discs, as we should. Basically it's just the cartridge, arm, preamp and and amp reproducing the warp frequency and pushing it through to the speakers, as they should. But in our setup this never results in sonic breakup or "clipping" unless a warp's so bad the cartridge mistracks. We have exactly one LP that can cause that, a nasty pinch warp. It's our torture test for vertical tracking ability. ;-)

I suspect you have some combination of room interactions reinforcing a low frequency and/or amplifier headroom issues. Both would be volume sensitive and could lead to breakup at higher SPLs.

Just for fun, try blocking the ports on your speakers and see what that does. Try borrowing a different amp too, if you can.

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.