Vinyl and subwoofers

golferboy

Why is having the sub only 4 ft away from table a problem with concrete?

The concrete has nothing to do with it. The close proximity between subwoofer and turntable suggests you may have some acoustic feedback between the two. That is only going to exacerbate any other problem you're having with setup.

I'm not familiar with your turntable. It's possible that it's just not well isolated. That may also be contributing to your problem.

golferboy

BTW, the query "pumping woofer vinyl" resulted in over 100,000 results on Google.

That is not at all surprising! There are more cheap turntables in the world than good ones. I'd wager more turntables suffer from improper setup than those that benefit from proper setup. As audiophiles, we're just a tiny percentage of those who listen to LPs.

It seems somewhat counter to logic to purchase a subwoofer that now requires a rumble filter.  If you can "hear" the subwoofer operating during normal playback, that typically indicates the level is set too high; turn it down a bit and see if that alleviates your intermittent problem.  Someone else mentioned this.  But as a matter of fact, 30 and more years ago good receivers and integrated amplifiers often did come with rumble filters.  They went away with the purist movement of the late 80s and 90s and possibly the realization that there was more profit to be had by not incorporating a rumble filter.  Do you perceive that the diaphragm of the subwoofer or your main speaker woofer is "pumping" when the problem is occurring?  In that case, and after you have exhausted the possibilities of re-arraging your components (see below), a rumble filter might help.

Your problem can also be due to placement of the components in your listening room.  Low frequencies can produce standing waves that contain quite a bit of energy which can induce physical movement of the tonearm/cantilever, generating spurious low frequency interference. Where is the tt with respect to the sub woof?  Try moving one or the other and see if that affects the problem you are trying to solve.  Someone else mentioned this, too.

Do you really know for sure that the sub woof is the culprit? Does the intermittent problem disappear when you disconnect the subwoof and run the main speakers full range?

Hi,
Is there a 'connectivity' set up diagram to show how to set up a sub woofer in a vinyl system i.e. how/where the speaker wires connect and do the main speaker wires change at all?
Bob

The original description was "vinyl sounds muddied."
While all the comments about setup, amps, etc. may have merit, the fact that it appears only on vinyl means - well, it must be associated with vinyl playback.

Two possibilities:

1. Acoustic feedback
2. Eccentric recording.

If it’s acoustic feedback being picked up by the cartridge, fix that.
But more likely is #2.

Almost all records have some warpage, which is amplified at 33 1/3 rpm, or 0.5 hz. (33.3 cycles per second/60 seconds per minute = 0.555)
Plus there are various imperfections in the surface. Say there are three imperfections - they will be played back at 1.5 hz.
OR, many records don’t have the spindle hole punched exactly in the center - another source of 0.5 hz.

In all of these subsonic cases, the amp will be pushing or pulling at very low frequencies, which will stress it. And the woofer will be struggling to produce an in-phase signal while the woofer moves in or out, with large excursions.
The simplest form of speaker distortion is the Doppler Effect, but there are other phase-shift effects that will affect the sound you hear. Muddied is a good description.

That’s why amps of vinyl vintage had subsonic filters, usually switchable. And they usually acted below 10 hz. Simple solution (if the slope of the filter didn’t introduce too much phase shift of its own).

In the vinyl era, rumble filters were different from subsonic filters. Rumble filters were designed to mask bearing noise, which occurs in the audible range. Using them eliminates audible sound - better to get rid of noisy bearings.

Subsonic filters were strictly for eccentric recordings. You could actually see the woofer moving in and out at 33 1/3 hz - I thought it looked like they were breathing.
Different problems, different solutions.