Why the woofer moves badly when playing certain LPs

millercarbon

... A certain amount of very low frequency woofer excursion with records is perfectly normal ...

Perhaps it’s "normal" for your system, but that needn’t happen in the absence of a signal and if it does, you’re wasting amplifier power and introducing distortion. My system is flat to below 20 hZ and I have no such problem, but I also pay a lot of attention to phono setup and matching phono cartridge to pickup arm.

It sure looks to me like a stellar example of pickup arm/phono cartridge mismatch.

mijostyn

Are you using digital room control?

No.

... even if you have your tonearm set at say 12 Hz there is still going to be plenty of rubbish below 10 Hz that is going to get through.

Not so. Not even close.
I understand that this will be a problem in many systems, and that a rumble filter may be the only way to fully correct the problem in those cases. But to insist that "plenty of rubbish below 10 Hz" is going to reach the woofers in every system and is an inherent problem in LP playback is simply false.

With the volume high enough everybody’s woofers are going to flap at least a little unless they have a filter ...

Nope. Not in my system.

mijostyn

IMHO anyone who listens to vinyl and has a subwoofer system needs a subsonic filter.

Why?
Why not treat the problem at the source?

mhmeyers

Use of a Subsonic filter or a preamp with one built in is almost a MUST when playing LPs.

Such filters are necessary when there is such a profound pickup arm/phono cartridge mismatch, as in the example shown in the linked Youtube video. If the OP’s cartridge is not a mismatch for the pickup arm, then there is something amiss with the cartridge itself, such as its suspension. I think it’s preferable to treat this problem at the source - in this instance, by selecting a cartridge properly suited to the pickup arm - rather than subject the signal to a filter.

I play LPs and have no issues with woofer pumping, even on warped records, and my system is flat to below 20 hZ. But my phono cartridge is matched to the pickup arm, and I’m meticulous with setup.

mijostyn

Cleeds, since when is a resonance point a "brick wall" situation.

I’m not aware that any person has made such suggestion, so it’s not clear why you’d ask that question.

If your woofers do not move at all visibly and you are playing vinyl either your woofers do not go down very low or your cartridge is too stiff for your tonearm and your bass is rolling off prematurely.

No, my system has no problem at all reproducing low bass from LP; it's flat in-room to below 20 hZ.

I would never use an analog filter ... There are no downsides to a digital filter up to 80 dB/oct. With a 3 dB down point at 18 Hz the effect is totally inaudible.

Given that the manufacturer of my phono preamp specs it as being within .2 dB of RIAA at 10 hZ, and down 3 dB at .3 hZ, why would I add a rumble filter in the absence of rumble?? I’d rather have an LP playback system that doesn’t require such a filter, be it analog or digital.

The problem Cleeds is that the source is vinyl, a medium that is imperfect at best. So, treating it at it’s source means not playing records.

That’s the logical error known as argumentum ad absurdum. I’m not going to stop playing LPs because the medium is imperfect, or because you insist that I need a rumble filter.

mijostyn

Cleeds, what your equipment is speced at has nothing to do with your system’s bass performance.

I’d agree, but only to a point. The specs merely indicate a component’s potential, according to the manufacturer, and are certainly no guarantee of actual performance. That’s why component matching and system setup are so critical.

Judging by your opinion you do not have any bass. Impulse test your system. I’ll bet there is nothing below 40 Hz.

I understand why you say that, because you’ve previously stated that, "anyone who listens to vinyl and has a subwoofer system needs a subsonic filter." Apparently your system has some rumble problems that cannot otherwise be ameliorated. But my system doesn’t have that issue, and I can get more than a full octave below 40 hZ from LP. We are talking down into LF that really can’t be heard, but only felt.

It’s not easy to get good, clean, flat LF performance from LP, but that doesn’t mean that it can’t be done.