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Subsonic Rumble Solutions

I know many of you have tried to address this issue. Short of buying or building a subsonic filter (that will/may negatively affect your transparency) - what methods reduce subsonics (meaning the pumping of woofers and subs when a record is playing)?

My system:
I have a DIY VPI Aries clone with a 1" thick Corian plinth, a Moerch DP6 tonearm and Dynavector 20X-H cartridge. This sits on a maple shelf. The shelf sits on squash balls. The balls sit on another maple board floating in a 3" deep sand box. All this on a rack spiked to a cement floor. The phono stage is a Hagerman Trumpet (no built in subsonic filter and very wide bandwidth). I use the 1 piece Delrin clamp on the TT. Yes, I clean records thoroughly and there are no obvious warps, especially after being clamped.

So my isolation is very good - no thumps or thwacks on the rack coming through the speakers. But if I turn the sub on I get that extra low end pumping on some records that hurts my ears. Mostly I leave the sub off when playing vinyl, but I would like to use it if possible.

There was some brief discussion of this on Albert Porter's system thread. I'm hoping to get more answers here.

So ... what methods have you tried to reduce subsonics that you have found effective?

Thanks,
Bob
ptmconsulting
mapman's avatar
mapman
22,970 posts
 
I've seen or been able to feel (to the touch) unwanted low end woofer excursions in smaller bookshelf/monitor speaks I've owned in the past during record playback that on paper could not produce subsonic frequencies.

This tells me that the unwanted signal was not subsonic, yet still undesirable in terms of reproducing unwanted low frequency noise often associated with record playback that one would ideally prefer to not exist.

Despite having access to low in addition to subsonic filters available, my choice was most always to not apply low (high pass) filters that would also negatively impact the real music signal in that range of the audio spectrum.

Effective isolation, clamps, etc. are probably more effective ways of dealing with low end noise introduced during playback of warped records, etc. without impacting the music.
mapman's avatar
mapman
22,970 posts
 
If your record is warped or cut too poorly to deliver satisfactory sound, even with filters, clamps, etc., then you have two practical options:

1) get a better pressing of the record
2) buy the CD or digital equivalent if possible.

Unless the tt is not operating properly, that is seldom the cause IMHO.

Low end noise, audible or not, is one of the inherent banes of vinyl.

That's just the way it is.
acoustat6
357 posts
 
Bob#1 said, "I can say with some certainty that the woofer pumping is there on most LP's to one extent of the other."

I say, you are correct on your assesment.

Bob#1 said, "But my ears feel like they are popping on some, but not all, LP's."

Yep, no doubt some are worse than others and some have almost zero rumble, or less subsonic noise.

Bob#1 said, "If I turn the sub off on these I don't get that annoyance (my regular speakers probably drop down to about 30hZ).

Sure you are not reproducing it! But its still there!

Bob#2
acoustat6
357 posts
 
Mapman said, "I've seen or been able to feel (to the touch) unwanted low end woofer excursions in smaller bookshelf/monitor speaks I've owned in the past during record playback that on paper could not produce subsonic frequencies."

I say, yes, that's true but we are dealing with two different entities, though they may have the same mother. Subsonics is a different ball of wax from rumble.

Mapman said, "Despite having access to low in addition to subsonic filters available, my choice was most always to not apply low (high pass) filters that would also negatively impact the real music signal in that range of the audio spectrum.
Effective isolation, clamps, etc. are probably more effective ways of dealing with low end noise introduced during playback of warped records, etc. without impacting the music."

I say,I am so happy that that works for you, but it does not seem to be working for me or Bob#1. It seems to me that the more effective way is the two filters, for me. Without impacting the music.

Mapman said,"Low end noise, audible or not, is one of the inherent banes of vinyl.
That's just the way it is."

I say, why not put the filter in, if it is a problem. If you don't hear it, don't worry about it.

Bob#2
mapman's avatar
mapman
22,970 posts
 
"I say, why not put the filter in, if it is a problem. If you don't hear it, don't worry about it."

Agree. It's not illegal. If it works for the better for you, then you should do it.

BTW the other common negative effect I've seen with rumble and other types of low frequency noise, is that even if it is not audibly disturbing to someone , the fact is it uses up significant amplifier power to produce noise. This can result in the amp clipping and damaging the speaker. Ironically, the low frequency noise usually ends up damaging the tweeter first, at least in most cases that I have observed over the years.
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