Are subsonic filters important?

The industry devised such things because the TT/speaker used to go into oscillation.
And even though the oscillation was inaudible, it was detrimental to sound quality.
The direct way to approach the problem is to create a filter, and run the risk of sucking the life out of the very thing you're playing through the system.
Or you create something that doesn't utilise filters, and create it by good design.

It's possible to design a speaker system that is mechanically well damped (ie. it doesn't rely on amplifier damping factor, and doesn't exhibit errant port resonance either).
My speakers were designed (cabinet and crossover) by a very good friend of mine, and built by another very good friend.

My designer friend, Scott (aka Scottmoose) has come up with some very effective designs.

 

Yeah I notice how small the room sounds when my stereo subs become instantly MONO.
I didn't go to all that trouble to live large with huge soundfield in stereo only to see it all go bye bye.
The minute I switched in the KAB and heard what it did I doubled down on figuring out how to NOT use the darn thing unless I had to.
Intense use of silicone cushions to completely isolate my table COMPLETELY---and silicone arm wrap PLUS silicone oil bath arm dampener from KAB---all problems VANISHED.
And so it goes.

 

Exactly. My feeling is that rumble filters are a kludge, a band-aide masking the real problem/cause: often isolation issues.

 

no kidding
I fail to see your point - what speakers the public owns is not a monolithic proposition and not everyone knows Scott
Every piece of equipment with a subsonic filter feature also had/has an "on/off" switch and different cut points as well on the better stuff
don't want it? don't use it
the topic is "are they important?"
I'd rather have an option than to not have an option (if it's a good one)
Subsonic filters that are worth anything are like the early CD players with the index feature - the feature(s) disappeared because it was cheaper to build machines without them and they discovered they could get away with it - not because there was anything wrong with the feature or the public didn't appreciate them
everything in the electronics business is price point driven - even the so called "high end"

I personally think the answer to the topic question is "yes" and I have thoughtfully outlined my reasons why
If you disagree then fine
I don't understand why everything has to be a campaign here?
You're not going to change my mind
It's all good
Michael

 

I don't have any problems with system isolation, rumble is in the grooves of some LPs. Many will be in denial about it but it's a fact.

 

The speakers are ported and are as susceptible to woofer pumping as any other, live in denial if you'd like but that's the fact, no way around it.

 

How about naming some of those LPs and I'll see if I have any. So far I found one with issues in my collection of 3500+. If I had rumble issues I would hear them. My bass response goes pretty deep and is highly resolving.

 

It's not called being in denial IF you eliminate the groove scrape/rumble at the source.
An inert arm setup WITH silicone dampening goes a LONG way toward minimizing how audible groove scrape and rumble can get.
By installing "shock absorbers" (silicone tray from KAB) and killing vibrational energy at the source (silicone pads/plinth/more silicone pads) you might be surprised how your set clears up---on a system that plays flat to low 20s!
The incredible stiffness of my Denon DL103r cartridges' cantilever suspension may also be a big help in this department---especially how quiet the grooves are.
Honestly if you heard the lead in total black silence you might think my records were all digital!
And that's no river in Egypt.

 

You don't know how a mass loaded transmission line works, do you?

 

So that arm damping magically eliminates the groove modulations. It's funny, the same guy who designed your amazing arm damper apparently doesn't know what he's talking about when it comes to causes of LP rumble.

I know enough to know that nothing about them excludes them from the potential of woofer pumping.

 

One off the top of my head is the reissue of Jame's Taylor's Greatest Hits Volume 1. Woofers begin to pump on the lead-in grooves.

The thing about subsonic noise is it's not audible, hence the term subsonic.

 

He does know what he is talking about. But damping isn´t something he invented, it has been well known for a long time.

 

I thought I would get like three answers to my question. It’s on page five. I love this forum.

 

I have a pair of floorstanders, each with two woofers, and a pair of REL subs, each with active and passive radiators. There's no woofer pumping, ever. I never see unexpected excursion, and using a subsonic filter makes the system sound worse. So even if there is undetectable (by me) subsonic noise, and I don't hear it, and my woofers don't pump, and I never notice unexpected excursions of the eight LF drivers in my system, then it's really rather all very moot, isn't it?

 

If you say so.

 

As a matter of fact, yes, I do. Music playback in my house is just plain awesome and trouble free.

 

I tend to agree with your assessment that woofer "pumping" is a function of subsonic noise present on certain analog recordings and not necessarily any inherent system fault.

Since only very few of my records present with this "issue", I know that it is not system related and is related to the subsonic noise on certain records.

Though, I do acknowledge, that it may be an issue that is system related, on certain systems.

I have, curiously enough, never had any "feedback" issues with any of the turntables that I have had set up on my system, even though I have a 1,600-Watt commercial harn loaded passive subwoofer in the system. It has never given me any problems with feedback at all and I don't do anything special to isolate the turntables.

I do note, that his is in South Florida, where we have tile over concrete floors. In other environments, mechanical vibration can certainly be a problem.

 

I have never seen woofer pumping inherent to any records. I have worked hard on my TT isolation using tonearm bearing damping and a combination of room acoustic treatments, a Symposium Foundation rack, BDR "The Source" platform, and BDR carbon cones under the TT platform. The only time I see woofer pumping is on very badly warped records. I would only use a subsonic filter as a last resort or if you're dogmatic about not addressing the underlying problem.

 

I see rumble in my subwoofer flaps! Subsonic filter = long life speakers and no neighbors banging angry at your door.

I replaced the Sumiko Pearl elliptical stylus
(compliance 12, VTF 1.5-2.0 g, the resonant frequency of the tonearm/cartridge pairing: ~11.86 hz)
with the JICO SAS-1 boron stylus
(compliance 20, VTF 1.00-1.5 g, the resonant frequency of the tonearm/cartridge pairing: ~9.35 hz)
I felt something changed in sound. The tonearm/cartridge resonance is found in the subsonic range and will exaggerate the effects of record warps, or rumble produced by the turntable/record.

The high-compliance cartridges need to mate with very low effective mass tonearms. To prevent the tonearm from shaking and the stylus to jump in the groove I decided to lower the tonearm effective mass. The fix was to increase the weight of the tonearm rear-mounted counterweight eg. by wrapping it with insulating tape. A heavier counterweight means lower tonearm effective mass and the resonant frequency of the tonearm/cartridge pairing move to a higher value. People say the best resonant frequency of the tonearm/cartridge pairing is at 10-11 Hz around. I don't know why, maybe is some kind of woo-doo science.

When pure sine waves are reproduced under ideal conditions and at very high volume, a human listener will be able to identify tones as low as 12 Hz. Below 10 Hz it is possible to perceive the single cycles of the sound, along with a sensation of pressure at the eardrums.

 

To the OP @CBackley , for what it's worth the last time I looked at graphs of needledrops from my MoFi StudioPhono I remember the cut-off for the subsonic filter was pretty low, so it's certainly not a heavy handed filter. I can't contribute too much here as I can't seem to find where I put those graphs, but I do remember the cut-off being decently below 20Hz, which is where a lot of non-deflatable filters cut off. Personally I do see woofer pumping on my speakers with crappy modern pressings (sadly many bad pressings will still exhibit this, despite having my resonance in the 8-9Hz zone) and don't hear much sonic detriment, so it's usually engaged. Of course the good thing is it's easy to toggle on and off.

 

Looking at the spec of the KAB, it clearly has a crossfeed circuit of some sort that kicks in at 140Hz (just like the devinyliser I mentioned in an earlier post), and a third order filter that kicks in at 20Hz (again my earlier post).

But at the price, it is a real bargain.

 

I have the same preamp. I too can’t hear any difference, which I take to be a good thing. I leave mine on.

 

The KAB site is a PITA for finding things - navigation is a nightmare. There seems to be a view that they do a silicone arm damper - can anyone supply a link to where that is on KAB's site?

Scratch that - you find things on the KAB site by googling. It seems to be specific to Technics arms, and is the same principle that used to be supplied for certain SME arms. It even uses the same viscosity fluid (60,000cst).

 

If it hasn't been mentioned yet try spiking your sub or speakers. In my case I had feedback-rumble issues with my 18'' sub that spiking fixed.

 

I was referring to Kevin's assertion that subsonic noise is often in the recording, and that even the very best turntables won't mitigate it. In other words, an arm damper is not a total solution.