Are subsonic filters important?

They don't wobble about like jellies

 

+1 - that's the way to do it

 

Look folks, subsonic noise is often cut into the grooves of LPs. It's a fact I've verified many times. So unless you want to examine your cones and document whether they pump for each LP you own, it's easier to run a rumble filter at all times. And few speakers are impervious to the detrimental effects of rumble/subsonic noise, even though some designs are far less susceptible.

 

My design is impervious.
No cone "flapping".
It CAN be done...

 

How did you verify the subsonic artifacts were not being produced by the turntable?

 

It is even present on some CD's that have only ever known the digital domain. My take on it is that is studio air conditioning causing flutter at a few Hz, but would welcome other theories or hard knowlege.

 

Graham LS5/8s can be really alarming to watch when playing vinyl.
That degree of movement must be generating back EMF.

 

It doesn't occur on very many LPs and I listen to a wide variety of music.

 

I don't know about CDs but LP-cutting lathes and the locations where they reside are imperfect.

 

people will debate/argue just about anything
sub sonic filters are good things
you will know it when you need it
right now I am crammed into a very small room so anytime I go anywhere near loud it's engaged
be glad you have it - a lot of "modern" equipment doesn't even have it
for me it's a set it and forget it proposition - better safe than sorry
not like dolby - it doesn't hurt anything - protects more than your speakers
Michael

 

I suspect a QC issue rather than a result of subsonics being cut into the master.

 

Only if you consider your speakers and nothing else in the reproduction chain.

 

Please elucidate further

 

So every master cut is perfect, there are no lathes located in places susceptible to outside influence?

 

Sure, if your Harbeths have driver cone suspensions so stiff that they make the excursion impossible, or they're impervious because they're high-passed upstream.

 

Any pumping will be much less visible in your speakers because each has three bass drivers, therefore much less excursion is required for a given SPL. However, your woofers are unloaded below the port-tuning frequency, unless the designer came up with some unheard of workaround, for which the engineering community would be forever grateful.

You might not see your driver cones flopping around like jelly even though they are compared to their normal operation.

 

I do notice a difference but still keep mine on.

A lot of people say that there isn't much, if any musical content below 30Hz, but I hear it with my modest system. With my system, even if I set a high-pass filter at 18Hz with the sub-sonic filter engaged, it affects the phase and timbre of the bass frequencies. My hearing is also pretty damn good at low frequencies.

 

OP here. It appears the answer to my initial question is Yes, No, Maybe, It Depends, and Who Knows But Hey Why Not?

 

Not likely, especially not subsonic artifacts. Far more likely irregularities in the pressing itself to be the cause of what you're observing.

 

Don't need to peel off the covers to see my Harbeths.
They don't respond to much below 35hZ anyway.
My Velodynes are NOT sealed box.
I can easily remove their covers and watch for errant excursions.
As I noted these go flat down to low 20s.
Yet-----No cone flap.
Zero.
You guys with cone flap are set up wrong.
Or using speakers that can't be run using vinyl because they "flap."
The entire reason I use a multi-speaker driver array is to have total control over what comes out of the boxes at WHAT frequency.
The Harbeths are allowed to run "full range" but all the other boxes are shaped for crossover/phase/time coherence/dispersion pattern.
Like a big Wilson setup each "box" is doing exactly what it does best---and no MORE.
So excess cone excursion is a non event.
Not my problem.
But to each his own.

 

I vote for "it depends."
By a nose.

 

It doesn't matter that they don't produce much below 35Hz (more like 40Hz really). They are still susceptible to inaudible cone flap because they're a vented design and the port resonance freq is well above subsonic noise. There is nothing about the design of your Harbeths that would exclude them from this phenomenon, nothing. Subsonic noise can be of a much higher amplitude relative to the music, and the drivers will respond with high excursion if unloaded at that frequency. Given that your Harbeths are capable of any bass below 60Hz with a single 8" driver, there is no way their suspension is a limiting factor, therefore, they're susceptible to pumping about as much as any ported speaker.

I get it though, it's an inconvenient truth.

 

I suspect the likelihood of poor cutting setups and poor pressing quality are probably about equal. I've lost much confidence in the competence of the average "professional" in various industries. We have planes plummeting to the Earth because aircraft engineers have begun to neglect the most fundamental of design principles. So it's not hard to fathom the failing of proper lathe setup.

 

How do you explain that my 15" Velodynes don't flap?
If no junk is down there---it ain't gonna make the cones move is all I'm sayin.
Hey---Are you the guy that invented the internet?

 

My speakers are dual concentic.
Each driver assembly has a mid/bass with a tweeter in the middle.

The other speakers you mention do not have three bass drivers.
They are two way speakers.