Phono-pre: subsonic filter on or off ?

They vary widely in effect in my experence. If I didn't have a problem I would leave it off,I do: if the woofers flap wildly then use it. It does have an effect on the bass but if you need it you need it. One of my phono stages has both RIAA and IEC {?] curves; the latter rolls off the bass more. See which works better on your system, off or on, and go with that.

In addition to Viridian I'd turn it on when I play warped records.

Off if possible, but on if needed.

Whichever sounds better in your rig on particular recordings.

If you leave it off and it is needed, your amps power gets used up producing low frequency noise leaving little for the music,which can be a precarious situation in regards to sound quality at best and potential damage to speakers at worst.

If you find it to be a significant problem on a consistent basis, you can eliminate or at least reduce the problem by tweaking the phono rig configuration (cart and tonearm matching) to change the resonance frequency, but that is a more significant undertaking that requires some expertise up front.

Better physical isolation of the table from the sonic energy transmitted from the speakers via the air and floor can also help. For example, if the turntable is sitting high up on a less rigid platform, like the top of a cabinet in a room that is on an upper level of a dwelling rather than sitting on the solid concrete foundation, move it lower to the floor on a rigid, solid platform and away from the direct line of fire of the speakers.

It also depends on what frequency the cut off is omplemented. If at 70Hz, then you are definitely losing something with it on. In which case I would leave it off unless your woofers are pumping hard from rumble.

If it cuts off at 30Hz or below then it may not make much difference leaving it on all the time

Ptm,
I've never seen rumble filter adjustable. It's mostly oriented on sub-sonic frequencies of a large amplitude. Hence the alternate name is SUBSONIC filter.
SUB-SONIC means UNDER-AUDIABLE.

Actually, subsonic means 'under the speed of sound'. The proper term is Infrasonic. We don't say sub-red for infra red do we?

Also, Carver produced an infrasonic filter that automatically adjusted its cutoff properties to the low frequency content of the recording and the turntable's inherent rumble or lack of.
Salut, Bob P.

INFRA -- SUB
ULTRA -- SUPER

are synonims
as well as SUBSONIC or INFRASONIC.
Technically you can say SUB RED but it's not common.

Not only Carver produced the infrasonic dynamic filter. I've seen that in works of many different electronics designers adn Carver probably not the first implementing this circuit.

Marakanetz, Infra and Sub are NOT synonymous. neither are Ultra and Super.

Ever heard of super violet? SUB-Sonic has always been used for the speed of an object being lower than the speed of sound and never for UNDER-AUDIABLE, whatever that is. If you meant audio or audible, then that is not synonymous with sonic either. Sonic has to do with sound, not audibility.

Infra and ultra have always been associated with frequency, low and high, of vibration, sound and light, among others.

Perhaps this is a second language thing.

respectfully, Bob p.

Bob,

"Sub" prefix denotes "under" or "below" when attached to a word. "Sonic" means having to do with, or using, sound waves. So "subsonic" can describe something that is below sound waves, meaning you cannot hear it. Granted, "sonic" is also an adjective used to describe something that has to do with the rate at which sound travels under another meaning, and "subsonic" generally means under the speed of sound. However, before we let semantics get too much in the way, let's use common sense, shall we? Do you really think subsonic filters are designed to cut off the frequencies that travel below the speed of sound rather than frequencies that cannot be heard by the human ear but produce inaudible rumble? C'mon, you can't be serious! I don't know how fast sound waves of 20 Hz or less travel, but I do know it is generally accepted that 20 Hz is the lower limit of the human hearing. Rumble filters such as KAB are designed to suppress sound waves of frequencies under 20 Hz, meaning they suppress sound waves that cannot be heard by the human ear, but are still reproduced by the amp and the speaker and cause the woofer pumping. Not the dictionary, but the common sense in the design goal dictates it.

I had a KAB rumble filter that I could switch in and out. Woofer movement was a problem with my HW-19 an assortment of tube gear and TT positioned well away on a wall rack. I was even surprised when I had the TT sitting solidly on a brick hearth. I tried springs vs sorbothane, vs Navcom with absolutely no change. Tonearm change from Linn Basik to Audioquest PT-9 again, no change. Speakers changed from Snell Ellls to Salks TL-2s. No change. Well the KAB fixed that in a heartbeat. Never could I hear a speck of difference. I am now using a TNT Mk-3 without the filter as it doesn't need it but I would slap it back in the tape loop if those woofers started flopping around

It's clear that music is a complexed signal that has over and under tones.
Rumble or subsonic waves of a large amplitude are not safe for the listener and can cause heart problem if not collapsing and should be voided.
I've always thought that it's part of RIAA standards to have subsonic filters as a matter of fact since becides EMI causing rumble there are record or pressing imperfections that also can take part especially if played at the high volumes.

Actusreus, you are missing my point. It is Marakanetz who is saying to use the term Subsonic (or at least that it is synonymous to Infrasonic) for the Rumble filter. I am saying that the proper term is Infrasonic. Note that KAB avoids either term in all its literature.

You know what Will Rogers said about 'common sense', don't you? Or was that Mark Twain?
salut, Bob P.

Sorry Bob, but I think you're missing the point as you're getting too hung up on semantics rather than the design purpose. The point is that subsonic filters are designed to suppress low frequencies that are not audible to the human ear, and are not concerned with the speed of the sound waves, despite the arguably semantically incorrect nomenclature. So if you want to be the Thesaurus police (and as I explained in my previous post, an argument can be made you're wrong about that too), go ahead, but the Marakenetz's point is correct.
Btw, KAB does use the word "subsonic" when describing the filter. I took a quick look and saw the reference at least thrice on their website.

http://www.kabusa.com/rf1.htm

And who the hell is Will Rogers?

Actusreus, I guess its the engineer in me that prefers to use the correct terms to express ideas or concepts, notwithstanding KAB's incorrect use of the term SubSonic. KAB is probably using that term because they know that the 'layman' would not understand their descriptions if they did use the correct term - infrasonic.

With respect, Bob P.

Bob,
You're probably right. I did notice, however, that the use of the term "subsonic" is actually quite pervasive in audio nomenclature when discussing rumble-related issues (I did a search on the internet for "subsonic filter"). It often seems to be used interchangeably with "infrasonic," which I agree is a more correct term. I wonder if the use originated together with the term "sub"/"subwoofer" and then caught on.

2 beats per minute is the rough estimate of the heart beat.
4 beats per minute is 2x the heart beat that is blood circulating in/out...
anything that is the closest magnitude of that is dangerous if reaches certain SPL magnitude levels and considered to be a weapon.
4hz, 6hz, 8... 12 could resonance with heartbeat.
INSANE???
ANYONE WANTS TO AUDITION THIS MUSIC AND EXPERIENCE???
RAISE YOUR INSANE HAND...

03-26-11: Marakanetz
"ANYONE WANTS TO AUDITION THIS MUSIC AND EXPERIENCE???
RAISE YOUR INSANE HAND..."

Is this before or after the "brown note" makes you s..t your pants?
Really, I've got to stop reading this crap. How can you write this bs and expect people to believe anything else you write.

Bob

mmm sorry per second

Check that out...
http://www.cabinetmagazine.org/issues/5/acousticsofwar.php

Marakanetz, and the normal heartbeat is closer to 1 beat per second ( mine is about 51 beats per minute, when I don't get upset over utter nonesense such as this).
Although the literature does show that there are health issues associated with continuous exposure to ultra low frequency vibrations, including sound, there is nothing that indicates that there is any immediate effect on the heart. It can make one nauseous, however. Believe me, I have taken many vibration readings on industrial machinery where I was surrounded by loud low frequency vibrations and sound, it wasn't pleasant, but I never suffered any heart problems.
Salut, Bob p.

Marakanaetz, I read that article and find nothing nothing in it that proves your contention that low frequency sound causes the heart to burst from 'sympathetic' beating with the low frequency and therefore bursting. That some people are susceptible to low frequency sound and become nauseated is well known, however.

Also, note that the low frequency sound is referred to as INFRA sound and never is the term SUBsonic used to describe low frequency sound below normal hearing capability.

Respectfully, Bob P.

03-26-11: Marakanetz
Check that out...

And you think your puny system is capable of this? Even if this is true....which sounds like the crap that you are espousing (2. To give one's loyalty or support to (a cause, for example); adopt.) Why didnt millions die in the Japan earthquake?

--------------------------------------------------------------------------------

I use the sub filter on my Cambridge 640P because it works really well by blocking speaker pumping with no difference I can hear...tried an experiment: I put my cat in front of a speaker and switched the filter off to see if it would kill him...he survived...damn.

51 beats per minute! What?!?! You a marathoner, Bob? ;-)

Does this mean I'm rolling off some bass and perhaps not getting the full bass slam I should ?

Maybe. However, you may also not be getting the full bass slam without using the filter. Many times there are sonic benefits to not feeding frequencies to an amp that it does not need to reproduce. In this case there is more of the power supply output available to reproducing the thwack of a kick drum rather than the rumble from the table. Only you and your ears can tell us which works better for your speakers.

I use both active and passive filtering when I find it beneficial. I have two, 18" drivers in my bass horns that handle from ~100Hz and down. I do not use a rumble filter with my horns because they roll off very quickly below 25Hz or so. I also have a pair of Aerial 10t's that get down about the same. These speakers are ported in order to get down there. As you can imagine they pump a bit when I move them into the system. If these were my main speakers I would most likely use such a filter, but it would be of a much higher quality than the KAB filter mentioned on this thread. Nothing wrong with the KAB, but it can be bettered.

No Dan_ed, I am not a marathoner, but, ironically, my breathing training for playing brass instruments (french horn and trumpet) has helped me in lowering my heart beat rate.

Salut, Bob P.