• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

40hz....subsonic or audible

Subharmonic oscillation can be a problem with some turntable systems.

The cartridge/tonearm will try to reproduce something like vibrations from people walking on the floor.

The woofer will slowly travel its entire stroke through the voice coil. It will bottom out, and then 'top out' .

It has the potential to be very destructive.
 
MadcapLaughs said:
Can I basically use the 40hz low filter as a subsonic filter without missing anything?
Click to expand...

It's important to understand that the lower you get in terms of bass frequency, the more that your ability to feel it becomes just as important as your ability to hear it. Being able to feel the bass contributes substantially to the overall listening experience, and makes it feel considerably more "real".

So no, you really can't cut off any of the lower frequencies with the idea that you won't be "missing anything". If there is content below those frequencies, you'll be missing it. Even if your speakers can't reproduce those frequencies, you're still "missing" it, just for a different reason...
 
As mfrench pointed out; this may not be a pure tone.

My L1290s can reproduce it. They're so rolled off at 20 Hz that the presence of this bass might not be felt from a music source.

It's more of a feeling than a sound.


The sound is more of a 'popping', just like vocal chords at low frequency.
 
Last edited:
vwestlife said:
I've heard that old-time radio preachers would say "Put your hand on your radio and FEEL the POWER of the LORD!" and then play a 25 Hz tone, which would cause the listener's radio to vibrate near-noiselessly. :angel:
Click to expand...

Some of those old floor stand radios have 15" drivers. I suppose it's possible.
 
62vauxhall said:
Just remembered that years ago (decades actually) some loudspeaker distributor's sales rep suggested the Genesis track Firth of Fifth to demo their speakers. I never heard that cut ever but somewhere there is supposed to be a 32hz organ pedal note.
Click to expand...

Taurus Bass pedals are featured on many '70's progressive rock albums. Genesis' Room of 32 Doors is another excellent example.
 
62vauxhall said:
I've used a 30hz test tone CD when refoaming speakers and I can hear that.

EDIT: Just remembered that years ago (decades actually) some loudspeaker distributor's sales rep suggested the Genesis track Firth of Fifth to demo their speakers. I never heard that cut ever but somewhere there is supposed to be a 32hz organ pedal note.
Click to expand...

Holy smokes...it starts at 6:50...it will shake the room. It's mixed with the kick drum.
 
Last edited:
BigElCat said:
As mfrench pointed out; this may not be a pure tone.

My L1290s can reproduce it. They're so rolled off at 20 Hz that the presence of this bass might not be felt from a music source.

It's more of a feeling than a sound.


The sound is more of a 'popping', just like vocal chords at low frequency.
Click to expand...

The image that I posted with the peaks starting from 3.75hz, @ 10hz, @ 16hz, @ 32hz,.......
That is from a pipe organ recording. From what I understand from an organist friend of mine, is that the 32hz peak is a fundamental from the big pipes (40'? easy 35' pipes). The 16hz peak is a harmonic from combining offset complimentary notes via the big pipes, that combine to form the harmonic.
The 6hz peak is what was described as a tremulant (sp?), which is an air flow controlling valve (for lack of better description by a non-musician; me), that controls the air flow into the windboxes of the pipes. The 6hz is what he described as that valve opening and closing at 6 beats per second. It is taking that massive 16hz and 32hz peaks and breaking it up into 6hz jackhammer strokes.

The "live feeling": Shirt pushed hard onto chest that was labored in heaving outward with breath, due to these jackhammering massive bass note. When the notes ended, the crowd simultaneously took an audible deep breath.
 
On the "Two Against Nature" CD by Steely Dan, there is some 1-3 Hz material present. I can see the woofer(s) moving in and out. So "rumble" isn't just for TT users!!
 
mfrench said:
The image that I posted with the peaks starting from 3.75hz, @ 10hz, @ 16hz, @ 32hz,.......
That is from a pipe organ recording. From what I understand from an organist friend of mine, is that the 32hz peak is a fundamental from the big pipes (40'? easy 35' pipes). The 16hz peak is a harmonic from combining offset complimentary notes via the big pipes, that combine to form the harmonic.
The 6hz peak is what was described as a tremulant (sp?), which is an air flow controlling valve (for lack of better description by a non-musician; me), that controls the air flow into the windboxes of the pipes. The 6hz is what he described as that valve opening and closing at 6 beats per second. It is taking that massive 16hz and 32hz peaks and breaking it up into 6hz jackhammer strokes.

The "live feeling": Shirt pushed hard onto chest that was labored in heaving outward with breath, due to these jackhammering massive bass note. When the notes ended, the crowd simultaneously took an audible deep breath.
Click to expand...

Cool !

Thanks for clarifying, I thought you had further analyzed the test tone. I'd go back and edit out my stupidity, but I if started doing that, I wouldn't have any content left. My posts are like an episode of Three's Company....Oooh....it's been a big misunderstanding all along.

I love the pipe organ. I used to listen to NPR shows of the major pipe organs around the world.

3.75...16...That's the one in London (joke)
 
Last edited:
mfrench said:
.....The "live feeling": Shirt pushed hard onto chest that was labored in heaving outward with breath, due to these jackhammering massive bass note. When the notes ended, the crowd simultaneously took an audible deep breath.
Click to expand...

Those of us who have been fortunate to experience a serious pipe organ in person have had that experience. In my case it was while visiting Notre Dame cathedral in Paris. A service began while my wife and I were in the nave so we sat down about 2/3 of the way back from the alter. The choir was positioned behind the alter and were unseen along with, as usual, the organist. Their voices, however, could clearly be located above the alter but were really reflecting off the ceiling far above us.

It took a bit to realize that while the organ playing was not loud in any way, the air around me seemed to become alive and took on a shimmering effect. I realized that the organist was using _very_ low notes that one could not hear in any way. My wife reported the same experience. This shimmering effect coupled with the massed voices that appears to come from the ceiling combined to provide a very real and distinct experience. If I was a 15th century poor farmer standing in that place and was told by my priest that this was a special place, I'd certainly have not missed the offering plate when it came around!

My wife tired of the service in French and left to climb up to see where the haunchback lived. For me, I couldn't get up off the pew - the effect was mesmerizing. Try as I might at home with all the bass I can muster, I have _never_ been able to recreate the effect I experienced in Paris.

It certainly made for a memorable trip.

Cheers,

David
 
Whether you hear a difference may depend more on the slope of the roll-off than the cut-off (3 db down) frequency. A steep slope may cause unwanted effects in the audible range. However, I think most rumble filters are first order. Anyone know?

However, 40hz is easily audible, but reproducing it well is easier with larger woofers, go figure.
 
Last edited:
You may not be able to hear 20Hz but you can feel it in the air provided your speakers can translate signal to SPL. IMO, feeling harmonics such as bass string and drum membrane are alternate sensory cues that immerse the listener with the ultimate goal of suspending belief that playback is through inanimate gear.
 
Back in the good old days of LP some companies like Deutche Gramophone among others, filtered their records, with little output below 45 hz, so turning on a 50 HZ rumble filter didn't take away from the recording. When I first got my Concert Grands using 275's in mono and a C-22 with a Thorens 121 and other tables it was easy to see the effect of the rumble filter of the C-22. At concert levels you could see the grill cloth flap from in audible rumble below 25 hz, during the lead in groove, exit grove, and between the different selections. Some records were worse than others, some the rumble was at higher frequencies, and some rumble was there to be seen and heard thru ought the recording. How much was the TT and how much was an individual LP I couldn't determine at the time, but when I got a spectrum analyzer it could all be easily seen. I will say bi-amping revealed more to the ear and the grill cloth . Procuring a TD-125, removed much of the issue. Later Mac preamps had a 30 hz filter in the phono section, that was a further aide. Today from what I can gather everyone is making their phono preamps flat over the 20 to 20,000 band and extending higher in some cases. All the issues with LP's, TT, and phono cartridges from the 70's and earlier were the reasons I gave away my first LP collection. I did keep 50 or so outstanding discs, that I played over the next 35 years.

Today after starting a second collection with higher standards the rumble issue is much less an issue. The phono stage I use now is full band, with out filters, but there is a high pass filter I installed in the system that rolls off everything below 25 hz at 18 db per octave. The records I choose are of better quality, and I refuse to buy classical LP recordings. They always disappoint. Even modern digital recordings disappoint more often than not to me. Normal LP levels easily 30 db below the max output of a classical recording leaves little dynamic capability left for a quiet noise floor with LP's. That said there are LP's produced by labels of the highest standards To be enjoyed. I hope new LP's are carrying on the standards set by a few labels 50 years ago.

The point is to install filters that match your speakers. If they are capable of 20 hz, no filter is really necessary, but if they aren't capable below 60, 50, 40, 35, 31, 25 hz filters should be installed to protect your speakers at those frequencies. . Then if you want to add a dedicated filter to remove the frequency modulation caused only by TT rumble, do that, too. Its surprising to me how some HT processors give you the option of selecting the perfect filter to protect your speakers and yet stereo pre-amps do not. I would think the rumble filter should be part of the phono stage to prevent contamination further on in the amplification process.
 
Last edited:
These low frequenses means just as much to open up the full picture as the highest frequenses does. Shoebox-speakers is English humor on it`s worst :whip:
 
You must log in or register to reply here.
Back
Top Bottom