I thought to be smart ...
I looked around whether I could buy such a thing (second hand) from someone in the neighbourhood, and couldn't find any. Ok ...
I hate it when I want something and can't get it right away, so I tought : why not create a 7.83Hz tone, and play it ...
Yeah, start laughing for the unexpected ending of this ...
So, generated the tone, put it in a nice "Schumann" folder, dragged in onto the playlist area and pressed play. At a really soft level of course, because one can't know what will happen when fooling with Mother Earth. Well, I didn't sense a thing, but walked to the woofer if I could feel it moving ...
... and immediately thought "fool, of course this won't work because the driver won't go as low as that". Yep.
That's me.
Next I thought, "no of course those drivers don't go as low as that, by maybe something comes from the subwoofers".
Felt those, and, nothing of course. Nope, they officially go to 12Hz with ports open, and I also have the ports closed.
But okay, the volume was still very low as well. So, maybe pump that up to more normal levels.
Nothing.
A "high" level maybe ? ...
Nothing.
Walked to the other sub as well to be sure, but no, nothing.
... But at standing there I very coincidentally saw the stif-ish flat wired cables to the mid-high section (which hang in free air for a meter or so), and saw them moving ! But it looked like from my walking there, or just a breeze in the room. But no, at standing completely still and not feeling any breeze or something, they just kept on moving. I even imagined that ~8 times per second. What the heck ...
Stopped the playback, and indeed, no movement anymore.
Set the timer to 10 seconds, clicked play and walked to the speaker, and ... yep, after 10 seconds the moving started.
Ahaaaa ...
Well, the level is fairly loud I guess (normal music would be kind of blasting, but still acceptable), and now it is the question : what should that level be ?
Oh, I just gabbed the dB (SPL) meter, and it nicely shows the frequency and 56dB SPL at 20cm distance (at 1 meter there's nothing visible).
Hahaha, oh ... oops ... I added 6dB, and indeed 6dB more shows. But while I still can't feel anything moving, the whole (over 100 Kg) speaker is moving now. Notice that the sub is not connecting to to the speaker, otherwise than via the concrete floor. Ok, so this is dangerous I guess, and the whole house must be shaking (it really can, and with some movie I had the outside earth (ground in the garden) really shaking). I now measure 56dB everywhere in the room, but over 60 in the back (standing waves).
Ok, I better stop it at this level.
What I don't quite understand is why I see the speaker moving (3mm back and forth on estimation), while I can't feel it. Am I moving myself on the same rythm maybe ? I'll admit it senses a bit strange, but sure not like that I'm shaking myself.
OUCH ... almost had a heart attack. I thought "let's look at that woofer again, because how can the speaker otherwise be moving back and forward" (the sub has its driver fireing downwards). So, I dove into the low-horn, and it *really* came to me as if something was trying to byte me. It was the woofer excursing sooo much that it it just came towards my face. And back of course. Brrrr ... that must be close to 7 cm back and forth (together). But it really shows a nice ~8 Hz frequency !
Ok, that woofer cabinet officially is straight to 27Hz, but that doesn't tell it can't do more. Btw, in another (newly designed) cabinet it goes straight to 18Hz (the BEST for a normal woofer cabinet !!). But pump in more juice and apparently it can even do more.
Ehh, don't try this at home ?
