This transmitted vibration suggests the speaker cones are
causing the speaker case to vibrate. This suggests poor
design of the speaker case (wasting energy that ought to
have been output through the speakers) but you may not wish
to rehouse the speakers -- just to reduce contact between
the cases and the floor. The cheapest way to do this is
to hang them on wires from the ceiling.
You could try some foam squares. It would help if you raise the
speakers on stands. Part of the sound transfer will be to the floor
in front of the speaker and raising it will reduce that. Don't expect
much improvement though. Is the room carpeted? The biggest
improvement will be from turning down the volume.
You actually want the speaker to be as rigid as possible for good
sound quality. If the speaker is free to vibrate it muddies the bass.
You either have to mount the speakers to heavy base (that you would have
to make yourself, likely out of concrete or stone) or suspend the
speakers from the ceiling so they have no contact with the floor at all.
I've seen custom-made speakers integrated into 100 pound blocks used as
the mounting base. The blocks were made from cement mixed with lead
I've never seen speakers suspended from the ceiling (so that they're
almost touching the floor) but if you want to isolate the speakers from
the floor - that's what you'd have to do. Use stainless-steel aircraft
cable for that modern look.
On 12/11/2010 9:30 AM, email@example.com wrote:
Or hit the dumpster behind the appliance store- those 2-inch slabs of
closed-cell foam (NOT the molded styro things) used to pack high-end
heavy electronics, make great vibration dampers. They are designed to
protect expensive stuff in the box, as the semi bounces over chuckholes.
Stack up a bunch of squares cut from those. I'm currently accumulating a
stack at work from an ongoing project, but haven't figured out how to
painlessly get them home yet. Great for carving equipment case liners
out of, and they don't rot away into black crud like the fancy foam kits do.
Not a bad start.
You could suspend them.
Or continue with your idea. A sandwich: Low density, high density,
low density, high density, low density...
The low density is what is stopping conductance of the bass. The high
density is what is holding it together. Lost of ways to go about that.
Low density could be air (use spacers or threaded rod/nuts), foam,
corrugated cardboard. High density could be plyood.
Even if you suspend the speakers from the ceiling, the low frequencies
coming from the speakers will still couple with the room acoustics and
your floor and walls will still probably vibrate almost as much as if
the speakers were in contact with the floor.
Does your speaker setup include a dedicated sub-woofer, or do you have
large, full-range speakers such that you don't need a sub-woofer?
I personally feel that any sound system with a sub-woofer is
sub-standard compared to having 2 or 4 large, full-range speakers. The
use of sub-woofers will almost certainly not accurately reproduce the
sonic content in recorded material - you will get an over-emphasis (to
the point of distortion) of the low frequency content.
Your goal may not be to obtain accurate sound reproduction, but instead
to impress your friends by having a sound system that rattles their
internal organs. I don't know.
You are a bright guy, but I don't know how much experience you have with
designing speakers and rooms.
The problem at hand is keeping bass from coupling into the concrete of
the apartment structure.
A speaker is a resonant box, whether it is sealed or ported. That
resonance is designed in to extend the bottom end. This is all
calculated. You make the box as stiff as possible, but there are
reasonable limits (there are sand filled double wall boxes, which is
really off the chart). As a result the box will vibrate, and you don't
want to conduct that into the floor or everyone in the apartment
building will hear that low end rumbling.
The sound coming from the speaker itself will be best contained by
having dense room walls, there is little that can be done for that now.
Some bass will couple into the floor regardless, but this is much weaker
Bass has limited directionality, the more so the lower you go. It's a
factor of the wavelength. That is why you can do dedicated sub woofers.
The sound origin does not have to be close as it does for higher
frequencies. Whether people crank up the sub too much is a different
matter. They do.
As far as speaker size, larger diameter speakers develop the sound
much further out. That is why large speakers in cars can be heard from
so far away, but are not that overbearing in the car. Somewhat related
to why bands can never get the bass player to turn down!
I've run live sound, built monster touring sound systems, worked as an
engineer in radio, designed high end car audio. Not the most
experienced, but I have a background... currently just a programmer and
out of the biz.
Are we talking about having the luxury of designing and building a room
specificially for A/V use, or are we talking about making do with
what-ever room we have?
Correct me if I'm wrong, but this thread did not seem to be about
"designing speakers and rooms", so I did not say anything on that topic.
Um, where exactly did the OP (Andy) say that? As far as I can see, he's
made only one post in this thread, and did not give details about the
I'm operating under the assumtion of a single-family dwelling, with
wood-stud / drywall construction.
Did I say anything to the contrary?
I said that attaching the speakers to a heavy, massive base would reduce
the speaker's ability to transfer low-frequencies into the floor, and I
said that suspending the speakers from the ceiling would do it as well.
Right in the first line of the OPs post. Apartment. My assumption is
concrete, because this is a common apartment construction and is a
common problem with that.
My girlfriend has lived in more than one of those, and I've beat on the
door (usually several apartments away) and dealt with this. Having a big
white guy pounding on your door at 1 AM leaves an impression, no matter
who you are!
There is probably not enough dampening there, isolation is preferable,
and practical. I still think 4 rolls of TP is the best and cheapest
I live in an apartment.
I could try mounting them from the ceiling and have them angled toward
the sweet spot.
I currently have an outdoor antenna mounted 4 inches from the ceiling.
It really doesn't look all that bad. :-)
You'll notice that our friend "Andy" disappeared after I pointed out an
obvious flaw in his thinking about this subject:
So - you don't actually know how much sound is actually getting through
to the apartment below. ?
This isin't based on a complaint, or any direct knowledge if your
current setup *needs* to be modified ?
: As far as speaker size, larger diameter speakers develop the sound
: much further out. That is why large speakers in cars can be heard from
: so far away, but are not that overbearing in the car.
Can you expand on this? Are you actually saying the sound is louder
farther away from the speaker than nearby? That violates the inverse-
propoertional law of acoustic perception, but I suspect I'm misreading you here
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