Late last year I posted a question ,on isolating my sub to prevent
annoying the neighbours.

Well I finally got a round to testing today.

With a Platform of 2 * 18mm layers of MFD with thin silicon rubber
interlayer glued with PVA and with sorbothane feet.
I got a reading of 70 db on my rat shack meter in the downstairs flat
from a 100 db in the listening room I was playing the trance dance
scene from the matrix revisited

Then added another layer: of duck rubber non slip router-matt/
drawlinner matting and another 18mil mdf sheet : that got it down
another 6ish or so db's .
Then I put partly inflated innertubes on the platform and another MDF
sheet between them and the sub (to stop the spikes rupturing the
tubes).
Got it down to barely flicking the needle downstairs (just 50db's) it
was barely audible and that was with a spl of 110db's in the listening
room.

I would like to thank all those who provided advice made suggestions.
and to those who said I was wasting my time - yhar-sucks-boo :¬)

Chris

chris wrote:

Late last year I posted a question ,on isolating my sub to prevent
annoying the neighbours.

Well I finally got a round to testing today.

With a Platform of 2 * 18mm layers of MFD with thin silicon rubber
interlayer glued with PVA and with sorbothane feet.
I got a reading of 70 db on my rat shack meter in the downstairs flat
from a 100 db in the listening room I was playing the trance dance
scene from the matrix revisited

Then added another layer: of duck rubber non slip router-matt/
drawlinner matting and another 18mil mdf sheet : that got it down
another 6ish or so db's .
Then I put partly inflated innertubes on the platform and another MDF
sheet between them and the sub (to stop the spikes rupturing the
tubes).

This just a sandwich of innertubes and MDF?


Got it down to barely flicking the needle downstairs (just 50db's) it
was barely audible and that was with a spl of 110db's in the listening
room.

Impressive result. Extremely impressive result.

You're sure of what you measured?
It shows a 60dB attenuation due to the interruption of *transmitted* energy
from the sub cabinet to the floor, the *air* transmitted component being a
scant 50dB remaining?

_-_-bear



I would like to thank all those who provided advice made suggestions.
and to those who said I was wasting my time - yhar-sucks-boo :¬)

Chris

--
_-_- BEAR Labs
- Custom Audio Equipment, Cables, Mods, Repairs -
http://www.bearlabs.com

"BEAR" wrote in message
news:LOiOb.88245$xy6.159691@attbi_s02...

This just a sandwich of innertubes and MDF?

Yep plus Sorbothane feet below the 2 layes of MDF bit more MFD and
rubber and innertubes and another layer of MFD allthough i should add
the MDF was treated with "noise killer" i dont know how much this
effected the whole sandwich ? just did it,- just in case.

Impressive result. Extremely impressive result.
I too was VERY supprised, my orignal thoughts were "here goes, not a
lot"-hope it works a bit, I never thought it would be "that" good, the
neighbour was also happy.

You're sure of what you measured?
yes a total attentuation of 60db from one flat to another.
my conversations with the neighbour in his flat was registering
between 54 and +66 db so i know the meter was working on its 60db
setting.
After measuring downstairs I went back upstairs to double check the
volume it was still at 110db.

the *air* transmitted component being a scant 50dB remaining?
Im not totaly sure what you mean by this ? but I will make a guess:-
As I have no absolute referance points I can't say how much of the
propergated sound was via the air. I guess it would be a bit difficult
to find out? But its got to in that ball park somewhere, i dont think
the platform gives 100% insulation.

All i have to do now is figure a way of keeping the sub from falling
off a not very stable platform. oh well, there has to be a
soultion -somewhere.

But as a happy neighbour was the project's primary objective, and I
dont really want to run another set of experiments which serve no
purpose to him, except annoyance.

I dont intend to run (normally) with an spl over about 95-ish db
anyway.
otherwise it looks like could be destined to become a totaly deaf
b'stard .

I just really posted the results to let everyone know what is
possible, especially for the other apartment dwellers out there, to be
able copy /replicate, keeping other neighbours happy.

Just wish the bloke above me would do the same .

All i have to do now is figure a way of keeping the sub from falling
off a not very stable platform. oh well, there has to be a
soultion -somewhere.

This is what I don't like about using innertubes.

"S888Wheel" wrote in message
...
All i have to do now is figure a way of keeping the sub from falling
off a not very stable platform. oh well, there has to be a
soultion -somewhere.

This is what I don't like about using innertubes.

I'd run an experiment where I removed the innertube....perhaps substitute a
square of medium pile carpet in between. My guess is that the sorborthane
feet plus the layers of mdf are doing most of the real work. Sorborthane
works wonders in absorbing really low frequencies and cleans up lots of
gear...turntables and cd players as well.

"S888Wheel" wrote in message
news:6k1Pb.103410$xy6.214317@attbi_s02...
I'd run an experiment where I removed the innertube....perhaps
substitute a
square of medium pile carpet in between. My guess is that the
sorborthane
feet plus the layers of mdf are doing most of the real work.
Sorborthane
works wonders in absorbing really low frequencies and cleans up
lots of
gear...turntables and cd players as well.


Nothing wrong with experimenting but I think you would be wrong.
I'll bet the
innertube is doing the lion's share of the isolation. Next time I
run a large
batch of near zero shore hardness silicone I'm going to e-mail Chris
and offer
him some. It will do what the innertube does and it will be much
more stable.


Thanks Wheel , I would apperciate that a great deal !
I would be interesting to see how good it is compared to the inner
tube (stability aside).