Reducing transmission of bass waves from sub to downstairs

If the suggestions of paving slabs and other isolation components do not work see if you can get a set of (3) Stillpoints. I used these with my sub (a monster unit too!), in a previous house upstairs to superb effect.
If you don't have a level base then you will also need to get the Stillpoint Risers so you can adjust each isolation point.
Stillpoints will also reveal how muddy and slow your sub was performing before too

 

For smaller subs you can use the Auralex Mo-Pads ((£25). This is one of my Velodyne DD10's which is part of my hi-fi:

http://i5.photobucket.com/albums/y186/q-max/DSC00252.jpg

For the bigger subs (DD15 in this case) you need the Gramma platform:

http://i5.photobucket.com/albums/y186/q-max/DSCF0096.jpg

 

I had a similar problem whereby my spiked speakers sitting on a suspended floor transmitted into the cavity below and it acted like a big sound box. nb I initially after a house move I seemed to have the opposite problem of no bass, but more furniture and some repositioning of the speakers brought the bass back ... but unfortunately seemed to kick the floor into action.

Steve (7_V) kindly gave me 8 doorstops and 8 superballs (cheapo bouncy balls from Toys R Us) to stand them on. They wobble a bit but are actually very stable. Problem solved. Wouldn't cost much to try it out. Certainly seemed to isolate the speakers from floor adequately enough to stop the cavity acting like a giant soundbox. Could well imagine that it might do the same for your downstairs neighbours. You might even try the superballs under the slab rather than directly under the sub.

 

If you get some spoons (well just the spoon part on the end) and fix them to a bit of wood and place the superballs in these, it should help to hold them still. With vibration they can move a tad and always end up back in the middle. I saw a similar design for isolateing a turntable.

 

That's what the rubber doorstops (inverted) that Steve gave me do - apparently though he had to get "special" doorstops from belgium because british ones don't have a big enough hole in the middle

From what I saw of the Funk turntables I saw at Heathrow, this is pretty much exactly how they are isolated - though I'm sure they must be extra shiny audiophile standard superballs with added fairy dust Nice TTs though.

 

Inner tubes, bouncy balls and foam all provide a flexible layer between the floor and speakers, so I can understand how they might work. What is the principle of isolation used in stillpoints? I thought that they are rigid.

 

Isn't it basically a small point of contact so there is not much material for the vibration to go through. Large impedance mismatch?

 

If you have a sub woofer that is capable of playing the bottom octave, sadly it will be the airborne vibration that the downstairs neighbours can hear and all these things won't help one iota.

The most effective cure is likely to be to treat for the room resonance, thereby reducing the amount of bass build up in the room.

 

move yer stereo down stairs.

 

Yes, I believe that's one of the lines of thinking. It's just that it's not true that that works. If Stillpoints work then it must be some other way.

 

“impedance mismatch†(between different materials) I think is more hi-fi blurb than anything else Tenson. There may be something there at a theoretical level but I doubt this translates to any sort of useful effect in terms of effectively decoupling one body from another. The point of contact can also be infinitely small; this is of no consequence.

There are two tried and tested methods to reduce the passage of structure borne waves; absorption and soundproofing. Any material that presents a convoluted path to waves will work for absorption (open cell PU foam or Melamine, mineral wools, natural wools, hemp etc). For soundproofing, high density mineral loaded sheets (bitumen sheet or 'Sheetblok') will reduce the transmission of sound.

And yes it was the Alesis Monitor One (MKI) that I owned.

 

Stillpoints use a type of lossy bearing arrangement (if I understand correctly) to convert vibration to frictional heat losses.

 

Isn't that the 'Feet of Silence' or whatever they are called?

 

there are a few products available at the moment, the gramma is the most well known, also available are Sorbathane feet, many types available, also other isolation pads and foam type strips.

 

For info on the Stillpoints best thing to do is check out their own web site data:

http://www.stillpoints.us/1Pages/home.html

 

So in spite of the superficial resemblance to spikes as "mechanical diodes" in that the first contact is a ballpoint, the Stillpoints are claiming a sort of spring-type damping. Interesting. I'd like to see a plot of their passband, preferably with different weights on top.

 

I aint got the specs for it, but believe me when i say, it would not get close to bottom octaves, its only a lil sub with a 6" driver, so its mostly mid-bass, i'd be surprised if it got lower than about 45 hz.

Thanks for the suggestions so far, i havent read them all properly, as i've just got back home and am tired, but i'll read them all and come to a decision. At the moment though, it looks like i'll see how it goes, maybe experiment with the cheaper options, and if that dont work out, maybe try some monitors

 

I haven't read all through this thread but I did see the title question and the first page of the thread. Absolutely the Auralex Gramma. I actually use two under my main speakers. Direct transmition is cut way way down. Very effective. I also use them because of an uneven floor which make setting spikes a nightmare. With these platforms you get a flat, hard and non-slip surface, with effective damping underneath.

Now on price, yes they are expensive here. They are American. I bought mine from a New York music store using Ebay. Price was about £30 or £35 quid each, even after post and charges. Have a browse around. Some people even combine with a granite block but you don't really need to. By the way the Grammas are well made and look good.

 

That would be me, yes, I'm still around!

My suggestion would be to keep the AEGO's and attempt to cut the bass somehow, I installed some recently for a client and was suprised by the quality, both build and audio.

I sell the Edirol active monitors, but to compete with the AEGO's you would be looking at the MA15D and the bass the little things kick out is ridiculous, they would be just as bad as the current setup (each speaker has its own amp!)

I've heard very good reports about the Swans active speaker range, but you'd have to find some from America because they aren't sold over here.

http://www.swanspeaker.com/mul/index.asp

Alternatively, a T-amp and some less bassy speakers

Andrew