Coupling vs. Decoupling for Bass Response


My work system is in the hay loft of a converted 100 year old horse barn. The floor is wide pine planks over wood beams and shakes with just the footsteps of someone walking across it. Needless to say it does not help my bass response. I have my LaScalas in this room, which are not exactly known for low bass in the first place. They have a rather large footprint (I believe around 2X3 feet). Any suggestions of some simple (re: inexpensive) ways to get back some of my bass that the floor is eating up? I'm currently using three cones under each speaker, but I'm thinking coupling may be counter-productive. I'm guessing that I should be looking at a means of decoupling. Thanks in advance for any suggestions.

Marco
jax2
A 1400 sq ft room (20 x 70?)will be tough to fill with bass regardless of the flooring. A well-matched sub-woofer might be in order.

Apart from the excellent suggestions above, you might want to stabilize the speakers themselves by placing some very heavy concrete pads on the floor and then use padding material (per Newbee) and/or spikes on top of that. At least you might be able to keep the cabinet itself from moving with the bass waves. Just a thought.
Hi Marco,

You are correct that the pointed spikes are coupling your speakers to the floor and their vibration is causing negative effects such as directing unwanted vibration towards the equipment rack, your listening location, possibly to neighbors, etc. Much of the speaker's energy is being used to set your flexible floor in motion rather than is producing music. Not only is your bass response being compromised but much of the musical range is being affected as well. This is the case for all suspended wood floors and is a significant issue for many audiophiles. It is also an issue for concrete floors but not quite to the same degree.

The best method to deal with your issue would probably be more expensive than you have in mind but there are a few inexpensive solutions that will be helpful. If you mass load the floor under the speakers much of the floor's flexing will be minimized. Some other areas of the floor may also benefit from mass loading. You mentioned that you are on a loft so floor jacks under the joists is probably not an option. You should also decouple the speakers from the floor and from any massive supports (the exception would be a high mass support that is also highly absorptive). There are high quality and inexpensive compliant feet available that will accomplish this. You can contact any of the major audio suppliers for a specific recommendation.

Best Regards,

Barry Kohan

Disclaimer: I am a manufacturer of vibration control products.
It's not the speakers, it's Diesel the dog that's pounding the floor with his big paws.

Put tennis balls on each of his four feet and see if that helps.

By the way, I'm jealous that your studio is so much bigger than mine.
P.S. Barry and I are on the same wave length. When I suggested the heavy concrete pads, I didn't specify that they were to only go under the speakers, but I hope it was clear through implication. I would not suggest 1400 sq ft of heavy concrete as that would surely collapse your flooring altogether ;-)
Sorry for not responding earlier, but I seriously suggest paying a visit to the audio asylum boards. There you will find a recipe for DIY platforms in numerous shapes, forms and sizes, but the predominant ingredient is PEF, aka closed cell polyethylene foam. It is quite a hard foam, the only way I can describe it is somewhere between a mattress and rubber :) however it does wonders. The rest of the platform depends on budget, availability, aesthetics etc. Probably the best design is a sandwhich which consists of the following:
- 1/8" aluminium (mainly for looks)
- 1" MDF
- 2-4" PE Foam
- 1" MDF
- 1/8" aluminium

You can play around with the rest of the sandwhich but the main thing to keep there is the foam. Then on top of the sandwhich place your speakers on their spikes.

Cheers,
X