HELP! Resonating Floor Horror at 40-50Hz

[brutze]

Hi

I have a 6m x 7m main room now for my project studio. Its a cellar.
I have 36 100mm readytrap bags with 55Kgm3 Rockwool: Corners, Ceiling, walls. They are top-notch. I'll post piccies soon.
I have no problems with neighbours. I'm isolated...although there IS a room below me but the neighbours there are a shop storage room, and they don't care. I don't have any other neighbours to the sides or above.

I have Genelec 8050As on Sandfilled MDF stands, on spikes, on concrete blocks. Wonderful Instruments, Mics, Preamps, Cables, Converter, DAW, FX and Plugs

My life was wonderful.Everything was set.
But I noticed rather late that with some deep notes I was getting some bad Nodes still, even with sooo much trapping.

This came to a head recording some heavy drumming in there the last days. Some of the mics were picking this up and when compressed it sounds horrendous.

Testing with a sine generator I found multiple nodes down around 40-55Hz. I found that they all dissappear in four spots just out from the room corners.
Its clearly caused by the floor resonating almost like a trampoline
.
So HELP! What can I do?

It is not a question of isolation for me...But I just can't mix or record any Bass with any degree of trust.
Do I have to move? Otherwise it's a great space. (ceiling IS a bit too low at 2.5 Meters
God knows what the hellfloor is doing at other frequencies. I can now notice this resonation with deep male voices in there too.

So
Floating Floor?
Are there any cheap fixes?
I'll do anything to solve this one.

Thanks as ever in advance

Brutze

[Kiwiburger]

Put down a layer of closed cell rubber (tramping bedrolls are cheap and effective) and then put down a wooden floor that suits your budget. (3/4" construction ply, or MDF or something nicer.

It's a small room - it's always going to have problems. The resonating floor will actually be sucking energy at it's resonant frequency, and functionling like a bass trap. The foam should dampen the Q of this effect.

But largely I think this is a room node problem based on the dimensions of the room.

Bass trapping is more effective away from the walls (1/4 wavelength). That's not always conventient, but maybe you could build this into some furniture that needs to be in the middle of the room. Your chair, or speaker stands etc.

I think large foam cubes, covered in vinyl, are a very useful piece of furniture. Sit on them, change guitar strings on them, stack them for gobos, rest a mic on them - and they absorb bass too.

[thethrillfactor]

Originally Posted by brutze

So
Floating Floor?
Are there any cheap fixes?
I'll do anything to solve this one.

Thanks as ever in advance

Brutze

Decouple the drums and mic stands.

Build a couple of solid risers and place the drums, bass cabinets and guitar amps on it.

[garysjo]

I'm curious as to the floor construction?? I don't think floating is an option for you given your already low ceiling height. If it truly is the floor resonating vs. mode issues, you may be better off just applying more mass, i.e. another layer of plywood to the floor (or two) which will lower the resonant frequency of the floor, and not cost you too much ceiling height. To get a floating floor with a resonant freq. out of the audible range will be very expensive and complex to design. And, you would lose valuable ceiling height. Stiffening the floor should lower the resonant frequency, although I am not an acoustician, so I do not know by how much. You also need to know the construction of the floor to assess how much additional load the floor system can take.

[brutze]

Thanks Guys, some good answers.
I'm still in the shock of discovery phase. I needed to get a fast feeling that IU could make somekinda comprimise solution. I mean, the space is not a really professional facility. I have other comprimises.

I really don't know if it's a Mode problem though. If I jump up and down on the floor I can feel the vibration at those frequencies. It seems like the floor is a bit like a trampoline.

As I said I have 36 ! Bass Traps in the Room. All 100mm off the wall/ceiling. Each one is 100mm x 600 x 2400. 50kgm3. Should that be enough to cover the modes in the room? Do I have to resort to Megachunks?

As for putting 1/4 wavelength away from the wall. At 40hz isn't that likely to be outside the room? Or at least be right in the middle (actually that I COULD do).

I could probably fit another sofa in. But I think the Megachunks would be better?

My brother in Law to be is an Architect, My brother is a civil engineer, I'll be asking them for tips on the structure. RE:Floor "stiffening"/load.

Keep those ideas flying.

[garysjo]

Originally Posted by brutze

If I jump up and down on the floor I can feel the vibration at those frequencies. It seems like the floor is a bit like a trampoline.

RE:Floor "stiffening"/load.

Keep those ideas flying.

Your floor is like a large bass drum, ringing at it's resonant frequency. Increasing the mass and therefore stiffness will drop the resonant frequency. Consider using high density MDF (the stuff they use to make countertops) It's very dense. Use damping glue between layers. Some advocate Green Glue, although I'm not real familiar with this product. There are other products used in the marine industry that have high damping qualities. Of course I suggest all this not knowing what your current finish floor is?

[nucelar]

Hi brutze,

I know how frustating this can be. There have been excellent answers here but also some inaccuracies. In order to lower the floor resonant frequency you must either increase the mass of the floor or DECREASE its stiffness. Stiffer things resonate at HIGHER frequencies.
As the first replyer suggests, I would do a combination of adding mass and dampening in form of a floating floor.
You can do a quick test: place a couple of sand sacks (or equivalent), maybe 200-300 kg in the middle of the room and reproduce your test tones. If the problematic frequency gets lower, then the floor is the culprit. If not, then i'ts probably caused by room modes, despite the bass traps.
Cheers

[Sui_City]

I have to say that it would be worth your while reading John L Sayers site and http://forum.studiotips.com before you try and float anything.

And get Rod Gervais's book called "Build it like the pros"

Rod is vehemently against building floating floors as you can cause yourself more harm than good.

Take your time sorting this out, if you don't, you'll waste money.

[TEMAS]

I have exactly the same problem here at my recently finished project studio. Read my thread about building a drum platform here: Building a Drum Platform I have not built it yet because I'm not sure whether to actually take the floor up and get the problem fixed.

I have the ground floor apartment in a large Victorian brick house. Beneath my floor is a cavity about 2 feet deep before reaching the ground/earth. When I took up the original floorboards, I discovered that the joists are suspended on evenly spaced brick 'pillars' which stick up out of the ground, not by walls. So, I placed anti-vibration rubber pads on the joists and built a new floor consisting of 1 layer plywood, 2 layers plasterboard, then the original floorboards. But when I walk across the floor it sounds like I'm walking on the worlds biggest bass drum and like the original posted commented, I can feel the vibrations as I walk across, like a trampoline.

[biggator6]

Take this question over to John L Sayers forum - they can definitely help you. (The aforementioned Rod Gervais hangs out over there)

Owens-Corning is making a product now for this very purpose, it's a thin material that goes between layers of flooring to reduce resonance - it's probably expensive, but effective.

"-)

[brutze]

Thanks everyone,

These audio forums never disappoint me. So, when I can, I always try to look through for any questions where I can help others.

I'll be investigating further.
I'm now away from the studio until Wednesday.
I figured I could gather advice while away. Ready for my return.

I'll try to post some pics also.

c u soon