fordtrannyman

I'm setting up an 80gal. tank in my living room.
Right next to it on the floor will be an 1185watt dual-radiator subwoofer.

Would the low frequency have any affect on the inhabitants of the tank?

sirdarksol

Yes. Sound is just little shockwaves, and water carries those shockwaves far better than air does. The end result is that the fish feel deep noises as little impacts on the sides of their bodies. At best, this will confuse them into never knowing if a large, dangerous predator is near. At worst, it will cause them physical harm. If there is no way to move the subwoofer, you may want to set up a screen of acoustic tiling between sub and tank.

Chief_waterchanger

Sirdarksol is right.

Dino and I would set the tank up as far as possible from that subwoofer as possible, if it has to go in the same room at all.

I never was into audio equipment, can I ask what the subwoofer is for?

andy65

CEC your funny!

A subwoofer is a big speaker that is used in home theater systems and at movies theaters to produce the low-frequency,deep, sounds in the movie.

Its what makes you chest "move" when you are at the movies theaters.

Chief_waterchanger

Thanks for clarifying, Andy.

Sorry for hijacking the thread, FordTrannyMan.

fordtrannyman

Yeh, what Andy said!
Home theater mostly. I do only have it set at 30hz, phazed at 180 degrees, and crossover off. So I'm typically only using 33% of it's full power. or 109db.
But it still shakes the floor with a good action flick.

I used to have it in a small closet on the opposite side of my fireplace wall.
Just didn't have the same effect.

I never really thought about it too much with my smaller tank. I always assume that the glass served as an insulation to the frequency.
I'll have to try a couple of experiments before introducing fish.
Which won't be for a while. This is going to be a high light planted tank.

Would frequencies in water be a measurement of pressure over time?

Chief_waterchanger

I believe frequency = wavelength/time.

Algebraic manipulation can then be utilized to figure out wavelength and time.

sirdarksol

Unfortunately, the glass probably doesn't provide enough protection against something that shakes the floor.
However, this may be workable. If you set the subwoofer near the tank, but with the front facing away, and then set up an acoustic screen between the two, there may be little enough noise that it wouldn't hurt the fish. I don't know as much about speakers as it seems you do, but I do know that when I stand behind my sub, or when something is directly between it and myself (even something small like my cat), the amount of thump that I get from it is next to nothing. Combine direction with something intervening, and there may be no problem.

neverendingninja

Another point is that, at least from what I've heard about car audio, is that you have to be at least 6 feet away to really get the full affect of the subwoofer. Is it possible that closer is better in this case?

Good point about water carrying sound better than air, SDS, but you have to consider the fact that the water will be picking up the sound from the air, so it can only be as loud in the water as it was in the air, and deteriorate from that point on.

Wolfgang8810

sounds waves will carry through the glass. I have played bass guitar for many years and have had to relocate my bass amp in another room because it stressed the fish so much. I had tiger barbs and a 200 watt bass amp with 1-15'' woofer and a 3'' tweeter. It would actually put ripples in the tank water.

sirdarksol

The impact can still be greater. Have you ever been holding a plastic cup full of water while sitting near a subwoofer? The impact you feel through your hand is stronger than that you feel from the air. I think it has something to do with the sound waves resonating in an enclosed container of water.

Wolfgang8810

i think your are right SDS but still i wouldnt want alot of noise around any of my tanks.

COBettaCouple

whoa! great subwoofer! Can I come over & watch LOTR! Yea, even a low-wattage one I'd put as far away as you could and definitely one that good. An acoustic screen or 2 in the line of fire from the waves would be good too, just to be sure you don't have the Death Star blow the tank apart.

sirdarksol

Another (far more difficult) possibility is to buy another subwoofer and set it up at an angle to perfectly negate the first subwoofer. This is actually possible. It used to happen at rock concerts. The worst place to be was front and center, a few rows back, because the soundwaves from the speakers hit each other just right to cancel out.
The problem is making such an area.

Xenomorph

I've set up the audio for a number of concerts and the problems with frequency cancelation go far deeper as wavelengths change during a performance depending on other factors such as air temperature and humidity, audience size/movement etc. We use frequency cancelation to help reduce feedback so we can run higher volumes

FTM: where are things located in the room and how large is it? My lounge room is 8m X4m with the tank at one end and the sub at the other - when we have 'big sound' movie nights the room is full of people anyway so much of the direct output is absorbed by bodies.

sirdarksol

This was just a matter of, at rock concerts many decades ago, there being two banks of speakers set at an angle, pointing toward the center of an arena. With the absolute size of the speakers, and the fact that the sound coming from one side was identical to the other with regards to wavelength, timing, and volume, there is going to be a point, somewhere between them, where the sound gets cancelled.
They figured out that by changing something in the setup made it less likely (though there is still the possibility of pockets, like what you're describing about having to worry about). Now the really big concerts (the ones that are most likely to have this kind of problem, due to the sheer size of the arena and volume of the speakers) use so many different banks of speakers scattered around the arena and scatter them in such a way that it would be pretty much impossible to have such a pocket.