Problems in recording studio

Posted: Fri Aug 24, 2007 1:05 pm

Hi, I´ve been remodeling my recording studio but I´ve come across a small problem. My tracking room is next to a parking lot ramp, so everytime a car passes by, some parts of the structure vibrate and produce a very low rumble. I already used a lot of fiberglass between the actual wall and the drywall in every wall in the room. What else can I do to resolve this problem?

Posted: Fri Aug 24, 2007 6:53 pm

Unfortunately there is now easy fix for this problem. To stop low frequency transfer (in or out of room) you need density, as in thick dense walls. That can be a double edged sword too. Your room will get smaller, and dense walls will reflect more sound. But on the plus side, it will be quieter!

There is also the law of diminishing returns with wall density.

The best way is building a room within a room, decoupling inside walls from outside walls, and using an air pocket between walls. This stops the majority of sound transfer. This is what I have been doing... 4 layers of 5/8th fire code drywall - 2 inside, and 2 outside, with a 6 inch air pocket between (also 2 layers of insulating fiberglass).

I'll let you know how well it works when I'm finished. I am under a flight path, and at least 2 days a week, my neighbors cut their lawns. I also want to be able to play drums late at night without being visited by the police...

Good luck with your quest!

Posted: Fri Aug 24, 2007 11:14 pm

Is there a way that I could at least reduce this transfer from the inside? because the room-within a room feature is too late to be applyied, maybe with some sort of resonating bass traps or something?

Posted: Sat Aug 25, 2007 3:00 am

Even at the finest studios in New York City, they many could never get rid of all of the subway noise. It never stopped a hit.

You think it'll pick up my stomach rumbling?
Ms. Remy Ann David

Posted: Sat Aug 25, 2007 5:38 am

Cosme, I'd suggest adding 1 or 2 more layers of drywall and call it even. Just lay it right over your existing walls.

You could probably use EQ to limit the effects of the ramp rumble. If you DI the bass, only the drums will need special attention, such as gating, to limit the ramp rumble. Nothing else should be recorded with the lowest frequencies present anyway.

Bass traps will help "tune" the room, and may help reduce the bleed from ramp rumble as well.

Another technique would be double mic'ing, and reversing the polarity of one mic so it is out of phase from the other, and set back an inch or more. I thought this was first used in concerts in the early 70s (helped control feedback in live situations), but I've found photos of The Beatles using this technique in the studio! Probably more complicated than it's worth however.

Try recording just the ramp rumble, and using it 180 degrees out of phase to filter it out of your track when needed... Also a bit complicated...

As Remy intimated, just make the best of it. Chances are it won't be noticed anyway (except maybe by you).

Posted: Sat Aug 25, 2007 7:04 pm

tifftunes wrote:

As Remy intimated, just make the best of it. Chances are it won't be noticed anyway (except maybe by you).

Ditto on that. The worst critics we have are ourselves. I've lost count of the number of times I hear a flat or sharp, or a muso's minor mistake that really bugs me, but nobody else notices when the complete song is played to them.

Try the above advice and let others listen. Don't tell them about the ramp rumble, and see if they notice anything - you may be pleasently suprised. Razz

Posted: Sat Aug 25, 2007 8:45 pm

Hey guys thanx for the advice, I´ve been cracking my head because of this for weeks, I thought about a possible solution: first I record the rumbling sound to see how bad and how low in frequency it is, then depending on the frequency, since it´s only one wall that´s vibrating, I could build a wooden resonance box that could be stuck airtight onto the vibrating drywall, transfering the vibration to the inside of the box, just like a bass trap, but attacking only the vibration coming from the wall, does this make sense? what do you guys think?

Posted: Sun Aug 26, 2007 5:24 am

Try Sights' test first. You may not need to spend anything on the ramp rumble if no one hears it. And even you will get used to it and learn to ignore it after a while.

However, one solution, if you have the space and money, would be to install a "new" wall in front of the "offending" wall, leaving a 6" gap between the two walls.

Frame a new wall, insert fiberglass unsulation between the studs, and install two layers of 5/8" drywall separated by a bead of clear latex sealant (lasts 50 years!) on each stud line.

Each layer of drywall will act as a bass trap and absorb much of the low frequency energy from the ramp rumble. If there is any remaining energy, chances are it will be very low level, and very low energy and go unnoticed.

As always, your mileage may vary...

Posted: Sun Aug 26, 2007 12:33 pm

Great idea, I think I´ll go with that, the problem is I can´t leave a 6 inch gap cause I´ll be loosing a lot of room space, Can I leave a 2 or 3 inch gap instead?, will it have the same effect?

Posted: Sun Aug 26, 2007 3:05 pm

If you build this wall...bear in mind that >any< place the new structure contacts the existing structure you will be building a "bridge" that will allow the annoying sound concerns to vibrate into your work area.

Gluing and screwing the sheetrock is far better then using nails in respect to minimizing vibration. Also any type of gunned on or troweled material in-between the layers of rock will yield a better result then simply installing two layers of rock on some studs. Some recommend the use of GreenGlue inbetween layers, but any type of adhesive material will yield a better result then none.

Vibration is your initial concern with applying multiple layers/products together. Remember those squeaky steps when trying to leave your girlfriends house late at night? Wood-on-wood produces that.

I, personally, do not allow the wall plates to directly contact the troubled area if at all possible. This may require the use of rubber spacers or even washers placed on the floor directly beneath the purposed floor plate area. Any small space will do just so long as you can minimize the direct transfering of vibrations from one place to the next. Then caulk/silicone or polyurethane(good to best order) the bottom of the plate and both sides of the bottom plate where the plate intersects the floor to close the void.

As I understand it, this is not a load bearing wall and is only for sound control so you are more free to build it in a more detached manner.

You might also want to consider applying the technique used on the bottom plate to all stud/wall members that intersect the existing structure to minimize transfer.

You may also want to consider not cutting the sheetrock in tight. You can leave it just shy enough on the ends that it can be filled as you filled the other joints.

Man that reads like a lot of work!

Brien

Posted: Sun Aug 26, 2007 8:53 pm

I was thinking of screwing the new 2 inch wooden beams that hold the drywall to the structure below, then screw the drywall onto a rubber spacer in front of the new wooden beams to separate the structure from the new drywall and inside this resulting gap, use another layer of fiberglass, everything sealed airtight with plaster filling, is that alright?

Posted: Sun Aug 26, 2007 10:35 pm

We aren't even totally certain that what we are trying to silence can be isolated behind this new wall.

Low rumbles can come from anywhere.

Would it be possible to get some kind of picture, diagram of where your wall of concern is and the ramp we are trying to part from is?

It seems like adding more mass to the wall that "looks" right at the parking lot would be the ideal position. But I have a picture in my head of what it looks like and it may not even look like what it really is:) Understand?

Do you have any type of bass trapping in your work area right now?

Brien

Posted: Mon Aug 27, 2007 4:56 am

Sights wrote:

tifftunes wrote:

As Remy intimated, just make the best of it. Chances are it won't be noticed anyway (except maybe by you).

Ditto on that. The worst critics we have are ourselves. I've lost count of the number of times I hear a flat or sharp, or a muso's minor mistake that really bugs me, but nobody else notices when the complete song is played to them.

Try the above advice and let others listen. Don't tell them about the ramp rumble, and see if they notice anything - you may be pleasently suprised. Razz

This is your next step. Use your ears, then others ears. You may not need anything else. Why spend money and time on something you're not even sure about? It's not even worth planning until it's definitely a problem.

Record a few tracks and see if it even comes through. Chances are it's too low in frequency to be heard. But you won't know 'til you try!

Posted: Mon Aug 27, 2007 5:00 am

dang dbl posts Rolling Eyes

Posted: Mon Aug 27, 2007 8:41 pm

I can´t really diagram anything from here, but I can tell you that It´s not just the frequency that bothers me, but the level in dB, it´s loud enough to be noticable in a moderately low conversation, It might not be much, but the lower it can get, the better, I´m totally convinced it´s mostly one of the walls, the one that is exactly between the room and the ramp, if you put your hand on that wall and compare with the ceiling and every other wall you can feel the difference in the vibration. There are certain 50, 40 even 20Hz rumbles, but there are certain 80 100Hz rumble harmonics that really bother me so that´s what I´m trying to attack mostly. I don´t have any bass trapping yet.

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