Teeny Tiny Mixing room

Hi all. I am new to thinking deeply about accoustic treatment. I've been mixing live for 20 odd years where I have just had to deal with what ever room accoustics I was dealt on the day and I am finally getting into home studio. I record live multitracks at gigs (with the aim to do mobile studio recordings - another thread pehaps) and mix at home. I have moved into a new house where the previous owners were planning to add a laundry to the end of the garage - it's a tiny space, but it is all I've got to work with for now. Basic layout: 2m x 2.9m with a sloped roof 2.4m to 2.3m across the width - High on left side at mix position hollow interior door at centre of one long wall window in one short wall Lino covered concrete floor Gyprock on internal face of all walls aluminium cladding on 3 external walls outside of wall with door is gyprock into garage Gyprock ceiling corrugated iron roof unsure about thermal/accoustic insulation in walls and roof - but it gets awful hot in here during summer, so my guess is not much if any... No HVAC - apart from the window and door. Effectively a lined tin shed... I currently have a 90mm thick single bed foam rubber matress vertically beside Left monitor (to allow door to open) and a 130mm thick Queen sized inner spring matress horizontal next to Right Monitor 3 layers of blockout curtain over window behind monitors bunched up denser closest to monitors. Lounge on back wall The matresses are a quick and dirty attempt to dampen first reflection points while I come up with a better solution. The room holds my recording/mixing rack which slips inside a home made workstation with a wide shelf at ~1.2m high that supports 2 PC monitors and a pair of Mackie HR824 audio monitors which are only 150mm off front and side walls and a sliding keyboard tray above a Yamaha 01V mixer in the top of the rack with the PC in the bottom of the rack. Fan noise is noticeable when no music playing. See artist impression picture attached. (sans matresses) The uplights are supposed to indicate speaker placement, but the speakers are at ear height when seated, not above as depicted, and are on a shelf not stands. Quick drawing with very few customisable object templates. I mix at about 85 dBA SPL, it does not appear to be excessively loud outside and I have not had any complaints from the neighbours. I have not done measurements outside yet. I did some REW sweeps tonight (with behringer ECM8000 :oops:) I haven't used REW before and may not have calibrated 100% correctly.. but from the 85dB peak at 112Hz there is a 25dB rolloff to 92~96 Hz @ 60 dB. Next lower freq peak ridges are 86Hz @ 67 dB, 67Hz @ 71 dB and 54Hz @ 73 dB respectively. Also a ~10 dB dip at 200~230Hz on the Left side graph. This is reflected in what I am hearing....no bottom end or snare body while mixing and then speaker cones shredded through the grilles in the car. Budget is very low as the studio work hasn't really created any significant income yet.. I can probably allocate up to $400 on a DIY basis. I don't really intend to do anything structural - but may look at insulating walls and roof if needed to reduce sound level outside. What would you recomend as a course of action to improve the internal sound of this room? I am guessing the answer is absorption and bass trapping, but what type would be most effective in my limited space? Would absorption behind the rack reduce the fan noise significantly? I would appreciate any asistance or advice provided. Regards, Lindsay Windsor NSW... Oz

Hi Lindsay, and Welcome! :) Unfortunately, there are lots of issues with what you describe, but if that's all you've got, then that's what it will have to be! But let's go through them anyway, so you can plan what to do in the future when the cash comes rolling in...

with a sloped roof 2.4m to 2.3m across the width - High on left side at mix position

Not good, because you need symmetry. Symmetry is critical. No symmetry = no left/right balance in your mixes.

hollow interior door at centre of one long wall

Not good. No isolation form a hollow-core door, and it might even be a resonant box at some frequencies. Replace that with a solid-core when you can.

window in one short wall

Not too much of a problem, as long as you can put treatment in front of it: it's your front wall, so it will need absorption right behind the speakers.

Lino covered concrete floor

:thu: :yahoo: That's good!

Gyprock on internal face of all walls ... aluminium cladding on 3 external walls ... unsure about thermal/accoustic insulation in walls - my guess is not much if any

Once again, without insulation in there, that's just a resonant box. Not much isolation, and possible resonance issues. In the future, I'd pull off the drywall on the inside, put mineral wool in there, put resilient channel up, then put new drywall on. For both acoustic and thermal reasons.

No HVAC - apart from the window and door.

The door and window don't count for HVAC! :) So at some point you'll need to get a proper mini-split system, and also install ducts for ventilation.

I currently have: a 90mm thick single bed foam rubber matress

Forget that: practically no use, acoustically. Wrong type of foam, wrong density.

a 130mm thick Queen sized inner spring matress

Forget that too: same reasons as above.

3 layers of blockout curtain over window behind monitors bunched up denser closest to monitors

Not ideal, but it should be doing something for the highs and high-mids.

Lounge on back wall

Probably doing something for bass, but hard to say how much.

The matresses are a quick and dirty attempt to dampen first reflection points while I come up with a better solution.

Pretty much ANY solution would be better than that! :) Well, OK, not really "any"... But a good starting point would be some OC-703, or something equivalent.

a home made workstation with a wide shelf at ~1.2m high that supports 2 PC monitors and a pair of Mackie HR824

The speakers MUST get off those shelves! That's a recipe for rotten sound. The speakers should be on stands behind the desk, or beside the desk, and the stands must be massive (as in "extremely heavy"). With speakers on shelves on the desk, you'll end up with a bunch of issues in the low end, and also in the mids. This should be one of your priorities.

audio monitors which are only 150mm off front and side walls

There's an optimum geometric arrangement for speakers in rooms, and that isn't it! :)

See artist impression picture attached.

Photos would be even better! :)

the speakers are at ear height when seated

When you say "at ear height", what do you mean? The correct placement is to have the acoustic axis at ear height, and you'll have to check the manual for your speakers to find out where the acoustic axis is: It will be at some point on a line between the center of the woofer and the center of the tweeter, and projects out perpendicular to the front baffle of the speaker. That's the point that matters.

I mix at about 85 dBA SPL,

For loudish music, you should measure with C weighting, not A. A weighting is more for environmental measurements, and is what the cops will be measuring if they come knocking on your door one day, but "A" doesn't tell you much about the perception of music. You need "C" for that.

I haven't used REW before and may not have calibrated 100% correctly..

We'll need to see the actual MDAT file, not just waterfall plots. If the file i too big to post here, then put is some place like DropBox, and post the link here. But anyway, from looking at the waterfalls, yeah, you sure do have a problem in there! :shock: It looks like that might be both SBIR and modal issues, but hard to say without doing additional tests.

Budget is very low as the studio work hasn't really created any significant income yet.. I can probably allocate up to $400 on a DIY basis.

To be very honest, that won't go very far, and certainly won't stretch to do any insulation inside the walls. It seems to me that your priority right now should be treatment, so I'd suggest that you blow most of that on absorption, such as fiberglass or mineral wool, placed correctly to deal with as much of the low-end issues as possible.

What would you recomend as a course of action to improve the internal sound of this room?

Firstly, get the speakers set up correctly, in terms of height, position, and geometry. Then do bass traps. Lots of them. Very, very big ones, in as many corners of the room as you can hit. It's a very small room, so it will need very large amounts of bass trapping. I'd go for superchunks in the corners, and thick absorption on the entire rear wall to start with.

I am guessing the answer is absorption and bass trapping, but what type would be most effective in my limited space?

Right! Superchunks are the answer, for sure: You can build those up from either mineral wool or fiberglass insulation.

Would absorption behind the rack reduce the fan noise significantly?

Probably not. It might be the fan itself that needs replacing. The only way to significantly reduce the noise of that, is to put the console in an isolation cabinet of some type, with a silencer box built in. You might be able to build that into your desk in the future. But for now, post the MDAT file, and also some pictures of the room, so we can get a better idea of what you are dealing with. - Stuart -

Thanks Stuart, mdats and photos uploaded to my website along with a couple of shots of one of my "live rooms".. :)

Not good, because you need symmetry. Symmetry is critical. No symmetry = no left/right balance in your mixes.

Would a cloud come into play here?

The speakers should be on stands behind the desk, or beside the desk, and the stands must be massive (as in "extremely heavy")

I have some stands currently not in use from the lounge room. They are heavy enough for the job as my home theatre surrounds are large and heavy.

There's an optimum geometric arrangement for speakers in rooms, and that isn't it!

Yeah, I made the workstation at the last house we were in. Firing down the 6m length of the 3m wide garage is very different to here. The old garage was nicely lined, this one... not so much - I had to seal it up to keep birds out initially, so I'm using the small room to keep the gear as clean as possible. Hmm, just had a quick look at the garage.... I might have a chat to the owner. I could put a wall in there and make a 2.9 x 4ish room with the slope in the roof running uphill from front to back (rotated 90 degrees from current space) or even remove the existing wall if it is not load bearing and create a 2.9 x 6ish space. I will look at room mode calculators tomorrow and see if any of those numbers work better. Yes, budget; I know... hey I 've got Scottish ancestry way back when, we can do almost anything with next to nothing.

The correct placement is to have the acoustic axis at ear height, and you'll have to check the manual for your speakers to find out where the acoustic axis is:

The User manuals was next to no help at all. No mention of the acoustic axis. But as situated, my ears are betweeen the woofer and tweeter height. Maybe a fraction closer to the centre of the tweeter if anything... depends if I slouch or sit upright.

Right! Superchunks are the answer

Looks easy enough to make after googling around a bit tonight. Thanks again, Lindsay.