help with small basement studio

hi, i'm looking for some input on what to do with my proposed basement studio. i have checked a few similar designs, but my room has a couple of mass concrete 'benches' (lower than desk height) and i have no idea how this will change things.. i've included a sketch of the room, with my ideas to date, although nothing is fixed, any comments would be much appreciated. thanks, jon

jon - do you use both doors?? i.e. is it possible to seal one off cheers john

yeah, unfortunately i need both doors. the one at the top is the main entrance, and the one at the bottom leads to a small ceiling level window which is required by building regulations as a fire exit. i can add treatment to the door, but not block it off entirely. this arangement means that i don't have enough room to use symetrical corner traps, what's the best way round this?

OK - then how high is the ceiling?? could you use that area for treatment?? cheers john

floor to ceiling is 2340mm, not great, but i'm free to treat that in any way suitable (ie; i don't mind obscuring/cutting the height of the emergency door as long as i can get out of it! although i'd prefer not to have to do this) thanks for your input, jon

Cool jon - for a room that small you need a lot of treatment - i.e. the smaller the room the more treatment is required. Instead of making panels I'd look at treating whole walls and even sections of the ceiling. cheers john

thanks for the pointers. i've had a good look through the example studios and tried to apply this to a smaller room. how about this for a starting point? not really sure what to put on the ceiling, but that kind of space allocation works ok. i've put high absorbtion behind the speakers as i can fix this to the door. should i place a different kind of panel centrally? it's all guesstimation from my end, although i like the shape i'm heading towards :) cheers, jon

Now you're talking jon. :) cheers john

ok, now for some detail... i'm asuming that the most important treatment will be the side walls, which i'm aiming to be 'broadband low-mid frequency absorber's' as you show on the SAE site (thanks for the great info btw!) from the formula i can see that varying slot width and box depth (achieved by angling the surface) affect the resonant frequency. do you think that varying these two factors will be enough (ie: i hope i don't have to vary slat width and slat depth too, i'm no DIY hero!) - what slot widths (and standard slat depth) would you suggest for my room?? i'll probably make two pannels either side to keep it structurally rigid, so i could mix up a fair number of slot widths (see dodgy diagram!) the rest of the treatment pretty much defines itself due to practicality. what kind of absorber would you suggest for the ceiling (i'm thinking more slots at the moment, but maybe at different fequencies??)?? that leaves the floor - a) carpet, to soak up more highs or b) wood to keep it 'live' thanks for all your help, i feel like i'm beginging to get a grasp of this, but to be honest i'm a bit worried i'll put in a lot of work and miss something important without checking the steps with someone who actually know's what they are doing!! :) jon

The depth varies because of the angle the slots are at so there's one variable. The next easiest variable is the slot width. If you use the same width timber (slat width) you can still create a broadband just using the first two variables. Try 6' x 1" slats with 1/16", 1/8", 1/4", 1/2" slot widths. or - here's an example where the slat width is varied cheers john

great, i think i can manage that. i'll have to limit the angle to 10 deg throughout to get things to fit, hope that doesn't drastically alter performance..., i assume that i evenly distribute the different slot widths to get even absorbtion. i'm thinking of using the same kind of absorber slots in the ceiling as shown on my section, unless you think that would be overkill! would i set up the slats to run along the length of the room (might look a bit wierd) or across it? just the floor to go. i have no idea here. most studios go for wooden floors, but then most of them are big enough not to have treatment over all the surfaces! a) wood parquet on concrete for 'live' sound b) carpet for more high damping?? c) wood + rug for a combination??? getting there :D

yeah - 10 degrees will be enough in this case. Just make sure that behind you is dead as a dodo. cheers john

ok, drawing everything together how does this look, keeping the sloping ceiling resonator as before? i'm going to go for a wood floor and throw rugs down if i get problems.

looking good mate. :) cheers john

thanks for all your promptings and the excellent info available, i think i'm ready for a trip to the timber yard. here are my final(?) drawings - now is the time to point out anything worth changing! thanks again, your help has been essential! :D jon

Looking good mate - just one thiong - break up the parallel ceiling in the front like this cheers john

that's a good point :wink: which raises a couple of questions, thanks for your patience! - how should i create the new space (see pic.) - do i need to separate the two 'shapes' of cavity? - is it ok to rest the insulation in the resonator on the slats or do i need to build an inner frame to hold it away? cheers, jon

- how should i create the new space (see pic.) - do i need to separate the two 'shapes' of cavity? - is it ok to rest the insulation in the resonator on the slats or do i need to build an inner frame to hold it away?

Yes separate the two spaces - why not build some of Ethan's panel absorbers but with an angled front, instead of flat like his. For the slots put the insulation on the ceiling. cheers john

why not build some of Ethan's panel absorbers but with an angled front, instead of flat like his.

good idea, makes sense to use the space. -would i need to back the absorbers with ply, as there is no existing wall to form the shape? - (A) or (B) in diagram? -thinking about panel absorbers, should i put one on the rear wall where i have the 8" rear wall absorber and cover that with 703 to prevent the ply from causing reflections, or stick with what i have?! cheers for the advice, it's getting beyond where i can guess now :)

I think I'd go with A. sorry I don't understand what you mean about the ply backing. Surely the ceiling and the wall become the rear of the cavity - you just create the sides to mount the plywood panel. Yes you could put them on the rear provided you put 703 in front. Maybe two next to each other and angled slightly as well. cheers john

great, i think that's me all set for some serious carpentry, looking at my original sketch it's a good job i checked in here! one final question. existing walls are double brick cavity. is it worth lining them with double plasterboard for sound proofing, or will single do. i don't know how much difference this will make to the STC (it's not essential, but i may as well get what i can and i don't have space for room within a room, although, as it's built off an isolated concrete slab i guess i kinda have a brick room within a room anyway) cheers, jon

I wouldn't wory about a room within a room - If you render the brick surface the STC is greatly improved. good luck with the building :) cheers john

If you render the brick surface the STC is greatly improved

plaster direct to the brick surface? ie. no messing about with plasterboard? sounds good :)

good luck with the building

thanks! :D

I think the easiest way is to bag it. That's a loose sand cement mix you wash onto the surface with a cloth. It seals the surface. I'd ask Steve in the construction forum what he recommends. cheers john

I'll save you having to make a trip "all the way over" to the construction zone - Since it looks like virtually all your walls will be covered with various treatments, aesthetics appear to play no part in the choices - you could either do the bagging thing with a light mortar mix to seal the brick, or if you can get access to an airless spray system you could use a heavy-bodied latex paint and apply two or three coats right to the brick, whichever way is more comfortable to you. Either way is 98% just for the sealing effect. If you want better sound proofing, additional layers of 5/8" (15mm) wallboard will add about 2-3 dB per layer. If you do this, you could seal the brick with floor mastic, and use it to also glue the wallboard to the brick. What you DON'T want to do is to create yet another air gap so you end up with 3 mass leaves and two air spaces. That will actually WORSEN the wall performance. One other thing I noticed in your drawings - if the layout is to scale (latest floorplan), you need to widen the speaker placement so that the distance from center of radiation of each speaker (baffle, midway between tweet and woof) is the same as the distance from each speaker to your EARS, not to a spot 3" from the edge of the desk. Widening the speakers should also allow you NOT to make the mistake of having the computer monitors off to the side, but instead place them between the speakers, and if they're the same height set the left CRT so its face is a continuation of the left speaker's front baffle, and set the right CRT so its face is a continuation of the right speaker's front baffle. This will give you a symmetrical mix position, effectively extend the size of the speaker baffles, and keep you from getting a stiff neck. Notice that, in your drawing, if you draw a line from the left speaker over to the face of the CRT's next to the right speaker, those CRT's will reflect into your right ear. Early reflections SUCK even when they're symmetrical, so I wouldn't do that... Steve