New attic-studio with A-sloped roof, need some advice

Hi, i have moved in a new house and my homestudio will be set up in the attic. the place is 4,80 m *5.10 , minimal height is 120 cm at the sides with A shaped roof (45 degrees).
normaly i would say i will face one of the the walls with the roof to the sides. that would be the side which is 4.80 so alittle bit shorter. But the bigger problem is that one half of the side wall is a big window from ground to top, the other half is concrete wall. the opposing side has the same problem but inverted... so i would expect crazy imaging in the upper lows.
right now i am facing one of the sloped roof walls, this way i have quite ok imaging even without a lot of acoustic treatment. i have some flutter echos which will be treated quite easy i hope.
I want to make the slope roof more or less ´dead´with some cloud  over my place.
i did not measure yet but i think i have no bass problems,due to plasterboard roof with thick isolation(50 cm !) and the two big windows.
disadvantage is that my monitors can not fill my room anymore, so i want to get new ones. thinking of some quested v3110 as mains. i would have to place them at the wall what means that they will be directly under the beginning of the roof shape (hope that makes sense..). as i would cover the space above the monitors with acoustik treatment i fear iwill have reflexions in the lower regions . (with a fast reflexion from above and a later one from the ground )
my question is if maybe the main monitor solution is not as good in this place and i should go the smaller monitor- with -sub(2 sub´s) route.i did not like sub´s for mixing yet..
i know i should hear the monitors in my place but lifting around 40 kg´s and get them shipped(ship them back is a major pita so i would like to sort out some no-go´s if there are any.
long post, but if anybody has some experience with attic studios please chime in for some hints !
greets
axel

Best thing to do is to use a program like google sketchup to draw out the shape and size of your room so we can all get a clear idea of what you mean.  Also look up John Sayers forums on studio building as there is lots of good info there.

My recording space (I would not call it a studio) is very similar to yours. Same A shaped roof but just a little smaller overall (4m by 3.5m). My biggest problem is a resonance at about 150 Hz due to the relatively low height of the ceiling. It is worth sticking an omni mic at the listening positions and recording a sweep of the room response. One hell of an eye opener I can tell you. I can understand why some of the best ever recordings were made in large spaces.

I have clouds all along the length of the ceiling.

Cheers

Ian

I have my eyes on buying a house with an attached two-car garage, approximately 24 feet wide. There is no space above it now, but my wish is to build above, using a Gambrel-Barn style roof, of which I have found a place online to purchase plans. My goal would be to raise a floor above the garage's ceiling joists, then build a half-wall all around the perimeter and, finally, build the self-supporting roof trusses. That would give me an overall interior height, at the peak, of approx. 13'4" and a usable height  at the first pitch of approx 10'.

ok, i will try to get a microphone first. iwould like to switch to more distant listening because of  getting tinnitus quit fast when intens listening to my nearfields even at low volumes..had my ears almost killed 3 jears ago with just 3 (!)songs of DRI playing over one marshall amp..

Hi Axel,

the quested monitors might be a bit overkill,from what I know they're designed for for medium to bigger sized rooms.Up to you.......

Anyway,I'd go for measuring first as Ian suggested.
The "normal" reflexions will not be as important as something else:The standing waves.
They are very tricky to handle in small rooms,that's why bigger rooms are better,hahaha.......
From your sizes between the parallel walls in your room expect to get them as follows:
For 4,80 m it will be 85,1Hz,for the 5,10m it will be around 68Hz after the math (plus their octaves).
Too low for treating with standard materials.
If they are too heavy (depends on the surfaces as well as on listening levels) you should look if the resonances are broad or narrow.
I have helped a good friend who had a 56Hz resonance (narrow) with building a "Helmholtz-Resonator".The result was a drop of close to 6dB without affecting the neighbour frequencies too much,a fantastic result I must say!Pro is that they are not too expensive.Contra is that they must be calculated as exactly as possible and built the same way.Best to let them be done by a professional carpenter on cnc machine.
Try not to place the monitors directly on the wall,give them some distance.
For room treatment concerning higher and more broad relexions starting from the low mids I would try to search for an article Hannes Bieger (?) once posted in "Sound & Recording",it's called "Dope-Traps".An isolating material based on hemp (not joking,that's where the name comes from....),housed in IKEA furniture "Billy".The material was also tested by Müller BBM with exemptional results!

Just some inspiration of course,

best,

Udo

Thanks so Far !
yes i will measure, but from listening i don´t have much lower bass problems. the walls are 2 cm plasterboard with 50 cm isolation and then the roof, the two big windows are helping ,too..
there is just one half of one side wall concrete.i have heavy flutter in the 300-800 Hz area just from what i can hear !
yup maybe the quested are too big for my room... since i am coming from a 3*4*2.5 meter room i thought my room is quite big now.
i thought the best position for the speakers would be overhead firing from the slope wall down on my listening position. this way i would have nearly no first reflection points from front and back !
i had  read about the billy dope trap before. just now i have some primacoustik traps with mass loaded vinyl and pressed stonewool. these are fitting perfect under the roof and are quite nice.
but a bit pricey...
i have to lend myself a microphone for measuring...
will report back then, together with some photos..
axel

there are some very detailed responses here and I think a lot of wisdom.... so, I'll keep this short since I'm no JJP, or Lord-Alge..... since I'm relatively new to this community, I'll at least qualify this by saying I've had opportunities to work in a full production house in Milwaukee some amazing engineers and producers. one thing that was stressed to me (regardless of the room shape and size) is to mix at very low levels which prevents a lot of standing waves from building and helps with ear fatigue. I've been very happy with my mixes even in the worst acoustic settings by mixing at extremely low levels, I was surprised it was possible to make big mixes with my monitors set so low.... also, using a mirror to set foam is a great trick for taming early reflections (though it works better in square rooms), basically have a friend hold a mirror against the wall while you sit in your mixing position, anywhere you can see the monitors in the mirror hang up acoustic foam; do this to the left, the right and the ceiling and perhaps put foam behind your head and behind the monitors. this is a minimalistic approach but both techniques put together will yield perfectly usable results IMHO. hope that's helpful. p.l.u.r.

Hi,

yes,a lot of ways leading to rome,hahaha......
I know the mirror "trick",but sadly acoustic foam doesn't affect long standing waves when it comes to the lower frequencies.For the mids and highs it is good of course.

Best,

Udo.

A few tips

John Sayers is god. Find the manual he sold to SAE.

Read his forum... Lots of amazing examples.

Don't be afraid to consult him by phone. His fees aren't crazy

Don't be cheap. Everyone skimps on acoustic.... That a crap decision. It flavors All your music.

Bad acoustics will make a U$20 to U$infinity monitor sound as U$20. Will flutter, bad freq response, bad damping, etc... You can hear better with better monitors unless you have a good acoustic enviromet. Then is up to you how much in acoustics and how much in monitors, the perfect balance is not known and depends on the previos sound (before treatment) of the room. But esential is once you have a room without big resonces you can pay atention to speaker resonances, before doesn't make much sense...

Then you have a lot of info in the web about bass traps, cylindrical, diaphragm, Helmholtz, corner, and maybe I forgot something.

JS

Axel, your biggest problem will be your flutter echoes.  This is due to perfectly parallel walls.  Your A-slope roof already deals with 2 main sets of surfaces and maybe more if the slant roof is also 2 of your walls.

If you are building, try to get any 'parallel' walls wonky.  Just 2 degrees is enough.  I did some FEA to look at this in the 90's when this was new in acoustics.

Trying to get rid of flutter echoes using absorption means your RT60 will become too low.  You need to break up the surface .. not damp it.

Bookshelves (with books) are practically ideal.  It's no coincidence that in old stately homes, the music room was often the library.

If one of the parallel walls is a window, try heavy curtains.  This allows you to adjust the amount of absorbtion.

Helmholtz resonanators are awesome, i have them hanging on chains in my mix room and they work wonders!!

bieckmusic said:

Helmholtz resonanators are awesome, i have them hanging on chains in my mix room and they work wonders!!

Click to expand...

Tuning systems could be used and they don't have to be for a narrow band, membrane resonators are broader, but bigger they are (smaller the hole) they get broader. I've seen a model that uses a cube and 6 holes so you can pick wich open or close and change it freq in 1/3 octave with 6 posibilities, the lower the freq the narrower, but still. (they look as a dice)

JS

A triangle section like your room is often used in speaker design because its very difficult to set up air resonance due to the lack of parallel sides, so that sounds good to me.  The ends of the room are the only parallel sides and their distance will determine the lowest half wavelength that can be reproduced.  Structural resonances might be your biggest problem and some panels may need damping for sure.
good luck
DaveP

I think we need pictures.  I am assuming the long dimension (5.1m) is the distance between two parallel triangular surfaces.

For recording there are advantages because you have a lot of non-parallel surfaces.  Only 2 parallel surfaces 5.1M apart, if they cause a problem some sort of gobo/obstruction along that dimension could help.

For mixing monitor positioning seems a problem.  Even without the end to end reflections  there is the issue of the ceiling panels and how close they hug the monitors. I would expect that you would have better results if you could position the monitors firing across the room, but that may be a bit tight (unless you are very very short ;D).