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Control room setup contradictions Utility Software
Old 26th December 2010
Gear Maniac
Hotstuff's Avatar

Control room setup contradictions


I have done a lot of searching and reading, and have followed the guidelines on how to setup monitors in a control room and I have got it sounding quite good and it is actually translating quite well to the outside world even though I still struggle to balance the levels of all the elements in a mix which leads me to think that the distance between the monitors is not optimal yet.
The room is 3Wx4Lx3H. Treatment wise I have 10 - 120x60x10cm fabric wrapped rockwool panels 2 in each corner 2 on the back wall, I have 6 - 120x60x5cm panels on the side and front walls 2 at the front 2 at the side reflection points and 2 further back to stop the flutter, I have one big 175x150x5cm cloud above the mix position and 2 - 120x60x5cm panels hanging from the ceiling at the back of the room.

Now, following the setup guideline of sitting at aprox. 38% back from the front wall puts me at 152cm from the front wall, then to setup the monitors in a equilateral triangle and running them up and down along that axis and getting them to a distance from me that sounds balanced puts them very close to the front wall, this is supposed to be a bad thing? as it builds up the bass due to proximity effect, at about 130cm from each other and me bring them to less than 30cm from the wall, never the less it sounds good, The monitors are Adam A7`s by the way.

Almost everywhere it is stated to stay 1m away from the front wall because of boundary effects and early reflections but that way they are to close together.

All I want to do is make my monitoring as accurate as possible.

Carlos Rocha
Old 27th December 2010
Registered User

You might want to measure and map the modal/pressure distribution within the room.

You state a room 3units(ft/m?)x 3 units x 4units.
The two dimensions being equal is not ideal!

Begin by addressing the LF modes. You are going to require substantial bass traps! And then, based upon the actual measured and mapped pressure distribution, locate your listening position in a spot relative to where you are now such that you are not in a peak or null. (One might note also that while the fundamental mode exhibits a null in the center of the room (at ~1/2 the wavelength) that the second and third harmonics will have 2 nulls and 3 nulls respectively distributed at 1/3 and 2/3, and 1/4 and 1/2 and 3/4 of their wavelengths, accordingly.)

The 38% 'rule' (how about "an idea that overly simplifies far too many other issues to be a rule") is, at best, guideline! It does not trump actual analysis based upon reality. And even more fundamentally, it is not aware of many of the other critical behavioral factors that contribute to a more complete (and accurate) behavioral model of the actual room. If only reality were so simple.

I would most definitely suggest you become familiar with programs such as Fuzzmeasure, RoomEQWizard, RPlusD or ARTA. They will most definitely enable you to progress with actual information rather than proceeding on the basis of generalized assumptions.

It sure would e nice if we would (individually or collaboratively, based upon interest, time, and knowledge, etc.) develop some simple FAQs to function as stickies that answer basic questions and qualify the 'rules' one finds stuck to the bottom of one's' shoes after perusing the 'net that can help defuse many common topics - of which the 38% 'rule' is just one - isolation versus treatment; general porous broadband and corner trap concepts and densities, room mode calculators and general guidelines of what to expect (and not to expect), links to commonly used measurement SW support sites, etc.
Old 27th December 2010
Gear Maniac
Hotstuff's Avatar

Hi, SAC whoever you are

Thank you for your input, I really appreciate your time and interest to answer my post!

I would suggest you send your suggestions to the forum moderators.

Sorry if I miss-led you, I´m in Portugal and the system here is metric.
The dimensions are 3 meters wide 4 meters long and 3.3 meters high!

How could a room be 3 feet wide and 4 feet long????

My question Is, is it really bad to have the monitors up against the front wall with absorption behind them.

Carlos Rocha
Old 27th December 2010
Registered User

You are going to have boundary effects in any 'small' acoustic space.

Placement against the wall minimizes reflections but increases the spatial loading - increasing the apparent low end as you have effectively reduced the radiated volume by 1/2 over the placement away from the boundary.

The problem in this case is not the room, but the speaker - and whether it was designed for such placement or not - or if it has a 6 dB shelving filter to accommodate the loading. But seeing as how many speakers come with only an anechoic free field Frequency response - that presence of that feature alone might serve as an indicator of quality design if only to indicate that the designers were at least cognizant of the potential real world placement outside of an anechoic chamber!.

If the speaker does not have a rear firing port and if it has a shelving filter, try placing them against the wall! Or better yet still, if the structure will accommodate them, refer to the Genelec website and see if soffit/in wall mounting is not a possibility!

LF modal activity will still be a much greater issue than SBIR - and the primary issues stand as stated in the previous post.

As far as can they be located against the wall? Try it! If you are asking if you may place them there, we will have to get back to you regarding the permission aspect... ;-)

And search the site - the 38% rule has been beat to death. Benefit from what has already been written.

The point about units is that they don't matter. The ratio does. Having two dimensions equal IS a problem, as the modes will reinforce each other. And if you have actually read other posts, you will discover that folks are trying to make mix environments in dorm rooms and other rooms much smaller with speakers not separated more than 3 or 4 feet.

And after that is addressed, you can select an appropriate acoustical response model begin to focus on early reflections using the ETC response as a guide.
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