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monitor placement (wall mount)

Posted: Sat Oct 15, 2016 6:05 pm
by gdgross
Hi, guys, I haven't been here in years, since I was seeing soundproofing advice for my rehearsal space/studio.

I the intervening years, i've been doing some mixing, and looking to optimise my room acoustic situation.

The room is 10x14' with 8' ceilings. Since it's small, I opted to make it quite dead - there are bass traps literally in every corner, floor to ceiling, as well as on the wall/ceiling junctions throughout most of the room. They're all homemade from 703, based on advice i received here years ago. I have my monitors mounted on the wall at about a 7' height, 77" separation, firing into the long direction of the room.

My major question is about the wall mounts for the monitors. I've been using them this way, mounted to the wall (pretty close, less than a foot away from the front wall) for years, and i've learned to always check on headphones, as I don't know that i can totally trust what im hearing in the room especially in the bass.

What's the general opinion about wall mounting monitors here? These are the standard nearfield monitors, krks in this case, not big soffit studio monitors or anything. I read recently that I should try to get them away from the wall, but as this space is also used for rehearsing and tracking, I dont have the luxury of placing them on a desk and optimizing the mix position. I have a standing desk and normally mix from the standing position, hence the 7' height - they're angled slightly downward to aim at my head when i'm standing in the mix position.

The front of the room is pretty dead as i mentioned, using mainly 703 with burlap wrapping and some auralex foam as well.

Bottom line question- is it acceptable to wall mount as i've described? If not, how can I make the best of this situation for mixing? I could move the monitors in a little bit to get closer together, but I don't know how far out from the wall I can get them - and in any case they are still somewhat acoustically coupled to the wall. Maybe I could hang them from the ceiling?

Thanks!!
Geoff

Re: monitor placement (wall mount)

Posted: Sat Nov 26, 2016 2:27 am
by Soundman2020
The room is 10x14' with 8' ceilings. Since it's small, I opted to make it quite dead
It's a control room, right? so it should not be dead. It might be small, but it should still be neutral, not dead. Take a look at the specs in ITU BS.1116-2 to see what you should be aiming for.
I have my monitors mounted on the wall at about a 7' height,
Seven feet??? :shock: I guess that must be a typo? At least I hope it is a typo! The correct height for monitors is 47 1/4" inches. You could go to maybe 49" or so, but above that you start getting into serious psycho-acoustic issues.
77" separation,
Why? For a room with those dimensions, they should be 53" apart (acoustic centers, of course: not the sides of the boxes), and therefore 33.5" from the side walls. At 77", they are too far apart for that room.
... i've learned to always check on headphones, as I don't know that i can totally trust what im hearing in the room especially in the bass.
Not surprising! With speakers mounted 7 feet above the floor, and only 21" from the side walls, as well as 12" from the front wall, there will be some various serious SBIR artifacts in the low end, plus heavy comb-filtering. That combined with the dead acoustics is not a recipe for a good critical listening environment.
What's the general opinion about wall mounting monitors here?
The general opinion is: DON'T!

Get the monitors off the walls, and put them on stands where they belong, with the acoustic axis 47.25" above the floor, and 33.5" from the side walls. Also, push them right up against the front wall, except for a 4" gap where you will place a panel of 4" 703.

Then set your mix position such that your head is 62" from the front wall, and angle the speakers inwards such that they are both aimed at a spot about 16" behind your head (NOT at your head!).

Now you have correct speaker geometry for that room.
I read recently that I should try to get them away from the wall,
Taht only applies to large rooms, where there is enough space to get them at least 4 feet away from the walls. Your room is not big enough for that, so the only other option is to have them tight up against the front wall, except for that 4" gap for the very necessary 4" panel of 703, that will help to control the SBIR and comb-filtering coming off that wall, as wall as slightly damping the low frequency reflections and edge diffraction artifacts.
I dont have the luxury of placing them on a desk
Good, because putting them on the desk is a terrible location! That's about the worst possible place for speakers.
and normally mix from the standing position, hence the 7' height
You should probably re-think that! If the speakers are at 7', and the ceiling is at 8', then the speakers are only 1' from the ceiling! :shock: :!: Major SBIR artifacts like that. Major bass build-up. Nowonder you can't trust the bass response in your room! You HAVE to get the speakers away from the ceiling. There is no option.
- they're angled slightly downward to aim at my head
:shock: :roll: Yet another big problem! That screws up the psycho-acoustic perception of where the sound is coming from (directionality) and therefore also messes up the perception of frequency response. Speakers should never be more than a couple of inches above the horizon.
The front of the room is pretty dead as i mentioned, using mainly 703 with burlap wrapping and some auralex foam as well.
The front of the room should NOT be dead. It should be reasonably live: The old LEDE concpet is no longer used in studios: it has been abandoned long since, at it was found to be uncomfortable to work in for long periods, and tiring. More modern concepts, such as RFZ, CID, MR, NER and suchlike take the good things about LEDE and re-apply it in different ways, with additions.
Bottom line question- is it acceptable to wall mount as i've described?
Nope. For all of the reasons above.
If not, how can I make the best of this situation for mixing?
First, sit down! Yeah, I know: that's a big change in your habits, but there are many, many good reasons for mixing like that: Acoustic reasons. So you'll have to choose if you want to have a mix setup where you can mix accurately, with good clarity, broad sound-stage, clear stereo imaging, flat frequency response, controlled time-domain response, and a low end that you can trust, on the one hand, or "none of the above but still feel cool mixing standing up" on the other hand. The choice is yours...
I could move the monitors in a little bit to get closer together,
Yes. Correct. Move them 24" closer, move your mix position to the correct location, and angle the speakers correctly.
but I don't know how far out from the wall I can get them
Don't! Not in that room. It is too small. Instead, push them up against the front wall, such that the rear corner of the monitor is touching the front surface of the panel of 703 that you will have on the front wall.
and in any case they are still somewhat acoustically coupled to the wall.
Right, and with distances between about 8" and about 3 feet, that coupling causes very major SBIR dips (and comb filtering) on the low end, grossly messing up your low end, and at frequencies where it is impossible for a piece of 703 to do anything about it. If you push the monitor as close as possible to the front wall, you move all of those artifacts up to a much higher frequency range, which can be dealt with using a 4" panel of 703... It's not rocket science, but it can look that way until you understand what the issues are. It's a simple matter of having the sound that comes off the back of the speaker reflecting from the front wall and interacting with the direct sound, causing phase cancellation. If the distance of the speaker from the wall is within the range about 8" to about 3 feet, then the phase cancellations fall in the bass area. If the distance is greater than about 4', then the phase cancellation can only happen at frequencies that are too low to hear. If it is less than 8", it happens in the lower end of the mid-range, where it is easy to treat.
Maybe I could hang them from the ceiling?
Just put them on stands behind the desk. make the stands massive, as in very heavy. Some people make them from hollow steel profile or large diameter PVC pipe, and fill them with sand. Others use concrete blocks or bricks stacked up. Just make them massive, and of the correct height such that the acoustic axis of the speaker is about 47-49" above the floor.

Here's an idea: Do a REW test with your current set up and post it here. Then set up the room correctly, as outlined above, and do another REW test. Post that here as well, and we'll take a look at the differences, to see just how much it improved. Then based on that we can help you figure out what to do to get some life back in the room, and get the frequency response and time domain response more in line with where they should be.

- Stuart -