I should probably start a new thread for this but it does apply, in part, to your post:
A week ago or so, I stumbled upon this guy's youtubes and emails he sends: jesco@acousticsinsider.com
Full Disclosure: I will tell you this Jesco guy, does want to sell you his "Educational Acoustics Course" but from what I can tell, his information does not conflict with the acoustic principles we discuss here but his focus seems to be professional dedicated mix rooms as opposed to home theater etc.
One email in particular was somewhat similar to your questions so I want to share the email with you and the forum.
Below is the email cut and pasted below (without graphics):
"In yesterday’s email I showed you why you shouldn’t obsess about densities when you’re picking an insulation material to build your own bass traps and panels.
But once you’ve found a suitable material the question quickly becomes:
OK, but where do I put my panels exactly?
And that tends to snowball into a whole range of other questions, like:
How many do I need in my room? (which we already saw is very difficult to predict)
How deep should I make them?
How big do they need to be?
Does it make sense to use an airgap behind them?
And what about diffusion?
You always read that you don’t want to end up with a “dead” sounding room. Maybe you’ve even experienced yourself how uncomfortable it can be to just BE in one.
And often our rooms are a little… odd. Weird little corners, odd angles, awkwardly placed doors and windows...
What do we do THEN?
What we need is a framework to follow to answer all those questions. A framework that we can apply to every room, no matter it’s exact shape and size.
Here’s the problem:
There’s no scientifically proven “correct” framework or placement strategy for small rooms that reliably leads to proper mix translation.
And the approaches that the “big boys” use are often confusingly contradictory.
The “Reflection Free Zone (RFZ)” approach for example has a fully reflective front part of the room, but with angled walls.
RFZ room diagram
Source:
www.soundonsound.comOr the older “Live End Dead End (LEDE)” which has a fully absorbing front end but a reflective back of the room.
LEDE diagram
Source:
www.soundonsound.comBut which approach actually works best, and why?
Unfortunately all we have is anecdotal evidence of these rooms giving a functional mixing environment.
To this date, there are no scientific studies that measure HOW WELL these rooms really work for mixing and mastering.
And this is not to be confused with pure high fidelity listening environments. There is plenty of research that analyses how PLEASURABLE certain spaces are to listen too.
But judging objectively how well they translate a mix? A different question entirely.
Of course this doesn’t mean that they DON’T work. It just means we don’t know exactly WHAT makes them work.
And it doesn’t end there.
Even if you try to apply them to your spare bedroom, basement or attic, you’ll quickly find that you’ll have to make LOTS of compromises in order to implement them within your budget, the shape and size of room available, or simply because of the sheer complexity of making it happen.
And what if those compromises end up breaking those exact (but unknown) aspects that make a certain approach work in the first place?
Pretty risky business in my opinion.
So for the typical home studio, it just doesn’t make sense to even try to emulate any particular control room concept.
It’s just a bad investment of your time and money…
So then what CAN we do that we KNOW leads to proper mix translation?
Let’s have a look at what modern control room approaches all have in common at their core.
What do they all do that we know will allow us to trust what we hear, make good mixing decisions, and that we CAN actually attempt to implement in a home studio?
First up, here’s a Northward Acoustics’ “Front-to-Back” room, probably the most state-of-the-art, over-engineered solution out there right now.
On the left the finished room, on the right before everything is hidden away under fabric.
Northward Acoustics FTB room covered vs uncovered
Source:
www.northwardacoustics.com/What do we notice?
There’s absorption literally everywhere.
No angled walls.
No absorption on the front wall. (but the speakers are mounted inside the wall (or window in this case). So we can rule out sound reflecting off the front wall.)
There are a few diffusors, but seem strangely positioned (I’ll get to that in a bit).
Second: A MyRoom control room. Again finished on the left, and without all the slatted front surfaces on the right.
MyRoom control room covered vs uncovered
Source:
www.facebook.com/MyRoom.AcousticsWhat do we notice here?
We have these slatted diffusors everywhere, but with gaps in between the slats.
Behind the diffusor fronts: just more absorption.
It’s the same treatment everywhere. No attempt to mix up any spot with a different type of absorber or diffusor. (Except behind the speakers. Diffusion doesn’t work in such close proximity.)
So what do these two rooms have in common?
There’s treatment EVERYWHERE. Either just pure absorption, or a combination of diffusion and absorption. No wall is left untouched.
They try to get rid of anything and everything the actual physical room surfaces potentially contribute. ALL reflections, ALL low frequency resonances (standing waves) and ALL boundary interferences.
They essentially “remove” the room, or in other words: any distortion the room adds to the speakers.
Clearly their main goal is to get the most unaltered sound from the speakers as possible.
The designers simply assume in good faith that the sound from the speakers alone will tell the mixing engineer everything and exactly what they need to know.
The speaker’s sound is not just ALL we need, but in fact the BEST foundation to make mix decisions and reliably and consistently guarantee that mixes will translate to the outside world.
The room itself simply doesn’t contribute to mix translation anymore in any way.
So that gives us a first goal to aim for that we can actually try to implement:
Do your best to remove the room!
Or in more technical terms: reduce distortion of the speaker sound at the listening position to an absolute minimum.
Apparently it also doesn’t really matter where you place diffusion exactly, at least not in the grand scheme of things. Otherwise the MyRoom approach wouldn’t work.
So there’s no need to purposely “control” what diffusors reflect back to the listener. Their placement could be fine-tuned as the Northward room shows, but apparently it’s not actually essential.
That’s because the only purpose the diffusors have in both rooms is to give the user, YOU, a sense of the space from the noise you generate YOURSELF when you’re in the room.
THAT’S what tells your brain that the space isn’t dead. We don’t need the speakers for that purpose.
And that gives us a second goal that we can implement:
Apply high frequency diffusion any place you want to keep a sense of space.
Isn’t that liberating?
You can literally put diffusion anywhere you can and feel like it without breaking anything!
How much exactly? As much as you want! You can literally not overdo it even if you wanted to.
Just as long as it's focused on the high frequencies alone and you make sure you work on "removing" the room as best as possible first.
There’s just no need to “design” a particular reflection pattern or reverb decay.
Is this approach the most refined out there?
Definitely not!
But it'll put you on a trajectory that is actually GUARANTEED to get your mixes to translate without overdamping the room.
And it gives us the framework we need to answer all those placement questions we originally had.
Example: How deep should you make the panels at the left and right early reflection points?
Well, if the goal is to “remove” the room, which means getting rid of those reflections completely, then the answer is simple:
Make them as deep as you can within the space you’ve got available.
That’s because it’s no longer a question of somehow “correcting” the reflections (for which you’d have to know what exactly you’re correcting first). Instead you simply want to remove the reflections completely. You don’t need to know what you’re dealing with first. Just chop them off. Done.
That in turn means working truly broadband down to the lowest frequencies with your absorber, so making it as deep as possible within the space you’ve got.
And the same framework literally applies to any other spot in your room where you’re thinking about putting treatment.
You just have to ask yourself:
Can I use this spot to better “remove” the room?
Do I want to apply high frequency diffusion to help keep a sense of space?
It’s as simple as that.
Now here’s what I want you to do right now:
Have a look around your room. From what you’ve just learned, where do you already know you can make an improvement? Where do you know you could do better to remove the room?
Hit reply and let me know what you’re thinking. I read every email (and answer as many as I can).
Jesco"
