Post by Michael Lawrence on May 31, 2018 15:03:08 GMT
Howdy, yall.
As part of a series of ongoing improvements in the recording studio I engineer for, we added some acoustic treatment to the control room. I have some photos and a ton of measurement data, and I thought you guys and gals might be interested. Grab a snack, it's going to be a long one.
Some background: This is a project studio, so both the live room and the control room are on the small side. Specifically, our control room measures 13'6" long, 14' wide, and 8'3" high. That's to the drop ceiling; there's another 9" or so above that which is packed full of fluffy pink stuff. The room was originally 14' square, but the reason it's shorter front-to-back is because the rear wall is treated with 4" of Owens-Corning 705 FRK spaced 2" from the wall. The back corners are straddled with slightly more 705 but not enough to constitute a serious bass trap. The ER points on the side walls and ceiling are treated with 705 as well. The front wall is untreated and, as par for recording studios, has a large window and a door that leads to the live room.
Engineer listening position is located slightly right of center line, 6'6" from the right wall and 6'6" from the front wall, with a Z height for seated engineer / reference mic at 4'.
The monitoring system consists of two separate rigs: a Yamaha and a JBL, each with a sub. I believe both systems use ƒc = 100 Hz but I’m not positive.
Obligatory crappy photo:
Yes, that is the Slate Raven MTi 2.
(For the gearheads, the rest of it is: Furman HDS-6 headphone distribution, PreSonus Central Station PLUS, Antelope Orion32 AD/DA, TrueSystems Precision8 preamps, Neve 5024 preamps, AEA TheRibbonPre, Avid ArtistMix control surface.)
To see larger versions of any of the images in this post, right-click and hit "Open Image in New Tab."
Currently, the subs for both systems are placed against the front wall, centered in front of the listener. REW Room Sim predicts the following curve below Schroeder(ish) accounting for axial modes only:
I guessed at the absorption coefficients but we can see the modal situation.
If we were able to move the subs for both systems into the front right corner and create eighth-space loading, we’d get this:
Unfortunately that would require a bit of rearranging the room.
So looking at the treatment options, we start by looking at the existing traces.
Here is the JBL system from engineer listening position, below 400Hz. Please note the linear frequency axis, as I find it more readily displays linearly spaced modal issues.
Red trace= JBL Left
Green Trace = JBL Right
Blue Trace = JBL L+R
And now for the Yamaha system:
Purple Trace= Yam L
Teal Trace = Yam R
Gold Trace = Yam L+R
In both cases, note the +6dB amplitude when both channels are playing together.
Overlaying the Group Delay traces shows clear resonance issues at about 74 Hz and about 105 Hz:
So, onto the treatment:
We installed a RealTraps MondoTrap in each of the four wall corners. In the rear of the room, the traps are suspended, straddling the corner about halfway up. In the front of the room, we have a temporary floor placement until I get around hanging them. On the right, it straddles the corner. On the left, it's flat against the side wall into the corner because of the doorway.
Additionally there are three RealTraps Near-style diffusors across the back wall of the room. Here's a photo:
Let's look at the before and after traces. Again, note the linear frequency axis.
In all of the following traces, black is the original trace and red is the trace after treatment.
JBL Left channel
JBL Right Channel:
The nulls near 190 Hz and 270 Hz have improved considerably, almost 20 dB in the former case.
JBL L+R
Big improvements around 110 and 275.
Yamaha L:
Yam R:
Significant improvement above 175.
Yamaha L + R
Sample phase data:
JBL L channel
One thing we've had very good success with is a clean listening environment in terms of early reflections. This is mostly the effect of the existing treatment as our newest treatment focused on LF, but here's the ETC plots.
JBL:
Yamaha:
Only a couple of ERs and they're -15dB.
Finally, let's look at RT60.
JBL:
Yamaha:
I would interpret this as a moderate reduction in LF ringing.
Oh. Anyone heard of this guy?
Okay, that just about does it. Anyone have thoughts or alternative insights? Please do share. (Ethan, that means you!)
As part of a series of ongoing improvements in the recording studio I engineer for, we added some acoustic treatment to the control room. I have some photos and a ton of measurement data, and I thought you guys and gals might be interested. Grab a snack, it's going to be a long one.
Some background: This is a project studio, so both the live room and the control room are on the small side. Specifically, our control room measures 13'6" long, 14' wide, and 8'3" high. That's to the drop ceiling; there's another 9" or so above that which is packed full of fluffy pink stuff. The room was originally 14' square, but the reason it's shorter front-to-back is because the rear wall is treated with 4" of Owens-Corning 705 FRK spaced 2" from the wall. The back corners are straddled with slightly more 705 but not enough to constitute a serious bass trap. The ER points on the side walls and ceiling are treated with 705 as well. The front wall is untreated and, as par for recording studios, has a large window and a door that leads to the live room.
Engineer listening position is located slightly right of center line, 6'6" from the right wall and 6'6" from the front wall, with a Z height for seated engineer / reference mic at 4'.
The monitoring system consists of two separate rigs: a Yamaha and a JBL, each with a sub. I believe both systems use ƒc = 100 Hz but I’m not positive.
Obligatory crappy photo:
Yes, that is the Slate Raven MTi 2.
(For the gearheads, the rest of it is: Furman HDS-6 headphone distribution, PreSonus Central Station PLUS, Antelope Orion32 AD/DA, TrueSystems Precision8 preamps, Neve 5024 preamps, AEA TheRibbonPre, Avid ArtistMix control surface.)
To see larger versions of any of the images in this post, right-click and hit "Open Image in New Tab."
Currently, the subs for both systems are placed against the front wall, centered in front of the listener. REW Room Sim predicts the following curve below Schroeder(ish) accounting for axial modes only:
I guessed at the absorption coefficients but we can see the modal situation.
If we were able to move the subs for both systems into the front right corner and create eighth-space loading, we’d get this:
Unfortunately that would require a bit of rearranging the room.
So looking at the treatment options, we start by looking at the existing traces.
Here is the JBL system from engineer listening position, below 400Hz. Please note the linear frequency axis, as I find it more readily displays linearly spaced modal issues.
Red trace= JBL Left
Green Trace = JBL Right
Blue Trace = JBL L+R
And now for the Yamaha system:
Purple Trace= Yam L
Teal Trace = Yam R
Gold Trace = Yam L+R
In both cases, note the +6dB amplitude when both channels are playing together.
Overlaying the Group Delay traces shows clear resonance issues at about 74 Hz and about 105 Hz:
So, onto the treatment:
We installed a RealTraps MondoTrap in each of the four wall corners. In the rear of the room, the traps are suspended, straddling the corner about halfway up. In the front of the room, we have a temporary floor placement until I get around hanging them. On the right, it straddles the corner. On the left, it's flat against the side wall into the corner because of the doorway.
Additionally there are three RealTraps Near-style diffusors across the back wall of the room. Here's a photo:
Let's look at the before and after traces. Again, note the linear frequency axis.
In all of the following traces, black is the original trace and red is the trace after treatment.
JBL Left channel
JBL Right Channel:
The nulls near 190 Hz and 270 Hz have improved considerably, almost 20 dB in the former case.
JBL L+R
Big improvements around 110 and 275.
Yamaha L:
Yam R:
Significant improvement above 175.
Yamaha L + R
Sample phase data:
JBL L channel
One thing we've had very good success with is a clean listening environment in terms of early reflections. This is mostly the effect of the existing treatment as our newest treatment focused on LF, but here's the ETC plots.
JBL:
Yamaha:
Only a couple of ERs and they're -15dB.
Finally, let's look at RT60.
JBL:
Yamaha:
I would interpret this as a moderate reduction in LF ringing.
Oh. Anyone heard of this guy?
Okay, that just about does it. Anyone have thoughts or alternative insights? Please do share. (Ethan, that means you!)
