Plan Your Acoustic Treatment Before You Buy: 4 Free Tools
Most rooms need less acoustic treatment than people order, placed in the right spots. Before you buy panels or bass traps, four free browser tools from The Audio Stuff show you what your room is doing. They run in the browser with nothing to install, and the order below takes you from measuring the room to checking the result.
1. Find your room's problem frequencies
Start with the Room Mode Calculator. Enter your room's length, width and height in metres or feet, measured wall to wall at floor level. It lists every standing wave below 300 Hz, the bass notes your room will boost or swallow, and scores the room from 0 to 100. A 3D pressure map shows where each of those notes is loud or quiet, and you can drag your seat and speakers around to see what changes. It also handles L-shaped, round and arched-ceiling rooms.
Every standing wave below 300 Hz in a 5.5 x 4.2 x 2.7 m room. The tall red spikes are the strongest.
Two things to take from it before you spend anything. If your chair sits where a strong mode cancels out, moving the chair or the speakers is free. Whatever is left builds up in the corners, and that is where a bass trap does the most work.
The 3D pressure map: warm areas are loud, cool areas are quiet. Drag the seat and the speakers to see what changes.
The London BT (a pair) mounts in the room corners where bass collects. The MaxTrap (corner) and FullTrap (flat wall) put a Broadway panel in front of a suspended diaphragm that soaks up the deepest bass. The Cumulus Tri-Corner (a pair) goes where two walls meet the ceiling and leaves a 17 inch air cavity behind it. See every option in bass traps.
2. Pick the right panel thickness
The Acoustic Panel Calculator answers "2 inch or 3 inch?" before you order. Choose a thickness, a material and the air gap behind the panel, and it plots how much the panel absorbs from 20 Hz to 8 kHz, with the NRC and the lowest frequency where the panel starts to work well. The page says NRC is useful for paperwork and useless for bass, and it is right, so watch the low end of the chart.
A 2 inch fibreglass panel flat on the wall: strong from about 630 Hz up, very little below 200 Hz.
Primacoustic's lab figures for its Broadway panels show the same thing. At 125 Hz a 1 inch panel absorbs 0.17, a 2 inch panel 0.45 and a 3 inch panel 0.92, while the 2 and 3 inch panels both rate NRC 1.00 (Primacoustic engineering data sheet, Riverbank Acoustical Laboratories). If the Room Mode Calculator showed trouble in the low end, the extra inch matters. If your problem is echo and harsh reflections, 2 inch panels at the side walls and above the desk cover it.
The 3 inch Broadband panel is in stock now. The 2 inch Broadband panel comes in grey, black, linen and arctic white. Both are 24 x 48 inches and made from 6 lb high-density glass wool. More sizes and finishes are in wall panels.
3. Hear the problem, then hear the fix
Numbers are easier to trust once you hear them. Open the Tone Generator, set a slow sine sweep from 20 Hz to 200 Hz, and listen from your seat. The notes that jump out or vanish are the room modes from step 1. Write them down, treat the room, and run the same sweep again. Start with your volume low: the page suggests about -20 dBFS and never above 95 dB SPL for steady tones.
The Tone Generator set to sweep 20 Hz to 200 Hz on a log scale.
If you would rather buy one box than plan every panel, Primacoustic's London room kits bundle panels and mounting hardware sized to the room.
The London 8 suits rooms up to 100 sq ft, the London 10 rooms up to 120 sq ft, and the London 12 rooms up to 150 sq ft.
4. Check the monitors are set up right
Treatment cannot fix a speaker wired backwards. Run the Speaker Test right after you set up your monitors. It plays pink noise on the left, then the right, so you know the channels are not swapped. A phase check plays the same noise in and out of phase, so you can hear if one speaker is wired backwards. A bass test steps from 200 Hz down to 20 Hz to show where your monitors run out of low end.
The Speaker Test: the channel check, the phase check and the bass steps from 200 Hz down to 20 Hz.
If the bass test makes the desk buzz, the monitors are shaking the furniture. Primacoustic Recoil Stabilizers sit under each monitor and keep the stand or desk from ringing along with the mix.
Where to go from here
Measure first, treat the corners and first reflections, then measure again. If you are still deciding between absorption and bass trapping, our guide to panels and bass traps walks through it.
Frequently Asked Questions
Should I buy bass traps or wall panels first?
Run the Room Mode Calculator first. If your problems sit below about 300 Hz, start with bass traps in the corners. If the room sounds echoey or harsh, start with panels at the side walls and above the desk.
Is a 2 inch panel thick enough?
For echo and reflections, yes. For bass, a 3 inch panel does much more: Primacoustic measures 0.92 absorption at 125 Hz for its 3 inch Broadway panel against 0.45 for the 2 inch.
Do these tools cost anything?
No. All four run in the browser with nothing to install.
How loud should test tones be?
Quiet to start. The Tone Generator page suggests about -20 dBFS and never above 95 dB SPL for steady tones, because a sustained tone puts far more energy into a tweeter than music does.