Your speakers and subwoofer only tell half the story. The other half is the room they are playing in, and the room almost always has the louder opinion. Hard walls, parallel surfaces and the distance between them create room modes: frequencies where the bass piles up in some spots and disappears in others. It is the reason a subwoofer can sound thunderous on one seat and thin on the next.
You do not have to guess at any of this. With a measurement microphone and a free program called REW (Room EQ Wizard), you can see exactly what your room is doing and make confident decisions instead of moving gear around by ear for a weekend. Here is how to get a trustworthy measurement, and how to read it once you have one.
What you need
The good news is that a proper measurement setup is inexpensive next to the gear it is protecting the performance of.
- A calibrated USB measurement microphone. A UMIK-style mic is the standard choice because it plugs straight into a laptop and comes with a calibration file for its exact serial number. We keep these in calibration gear.
- A laptop with REW installed. It is free, and runs on Windows, macOS and Linux.
- A mic stand, or anything that holds the mic steady at ear height in your main listening seat.
- A way to play REW's test signal through your system, usually an HDMI or USB connection from the laptop to your AV receiver or amplifier.
Setting up for a measurement you can trust
A measurement is only as honest as the setup around it, so spend a few minutes here.
Load the calibration file. When you first open REW it will ask for your mic's calibration file. Use the one that matches your microphone's serial number, not a generic one. This is what turns a cheap mic into an accurate instrument.
Position the mic properly. Put it exactly where your head sits, pointing at the ceiling, at ear height. For a first look at the bass, one seat is fine. When you want to optimise for the whole lounge or a row of seats, you will take several measurements across the seating area and work with the average.
Set a sensible level. Run REW's level check and aim for a test tone that is clearly audible but not uncomfortable, around 75 dB is a common target. Too quiet and the measurement is noisy; too loud and you are just annoying the neighbours.
Kill the background noise. Turn off the dishwasher, the ducted air conditioning and anything with a fan. REW measures everything the mic hears, including your fridge.
Taking the measurement
With that done, the measurement itself takes seconds. Run a full-range sweep from REW's Measure button and let the test tone play through. REW will show you a frequency response graph almost immediately: the horizontal axis is frequency from deep bass on the left to treble on the right, and the vertical axis is level.
For room and subwoofer work, the part that matters most is everything below about 300 Hz, and especially the 20 to 120 Hz region where room modes live.
Reading the graph without a degree in acoustics
You are not looking for a perfectly flat line. Real rooms are never flat, and chasing a ruler-flat response is a fast way to make a system sound worse. You are looking for the big, obvious problems.
Peaks are the tall spikes. These are room modes reinforcing a frequency, and they are what make bass sound boomy or one-note. A stubborn peak at, say, 45 Hz means that note is being played much louder than the ones around it.
Nulls (also called dips) are the deep, narrow valleys where a frequency has largely cancelled itself out. Nulls are the more frustrating of the two, because unlike peaks you usually cannot fix a deep null with EQ. Turning that frequency up just wastes amplifier power on energy the room keeps cancelling. Nulls are solved by moving the subwoofer or the seat, not with a dial.
The general slope should tilt gently downward from bass to treble in most home theatre rooms. A slight lift in the deep bass is normal and pleasant. A giant peak or a canyon-deep null is what you are hunting.
Turning the measurement into a better room
Once you can see the problems, the fixes follow a clear order, and it is worth doing them in this order because each step is cheaper and more effective than the one after it.
- Move things first. Placement is free and more powerful than any EQ. Shifting the subwoofer along a wall, or your seat forward or back by half a metre, can move a null right off your listening position. Our Room Mode Calculator predicts where your room's modes fall from its dimensions, which gives you a sensible starting point before you even pick up the mic.
- Add a second subwoofer. Two subs in the right spots average out the room's peaks and nulls far more evenly than one sub ever can, so every seat gets more consistent bass. It is the single biggest upgrade most rooms can make. Browse the range in subwoofers.
- Then EQ what is left. Once placement has done its work, a room-correction processor or a MiniDSP can gently pull down the remaining peaks. EQ is the finishing tool, not the first resort, and it is best used to cut peaks rather than fill nulls.
When to let us do it
Measuring your own room is genuinely rewarding, and for a lot of setups a mic, REW and an afternoon are all you need. But if you would rather have it dialled in properly, or you are commissioning a dedicated room where the acoustics need to be right the first time, this is exactly what we do every day. You can book a consult and talk to a specialist, or have us handle the full reference calibration.
Either way, the principle is the same one we have worked to since 2009: measure, do not guess. Your room will tell you what it needs if you give it a way to speak.
