Try moving a speaker twenty centimetres forwards, turning it in slightly less, or moving your listening chair a little further away from the back wall. Such small changes can have a surprisingly big effect. The bass becomes smoother, a voice sits more naturally in the soundstage and instruments are given more space around them. The music seems to come away from the speakers, whilst nothing about the system itself has changed.
The room always plays a part
Every room colours the sound. Hard floors, glass and bare walls reflect sound, whilst corners can amplify low frequencies and large surfaces can cause sound to linger in the room longer than you’d actually like.
That doesn’t necessarily have to be a problem. A room should have character, and a completely soundproofed room often sounds just as unnatural as one where everything echoes.
It’s therefore not about maximising damping, but about balance. A rug can make a difference, as can curtains, furniture, a bookcase or a few well-placed acoustic panels. Not to kill the sound, but to bring a bit of calm.
Broadly speaking, there are three types of acoustic measures, each of which does something slightly different: absorption, diffusion and surface treatment.
Absorption draws energy from reflections. This is particularly useful in places where the sound becomes too loud, sharp or unsettling, for example at the first reflection points on the side walls.
Diffusion works differently. A diffuser does not so much remove the sound as scatter it in different directions. This keeps the room lively, whilst breaking up disruptive, strong reflections. Diffusers are particularly useful when the room is already sufficiently dampened but still sounds a bit flat or too direct.
They are often installed on the wall behind the listening position, provided there is sufficient distance from the listener. They can also work well on the front wall, between or behind the speakers. It is best not to place a diffuser too close behind your head; it needs some distance to allow the scattered sound to blend properly with the direct sound.
Bass traps, on the other hand, target the low frequencies. Low frequencies carry a lot of energy and tend to build up in corners and along walls. The result can be bass that sounds too heavy on some notes and fades away on others.
Bass traps are therefore usually placed in the corners of the room, often in the vertical corners behind the speakers or in all four corners if there is space for them. The junction between the wall and the ceiling can also be an effective spot. They are particularly useful when the bass continues to rumble or lingers for too long, even after the speaker and listening positions have already been optimised.
An important point to note: bass traps do not resolve every dip in the frequency response. Some dips are caused by the position of the speakers and the listening position and are better remedied by adjusting the position rather than by adding more material.
The listening position matters too
Perhaps one of the most underestimated components of an audio system is the chair. In the bass range in particular, a difference of half a metre can make a huge difference.
In one spot, the bass might sound heavy and pronounced, whilst just a little further away it suddenly sounds much more natural. That’s why it’s worth not only moving the speakers around, but also adjusting your own position. It costs nothing and can yield surprisingly good results.
Measuring to gain a better understanding
If, after listening and adjusting your position, you want a bit more guidance, you can measure the room. That sounds more complicated than it is. With a simple measurement microphone and free software, you can visualise in a few minutes what’s happening between your speakers, your room and your listening position.
Such a measurement doesn’t necessarily tell you what sounds right or wrong. Think of it primarily as additional information: for example, you might hear that certain bass frequencies are too prominent, and you can then see from the measurement where that’s happening. This makes it easier to narrow down your search.
Get started yourself: a simple step-by-step guide
1. Choose a standard reference track. Use a couple of tracks that you know inside out. A good reference is Nils Lofgren – Keith Don’t Go (Acoustic Live). The recording makes it relatively easy to assess whether the guitar sounds natural, whether the applause and hall acoustics are given sufficient space, and whether the vocals and guitar are convincingly positioned between the speakers.
It’s also best to choose a track with a well-recorded, continuous bass line. It’s precisely in the lower frequencies that issues with the room acoustics quickly become audible.
2. Start with a logical basic formation. A good starting point is an approximately equilateral triangle: the distance between the two speakers is roughly equal to the distance from each speaker to your listening position. For example, if the speakers are 2.5 metres apart, start with a listening distance of approximately 2.5 metres.
If space allows, try to position the speakers at least 50 centimetres away from the wall behind them and from the side walls. Larger floor-standing speakers may require more space. Always measure from the same point, such as the front of the speaker.
Ensure that both speakers are positioned as symmetrically as possible and that the tweeters are approximately at ear level. Treat these distances primarily as a starting point, not as fixed rules.
3. Build on that foundation, taking small steps. Next, move the speakers in increments of ten to twenty centimetres. Pay particular attention to changes in bass reproduction, focus and depth. Only when the position in the room feels right would I start experimenting with the tilt angle.
Increasing the angle of inclination often results in sharper focus and a clearer central image. Reducing the angle of inclination can make the stereo image wider and more airy. What works best depends very much on the speakers and the room.
4. Next, find the best place to listen. It is best not to place the chair right up against the back wall, nor exactly halfway along the length of the room. Both positions can exacerbate bass issues.
As an initial experiment, a distance of around 35 to 40 per cent of the room’s length, measured from the wall behind the speakers, is sometimes used. Again, regard this primarily as a starting point. Then move the chair in increments of twenty to thirty centimetres and listen to how the bass changes.
5. Next, take a look at the room itself. If the sound remains loud or uneven, start with the most obvious reflections. A rug between the speakers and your listening position, curtains on large windows, or sound-absorbing materials at the primary reflection points can make a big difference.
A simple way to find such a reflection point is the mirror method: ask someone to move a mirror along the side wall whilst you’re sitting in the listening position. Wherever you see a loudspeaker in the mirror, there is a significant primary reflection point.
If the sound in the room then becomes a bit dry or flat, diffusion may be a better option than adding more absorption. A diffuser on the rear wall or, if necessary, between the speakers can help restore a sense of spaciousness without creating new harsh reflections.
6. Learn to recognise when things are going wrong. Problems usually give fairly clear warning signs. A bass that suddenly sounds much louder on certain notes often indicates room resonance. If, on the other hand, certain low frequencies disappear almost entirely, this may be due to a phase cancellation between direct and reflected sound.
If low frequencies linger for a long time, a bass line sounds sluggish, or a single frequency seems to remain suspended in the room, a bass trap may be useful. This is particularly the case when the problem recurs at multiple listening positions and does not disappear simply by moving the chair or the speakers.
A voice that isn’t centred, a stereo image that seems larger on one side, or a recording that becomes noticeably sharp and harsh, may indicate asymmetry or strong early reflections. An audible, metallic echo when you clap your hands in an empty or hard-surfaced room is also an indication that too much energy is bouncing back and forth between parallel surfaces.
The interesting thing is that you usually don’t need specialist knowledge for this. Once you know what to look out for, these kinds of characteristics become recognisable quite quickly.
7. Use a measurement as an extra pair of eyes. If you want to understand what you’re hearing better, you don’t need much. A simple USB measurement microphone, such as a UMIK-1, a laptop and the free Room EQ Wizard (REW) programme are all you need to get started.
Place the microphone where your head would normally be, roughly at ear level. REW will then play a short tone through your audio system, ranging from low to high. It might sound a bit strange at first, but a few seconds later a graph will appear showing what’s happening at your listening position.
You don’t need to be able to read the graph in full. To begin with, focus mainly on the low frequencies. If you see large peaks there, this usually means that certain bass tones are being amplified by the room. A deep dip, on the other hand, may explain why a particular tone is barely audible.
Next, go back to what you heard whilst listening. If that one bass note is consistently too pronounced and you see a clear peak in the graph at roughly the same spot, you’ve probably found a correlation.
Next, move the chair or the speakers, for example, and take the same measurement again. Place the two graphs side by side. This will immediately show whether a change has made a difference.
REW can also show how long certain tones linger in the room. This is particularly useful when assessing whether bass traps are needed. If you notice that low frequencies clearly persist for longer than the rest of the spectrum, this often confirms what you already heard whilst listening.
When it comes to diffusion, measuring is less straightforward. Listening remains important here: if the stereo image becomes more spacious and natural without losing focus, you’re usually on the right track.
So simply start with three questions: where are the biggest anomalies, can I recognise them whilst listening, and what happens if I move or add something?
This way, measuring isn’t an end in itself, but a tool to help you understand more quickly what your ears are already telling you.
Ultimately, it’s all about the music
Good acoustics don’t draw attention to themselves. Instead, they fade into the background, so you think less about the room, the speakers or the technology.
Measuring, adjusting and treating are ultimately not ends in themselves. Their purpose is to ensure that a voice naturally finds its place, that a double bass doesn’t wander around the room, and that a recording is given the space it deserves.
What remains is music.
And when that happens, there’s really little else needed.
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