Most people don't know their system is running out of headroom. Instinctively we want to defend what we have. Surely nothing's wrong with our system. Instead we make up other reasons why we choose not to play loud.
A short diagnostic
- Do you reach for the volume control to turn it down when a piece of music opens up: The full orchestra, the chorus entry, the drop?
- Have you concluded that certain albums are "badly recorded" or "compressed," while other albums sound fine?
- Does your system sound best at moderate volume, and have you decided that's simply your preference?
- Have you gradually stopped playing certain records?
- Do you feel like your room can't handle loud music?
If several of those are true, you probably have a headroom problem.
Distortion and compression aren't always obvious, nothing necessarily sounds broken. The music just gets flatter, harder and less involving as it gets louder, and the natural response is to turn it down and conclude you like it quieter. Or that it must be the room.
What actually happens
1. Excursion. A driver can only move so far before its motor leaves the linear part of its travel. Push past that and distortion rises steeply. This is the dominant limit especially at low frequencies.
2. Thermal compression. As a voice coil heats, its resistance rises, so it draws less power for the same input voltage. Dynamics flatten. It happens gradually across a listening session. The system that sounded alive in the first ten minutes somehow runs out of steam.
3. Amplifier clipping. Usually the last to arrive in a well-designed system, and the most audible when it does.
A speaker doesn't necessarily fail completely at its limits, it degrades more subtly. And it usually starts degrading well below whatever "maximum SPL" number is specified by the manufacturer. If there even is such a number published.
Working out what you need
Step 1: Your real peak level
Most people badly underestimate this, because they think in terms of average level while the speaker has to reproduce peaks.
The gap between average and peak is called the crest factor. For heavily compressed pop it might be 10–12 dB. For a well-recorded, dynamic recording it's commonly 18–20 dB, occasionally more. So 2x-4x of perceived loudness.
So:
- Comfortable average listening level: 85 dB
- Crest factor of a dynamic recording: 20 dB
- Required peak capability: 105 dB
85dB isn't crazy loud, roughly the level of an animated dinner party. You need 105 dB peaks. Every one of those peaks has to be reproduced without compression to faithfully convey your music and avoid listening fatigue from distortion. You can use a simple SPL meter on your phone to get a feeling for how loud you normally listen.
Step 2: Distance
In a typical domestic room, the loss is slightly less than free-field (6 dB per doubling), because reflections help.
2m listening distance: 4-6dB loss from a 1m specification
3m listening distance: 7-9dB loss from a 1m specification
4m listening distance: 9-12dB loss from a 1m specification
So a 105 dB peak at a 3 m listening position requires roughly 112–114 dB at 1 m from the speaker.
This is a number that most compact loudspeakers cannot dream of achieving. A surprising amount of floorstanders will struggle too.
Step 3: Low frequencies
A speaker makes bass by moving air. Did you know that to play an octave lower at the same volume, it has to move four times as much air? That's why deep bass at real levels needs big drivers, or many of them.
And getting the output at all is only the first obstacle. The second is to reproduce it in a linear, non-distorted fashion. This is why our SBS and Manta speaker systems make so much sense, as this allows the bass to be handled by subwoofers. And you can build out with as many subwoofers that are needed to reach the desired capacity.
What this means practically
If you listen at moderate levels, in a small room, a well-executed compact active speaker may have all the capability you will ever use. Spending more on output is spending on nothing.
But if any of the following are true, output capability is likely to be your binding constraint, and no amount of refinement elsewhere will compensate:
- A room above roughly 30 m² / 300 square feet, and/or with an open-plan connection to other spaces
- A listening distance of 3 m or more
- Any interest in playing at levels approaching those of the original performance
- Home cinema use alongside music
There's no real standard on how brands define their SPL capabilities. You have to hear a system with genuine headroom, playing material you know well, at a level you'd normally back away from. Notice whether the impulse to reach for the volume control appears at all.
What Sigberg Audio does differently
Even our smallest system has very high dynamic capacity, and all our systems are built from the ground up to provide realistic sound levels without falling apart. This focus on capacity isn't about playing loud for its own sake. It's simply what's needed to maintain a natural sound for your favorite music at realistic sound levels. This also means that at moderate listening levels the distortion is vanishingly low.
With enough headroom, loud still sounds loud. But in a way that makes you want to turn it up, not down.
