Do you want bass that gives you goosebumps…

…and not just BOOOMY sound?

Welcome to the second episode in our series about subwoofers. In the first episode, you heard how sound has changed from almost no bass in the 70s and 80s to deeper bass in the 90s and onwards. The new sound makes music bigger and more engaging and requires a music system with updated performance. This episode is about something crucial for our sound experiences. We call it speed.

Most subwoofers are built according to one of two principles:

• Bass reflex (ported) – fantastic for creating low frequencies.
• Sealed enclosure – incredibly fast and precise.

Why does speed matter? Because it determines whether you experience music – or (something like) a bunch of tones muddled together.

Speed = musical bass

Speed is about how quickly the subwoofer can start and stop. It is measured in milliseconds, but we hear it as timing and rhythm.

When the subwoofer is fast, the bass notes begin and end at the right moment and give the sound shape and direction.

When the subwoofer is slow, the notes blur together. The rhythm loses energy, the music becomes heavier, and the bass sits like an extra layer on top of the sound instead of becoming a natural part of it.

Our ears are sensitive to timing, and when a delay becomes longer than about 30–50 milliseconds, we can hear that the sound is no longer integrated. Milliseconds are not just numbers.

It is the difference between bass that follows the music and bass that arrives too late. That is why a subwoofer must stop faster than 30–50 milliseconds, so the bass blends with the rest of the sound.

The technical term for this delay is group delay. It describes how much time passes from the moment the subwoofer receives the signal until the acoustic energy is in the room.

Two subwoofers can have almost the same frequency range on paper but sound completely different in real life. That is why speed is so important – and why it should be easy to compare.

Why specifications don’t tell the whole truth

When choosing a subwoofer, it is tempting to look at the technical specifications and search for the model with the deepest bass. But one of the most important pieces of information is missing: the subwoofer’s speed (group delay) is almost never listed in the specifications.

As a customer, you can’t simply look up the number. You can’t compare the models on paper. And in many stores, you are not given the opportunity to hear several subwoofers under the same conditions. That makes it easy to choose deep bass on paper, but slow bass in real life.

You can often hear the difference between fast and slow bass with ordinary music. Listen to a track with clear bass. If the bass is fast, it follows the rhythm.

If it is slow, it makes the sound heavier. This is where specifications are not enough. Your ears reveal whether the subwoofer is playing music – or just producing tones.

We make fast subwoofers

Speed requires a different approach to subwoofers. Our models are built according to the sealed enclosure principle, which reacts faster than bass reflex.

They stop in just 10 milliseconds. That is far below the delay our ears can normally hear. This allows the bass to fall into place in the music – precisely, naturally, and without arriving too late.

But sealed enclosures have one challenge: They are not as good at the very deepest frequencies. That is why we use another tool.

We utilize room acoustics

A subwoofer should play with the room – not against it. That is why System Audio subwoofers are designed to be placed close to a wall or in a corner.

Surfaces amplify the sound and a wall gives an effect equivalent to doubling the size of the subwoofer. A corner amplifies even more – like a natural horn. We have factored this effect into the design, so our subwoofers can be smaller, but still sound big.

Silverback Sub Solo and Sub Duo have built-in wall mounts, so they’re easy to hang on the wall without causing vibrations. Signature Sub 8 is designed for both corner placement and close to a wall and works perfectly in music systems or home theaters.

Precision down to the millisecond

Sound travels about 3 milliseconds per meter. This means that even small distances affect precision. SA Cockpit – our app – can fine-tune the system down to the smallest detail.

Here you can set the distance for each speaker, so the sound from all units reaches your ears at the same time. This is crucial for a perfect sound experience.

Signature Sub 8 also supports this feature when used with Stereo Hub HT and Surround Hub.

Summary

This was the second episode in our series about subwoofers. You have heard why speed is crucial for a good subwoofer: A slow subwoofer makes the sound stay in the room too long, while a fast subwoofer delivers precision and rhythm that blend with the rest of the sound of the soundstage.

You have heard why speed is difficult to evaluate as a customer. Group delay is rarely listed in the specifications, which means two subwoofers that look similar on paper can sound very different in real life.

We have talked about how System Audio combines sealed enclosure technology with the power of acoustics and intelligent control to create subwoofers with both speed and depth.

The next episode is about another issue that affects us all: We play at low volume 95% of the time, and that means our ears hardly hear bass. We have technology that makes bass audible at low volume. More about that next time!

Looking for Episode 1 ? Here it is