We regularly write about the technical side of our hi-fi hobby. We also test numerous devices. From speakers to amplifiers, streamers, cables and countless tweaks. However, there is one crucial element that we have also written about, but not enough: acoustics. Let’s take a closer look right now!
To make a statement right away: the room is responsible for more than 50% of the playback quality. And to explain that statement, let’s give an extreme example: just put a decent hi-fi system in an empty, concrete room. It will sound horrible. Next, put the same system in a anechoic chamber. That’s also going to sound terrible, but in a very different way. Finally, put the system in a nice, balanced studio or listening room: now the system will most likely sound excellent. You get our point now, we assume.
Balance
What acoustics is basically about, is a balance between energy being diffused (reflection) and excess energy being “dampened”: absorption. So with diffusion or reflection, the energy is not lost directly, but is distributed more widely across the room.
Absorption does involve ‘absorbing’ energy. Now energy is never simply lost (law of energy conservation), but the vibrations (or pressure) are converted into heat. However, the heat generated is very small and cannot be felt by a human being.
So the trick is to find a balance between ‘spreading’ the sound via diffusion and absorbing energy (mostly the so-called ‘room modes’) via absorption.
Measuring
Now, finding the balance seems to be a matter of foolishly trying things. And you can, but let’s face it: randomly dropping diffusers and absorbers in the room and hoping for good results is not really a sound plan. Better to simply measure the room properly first to gain insight into the problem areas you need to address.
Now you will probably understand that a measurement can be slightly different with system A or system B. This is due to both the tuning of a system and the bandwidth in which you measure. A full range system can reveal a problem in the bass that a pair of monitors playing from 50 Hz does not have. It’s not that the room suddenly acts different; the speaker simply ‘activates’ certain room modes, or not. Usually this is the case in the lower frequencies; the more bass, the bigger the problems usually become.
Free
There is a lot of software on the market that allows you to measure the room. A fair amount of good software is just free. Consider REW – Room EQ Wizzard. This is one of the best software packages to do a decent measurement with. It does take some figuring out exactly how it works, but the manual is pretty clear, we must say.
Other than that, of course, you need a microphone to do the measurement with. The MiniDSP USB microphone is a good option: not super expensive, but decent quality and it comes with a correction file to compensate for deviations of the microphone frequency respons: not unimportant.
Next episode
In this episode we simply wanted to point out that acoustics are important and why. In the next installments, we will discuss diffusion and absorption, fume boxes, active and passive correction, measurement and, for example, how to place speakers.