Acoustics Doesn't Matter?

Arts & Entertainment

  • Author Spencer Miles
  • Published May 22, 2023
  • Word count 886

Lancaster Pennsylvania is a hotbed for home recording studios and artists practicing their craft before linking up to get their mixes done by a pro in the studio. My name is Spencer, the owner of Spencer Studios. This is our first blog post and today we're going to talk about why the acoustics in your studio matters more than those fancy monitors you may have been talked into purchasing for their "ultra-flat frequency response."

My first recommendation to home audio engineers and clients is to buy a nice pair of open back reference headphones. An increasingly popular option being acoustic simulation headphones such as the slate VSX that simulate a virtual studio environment. I say this because acoustic treatment can be expensive and difficult to implement correctly. Reference headphones, while not a perfect solution remove the variable of your room from your sound. When an audio engineer uses headphones the sound goes directly from the transducer to their ears. When we use monitors the sound is created at the transducer, goes into the room and then reaches the ears. Rooms have their own reverb time and frequency response. When you work with monitors in a room, if the frequency response is not even you are not able to hear an accurate version your mix. Small rooms as an example, commonly have issues with bass build up and room modes, especially if your speakers are against the wall. A result is that bass sounds louder than it actually is. When you mix in this environment bass will sound louder than it exists in the mix and you will end up with a final mix lacking bass as a result when it is played on a system other than your monitors outside of your room.

Let's take a look at the frequency response of an untreated small room using small 4inch $100 budget monitors against the wall.

The first thing you notice is a massive bass buildup of around 20db. The next thing you see is a rather jagged frequency response. The overall frequency response is plus or minus 22db. You may wonder how can this be? The frequency response of the speakers was shown online to be flat. The answer to this is the speakers are interacting with the acoustics of your room.

To avoid bass build up, our monitors need to be spaced from the wall however, not any space will do. If we don't move the monitors at least 1.3 meters off of the wall we run into the issue of speaker boundary interference which will make the frequency response worse. In most homes our rooms are multipurpose and moving the monitors 12 feet off of the wall isn't feasible. The answer here is to use the built in eq the most monitors have on the back and turn the low frequency down likely by 6db or more.

If you want to know more about speaker placement check out this free article from genelec: https://www.genelec.com/monitor-placement

Now that we have solved the bass issue it's time to tackle those jagged peaks. These peaks are occurring because sound is traveling out of your speakers hitting the closet wall or boundary and then interfering with sound directly as it hits your ears creating dips and peaks or comb filtering. We must treat our first reflection points ideally to the sides at a minimum, but also the ceiling and potentially your desk. The way to locate these points is to sit in your listening position. Have another person move a mirror parallel on the boundary until you can see your monitor in the refection. Anywhere you can see your monitor in the reflection is a place that will need treatment of at least a 2 inch absorber minimum. If you look at the graph above we have some comb filtering even at 500hz. Thin 1 inch panels simply aren't thick enough to absorb that low of a frequency in an effective manner.

Now that we have treated our first reflections, avoided SBI issues, and EQ'd our bass build up let's see what our frequency response looks like now.

We now have a significantly flatter frequency response across the spectrum. You may be wondering why the small ripples still exist. The first reason is that the monitors used in this example are what we would call budget studio monitors and were not perfectly flat to begin with. The second reason is that we did not discuss room modes. Room modes are a result of pressure build up due to the size constraints of your physical space with relation to the physical length of lower frequencies. Lower frequencies do not fit freely in small spaces and as a result of what you might call squishing you have an increase in pressure that exists at a fundamental frequency and the harmonics above. Treating bass modes is expensive, can consume a great amount of space and also requires specific positioning none of which are conducive to a multipurpose home studio so for the purposes of this article we are going to call a frequency response of plus or minus 5db a win. Consider that many budget monitors are just under that threshold of +- 4.5db so we are very close.

If you want to know more consider scheduling a free first session with us,

Spencer Miles

Spencer Studios

313 W Liberty St, Lancaster, PA 17603

spencerstudios.info

spencerstudios.info/blog

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