Text: Omer Karni
Only after the studio has properly processed can you get a beautiful and balanced mix from the speaker. This practical step-by-step guide will explore how to acoustically handle a home studio for better mixing.
Most musicians, producers and mixing engineers tend to be a little nervous when it comes to the topic of “acoustic processing”, especially when it comes to their own home studio. It is crucial to correctly understand the physical principles of sound waves. Countless factors can change the frequency response , reverberation time (RT60), stereo sound field, clarity, impact force, etc.
Home Studio Home People are blessed! Without having to get too deep into physics, today you can know how to fix your room and fill it with the golden value of the mix.
1. Find the right room for your audio studio
When it comes to rooms that are suitable as studios, the first choice we look for is a rectangular room. The recommended minimum size, for example, is 3.2x2.7 meters. But if you have to compromise, then just go for a moment. Being able to make the ready-made room the best is victory.
2. Place your speaker correctly
Step 1
You need to place the monitor speaker on the floor stand, as close to the narrow wall of the room as possible. The distance between the two speakers is about 1.1-1.3 meters, and the distance from the walls on both sides is equal. If the house has windows, don't worry. Fresh air and daylight are usually more important to your studio than the acoustic advantage.
Step 2
Plant for the first measurement and place the microphone at a perfect equilateral triangle distance from the speaker.
Note: In a small room, the microphone will be placed around 35%-40% of the room (that is in front of the midpoint of the room). In larger rooms, you may need to increase the distance between speakers slightly to place the microphone beyond 1/4 of the room (the exact 1/4 and midpoint positions are usually not good for the microphone and your future ear listening).
The first measurement will show the room mode of your studio space. The room mode is the room resonance frequency caused by 3 sets of parallel surfaces, and the calculation method is to divide the speed of sound (343 meters/sec) by twice the distance between parallel walls.
For example: if the room is 3.8m long/2.9m wide/2.6m high, the room mode will be:
343/(3.8x2) = 45.1hz
343/(2.9x2) = 59.1hz
343/(2.6x2) = 65.9hz
This means that your frequency response will display peaks and zeros around these frequencies and their primary harmonics (90.2hz, 118.2hz, 131.8hz), depending on where the microphone is placed during the measurement. The RT60 reverberation time chart will then display longer reverberation times on those same frequencies.
*RT60 = The time required for a certain frequency to decay 60db.
Don’t worry about medium and high frequency for the time being, let’s focus on 150Hz and lower frequencies first. Room SPL measurement before
treatment.
room RT60 measurement before processing.
Now, the mathematics and physics parts are finished! Let's continue to work on the best and most satisfying part of the process: Beat Room Mode!
3. Set your low frequency trap
The easiest low frequency trap DIY method is to create broadband low frequency trap using the absorption method. In small rooms, the disadvantage of this method is that it takes up space, because sound absorbing material consumes more space than other types of traps (membranes or resonators), but don't be mistaken - absorbing low frequencies is key! There are actually many "useless areas" in the room that emphasize low frequencies, and those low frequencies can be absorbed. If placed on the narrow wall of the room (the one behind you), the built-in cabinet can be used well as a low-frequency trap.
Back to our previous room example: 45.1Hz is the length mode. This frequency will be enhanced on the front and rear walls and will be offset at the midpoint of the room. Its primary harmonic 90.2Hz will be enhanced at the front, back and midpoints and will be offset at 1/4 and 3/4 of the room. You can easily demonstrate this by generating sine wave with the Room EQ Wizard - searching from front to back in the room, then changing the frequency to one harmonic and performing the same operation. Very cool, isn't it?
90.2Hz (45.1Hz primary harmonic) is a very high low frequency frequency, so it is not difficult to absorb. Putting enough sound-absorbing material on the front and back walls is likely to eliminate the resonance of the two mode frequencies. (In larger rooms, it may be necessary to add low-frequency traps to the walls on both sides of the midpoint of the room to absorb lower primary harmonics, or to increase the width of the front and rear traps).
Low-frequency trap construction
In order to absorb low frequencies and reduce their RT60, we need a low-frequency trap at least 25 cm thick. Width and height, the specifications I recommend are 1 meter wide/2 meter high. The sound absorbing material can be 40-80kg rock wool per cubic meter or 30-40kg open-hole polyurethane foam layers (the kind used by mattress manufacturers). The biggest advantage of foam is that it does not require a shell, can be easily moved during the construction process, and does not require drilling holes in the wall for installation.
Step 1
Step the first low frequency trap on the floor between the speakers and place it against the wall. Then a second measurement is performed. I would like to emphasize again: put it against the wall. Directional frequencies have the least energy when encountering walls, so the air gap in low-frequency traps is very effective in the wall position where the room mode low-frequency frequency enhances the most.
In the second measurement, you will see significant improvements in both frequency response and RT60.
Step 2
Place two to three low frequency traps side by side on the floor, lean against your back wall (depending on the room width), and take the third measurement. This should produce a minimum peak or no at the lowest room mode frequency, while a RT60 at the low frequency of 0.2-0.4 seconds.
Note: If you still see peaks in the room mode frequency, or if the RT60 exceeds 0.4 seconds, please add another layer of sound absorbing material to the back wall (two layers of the bass trap may be enough). Generally speaking, increasing the depth of low-frequency traps will be more effective than spreading them over the same boundary.
Step 3
Place another trap at the front corner of each side wall and perform measurements. These traps will handle the second room mode and its harmonics in the low and medium frequency regions. Room SPL measurement after
treatment. Room RT60 measurement after
treatment.
Step 4
Add another 5-10cm of sound-absorbing material at the untreated early reflection points (ceiling and side walls), leaving air gaps, and then measure again. Now start moving the speaker from the front wall to the listening position and move the microphone accordingly—repeat every 5 cm of movement. Separating the speaker from the front wall will increase clarity and depth, but will also cause phase problems in the low frequency.
finds the best position where phase problems will not occur. At this time, your RT60 should be about 0.2 seconds over the entire frequency range. If it is lower than the data at medium and high frequency, it means that your room is too dry and you should continue reading.
Last step
Fix the acoustic treatment material to the wall ( polyurethane can be glued to the wall with a hot glue gun), and you can start mixing!
4. Problem exclusion
a. My room sounds dead. Too dry.
When mixing sounds in a studio environment, our main goal is to communicate. The room must listen to "natural" on a conversational level before your work can be conveyed and presented well.To make the room "active", you can add perforated thin wood panels before the low frequency trap. This will make the room sound more natural and bring better results.
Note: Too many perforations may not help improve room dryness, and insufficient perforations may lead to delayed knocking. Trial and error is the only way out.
b. 110Hz – 130Hz Peak
You can try to move the table away or move the workbench to the back of the room and measure again. If the problem disappears, change to a small table and place the equipment that is not necessarily placed between you and the speaker on the side cabinet or shelf.
c. Too much medium and low frequency/not enough
You can move the speaker further away, or you can try to place the speaker in a fixed installation position on the side, with the subwoofer facing the side wall. This will bring you more low frequencies, while not making the stereo sound field too wide.
Note: The wide stereo sound field can make everything sound big and impressive, but it may sound smaller in different listening environments. I recommend you work hard with a smaller stereo setup – if the mix sounds great at this point, it will sound great anywhere.
d. In the wide band frequency range of medium and high frequencies, there is an increase or attenuation.
You can try to adjust the speaker axis to the listening position, slightly change the front and rear positions of the microphone, or adjust the built-in equalizer in the speaker.
In short, I can't guarantee you will have a flat frequency response, as each room has differences in size, shape and material. But by following these steps, you will be able to significantly improve your listening experience and mixing. I hope you can enjoy this DIY process, too.
Omer Karni, a famous acoustic expert, has designed and built hundreds of audio studios for many musicians and mixing engineers, such as the Infected Mushrooms Studio and Waves Audio headquarters.
Text: Omer Karni
Only after the studio has properly processed can you get a beautiful and balanced mix from the speaker. This practical step-by-step guide will explore how to acoustically handle a home studio for better mixing.
Most musicians, producers and mixing engineers tend to be a little nervous when it comes to the topic of “acoustic processing”, especially when it comes to their own home studio. It is crucial to correctly understand the physical principles of sound waves. Countless factors can change frequency response, reverberation time (RT60), stereo sound field, clarity, impact force, and more.
Home Studio Home People are blessed! Without having to get too deep into physics, today you can know how to fix your room and fill it with the golden value of the mix.
1. Find the right room for your audio studio
When it comes to rooms that are suitable as studios, the first choice we are looking for is a rectangular room. The recommended minimum size, for example, is 3.2x2.7 meters. But if you have to compromise, then just go for a moment. Being able to make the ready-made room the best is victory.
2. Place your speaker correctly
Step 1
You need to place the monitor speaker on the floor stand and be as close to the narrow wall of the room as possible. The distance between the two speakers is about 1.1-1.3 meters, and the distance from the walls on both sides is equal. If the house has windows, don't worry. Fresh air and daylight are usually more important to your studio than the acoustic advantage.
Step 2
Plant for the first measurement and place the microphone at a perfect equilateral triangle distance from the speaker.
Note: In a small room, the microphone will be placed around 35%-40% of the room (that is in front of the midpoint of the room).In larger rooms, you may need to increase the distance between speakers slightly to place the microphone beyond 1/4 of the room (the exact 1/4 and midpoint positions are usually not good for the microphone and your future ear listening).
The first measurement will show the room mode of your studio space. The room mode is the room resonance frequency caused by 3 sets of parallel surfaces, calculated by dividing the speed of sound (343 meters/sec) by twice the distance between parallel walls.
For example: if the room is 3.8m long/2.9m wide/2.6m high, the room mode will be:
343/(3.8x2) = 45.1hz
343/(2.9x2) = 59.1hz
343/(2.6x2) = 65.9hz
This means that your frequency response will display peaks and zeros around these frequencies and their primary harmonics (90.2hz, 118.2hz, 131.8hz), depending on where the microphone is placed during the measurement. The RT60 reverberation time chart will then display longer reverberation times on those same frequencies.
*RT60 = The time required for a certain frequency to decay 60db.
Don’t worry about medium and high frequency for the time being, let’s focus on 150Hz and lower frequencies first. Room SPL measurement before
treatment.
room RT60 measurement before processing.
Now, the mathematics and physics parts are finished! Let's continue to work on the best and most satisfying part of the process: Beat Room Mode!
3. Set your low frequency trap
The easiest low frequency trap DIY method is to create broadband low frequency trap using the absorption method. In small rooms, the disadvantage of this approach is that it takes up space, because sound-absorbing materials consume more space than other types of traps (membranes or resonators), but don't be mistaken - absorbing low frequencies is key! There are actually many "useless areas" in the room that emphasize low frequencies, and those low frequencies can be absorbed. If placed on the narrow wall of the room (the one behind you), the built-in cabinet can be used well as a low-frequency trap.
Back to our previous room example: 45.1Hz is the length mode. This frequency will be enhanced on the front and rear walls and will be offset at the midpoint of the room. Its primary harmonic 90.2Hz will be enhanced at the front, back and midpoints and will be offset at 1/4 and 3/4 of the room. You can easily demonstrate this by generating a sine wave of the mode frequency by the Room EQ Wizard - searching from front to back in the room, then changing the frequency to a harmonic and performing the same operation. Very cool, isn't it?
90.2Hz (45.1Hz primary harmonic) is a very high low frequency frequency, so it is not difficult to absorb. Putting enough sound-absorbing material on the front and back walls is likely to eliminate the resonance of the two mode frequencies. (In larger rooms, it may be necessary to add low-frequency traps to the walls on both sides of the midpoint of the room to absorb lower primary harmonics, or to increase the width of the front and rear traps).
Low-frequency trap construction
In order to absorb low frequencies and reduce their RT60, we need a low-frequency trap at least 25 cm thick. Width and height, the specifications I recommend are 1 meter wide/2 meter high. The sound absorbing material can be 40-80 kg of rock wool per cubic meter or 30-40 kg of open-cell polyurethane foam layer (the type used by mattress manufacturers). The biggest advantage of foam is that it does not require a shell, can be easily moved during the construction process, and does not require drilling holes in the wall for installation.
Step 1
Step the first low frequency trap on the floor between the speakers and place it against the wall. Then a second measurement is performed. I would like to emphasize again: put it against the wall. Directional frequencies have the least energy when encountering walls, so the air gap in low-frequency traps is very effective in the wall position where the room mode low-frequency frequency enhances the most.
In the second measurement, you will see significant improvements in both frequency response and RT60.
Step 2
Place two to three low frequency traps side by side on the floor, lean against your back wall (depending on the room width), and take the third measurement. This should produce a minimum peak or no at the lowest room mode frequency, while a RT60 at the low frequency of 0.2-0.4 seconds.
Note: If you still see peaks in the room mode frequency, or if the RT60 exceeds 0.4 seconds, please add another layer of sound absorbing material to the back wall (two layers of the bass trap may be enough). Generally speaking, increasing the depth of low-frequency traps will be more effective than spreading them over the same boundary.
Step 3
Place another trap at the front corner of each side wall and perform measurements. These traps will handle the second room mode and its harmonics in the low and medium frequency regions. Room SPL measurement after
treatment. Room RT60 measurement after
treatment.
Step 4
Add another 5-10cm of sound-absorbing material at the untreated early reflection points (ceiling and side walls), leaving air gaps, and then measure again. Now start moving the speaker from the front wall to the listening position and move the microphone accordingly—repeat every 5 cm of movement. Separating the speaker from the front wall will increase clarity and depth, but will also cause phase problems in the low frequency.
finds the best position where phase problems will not occur. At this time, your RT60 should be about 0.2 seconds over the entire frequency range. If it is lower than the data at medium and high frequency, it means that your room is too dry and you should continue reading.
Last step
Fix the acoustic treatment material to the wall (polyurethane can be glued to the wall with a hot glue gun), and you can start mixing!
4. Problem exclusion
a. My room sounds dead. Too dry.
When mixing sounds in a studio environment, our main goal is to communicate. The room must listen to "natural" on a conversational level before your work can be conveyed and presented well. To make the room "active", you can add perforated thin wood panels before the low frequency trap. This will make the room sound more natural and bring better results.
Note: Too many perforations may not help improve room dryness, and insufficient perforations may lead to delayed knocking. Trial and error is the only way out.
b. 110Hz – 130Hz Peak
You can try to move the table away or move the workbench to the back of the room and measure again. If the problem disappears, change to a small table and place the equipment that is not necessarily placed between you and the speaker on the side cabinet or shelf.
c. Too much medium and low frequency/not enough
You can move the speaker further away, or you can try to place the speaker in a fixed installation position on the side, with the subwoofer facing the side wall. This will bring you more low frequencies, while not making the stereo sound field too wide.
Note: The wide stereo sound field can make everything sound big and impressive, but it may sound smaller in different listening environments. I recommend you work hard with a smaller stereo setup – if the mix sounds great at this point, it will sound great anywhere.
d. In the wide band frequency range of medium and high frequencies, there is an increase or attenuation.
You can try to adjust the speaker axis to the listening position, slightly change the front and rear positions of the microphone, or adjust the built-in equalizer in the speaker.
In short, I can't guarantee you will have a flat frequency response, as each room has differences in size, shape and material. But by following these steps, you will be able to significantly improve your listening experience and mixing. I hope you can enjoy this DIY process, too.
Omer Karni, a famous acoustic expert, has designed and built hundreds of audio studios for many musicians and mixing engineers, such as the Infected Mushrooms Studio and Waves Audio headquarters.
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