PART 2: THE POSITION IN THE ROOM


In today's home studio situations it is normal to record and mix in the same room. This is always a compromise solution.
Therefore, beginners often have the idea to build a hardwood storage shed, called Booth, for the recordings.
Please don't do that! It is counterproductive (see comb filtering).


Our listening position:

Before we go deeper into the substance and acoustically optimize our room, we look first at what we can do in advance.
For this we have to deal with the relationships between the sound behavior and the geometry of the room. Don't worry, that's relatively easy.

The cut lengths of a room mode are always compound numbers in relation to the room. So to avoid that we affect longitudinal modes disproportionately at our listening position, we put our listening position on a prim!
Long story short, we divide our room length by 3. At our listening position, 1/3 of the room should face us and 2/3 of the room should be behind us.
To the left and right we should have the same distance to the side wall.

At this exact point is the vibration node of the third harmonic of the standing longitudinal wave. A so-called zero pressure zone.
This means that the frequency of this wavelength can not be perceived by you. Therefore, the position must be adjusted later with acoustic measurements to find an optimal alignment. But it's a good starting point!

(If you plan a pure vocal recording room, the red circle symbolizes the microphone position.)





Speaker position:

We divide again by 3. However, this time we calculate the distance between our listening position and the front wall.
We position our loudspeakers on one of the cut lengths.
If we work in a large room with small speakers, then we position them on the first third.
Large speakers are positioned on the second third.

If we work in a small room with small speakers, then we position these on the second third, closer to the front wall.
This is because the distance between our listening position and the speaker position is smaller in a small room. Also, with the speakers close to the wall, we don't struggle so much with phase cancellations.

If possible, the speakers should be at least 60 cm away from each wall.
Also, you shouldn't put the speakers on your desk. Buy decent speaker stands !!

The speakers should be at ear level.
For 2-way systems this usually means that the tweeter is at ear level.
For 3-way systems, the reference is mostly the midrange woofer.
Please consult the manual of your speakers to determine the correct height adjustment for your system.





Once again, if you plan a pure vocal recording room, the test setup looks like this:




Please note that the listening positioning and speaker positioning tips are intended only as a starting point for subsequent measurements and fine adjustments.




First measurements:

To make a meaningful measurement of the room, you need three things

• A measuring microphone with omnidirectional directional characteristics (this doesn't have to be anything super-high quality - a Behringer ECM-8000 for 30€ is sufficient)
• A free measurement software. Download: REW Room EQ Wizard
• A SPL Meter type-C for calibrating the speakers (a Voltcraft SL-50 costs about 30€)

I will not go deep into the details of calibration and how to deal with REW here.
That would go beyond the scope of this thread. I will describe the process only superficially.

Here's one of many detailed REW tutorials on YT:

For the first measurement we are only interested in the Frequency Response. Therefore, we perform REW measurements under the tab "SPL & Phase".
This measurement is used to fine-tune the listening position and speaker positioning.
But don't let yourself go crazy: You can neglect all frequencies above 5 kHz when measuring,
because they can change drastically even with the slightest change of the axis.
We are only interested in the range from 20Hz to 5kHz for this measurement.

To perform a measurement, proceed as follows:
Place the microphone on a microphone stand and position it directly on the top of the stereo triangle behind your head.
Calibrate your speakers to 83dB SPL Type-C using the SPL level meter and REWs calibration noise.
Get ready for it! 83dB SPL is really damn loud !!

• Mark the exact position of your speaker stands and the microphone stand on the floor with adhesive tape. Take a picture of the position and name it Position 1.
• Make three frequency response measurements: a measurement with only the left speaker, only the right speaker, and both speakers together.
  
• Name the measurements in REW with "Position 1 - Left", "Position 1 - Right" and "Position 1 - L&R".
  
• Experiment with the listening position (position of the measuring microphone). Take one measurement each time you move the microphone stand 10cm farther forward or 10cm farther back. Mark these places with tape so that you have the same 3 reference positions for each measurement.
  
• Experiment with the speaker position and take new measurements. Repeat all the points already mentioned and name them Position 2, Position 3, etc... Try another speaker angle - outward or inward. Try another position on the latitudinal axis of the room or between the 1/3 cut positions.

Once you have determined the optimal position of your speakers and the listening position in your room, we will take care of the position of the subwoofer. If you don't have a subwoofer, you can jump directly to PART 3.

• Place the subwoofer exactly between your speakers, make a solo measurement with the subwoofer.
  
• Do a new measurement with both speakers (L & R).
  
• Now do a measurement with the subwoofer and the speakers together. Experiment with the crossover frequency between subwoofer and speakers. Repeat these measurements until you have determined the optimal crossover.
  
• Then move the subwoofer on the latitudinal and longitudinal axes until you have found the optimum position and phase between subwoofer and speakers.

Please keep in mind that the subwoofer should also be at least 60 cm away from the front wall.

<- PART 1
PART 3 ->

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Last edited: Oct 1, 2019