Hi. I have a lovely new DAC that enables me to adjust its output by resonant frequencies in the room. I have fed a test signal 20 to 20K Hz through the system and measured the decibel levels. I can make two adjustments:
“Q”: the amount of bandwidth around a target frequency that resonates, and “Gain”: the degree to which I reduce the gain within that piece of the spectrum. I have attached a graph of my initial results.
For example, it’s worst at 121 Hz.
Does anyone have experience in this sort of thing? Do I create a Q notch of +/- 2 Hz or something larger? (I also am to reduce the gain, and then resample, the goal being to flatten the peak. I can do this for up to five peaks.)
Thanking you in advance.
For hifi purposes I would tend to steer clear of room eq where you are looking at specific and narrow alterations. I would focus more on room treatment and look at absorbers soft furnishings on walls/flood and in room.
Looking at your graph it suggests you have strong constructive and destructive interference… this will be best dealt with with room treatment.
I would leave eq to to subtle shelf filters, like a subtle shelf treble lift or bass cut etc should you need it. This is like the traditional bass treble tone control setup.
If you do feel you need to undertake digital eq and prepared to accept the compromise in performance, then to minimise artefacts, focus on filters with a low Q, that is they cover a broader range of frequencies say at least half an octave (an octave is a relative doubling of frequencies), focus on gain cuts, and avoid boosts. Aim to keep filters less than 3dB cut. Focus more on mid and treble frequencies.
Your graph suggests strong room cancellations in the lower to low mid frequencies. Absorbers will help, but so will moving speakers within the room, as well as the listening position. You also seem to have a notable drop above 200Hz. 200 Hz is considered a bass frequency… so this almost looks like a sub with strong room resonances.
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