- EQ Does Improve Bass Decay
I wanted to share some examples of how EQ does reduce ringing in the bass, or rather, improves bass decay. Why? Because it's minimum phase and it must. I'm including both simulations of the EQ effect, as generated in REW, as well as an actual measurement using DIRAC (which is still EQ, even if it's very special EQ). It shows that EQ does improve bass decay. This comes up a lot and I wanted to provide some solid results to make the point.
First, a few animations to show a comparison of the waterfall (what most are used to seeing). This is an actual speaker measurement but showing the simulated effect on the waterfall when EQ is applied to flatten the response.
Here is a similar animation showing what DIRAC did as compared to the No EQ result. This is not a simulation but a real-world measurement.
However this may only be somewhat interesting, as many might suggest that cutting the peak lowers the level of the peak, but decay is a slope not a level, so what effect does it have on the slope? Well, look for yourself. These are comparison of the impulse response filtered at 63hz (1/3 octave) which was around where a large peak in the untreated response showed up.
Look at the slope of that black line.
Here is the same information as above, but using just PEQ and not DIRAC.
And finally an overlay to show just how seriously it impacted decay. Look at the tail.
And again, same information as above, but using PEQ
EQ clearly improves bass decay and does so far better than reasonable bass traps could achieve at such low frequencies. That isn't to say that LF damping is not important in a room, but my view is you need both. Now keep in mind that in general EQ will not provide identical results (and thus identical improvement in bass decay) at different positions in the room. That is why multiple low frequency sources (i.e. subwoofers) and some bass trapping is still needed.