Dr. Toole's - A Rational Approach To Calibrations

[Tom C]

If it is in the on-axis and off-axis plots, it is a resonance and cannot be remedied by EQ

 

[Buckchester]

If it is in the on-axis and off-axis plots, it is a resonance and cannot be remedied by EQ

That is incorrect. That is an example of a measurement that can be fixed by EQ.

In-room measurements can be EQed below the room-transition frequency. However, above the room-transition frequency any EQ needs to be based on anechoic measurements.

What cannot be fixed with EQ is a directivity mismatch. This is where you see one curve on-axis and a different curve at the same frequency off-axis (or vice versa).

 

[Jaxjax]

They should not be "corrected". They can be equalized as you like, usually by dialing in a tilt.

Correction implies fixing nulls or peaks in a steady state response according to some target.

Reasons are to do with how our hearing works and how rooms work. It's all in Toole's book, but takes some thinking.

When I 1st tried Dirac 4 years ago or so I didn't like it with my not so good measuring core 59's. Then a few weeks ago I fired Dirac live 3 back up & curtained it off @ 400hz & tilted from 700hz @ 1.5db up & was amazed. The full range correction I had used 4 years ago indeed didn't sound right at all. The simple settings I'm using now does, well the best these have sounded so far at least. The Dirac screen shot doesn't show the tilt as I'm using my Elysia to do that for now.

 

[Lars Risbo]

It can be corrected using a mixed-phase approach using FIR filters, seen in autoEQ systems like Dirac, Trinnov, Neumann's MA-1 based system and (I'm not entirely sure) Genelec's GLM. Manually this can be done in Acourate, Audiolense and (again not sure) BruteFIR and rePhase.

just driving by and not sure if this was ever commented: non minimum phase means that there are right half plane zeros (or the system is unstable but we can rule that out). From this follows that a correction (inversion) requires right hand side poles, ie the correction filter is unstable