Peaks on the other hand are very easy to hear. Result: The same, it is barely noticeable only when it hits the bass drum fundamental.Īnd plus, the nulls in my tiny crappy square room is about -15dB only. I set up my DAW so that I could sweep both at the same time. I didn't stop there and duplicated that EQ, so two adjustment EQs with -15dB attenuation with 18 Q. The only place it was noticeable was when it hit to the fundamental frequency of the bass drum. The result is barely noticeable in overall track. I've just opened up a track in my DAW and did a sweep with -15dB Q18 EQ. It also applies more weighting to peaks by using a cubic mean (cube root of the average of the cubed values) to produce a plot that more closely corresponds to the perceived frequency responseĪlso, it's a known technique to add upper harmonics of a bass note to make it audible on smaller speakers because brain can complete the lower ends based on the upper ends, obviously there's no thump in the chest but there are plugins just for this objective. The measurement protocol is was exactly the same used in the DLCT 9 points of individual right and left impulse response sweeps.Psychoacoustic smoothing uses 1/3 octave below 100Hz, 1/6 octave above 1 kHz and varies from 1/3 octave to 1/6 octave between 100 Hz and 1 kHz. So all measurements go through the exact same system with which I listen. I ran all measurement through my DEQX HDP-4 which acts as a crossover and some small speaker correction. There's no need for a loopback FR correction. It's very simple to use, very powerful and super accurate. The USB pre2 is an awesome high end calibration device. So my setup for measurement is a calibrated Earthworks m23 with the calibration file installed in fuzzmeausure. If you've ever felt that REW was too complicated or intimidating (like me), you should try out fuzzmeausure if you have a mac. Rejoice!! I like using it so much and found it so intuitive, I bought it. When I fired up fuzzmeasure, I was taking good measurements through the DAP with my desired filter in five minutes.
I am sure you mac folks know this wonderful measurement tool very well. I turned it on and downloaded a program called fuzzmeasure.
I haven't turned it on on more than a year. But then I remembered that I have a mac book pro. I tried everything and it's impossible.Īt this point, I almost gave up. I think the problem has something to do with the REW interface with DAP. I couldn't get a valid measurement through the DAP filter. So, instead of taking 18 measurements in 9 positions, this experiment requires a total of 36 measurements in 9 positions. To do this, one needs to be able to take a log sweep measurement through the DAP with the desired filter on and then take the same measurement through DAP with the desired filter off. Now, I must say that I've wondered what the "real world" measurements would be if I were to combine the same 18 measurements that DIRAC takes and do a before and after DIRAC filter to determine whether the DIRAC filter actually comes close to the "predicted response." So the problem is: How can I validate the DIRAC filter to see if it's really working? These graphs are intended to represent the before and after responses as they are combined inside DIRAC as derived from the 18 measurements taken. When the user has completed their DLCT session and created an optimized filter, DLCT creates a "predicted" frequency response and "predicted" impulse response. Here is an image of the measurement points in 3D: In my experience, the measurement is THE most important part of DSP: Garbage in->Garbage out. It's my understanding that DIRAC doesn't simply average the 9 points, but rather, it combines the measurements in a way that helps create filters that can correct what needs to be corrected and not correct what doesn't need to be corrected. Why is this so important? First of all AES member JJ Johnston ("In the rain" on this forum) opened my mind to the limitations related to condenser mics (measurement mics). Second and more importantly, DIRAC uses a measurement protocol which requires a total of 9 measurement positions for both the right and left speakers. It's designed to be low enough latency so that one can turn it on and off on the fly to clearly hear what the filter is doing in real time and sound super transparent. First, the mixed phase filter is unique in that it's not a fully FIR filter nor IIR filter.
DIRAC is very different from any of the other full frequency target based DSP tools in two important ways.
The filter is stored inside of the Dirac Audio Processor (DAP).
It is called the Dirac Live Calibration Tool (DLCT). The first part is the measurement and filter creation tool. I have been an avid DIRAC Live user for a while now.