Can You Emulate Audyssey Dynamic EQ with Dirac Live?


This question concerned me as I was considering a (temporary) move to Dirac Live (whether the new Onkyo, Pioneer or Integra receivers). I have used Dirac Live in MiniDSP products and my frustration has always been the lack of loudness compensation. As I wrote before, I don’t agree with using random house curves without some more numerical / scientific background to the deal.

Plus I have been really spoilt by Audyssey and when set up correctly, Dynamic EQ can really sing.

The Plan

So with my home cinema background, I knew that I would have to measure what Audyssey is doing exactly, and possibly try and look at YPAO Volume. However, I knew that the latest research – and in fact Audyssey Dynamic EQ – is based on the ISO226:2003 international standard so I somehow needed to model that as well and compare them.

The Measurements

So I took out my UMIK-1 and REW and told my partner: “See you in a day or two!” as I got swallowed up by the Home Cinema black hole as it sometimes happens when I’m fully focused on a task.

The measurements of Audyssey took about 4 runs altogether, but were fairly straight-forward.

Measuring Dolby Volume turned out to be an absolute nightmare. Dolby Volume doesn’t allow you to switch off it’s leveller (which is its dynamic range compression module) so the measurements would be randomly messed up by the leveller – outputting the measurement sweep at different volume levels. While I could get a general idea of what Dolby is doing, let’s just say I was ready to smash the receiver. Oh well, no harm done. See ya later Dolby.

Onto YPAO Volume. Thankfully I had plots already from a previous set of measurements here which I could input into the spreadsheet straight away.

ISO226:2003 turned out to be the simplest one to get.

Plotting the Results

I created a spreadsheet where I plotted the results and started normalising them. For example, ISO226:2003 data is not usable until it is normalised to your chosen reference volume. Oh, we have a reference for our home theatre receivers: 85dB. That was easy!

Audyssey and YPAO data had to be plotted and then error-corrected as there are errors that the room, sound-system and microphone introduce at different sound pressure levels. The error correction isn’t straight-forward, but Excel makes things relatively simple.

The final thing I did was create two blended approaches: Audyssey Dynamic EQ and ISO226:2003 with high-frequency correction on and another with high-frequency correction off in case I wanted to test that.

The End Result

The end result is the Dirac Live Curve Editor Excel Tool which allows you to create the loudness compensation curves and another spreadsheet called Dirac Live Memories which allows you to create a cheat sheet for the curves you load into your AVR or DSP. These two tools allow me to emulate Audyssey Dynamic EQ and not miss it so much! Problem solved!

What about Audyssey Dynamic Volume?

Unfortunately, most Dirac Live AVRs don’t have a similar solution that can work while Dirac is enabled. However, they normally have a basic compressor that does similar. This compressor is normally called Dynamic Range Compression (or DRC for short) on the front-end – and is sometimes turned on using a “Night Mode” or “Late Night” function.

Lower-end AVRs only have the DRC module working for Dolby signals, since it’s lower-cost to implement (Dolby bitstreams implement DRC-compatible meta-data). Higher-end AVRs will have it working across DTS (and some with PCM) signals. It’s best to read the manual for your hardware.

While these DRC modules aren’t as sophisticated as Audyssey Dynamic Volume, they can come in handy for late-night listening or when dialogue is just low and hard-to-hear on a particular movie.

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