The Room
Optimization
Optimization
It is highly recommended to acoustically prepare your listening room. There is plenty of advice on how to do it (Literature). Usually, this takes a while and some trial and error. If you can already build your room following good common practise, everything you are going to do with Acourate will become even better. For small room you may also consider active absorbing devices such as the PSI AVA.
A purely passive installation can already results into some smooth reverberation and decay plots.
The Speakers frequency response before applying Acourate looks like this:
Tools
Tools
As already described in detail, I do prefer the Acourate toolbox because it allows you to work on almost all aspects of digital room correction. And – to my ears – it gives the best sonic performance. The very well written book from Mitch Barnett “Accurate Sound Reproduction Using DSP” does walk you through this process in a step-by-step approach. In addition, please also use the Acourate forum for further technical support. You may also have a look at two viable alternatives: Focus Fidelty or Audiolense. Both offer state-of-the-art DSP toolsets for digital room EQ as well.
Prefilters
Prefilters
The most annoying element of loudspeaker sound reproduction in small rooms are the room modes. They cause the highest sonic degradations in almost everyday life listening environment. Acourate can correct this to a very high degree. However, it is quite useful – before the application of the Room macros – to pre-filter the modal region of the sound spectrum. This flattens the bass curve.
Amplitude Preparation
Amplitude Preparation
For any digital processing smoothing needs to be applied before processing the data. The preferred model in Acourate is a psychoacoustic smoothing model. After treatment, the amplitude looks like this. The higher amplitude of the mid and high chassis is due to the fact, that their sensitivity is higher. This will be corrected in the overall process.
Target Curve Design
Target Curve Design
You can find a plenty of literature about what is experienced by listeners as a good sounding target curve. The scientific research has produced evidence that an absolute linear magnitude response isn’t sonically appreciated. The majority view sees a preference with a linear curve from 20Hz to about 1kHz, then declining gently to -minus 3-6dB at 20kHz. Acourate allows you to design your own curve. Take your time creating different curves and listen. Tilting the curve by half a dB up or down at the highest frequency does make a big sound difference. This is a sample target curve for the purpose of this project.
Inversion
Inversion
As a logical consequence of the previous steps, the prepared amplitude curve is mirrored with the selected target curve and an inverted amplitude response is created.
Filter Generation
Filter Generation
Now it gets tricky. We want to generate a set of filters, one for each chassis of the loudspeaker and one for each sample rate. This does require some familiarity with the software and some good experience with the interpretation of the results. In doubt, use the service provided by Uli Brüggemann from Audiovero to do it on your behalf!
Test Convolution
Test Convolution
Almost done. You can now simulate the outcome of your new system. The performance is outstanding, unachievable with traditional means. Have a look yourself: Look at the step response: This is a real step response of a real system in a real (small) room. Wow!
Look at the step response: This is a real step response of a real system in an everyday life room. Wow!
To illustrate the power of the correction with Acourate, have a look at the comparison of the amplitudes (psychoacoustically prepared) before and after.
Conversion Files
Conversion Files
The final step is to prepare the generated conversion files into a format your digital audio player such as Roon, Foobar or JRiver MC does understand.
So how does it sound? No juicy words on this, trust ONLY your ears. Caution: It may blow you away and it may question how you could have been able to live till this day with such a low sonic performance in your listening room!
