Acourate is so much more than a digital room correction software

[ecwl]

While I have read many times that Acourate is primarily a digital audio toolbox, not just a digital room correction software, I have to admit, I never really fully understood it. I only purchased the software because @mitchco’s book primarily explains how to generate digital room correction convolution filters using Acourate (as opposed to other pieces of software).

 

After 9 months of playing with it, I’m really appreciating the power of Acourate. Sure, one can generate a convolution filter and optimize it within the Acourate macro workflow. But over time I realize, I can address specific acoustic issues on top of the standard digital room correction macros.

First, I definitely have an echo/resonance/peak from front to back wall at around 52Hz. And using Virtual Bass Array, I can significantly reduce this echo:

https://www.audiovero.de/acourateforum/viewtopic.php?t=44

Second, I have an asymmetric room with asymmetric speaker setup so while all digital room correction can get each speaker to have a flat frequency bass response, the two speakers playing in unison would generate a phase cancellation at 70-90Hz with -10dB. But Acourate can adjust each speaker to have the same phase shifts in that specific bass region so that they won’t cancel each other and create better coherence in the bass in stereo:

https://www.audiovero.de/acourateforum/viewtopic.php?f=8&t=171

Combining these two techniques and then adding the digital room correction macros produced sound I never imagined was possible in my room.

 

The learning process was steep but the rewards were tremendous. Of course, for those who don’t want to spend the time, they can always just go to https://accuratesound.ca

 

But I really enjoyed my personal journey on this.

 

[macuniverse]

I totally agree. I also started with Mitch's book last year. My setup is in the living room with no space/acoustic treatment to play around. So DSP was the only option available. My expectation was moderate; basically fix some sub-bass/bass issues and fill in light frequency response irregularities.

 

Long story short, after countless iterations the SQ I'm getting now is well above my expectations. The whole frequency range is smooth, timing is spot on, sound stage is rock solid. I have tried a number of room correction DSP products (Dirac, REW+rePhase, DRC Designer, etc). None worked as good. Acourate's ability to mix and match DSP functionality is incredible!  The more you learn the more ways you discover that you thought it was not possible.

 

I think the user interface and documentation need a re-work. Mitch's book cover some of the functionality but there is so much more to unearth.

 

I also strongly recommend Mitch Barnett's  new DSP app "Hang Loose Convolver" to Acourate users as it directly uses filters generated including auto sample rate change (in zip format). However, for me, the most useful function of this app has been the ability to compare different filters on the spot and fine tune them. Well done Mitch!

 

[LewinskiH01]

On 7/24/2021 at 8:42 PM, ecwl said:

 

First, I definitely have an echo/resonance/peak from front to back wall at around 52Hz. And using Virtual Bass Array, I can significantly reduce this echo:

https://www.audiovero.de/acourateforum/viewtopic.php?t=44

 

 

I couldn't agree more. I also got it because of Mitch's early articles in this forum, and have gone from 2-channel to now 8-channel active stereo and Acourate is the centerpiece. I admit I have not gone beyond what Mitch covers in his book though.

 

I am intrigued about the situation you mentioned, quoted above. I'm aware of Uli's thread on VBA, where 4 subs mounted on the front wall are needed and 2 are well above ground level. Do you have such a setup? I'm intrigued because I have 2 subs against the front wall (on the floor) and assumed that in order to apply the VBA approach I needed to have the 4 subs on the wall...does it work with 2??

 

Thanks for bringing it up/sharing!

[ecwl]

1 hour ago, LewinskiH01 said:

I am intrigued about the situation you mentioned, quoted above. I'm aware of Uli's thread on VBA, where 4 subs mounted on the front wall are needed and 2 are well above ground level. Do you have such a setup? I'm intrigued because I have 2 subs against the front wall (on the floor) and assumed that in order to apply the VBA approach I needed to have the 4 subs on the wall...does it work with 2??

You can read the link I provided, even though I know sometimes Uli’s instructions are hard to follow.

This is what I meant about Acourate being a digital toolbox rather than just a Room Correction Convolution Filter generator (or active crossover generator).

 

Basically, the principle of a true double bass array is that the back subwoofers are supposed to be slightly out of phase with the front subwoofers to cancel the room mode. This is what you describe as 4 subwoofer setup.

But you can actually not have back subwoofers but instead just DSP your audio signal going to the speakers so that the front subwoofers would play the original bass note and then after a short delay, play a softer version of the same bass note out of phase to cancel out the longitudinal room mode. This is what Uli describes as the Virtual Bass Array. This way, the subwoofers don’t even have to be at the back of the wall.

 

So in the link I provided, Uli explains first why this works digitally. And then he provides how to do it near the end. Basically, you would have to measure the length of your room. And then you can look at your uncorrected frequency response curve to see if without room correction, you have a resonance at that frequency where VBA can potentially correct. And then there is a little bit of trial and error to determine how soft the out of phase sound you want to generate is to correct that particular room mode peak. Once you’ve figured it out, you now have a Prefilter that works as VBA. You may want the same filter for both channels or if you have an asymmetric setup, you may want different prefilters for left & right channels. Now that you have the VBA pre-filter, you can add it to Macro 0 in the room correction macros. But unfortunately, you will have to completely re-run your Macros 1-5 to generate a completely new set of convolution filters because now, you’re first introducing the VBA prefilter, which would correct for the longitudinal room mode, and then the convolution filter would correct everything else that the VBA doesn’t correct (which is still a lot of stuff). But the main advantage here is that a generic convolution filter would not correct specifically for the longitudinal room mode as well as a VBA filter. At least in my system when I compare the two convolution filters, that’s what I’ve found (aka. better sound with VBA).

 

The other crazy part is that you don’t even need subwoofers to do this. In fact, you can just run the whole thing on your passive crossover full-range speakers if you want. Because you’re just generating a VBA filter that only works on sound <100-150Hz (your choice) and you can use your full-range speaker to generate the time-delayed soft out-of-phase bass notes to cancel out the original bass notes that trigger the room mode.

 

Keep in mind VBA is a technique that primarily targets the primary longitudinal room mode resonance frequency but it usually is one of the dominant frequencies in the room so I find it’s worth the trouble to generate the filter on top of the standard convolution filter macro workflow. Moreover, because you’re generating a softer out-of-phase low-bass sound at <100-150Hz, you can introduce slight artifacts into other low bass frequencies that this low-bass sound doesn’t cancel. But like I said, in my system, VBA is better than without VBA.