ASR Acourate users

[morpheusX]

I am using an Intel i9-9900K PC. Hardware is RME Fireface UC and Earthworks M30 microphone.

Are you using this on a stereo or multichannel setup?

 

[3ll3d00d]

primarily designed for those willing to modify their speakers for tri-amplification

I think it's nonsense, I used it for years in a passive setup and got great results.

 

[labdoc]

There are a number of threads about Acourate on ASR, but there does not seem to be an "Acourate user group". There is an actual Acourate User Group, but that place is pretty quiet and full of existing Acourate users. I thought I would create a thread so that we can discuss and share what we are doing and get some new ideas on how to use this powerful software, and maybe spread the word to encourage other users to try.

It is my experience that even seasoned audiophiles are blown away when they encounter a fully corrected DSP system for the first time. We all know that speakers corrupt the signal, and rooms corrupt the speaker even more. Software like Acourate allows you to remove these influences and achieve transparency, dynamics, and impact like you have never heard. Veils were lifted, wife heard it in the kitchen, etc. - all that really happens. Forget those miniscule differences in SINAD between DAC's, the objective and subjective benefit of Acourate is magnitudes above that, and I think that every ASR member who is serious about audio should have some kind of DSP in their system.

Acourate is described by the author as a "digital audio toolbox". Although it does do room correction, it is much more than that. There are other room correction products on the market, e.g. Audiolense and Dirac Live. Although I do not own licenses for AL or Dirac, I have friends who use it and I have seen what they do. AL and Dirac are very much focused on crossover generation and room correction. They do a good job, and they do it quickly and conveniently. For comparison, I saw a friend generate a set of correction filters in Audiolense, and it took him 15 minutes from start to finish, from setting up the microphone to filters ready to be loaded into the convolver. I was very much impressed by the speed and ease of use of the software.

However, Acourate is not like that. While it does have room correction macros that provide some degree of automation, performing almost any other function is entirely manual, and requires your participation and interpretation of what the software is telling you. It really is a toolbox, in that you have a bunch of various tools that you have to learn to use and deploy at the right time, a bit like deciding whether you need a screw or a nail to do the job. While both will nominally hold two pieces of wood together, they have advantages and disadvantages and it is up to you to decide which is better. One example I recently encountered in Acourate was when I found that my tweeter had a 90 degree phase lag. My solution was to apply the Hilbert transform three times to rotate it back to position. Uli's solution was to invert the polarity of the tweeter and correct the measured phase lag via a reverse all pass filter.

There are other audio toolboxes as well, such as rePhase, OpenDRC, and others - I have no experience with those, and the intention of this thread is not to discuss other types of room correction software. This is for what Acourate can do, and how to use Acourate only. I politely request that discussion of other types of software should be limited to features that Acourate does not have, or better ways of doing things.

To get the full potential from Acourate, it is best to have full control of each individual driver in your speaker system. In my case, I already own the speaker. My solution was to bypass the internal passive crossovers and solder the cables from the drivers directly to the binding posts. Each driver has its own amplifier and DAC channel, and each DAC channel has an individual correction filter designed with the help of Acourate. I know of another person with a DIY cardioid speaker emulating Kii 3's with 30 drivers, 30 DAC channels, 30 amp channels, and filters for each individual driver made by Acourate. I am also aware that Acourate can work with a passive filter in place, but I do not know how well it would work since I do not have direct first-hand experience.

Here is the thing I love most about Acourate. Unlike ANY other audio upgrade, once you pay the cost of entry (a modest sum of €340 for EU countries, and €286 for everyone else), all upgrades are FREE. Since Uli introduced the first version of Acourate in 2003 (?) there has been one version change, the only time he has ever asked for more money from his users. And even then the upgrade was optional, your old copy of Acourate would continue to work. The other thing that is free are refinements to the way you use the software - because I have learnt a lot since the start of this journey, the measured and audible performance of my system has improved - all without me having to spend a cent. Improving the accuracy of your workflow, refining the way you use this software, and rethinking the way you do things WILL improve the sound objectively and subjectively, which is yet another reason Acourate users should be discussing this.

Unfortunately, for such a complex and powerful piece of software, online resources and even an explanation of what all the functions do is frustratingly lacking. I have to learn by trying out different functions to see if they work, and even then I have no idea of what side effects I may be causing. One aim of this thread is to help complete that information.

These are the corrections I have implemented in my current system:

- Crossovers. Acourate allows the creation of a number of crossover types, including Linkwitz-Riley, Neville-Thiele, Butterworth, and some exotic types like Horbach-Keele and some of Uli's new crossovers which I have never heard of. I have experimented with a number of these crossovers, and I would be keen to discuss with other users the pros and cons of different types, as well as your subjective listening impressions of these crossovers.

- Driver linearization. Uli has a new method of driver linearization which involves convolution of a reverse all pass filter which to my knowledge has not been described anywhere else. I will post the method shortly.

- Time alignment. Although the time alignment procedure in Acourate is well described, there are several insights which I learnt recently that I will share in an upcoming post.

- Virtual Bass Array. I have done some experiments with this, which has been discussed in a separate thread on ASR.

- Bass phased array. I am currently experimenting with this. Discussion to follow once I have results.

- Room Correction with different target curves and settings. There are different strategies for room correction (e.g. up to Schroder, or full range, with harder or softer settings, etc). I have my own thoughts on target curves and I would be keen to hear other opinions. I am still experimenting with "hard" and "soft" settings (e.g. FDW 30/30 vs. FDW 5/5) and my opinion of the subjective sound quality is still out. I am undecided. Let us discuss.

- Interchannel Phase Alignment (ICPA) - a new feature introduced in Acourate v2.0 a few years ago. This aligns the phase of the left and right channels. Although I can see measured improvements, I am not sure I can hear a difference. Keen to hear thoughts on this.

Acourate resources:
- Accurate Sound Reproduction using DSP (Kindle, paperback) by Mitch Barnett (@mitchco on ASR). This is essential reading for every Acourate user.
- Acourate Digital Room and Loudspeaker Correction Software Walkthrough by @mitchco on Audiophile Style, 2013.
- Advanced Acourate Digital XO Time Alignment Driver Linearization Walkthrough by @mitchco on Audiophile Style, 2013.
- Understanding the "state of the art" of Digital Room Correction video on Youtube by @mitchco 2021, with ASR discussion thread (sadly closed)
- Some basic articles and white papers hosted on Acourate.com by Dr. Uli Brueggemann, author of Acourate (@UliBru on ASR)
- Archimago's Musings in 2015 and 2019 update, by @Archimago
- Digital Room Correction HK by ACK Cheng
- Acourate User Group at the Audio Vero website.
- Acourate Wiki (sadly very incomplete)

@Keith_W - Thanks for doing this. If you haven't done so already, consider an "announcement' on the Acourate user forum.
Also, please describe your equipment and listening environment

 

[Keith_W]

It would help if you mentioned this in post 1 or 2. I was thinking you must be full active to get the benefits you describe, otherwise you are just "fighting" the passive crossover(s).

Yeah, all DSP software I am aware of requires an active system for best results. Acourate is the same. You are right, I should have mentioned it, but to me it seemed pretty self-evident.

It seems quite capable, but it is very "proper" and expensive.

By proper I mean the way it works in samples and with functions, whereas something like REW turns samples in to time for convenience, and functions are just things you click/do (tick invert, set time offset rather than do "rotations", do arithmetic, etc).

I agree. You do have to do some maths if you want to make sense of the output. For example, before I do my subwoofer time alignment, I do a quick calculation to see if the result Acourate is reporting is feasible or not. This involves:

- Measure distance from tweeter to subwoofer = 1.2 meters
- Convert distance into time (assuming speed of sound 343m/s): 1.2 / 343 = 0.0035ms
- Convert time into samples (48kHz): (0.0035 * 48000) = 168 samples

Actually, it is a good idea to do this calculation before doing any time alignment using any software. With Acourate, there is only one additional maths step to convert time into samples, and Acourate does report the time, only that it does it in a not so obvious way.

And by being expensive it has probably hampered its own reach (adoption within the DIY community). Between REW and RePhase, it seems many of the same things can be achieved for free now?

I don't think it is expensive at all! It is cheaper than Dirac and Audiolense, and it does more. I have posted elsewhere about the strengths of Acourate vs. Audiolense. I suppose it is more expensive than REW or Rephase (both of which are free!). To be honest I have not looked closely to see what REW and Rephase can do in terms of correction, but I am sure that all the major boxes are ticked.

I am keen to see that info.

Sure, that will involve firing up my other PC, launching Acourate, and taking some screenshots. I will do that later

 

[Keith_W]

Are you using this on a stereo or multichannel setup?

Multichannel. See below.

@Keith_W - Thanks for doing this. If you haven't done so already, consider an "announcement' on the Acourate user forum.
Also, please describe your equipment and listening environment

If I wanted a system thread on ASR I would have created one I don't want this thread to be about me, I wanted it to be about Acourate. But since you asked:

Speakers: Acapella High Violon (3 way speaker, with tweeter and midrange horns and bass cabinet) + subwoofer. These speakers have been converted to active with the passive crossover bypassed. So, four drivers per side for a total of 8 drivers for a 2 channel setup.

Amplifiers: a mixture of solid state Class A/B, valve, and Class D amps. One amp channel per driver.

DAC: RME Fireface UC, Merging NADAC. Also on the shelf: Focusrite 2i2, Presonus Audiobox USB.

Microphone: Earthworks M30, Behringer ECM8000 (x2 ... I like to have backups!)

Software: Acourate for creating filters, REW for measuring and providing a second opinion. Playback is via JRiver and Acourate Convolver.

Room: 7m length x 6m wide x 3m high general purpose living room, although I have configured the room to be dedicated to the speakers. Minimal room treatment.

 

[Philbo King]

There are a number of threads about Acourate on ASR, but there does not seem to be an "Acourate user group". There is an actual Acourate User Group, but that place is pretty quiet and full of existing Acourate users. I thought I would create a thread so that we can discuss and share what we are doing and get some new ideas on how to use this powerful software, and maybe spread the word to encourage other users to try.

It is my experience that even seasoned audiophiles are blown away when they encounter a fully corrected DSP system for the first time. We all know that speakers corrupt the signal, and rooms corrupt the speaker even more. Software like Acourate allows you to remove these influences and achieve transparency, dynamics, and impact like you have never heard. Veils were lifted, wife heard it in the kitchen, etc. - all that really happens. Forget those miniscule differences in SINAD between DAC's, the objective and subjective benefit of Acourate is magnitudes above that, and I think that every ASR member who is serious about audio should have some kind of DSP in their system.

Acourate is described by the author as a "digital audio toolbox". Although it does do room correction, it is much more than that. There are other room correction products on the market, e.g. Audiolense and Dirac Live. Although I do not own licenses for AL or Dirac, I have friends who use it and I have seen what they do. AL and Dirac are very much focused on crossover generation and room correction. They do a good job, and they do it quickly and conveniently. For comparison, I saw a friend generate a set of correction filters in Audiolense, and it took him 15 minutes from start to finish, from setting up the microphone to filters ready to be loaded into the convolver. I was very much impressed by the speed and ease of use of the software.

However, Acourate is not like that. While it does have room correction macros that provide some degree of automation, performing almost any other function is entirely manual, and requires your participation and interpretation of what the software is telling you. It really is a toolbox, in that you have a bunch of various tools that you have to learn to use and deploy at the right time, a bit like deciding whether you need a screw or a nail to do the job. While both will nominally hold two pieces of wood together, they have advantages and disadvantages and it is up to you to decide which is better. One example I recently encountered in Acourate was when I found that my tweeter had a 90 degree phase lag. My solution was to apply the Hilbert transform three times to rotate it back to position. Uli's solution was to invert the polarity of the tweeter and correct the measured phase lag via a reverse all pass filter.

There are other audio toolboxes as well, such as rePhase, OpenDRC, and others - I have no experience with those, and the intention of this thread is not to discuss other types of room correction software. This is for what Acourate can do, and how to use Acourate only. I politely request that discussion of other types of software should be limited to features that Acourate does not have, or better ways of doing things.

To get the full potential from Acourate, it is best to have full control of each individual driver in your speaker system. In my case, I already own the speaker. My solution was to bypass the internal passive crossovers and solder the cables from the drivers directly to the binding posts. Each driver has its own amplifier and DAC channel, and each DAC channel has an individual correction filter designed with the help of Acourate. I know of another person with a DIY cardioid speaker emulating Kii 3's with 30 drivers, 30 DAC channels, 30 amp channels, and filters for each individual driver made by Acourate. I am also aware that Acourate can work with a passive filter in place, but I do not know how well it would work since I do not have direct first-hand experience.

Here is the thing I love most about Acourate. Unlike ANY other audio upgrade, once you pay the cost of entry (a modest sum of €340 for EU countries, and €286 for everyone else), all upgrades are FREE. Since Uli introduced the first version of Acourate in 2003 (?) there has been one version change, the only time he has ever asked for more money from his users. And even then the upgrade was optional, your old copy of Acourate would continue to work. The other thing that is free are refinements to the way you use the software - because I have learnt a lot since the start of this journey, the measured and audible performance of my system has improved - all without me having to spend a cent. Improving the accuracy of your workflow, refining the way you use this software, and rethinking the way you do things WILL improve the sound objectively and subjectively, which is yet another reason Acourate users should be discussing this.

Unfortunately, for such a complex and powerful piece of software, online resources and even an explanation of what all the functions do is frustratingly lacking. I have to learn by trying out different functions to see if they work, and even then I have no idea of what side effects I may be causing. One aim of this thread is to help complete that information.

These are the corrections I have implemented in my current system:

- Crossovers. Acourate allows the creation of a number of crossover types, including Linkwitz-Riley, Neville-Thiele, Butterworth, and some exotic types like Horbach-Keele and some of Uli's new crossovers which I have never heard of. I have experimented with a number of these crossovers, and I would be keen to discuss with other users the pros and cons of different types, as well as your subjective listening impressions of these crossovers.

- Driver linearization. Uli has a new method of driver linearization which involves convolution of a reverse all pass filter which to my knowledge has not been described anywhere else. I will post the method shortly.

- Time alignment. Although the time alignment procedure in Acourate is well described, there are several insights which I learnt recently that I will share in an upcoming post.

- Virtual Bass Array. I have done some experiments with this, which has been discussed in a separate thread on ASR.

- Bass phased array. I am currently experimenting with this. Discussion to follow once I have results.

- Room Correction with different target curves and settings. There are different strategies for room correction (e.g. up to Schroder, or full range, with harder or softer settings, etc). I have my own thoughts on target curves and I would be keen to hear other opinions. I am still experimenting with "hard" and "soft" settings (e.g. FDW 30/30 vs. FDW 5/5) and my opinion of the subjective sound quality is still out. I am undecided. Let us discuss.

- Interchannel Phase Alignment (ICPA) - a new feature introduced in Acourate v2.0 a few years ago. This aligns the phase of the left and right channels. Although I can see measured improvements, I am not sure I can hear a difference. Keen to hear thoughts on this.

Acourate resources:
- Accurate Sound Reproduction using DSP (Kindle, paperback) by Mitch Barnett (@mitchco on ASR). This is essential reading for every Acourate user.
- Acourate Digital Room and Loudspeaker Correction Software Walkthrough by @mitchco on Audiophile Style, 2013.
- Advanced Acourate Digital XO Time Alignment Driver Linearization Walkthrough by @mitchco on Audiophile Style, 2013.
- Understanding the "state of the art" of Digital Room Correction video on Youtube by @mitchco 2021, with ASR discussion thread (sadly closed)
- Some basic articles and white papers hosted on Acourate.com by Dr. Uli Brueggemann, author of Acourate (@UliBru on ASR)
- Archimago's Musings in 2015 and 2019 update, by @Archimago
- Digital Room Correction HK by ACK Cheng
- Acourate User Group at the Audio Vero website.
- Acourate Wiki (sadly very incomplete)

Nice summary and tutorial! I don't use Accourate, but someone I have huge respect for does: Bob Katz (@ digido.com)

 

[Daverz]

I think it's nonsense, I used it for years in a passive setup and got great results.

I agree; I get good results with two very different passive speaker sets, the Buchardt S400s and Vandersteen cloth Quatros. I have used it to integrate an SVS SB1000 Pro subwoofer with the Buchardts, but that didn't require any quasi-anechoic measurements.

I can very much understand the frustration, though.

 

[Justdafactsmaam]

Nice writeup, it's the same technique as https://www.audiovero.de/acourateforum/viewtopic.php?t=213&sid=6a62e92e9e39a69aae3d78a83cf0c633 isn't it?

You are definitely not talking to yourself! Thanks for posting all of this. A lot to digest