XMC / Dirac / multi-sub - how to prepare for Dirac.

[ansat]

Now that Dirac is out and everything is finalized, Its time for this to be updated. As of 12/31/2014

I would first like to talk about Dirac. Dirac's only focus is filter creation, time alignment to a fixed point and level calibration. What Dirac does is take a single speaker and creates a single filter for that speaker. It then repeats this process how ever many times is needed to create a filter for each output. Each speaker is treated by Dirac as a full range speaker (you can see an example of this in Dan's center channel measurement here) and is corrected as though you are going to use it as such. Is this a problem? No, in the big picture it will not matter at all. Once these filters are given to the XMC it is now the XMC's turn to take over everything else. Dirac has finished doing its job. Dirac will give priority to the main listening position and make corrections over the entire listening area via its 9 measurement points per speaker seen here.

Emotiva will be giving us professional level tools that can achieve professional level results. Unfortunately, rarely can professional level results be achieved in audio by just computer logic and a set it and forget it attitude. It can however produce good results, just not the best results that can be achieved. To get the best results, you will either need the help of a professional that understands how to manipulate the sound or the user will need to learn to use the measurement microphone that Emotiva will be providing.

X.1 setups
Since most of the average users out there are using a single subwoofer, Dirac should be able to give good results used by its self. The only short comings will be the crossovers and listener / speaker placement which can be done by ear, but will be more accurate when done with the calibration mic and REW. A quote from Mark Seaton over at AVS

While responding to some questions in this thread over Sunday morning coffee I found myself with a decent summary on subwoofer optimization using Room EQ Wizard (REW) or other measurement systems like the Dayton OmniMic or XTZ Room Analyzer. This is by no means comprehensive, as we could flesh out many bullet points on a few of these items, but I thought it was a worthwhile summary to post up before I go ahead and organize the measurements and data on thebland's system that I'll be posting on my forum. This is a generalized post that won't apply to all systems depending on number of subwoofers, inclusion of manual subwoofer EQ, and features and functions of each surround processor.


To summarize some of my thoughts and experience, here's my suggestion for most attacking their system with REW and other measurement systems:

1.Take a subwoofer only measurement in your first subwoofer location while noting signal levels to the subwoofer and volume setting.
2.Do NOT change any signal levels and start moving the subwoofer to any other possible locations saving a measurement at each location. The response should be louder or softer from different locations and you want to see this.
3.Choose the location with the balance of fewest dips and most efficiency across the subwoofer range.
4.If you have more than 1 subwoofer, pick locations that compliment each other where dips do not overlap.
5.With multiple subwoofers overlay individual responses and then measure both together driven at the same level to see how they sum. Maximum summation of 2 equal sources is +6dB. Unless there is a big peak, the goal is to get the sum to be +0-6dB and not negative. Moving the sub or adding delay to the closer sub is my preferred way to make this adjustment.
6.If manually EQ'ing, now apply EQ to the subwoofer alone while also watching for peaks out to 120-200Hz that go above the target or above flat if no HP is in the measurement.
7.Now run any auto-EQ/room correction.
8.Measure the subwoofer alone and center channel alone, then the combination of the two.
9.Make adjustments to the subwoofer distance setting, most often adding to the physically measured distance at 0-8ms.
10.Choose the smoothest interaction and adjust the crossovers up or down if you see room for improvement.
11.If you have separate EQ on the subwoofer you can sometimes improve a lumpy/peaky summation by adding a notch to the subwoofer around the crossover range. The benefit to dialog and music balance far outweighs a small dip to the LFE channel.
12.Next compare the interaction with the left & right speakers making crossover setting and delay adjustments to get a best fit for both.
13.The more you listen to movies & surround concerts, the more you should prioritize the center channel vs. left/right.
14.Now measure what happens when you increase the subwoofer level by 3,6 and 9dB to understand what happens when raising the sub level.
15.Do some listening and adjust the subwoofer level and/or shape to what you are after, and then re-measure subwoofer-center interaction to insure any ramping up in response you add is as smooth as practical.
16.Enjoy!

There have been many times when people have asked "What does Mark do that an auto-EQ system or typical enthusiast can't?" when they hear people raving about the results after I get into setting up or adjusting a system for 3-12 hours. My answer is that anyone COULD do it, very few do. Few will take the time to gather all the measurements and learn how to manipulate what they see. I encourage more to be some of the few, or search them out to set up their system.

How does this apply in the XMC-1 and Dirac? Steps 1-5 need to be done before Dirac. Currently the way that emotiva, has the XMC programmed, the other steps cannot be done.

X.2+ setups
Next, I would like to talk about multiple subwoofers. Once the decision has been made to increase the number of subs beyond 1, a can of worms has been opened that no automatic room correction (ACR) on the market can do properly (Dirac included). ARC cannot adjust the listening position, the subwoofers placement, the angle of the subwoofer, etc. ARC just tries to make everything sound as flat as possible and get the sound to the listener at the same time. For those who want a set it and forget it with Dirac, currently, the best method of doing so will be to only use the single subwoofer output and let dirac do the best that it can with your setup. If Emotiva will provide another bass management option to allow for multiple delays and using a single dirac filter for the summed subwoofer output, that should be used (Currently this is not an option. For those who are trying to achieve remarkable results, the only option will be an outboard DSP, such as a minidsp (or if you have a subwoofer with eq and a variable phase control). Instead of reposting all the info gained from AVS, I will just point everyone to this thread and make the assumption that you read through it and have at least a general understanding of what they were talking about.

In the thread over at AVS, it shows a great example of how two channels that have a flat response being played at the same time results in some drastically different results as well as the trade offs that will have to be made for listening position and time alignment to the crossover points in a multi channel environment. Dirac does not account for this as the bass management and time alignment between subwoofers is the responsibility of the hardware owner (in our case - The tools that we need to do this are not on the XMC and need an outboard DSP). Again - Dirac only cares about a single speaker at a time. Looking at the 16 bullet points by Mark S. (re-posted in the x.1) there is a lot of prep work that needs to be done before we get to the point of EQ. These are the items that ARC cannot control and account for and take a lot of time to complete. Luckily, all the items in Mark's list can be done with minimal knowledge of REW and all its functions. It just requires a measurement sweep run over and over again and comparing them. All the functions to determine your decay and treatment locations will in part be addressed by Dirac. The only thing that Mark missed in those bullet points that is addressed quite well in the AVS thread is subwoofer time alignment or a more accurate statement is a controlled subwoofer time miss-alignment. If you have not done so already, go read this thread.

Room problems
If your room has problems such as deep nulls and boomy bass, Dirac will not be able to correct the troubles. Both of those are caused by reflections and Dirac has no control of how the audio refects off a wall. It can shift the time a little to make things a little better, but that null or boomy bass can only be resolved by a combination of speaker placement and room treatments.


Again if you have not done so and have multiple subwoofers and curious about what Dirac CAN do with multiple subwoofers that have been set up properly before dirac was run. Go to this thread 

This is a lot of information to process all at once and there seems to be a common theme over the forums about what Dirac can and cannot do. Bottom line is that Dirac does a great job at doing what it was designed to do. EQ filters, fixed time alignment and levels. No home room correction (car audio is a different story) that I have seen pays any attention to how the speakers interact with each other as that would require complete control over the room, speaker placement, user placement and speakers used. While the implementation of dirac should provide good results as it has done with MiniDSP and Datasat, this is a professional level tool set (even more so with the higher versions of Dirac) and to maximize the results, a set it and forget it mentality will not be sufficient.

How can I tell if there is a problem or not
Your going to have to use REW or another measurement program, But I believe I have come up with the easiest method to test and verify that you can read at emotivalounge.proboards.com/post/703310/thread

Anyone have any thoughts?

Tony

[ansat]

Part 2
This is a nice transition place for the second part of Dirac.
The Dirac upgrade. I have heard many rumors to what this 100$ upgrade might be. When it comes to an upgrade, there are certain things that I would require to make the upgrade worth while for my custom installation. This would require added functionality to Dirac and the XMC

Needs
1. The ability to save at least 2 filters to the XMC. I would need to be able to have a measurement for just the front row and a measurement for the front and rear rows of seating.
2. Adjustable target curve (8 points).
3. Dual Mono sub with a single Dirac Filter.
4. Input mapping (2 different inputs being able to use HDMI 1)

Wants
1. The ability to use a microphone with a custom calibration.
2. The ability to use the auditorium feature in Dirac.
3. Fully Adjustable target curve.

Tony

[ansat]

Well - To practice what I preach - I spent about 6 hours on my three subwoofers (my 4th is loaned out).I still have a little work to do on integrating the ported THX subwoofer, but that is for another day as the earplugs are starting to hurt.

I moved all three subwoofers and time aligned to each other. I applied 6 filters each to the left and right front.(all pads) 3 filters to the left and right front combo. I applied 4 filters to the Monster THX. Looking at the graphs, I need to apply 3 more pads to the Monster THX. The other two main seats are -+ 6db (the goal is to get it down to -+4

no smoothing


6th octave smoothing

Tony

[ansat]

Interesting little note on delays. I had to add an additional 3 ft of distance to the rear sub to get the all sub graph to go +3-6 across the board. The actual distance gave me 2 giant nulls (-15 db each) at 40hz and 80hz.

Tony

[kofiv]

Tony, comment/share thoughts on treating the room before Dirac...?

[ansat]

Nov 2, 2014 13:21:16 GMT -5 kofiv said:

Tony, comment/share thoughts on treating the room before Dirac...?

Torquetube,
I do have a treated room currently and prefer treating the room over using just ACR when possible. However, the testing I did with Dirac was in an untreated space (living room) with vaulted ceilings. In the picture below, everywhere you see blue was where Dirac alone was able to reduce the decay (amount of time that particular frequency hangs around in your room).



A lot of the decay reduction was from flattening the response (that big 500 - 10k block seen in the picture, But direc was able to knock out that 40,60,80,100 that was just dominating the room. So Dirac has the ability to reduce the rooms effects. However I find that the treatments do a much better job over a much wider area. Simple answer is if your room needs treatments before Dirac, It will need it after Dirac and in the same locations.

I would not go all out on treatments as a preparation for Dirac. But taking care of the basics such as first reflection points on the sidewalls and corner bass traps would lay a good foundation for your room. Dirac really doesn't care if you have treatments or not and lightening the load on dirac will make no difference in the processing. There are just certain things that Dirac cannot do that treatments can.

Tony

[lbrown105]

the two channel version of Dirac Live DOES set delay and levels, not just the filters. I have not used the 8 channel version yet

[ansat]

Nov 2, 2014 21:49:33 GMT -5 lbrown105 said:

the two channel version of Dirac Live DOES set delay and levels, not just the filters. I have not used the 8 channel version yet

thanks lbrown105, I did some more digging and it does look like dirac does handle levels and delays in the nanoavr dl. I did double check and in all cases the bass management is not handled by dirac.

Tony

[ansat]

So after lbrown105 comments I dug deeper into what dirac is doing on each platform.

RS20i - Appears that delays, crossovers and levels are not controlled by initial Custom Dirac version. Later reports indicate that this was added, but I see posts to override it as it had accuracy issues.
nanoAVR DL - Delays and levels are controlled by the Custom Dirac version. Crossovers are handled by the AVR or pre/pro that it is connected to.

It is still not clear if this is implemented by Dirac or by the manufacturer.

Tony

[lbrown105]

I have been trialing the two channel version on my PC and using REW to verify improvements. Huge improvements in impulse response. I posted the measurements over on AVS in the XMC-1 chat thread a couple of days ago. No matter what happens with the XMC-1 DIRAC is in my future. After speakers choices it is the single best improvement I have heard and measured in my system. thanks for all your work to get a better handle on Dirac and how it works.

cheers

[hifiaudio2]

So when I eventually run the XMC version of Dirac I should expect it to leave all of my current distance, level, and crossover settings alone? This is a good thing if so because with the help of some fine folk at the Home Theater Shack and REW I time aligned my 4 subs and would prefer that Dirac's magic is applied on top of what I have already done, not changing the distances, etc.

[ansat]

Nov 4, 2014 10:37:56 GMT -5 hifiaudio2 said:

So when I eventually run the XMC version of Dirac I should expect it to leave all of my current distance, level, and crossover settings alone? This is a good thing if so because with the help of some fine folk at the Home Theater Shack and REW I time aligned my 4 subs and would prefer that Dirac's magic is applied on top of what I have already done, not changing the distances, etc.

The distances will not matter, just the relationship between them. Since you have time aligned your existing 4, I am assuming you are using an outboard DSP?

Tony

[hifiaudio2]

Yes I have a Xilica.

[ansat]

Nov 4, 2014 12:11:22 GMT -5 hifiaudio2 said:

Yes I have a Xilica.

Keep the outboard hooked up just as you have it now. (or sell it and grab a miniDSP.) It looks like Dirac/XMC combo will be able to handle everything except the phase alignment of the 4 subs. If you have already phase aligned the crossover points for the front 3, you just need to know your delays as a starting point. Since your subs are phase aligned outside the XMC, you should not have to redo that work. But you will have to play with the phase alignment at the crossovers as I do not believe at this time that Dirac will be able to best what can be done manually. If you look at the pro calibrations recommended by Dirac with the DataSat. You will see between 3 - 12 hours of calibration being done by the pro's. I expect for Dirac to meet my needs (and likely yours - given the amount of work you went through to phase align the 4 subs) even with the subs already being phase aligned, I will be looking at 8 hours of tweaking before I am satisfied.

Tony

[ansat]

Was playing around phase aligning my center xover while using three subs and the 2 main speaker subs in extended bass and I save the measurement and it is a great illustration of how delay in multiple subs can effect your frequency. I settled on 19ft for my rear sub placement (actual distance is about 8 feet from the mic. You can see a measurement from 8ft in the distance selection to 21 feet.




Correction. This was just the rear sub integration into the front 2 and enhanced bass turned on. So 3 12's and the two st-l's

[klinemj]

I am confused...from what I understand, with the XMC, we can't use the PEQ and drirac at the same time. It is one of the other. So, how does using REW as preparing for DIRAC play into using DIRAC once it is here?

Thanks, Mark

[geebo]

Nov 5, 2014 6:48:48 GMT -5 klinemj said:

I am confused...from what I understand, with the XMC, we can't use the PEQ and drirac at the same time. It is one of the other. So, how does using REW as preparing for DIRAC play into using DIRAC once it is here?

Thanks, Mark

I think we still have to set size, crossovers, and distances with Dirac.

[ansat]

Nov 5, 2014 6:48:48 GMT -5 klinemj said:

I am confused...from what I understand, with the XMC, we can't use the PEQ and drirac at the same time. It is one of the other. So, how does using REW as preparing for DIRAC play into using DIRAC once it is here?

Thanks, Mark

You are correct. PEQ and dirac cannot be mixed for the most part. I have conflicting info on the trims and cannot comment on that yet.

This is more for the proper integration of your speakers. If you look at the chart above the 8 db difference was corrected with only delay. All the responses were flat before I started the integration. The rear sub needed an additional 8-10 ms of delay ( over and above the actual distance) to play nice at my location. ARC will set the delays close to actual distance and with multiple subwoofers playing as an array, this will not work.

Tony

[KeithL]

What you can and cannot use with Dirac on the XMC-1....

Here's the easiest way to think abut it...

On the XMC-1, Dirac is one of the Speaker Presets (and the only setting you get in that Preset - other than the ones made by Dirac- is the Speaker Size menu).
The Speaker Size menu for the Dirac Preset will include the same configuration options as the other Speaker Size menus (including the Crossover Points for Small speakers).
So, anything that you can configure OUTSIDE of the Speaker Presets, you will still be able to use while the Dirac Preset is selected (like the various Trims).
And anything that you configure INSIDE of Preset 1 or Preset 2 will NOT be available when you choose the Dirac Preset (including the PEQs).

Nov 5, 2014 6:48:48 GMT -5 klinemj said:

I am confused...from what I understand, with the XMC, we can't use the PEQ and drirac at the same time. It is one of the other. So, how does using REW as preparing for DIRAC play into using DIRAC once it is here?

Thanks, Mark

[tubby]

Nov 5, 2014 11:47:14 GMT -5 KeithL said:

What you can and cannot use with Dirac on the XMC-1....

Here's the easiest way to think abut it...

On the XMC-1, Dirac is one of the Speaker Presets (and the only setting you get in that Preset - other than the ones made by Dirac- is the Speaker Size menu).
The Speaker Size menu for the Dirac Preset will include the same configuration options as the other Speaker Size menus (including the Crossover Points for Small speakers).
So, anything that you can configure OUTSIDE of the Speaker Presets, you will still be able to use while the Dirac Preset is selected (like the various Trims).
And anything that you configure INSIDE of Preset 1 or Preset 2 will NOT be available when you choose the Dirac Preset (including the PEQs).

Nov 5, 2014 6:48:48 GMT -5 klinemj said:

I am confused...from what I understand, with the XMC, we can't use the PEQ and drirac at the same time. It is one of the other. So, how does using REW as preparing for DIRAC play into using DIRAC once it is here?

Thanks, Mark

Does that mean we cannot change the levels and distance Dirac sets? As Tony shows some may want to tweak the distance and certainly folks will want to adjust levels for preference like running subs hot or bumping up the surrounds or center.