Welcome, Guest
Username: Password: Remember me
NOTE: This forum is community powered. Please be mindful that long time community members are here to help as part of a community effort. If you have a specific issue (e.g. hardware, failure), please use our tech support portal (Support menu - > Contact Us). Thanks a lot of your help in making a better community. :-)

TOPIC: Dirac Live set up for nearfield monitoring - how?

Dirac Live set up for nearfield monitoring - how? 2 months 1 week ago #41832

  • john.reekie
  • john.reekie's Avatar
  • Offline
  • Platinum Boarder
  • Posts: 3379
  • Thank you received: 1438
  • Karma: 133
Oh actually, never mind on that one, the 90 degree response is much closer to the diffuse field response than the on-axis (free field) response.

When you did your 0/90 comparison, did you look at the impulse responses?
I am not miniDSP support.

"You must ask the right questions." - Dr. Alfred Lanning's hologram.
-> Have you read the User Manual??
-> Have you drawn and posted a diagram?
-> Have you posted a screenshot?
-> Have you posted your config file?
The administrator has disabled public write access.

Dirac Live set up for nearfield monitoring - how? 2 months 1 week ago #41834

  • Skol303
  • Skol303's Avatar
  • Offline
  • Junior Boarder
  • Posts: 37
  • Thank you received: 7
  • Karma: 0
john.reekie wrote:
Oh actually, never mind on that one, the 90 degree response is much closer to the diffuse field response than the on-axis (free field) response.

When you did your 0/90 comparison, did you look at the impulse responses?

Thanks John, good to have your input here!

Here are the Impulse Response plots from REW:




Overlaid blue 90-degree, red 0-degree:


And here are the ETC plots for reference (zoomed in on the early reflections <30ms):



Overlaid blue 90-degree, red 0-degree:


Very similar to my eyes, but let me know if you spot anything.

This message has attachments images.
Please log in or register to see it.

Last Edit: 2 months 1 week ago by Skol303.
The administrator has disabled public write access.

Dirac Live set up for nearfield monitoring - how? 2 months 1 week ago #41835

  • Skol303
  • Skol303's Avatar
  • Offline
  • Junior Boarder
  • Posts: 37
  • Thank you received: 7
  • Karma: 0
Here's a link to the REW file (.mdat format) for anyone interested.

It contains L&R/L/R speaker measurements taken with the mic pointing between the speakers (0-degree calibration file) and vertically (90-degree calibration). Mic is a standard UMIK-1; Dirac Live DSP applied using the miniDSP DDRC-22A box.

Available via Dropbox here:
www.dropbox.com/s/11v3f2pucahh9a3/Skol303.mdat?dl=0
The administrator has disabled public write access.

Dirac Live set up for nearfield monitoring - how? 2 months 6 days ago #41848

  • john.reekie
  • john.reekie's Avatar
  • Offline
  • Platinum Boarder
  • Posts: 3379
  • Thank you received: 1438
  • Karma: 133
Oh, I meant the microphone response alone, no filtering etc. That is what you would want to look at if you want to know if and how 0 and 90 differ. Without running through the DSP would be better to remove the delay.

BTW your REW files seems to not have the impulse response in them, seems like a frequency response import.
I am not miniDSP support.

"You must ask the right questions." - Dr. Alfred Lanning's hologram.
-> Have you read the User Manual??
-> Have you drawn and posted a diagram?
-> Have you posted a screenshot?
-> Have you posted your config file?
The administrator has disabled public write access.

Dirac Live set up for nearfield monitoring - how? 2 months 6 days ago #41867

  • Skol303
  • Skol303's Avatar
  • Offline
  • Junior Boarder
  • Posts: 37
  • Thank you received: 7
  • Karma: 0
john.reekie wrote:
Oh, I meant the microphone response alone, no filtering etc. That is what you would want to look at if you want to know if and how 0 and 90 differ. Without running through the DSP would be better to remove the delay.
Ah! I don't have any comparative 0/90-degree measurements with Dirac Live off, but I can take some next time I fire up REW.

john.reekie wrote:
BTW your REW files seems to not have the impulse response in them, seems like a frequency response import.
I should have mentioned that the measurements were taken using the very latest version of REW (V5.20 Beta 8). Just checked on another PC and the file does contain the full set of measurements, but I had to install the latest version of REW in order to view them (otherwise they appear like a freq response import as you mention).
Last Edit: 2 months 6 days ago by Skol303.
The administrator has disabled public write access.

Dirac Live set up for nearfield monitoring - how? 2 months 5 days ago #41881

  • bugeyed
  • bugeyed's Avatar
  • Offline
  • Junior Boarder
  • Posts: 25
  • Thank you received: 5
  • Karma: 0
My letter to Dirac followed by their response.

Me
Here is a statement made by the MiniDSP "Devteam" forum administrator. There seems to be some confusion & conflicting recommendations for using Dirac Live with regards to 2 channel stereo applications.

MiniDSP "Devteam
"As far as we're concerned, directly pointing at the speaker is still the right way. Only if you have a 360 like speaker arrangement (i.e. 5.1/7.1) would we see some interest in having the mic pointing up, i.e. able to hear all speaker with the same angle of incidence.
-DevTeam"

Frans, can you comment on this?
Regards,
Kev

Frans - Dirac support.
"Hello Kevin,
As far as I know Dirac always recommends to use 90 degree measurements on any arbitrary stereo speaker system. As I said before, this is to get similar coloration on the room reflections as for the direct wave. Reflections from walls/ceiling/floor can be seen as imaginary speakers with lower magnitude placed around the microphone. These reflections will impact the sound and are also important to consider. However, we don't want to dictate on this subject, if better results can be achieved with 0 degree measurements then we don't want to force people to use 90 degree measurements. I can imagine that rooms which are well damped may get better results with 0 degree measurements.

Best regards

Frans"

I think that I have given Dirac enough information to explain why MiniDSP may recommend 0 Deg. for stereo & their only explanation is for a well damped room. Being that Dirac wrote the code & designs the filters to correct for the listening room acoustics, I consider them the authority. Since I don't use any MiniUSB electronics, except the UMIK-1, I don't have any reason to favor their recommendation over Dirac's. I did mention to Frans that the Dirac Live instructions DO say to use the orientation recommended by your microphone manufacturer. It's perfectly clear now, right?
The administrator has disabled public write access.
The following user(s) said Thank You: Skol303

Dirac Live set up for nearfield monitoring - how? 2 months 4 days ago #41892

  • Skol303
  • Skol303's Avatar
  • Offline
  • Junior Boarder
  • Posts: 37
  • Thank you received: 7
  • Karma: 0
Thanks Kev! Very insightful and perfect timing, as I received this follow-up response from miniDSP yesterday:

"We’re not exactly new at Dirac live (having sold for more than 7years) so we do know a tid bit.. Dirac research is 80% used by AVR manufacturer these days so a LOT of the “forum” comments you read online are actually from other 3rd party AVR manufacturers (NAD/EMOTIVA/THETA digital) who don’t do stereo. That’s maybe the explanation? Our recommendation doesn’t change. :-)"

Personally, I also favour the recommendation of Dirac Live: it's their software after all. And their suggestion to angle the mic upwards fits with the recommendation of most acousticians, which is to point the mic towards the ceiling or floor (usually by an angle of around 70 degrees). It might be worth noting that this recommendation is normally specific to diffuse field mics - and the UMIK-1 is instead free field, and so designed for pointing directly at what's being measured (the 90-degree calibration file allows the UMIK-1 to 'simulate' a diffuse field mic when pointed vertically). Perhaps miniDSP know about something specific to the UMIK-1 that underpins their recommendation to always use it at 0-degrees for stereo set ups? But I doubt that's the issue... and I think the advice from Dirac makes most sense here.

Interesting to note Dirac's point about "rooms which are well damped may get better results with 0 degree measurements". That's certainly the case in my experience, but as mentioned my room is heavily treated and the reflections dampened. I'm guessing that most users of miniDSP products - being hifi and home theatre enthusiasts - probably don't have such heavily treated rooms, which makes their own recommendation a little questionable. Perhaps the devteam can chime in here and explain why their view differs from that of Dirac Live?

In the meantime, it seems we at least have some clarity of sorts, even if miniDSP/Dirac Live have yet to fully agree on it :)

Thanks again for your input. Appreciated.
The administrator has disabled public write access.

Dirac Live set up for nearfield monitoring - how? 2 months 2 days ago #41916

  • bugeyed
  • bugeyed's Avatar
  • Offline
  • Junior Boarder
  • Posts: 25
  • Thank you received: 5
  • Karma: 0
I sent a message to MiniDSP including this statement from Dirac support.
""As far as I know Dirac always recommends to use 90 degree measurements on any arbitrary stereo speaker system. As I said before, this is to get similar coloration of the room reflections as for the direct wave." snip

Following is the response from MiniDSP.

"Thanks for the feedback and follow up information.
This statement is indeed interesting as it’s the first time we ever hear such statement from Dirac (yet we do talk to them a lot.. :-)
To be honest, we’re unsure at this point what is the explanation for this change… We’ll get our engineers to discuss further with them in the future to see what’s the reasoning.

For the time being, since you’re after a confirmation on this method, maybe just follow the one that works the best for you…
Then you can get back to us if indeed you can hear a major difference.. :-)
Best Regards

DevTeam

miniDSP Ltd"

Me: Hmmmmmmm, interesting.
The administrator has disabled public write access.
The following user(s) said Thank You: Skol303

Dirac Live set up for nearfield monitoring - how? 2 months 2 days ago #41918

  • Skol303
  • Skol303's Avatar
  • Offline
  • Junior Boarder
  • Posts: 37
  • Thank you received: 7
  • Karma: 0
Thanks Kev. They really need to get their story straight! :huh:

This part annoys me a little: "For the time being, since you’re after a confirmation on this method, maybe just follow the one that works the best for you… Then you can get back to us if indeed you can hear a major difference".

It shouldn't be the responsibility of users to find out what works best through trial and error. Acoustics is a science and the devteam should run their own tests to confirm the best method(s) for using their own products. Surely?!

As it stands, I still favour the response from Dirac HelpDesk: use the mic at 90-degree to capture a better picture of late-reflections (for frequency response correction); unless in a well-treated room where 0-degree may be more appropriate (favouring early reflections for time-domain correction).

My own test measurements show almost no difference between 90/0-degree mic position apart from what you'd expect: i.e. slightly more late reflections picked up by using the 90-degree calibration, but clearly not sufficient to influence the frequency response which is near-identical for both sets of results. But again, my room is heavily treated - and I imagine that the majority of miniDSP/Dirac users aren't using significant amounts of acoustic treatment, and so the effects may be more significant.

Kev: are you familiar with using REW or a similar acoustic measurement software? It may be useful if you could take two sets of measurements from the listening position in your room - one using the 0-degree calibration and another using 90-degree - so we can compare the results for a more 'normal' room (i.e. not so heavily treated).

Still, would be nice if the devteam had done such tests on our behalf! :pinch:
The administrator has disabled public write access.

Dirac Live set up for nearfield monitoring - how? 2 months 2 days ago #41920

  • bugeyed
  • bugeyed's Avatar
  • Offline
  • Junior Boarder
  • Posts: 25
  • Thank you received: 5
  • Karma: 0
Skol303 wrote:
Thanks Kev. They really need to get their story straight! :huh:

This part annoys me a little: "For the time being, since you’re after a confirmation on this method, maybe just follow the one that works the best for you… Then you can get back to us if indeed you can hear a major difference".

It shouldn't be the responsibility of users to find out what works best through trial and error. Acoustics is a science and the devteam should run their own tests to confirm the best method(s) for using their own products. Surely?!

snip

Kev: are you familiar with using REW or a similar acoustic measurement software? It may be useful if you could take two sets of measurements from the listening position in your room - one using the 0-degree calibration and another using 90-degree - so we can compare the results for a more 'normal' room (i.e. not so heavily treated).

Still, would be nice if the devteam had done such tests on our behalf! :pinch:

Did you notice that devteam put a smiley face after the statement about doing the test both ways & getting back to them if we hear a major difference?
I have REW, but have not worked with it. I have made some changes in my room & equipment so I need to run Dirac Live again & create some new filters. I am chasing a problem with me system/room regarding fairly loud soprano high C reproduction. Not sure if the slight distortion I hear is source, room or speaker generated. I have read that it is quite a challenge to record this. If the changes I am making don't fix it, I may employ REW to try to understand what is going on.
Kev
The administrator has disabled public write access.

Dirac Live set up for nearfield monitoring - how? 2 months 2 days ago #41923

  • Skol303
  • Skol303's Avatar
  • Offline
  • Junior Boarder
  • Posts: 37
  • Thank you received: 7
  • Karma: 0
Haha, yeah I noticed their smiley! They seem to like using them often.

But I still think it's cheeky of them to basically say: "Go and test our product and tell us if there is a problem with the method we suggest", rather than throughly testing it themselves. I mean, something like microphone position seems fairly crucial in my opinion.

And yes, they imply that if the difference is inaudible then perhaps it doesn't matter... which is true to some extent. But I'd argue that even small differences do matter, certainly to the professional market, where a few decibels or milliseconds can make all the difference to what an acoustician is trying to achieve. It just smacks of unprofessionalism to me *insert grumpy face* ;)

PS: let me know if you ever need help with REW. I'm not an expert, but I know my way around the software (and interpreting the results) well enough for most purposes. It would certainly be a good way to help identify what might be causing the slight distortion you mention. Another method would be to play some test tones around that high C to check whether the distortion is specific to the source material or not. I use this browser-based tone generator myself for quick tests and it works well... just be sure to have your output level set low to begin with!

www.szynalski.com/tone-generator/
Last Edit: 2 months 2 days ago by Skol303.
The administrator has disabled public write access.
The following user(s) said Thank You: bugeyed

Dirac Live set up for nearfield monitoring - how? 2 months 2 days ago #41926

  • plus5volt
  • plus5volt's Avatar
  • Offline
  • Junior Boarder
  • Posts: 25
  • Thank you received: 4
  • Karma: 0
Skol303, did you buy your audio equipment from someone else recommendation or by testing with your own ears?
For me devdeam is clear enough, that there is not much difference, if they know about it, they would tell it here.
I followed instructions from the Minidsp, and I calibrated my stereo for near field listening with mic pointed at 0 deg to the speaker axis, speakers distance below 1m from listener, and I am more than happy, I did not try 90deg, maybe will try another day. Please do measurements and tell us if your ears can hear the difference.
Last Edit: 2 months 1 day ago by plus5volt.
The administrator has disabled public write access.

Dirac Live set up for nearfield monitoring - how? 2 months 1 day ago #41934

  • bugeyed
  • bugeyed's Avatar
  • Offline
  • Junior Boarder
  • Posts: 25
  • Thank you received: 5
  • Karma: 0
Yes, "devteam is clear enough." & devteam did not design the software. Dirac recommends 90 deg. so that's what I do. I am not going to second guess Dirac in this matter & I just want to enjoy my system & not experiment with testing. BTW Following the recommendation of the software developer is not the same, at all, as selecting stereo components! Obviously a nearfield setup is less sensitive to the room acoustics, but "less" is not "completely". My room is small (not nearfield) & has some treatment, but the room still has a definite influence on the sound. I hope Dirac & MiniDSP get together on this. It surprises me that MiniDSP doesn't even know what Dirac is recommending.
Kev
The administrator has disabled public write access.

Dirac Live set up for nearfield monitoring - how? 2 months 1 day ago #41935

  • plus5volt
  • plus5volt's Avatar
  • Offline
  • Junior Boarder
  • Posts: 25
  • Thank you received: 4
  • Karma: 0
competition from Sonarworks advises to calibrates it software with mic at 0 deg for nearfield,
never seen studio engineers or speaker testers / designers who measure their stereo speakers with mic pointed to the ceiling, try to find any, I think it is not coincidence, because best uncorrected mic responce is at 0 deg, calibration for 90 deg requires higher degree of correction, that is why devteam can be surprised with this Dirac recomendation
The administrator has disabled public write access.

Dirac Live set up for nearfield monitoring - how? 2 months 1 day ago #41937

  • bugeyed
  • bugeyed's Avatar
  • Offline
  • Junior Boarder
  • Posts: 25
  • Thank you received: 5
  • Karma: 0
You do understand that Dirac Live is room correction software. It has nothing to do with designing speakers & studios usually have their room acoustics managed by various acoustic treatments. Room correction software is usually employed by those who must live with their setup in an environment that is not optimized to reduce early reflections. As I understand Dirac's explanation, their software needs to hear the room in order to design filters to minimize it's negative effects on the direct sound. Therefore they suggest 90 deg. Makes sense to me. Point is, Dirac wrote the software & designs the filters. Therefore they know what they need for soundfield measurements!
Kev
Last Edit: 2 months 1 day ago by bugeyed. Reason: Correction
The administrator has disabled public write access.
Moderators: devteam