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TOPIC: Re: Newby questions re OpenDRC and AcourateDRC

Newby questions re OpenDRC and AcourateDRC 6 years 6 months ago #8552

  • Bevan
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I've got a minidigi/dsp and I'm interested in the OpenDRC in the hope that phase correction might make my system sound better, obviously. (though after 8 hours of reading up on OpenDRC I havent found a single listener impression)

AcourateDRC seems the easiest and therefor only way for me to go, being not too clued up in these regards. Well, relatively easy, I still need to figure out how to get around the fact that I've got Mac, and find a price anywhere on the internet for AcourateDRC (anyone?)

My question is, given that I already have a Behringer EMC8000 mic and usb mic preamps, will the system be essential plug and play? Do I insert OpenDRC upstream of minidigi, and then let AcourateDRC run a sweep and automatically generate correction filters for phase and FR anomalies produced by my passive speakers and sub (active XO between them) that I then manually enter into OpenDRC? Have I got this correct?

My other question is wrt what AcourateDRC tries to correct for? As I understand it the best approach is to correct for speaker FR and phase irregularities anechoically and for room bellow 2-300hz.

Thanks for any advice
B
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Re: Newby questions re OpenDRC and AcourateDRC 6 years 6 months ago #8557

  • samoht
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Hi Bevan,

I just started to work with OpenDRC. In order to get familliar with you can download the AcourateDRC software from this website and register it free of charge. After registration you have access to the tool as well as to the help file describing the various steps.
You need a mic and a soundcard using an ASIO driver interface, that's all for taking measurements. Really easy to do.
The final step, i.e. Calculating the FIR correction filters is disabled until you purchase the software as described. The price is approx. 75 € plus VAT.
AcourateDRC creates a file for the right and left stereo channel which has to be imported by the OpenDRC plugin. No need to type it in.
I'm currently very busy but hope to provide first impressions within next 2 weeks.

BR

Thomas
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Re: Newby questions re OpenDRC and AcourateDRC 6 years 6 months ago #8558

  • thomasjefferson
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I too am somewhat skeptical about the audibility of linear phase, and looking forward to more reports. It does seem highly dependent on the speakers being used and how their response differs off axis vs. on axis. You might be able to get perfectly linear phase as measured from one point in space, but completely lose this from 10° above or below the listening axis, or from 45° to the side.
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Re: Newby questions re OpenDRC and AcourateDRC 6 years 6 months ago #8564

  • john.reekie
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Bevan wrote:
My question is, given that I already have a Behringer EMC8000 mic and usb mic preamps, will the system be essential plug and play?

Yes, as long as you have ASIO drivers as noted by samoht.
Do I insert OpenDRC upstream of minidigi, and then let AcourateDRC run a sweep and automatically generate correction filters for phase and FR anomalies produced by my passive speakers and sub (active XO between them) that I then manually enter into OpenDRC? Have I got this correct?

A couple of comments here (and bear in mind I have only been doing some experiments so far). AcourateDRC will correct for "minimum phase" but not for "excess phase." So if you were wanting to remove the phase shift caused by the passive crossover, this combo will not do that. You may be able to do the phase correction with rephase (I have not tried it yet) but you will need to know detailed information about the specifics of the passive crossover.
My other question is wrt what AcourateDRC tries to correct for? As I understand it the best approach is to correct for speaker FR and phase irregularities anechoically and for room bellow 2-300hz.

It corrects for the frequency response as you have measured it, with "minimum phase" phase correction. The correction tries to make the measured response meet a target response, which can include things like a slope from low-high (typical for in-room response), shelving filter, etc. You will be able to experiment with this in the trial version. The algorithm is quite smart but also conservative and won't (for example) boost the bass to meet the target. However OpenDRC includes a PEQ as well, so the approach I am using now is to use the PEQ to get the response roughly flat over the frequency range of interest, and then use AcourateDRC and the FIR filter to fine-tune it.

There's no ability to do separate correction for speaker and room. You need to choose which way you want to go. One approach (again, which I haven't tried) would be to use the FIR filtering for your "anechoic" measurement and then use the PEQ for the room response.

Hope that helps. FIR filtering is a fairly complex topic...
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?
Last Edit: 6 years 6 months ago by john.reekie.
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Re: Newby questions re OpenDRC and AcourateDRC 6 years 6 months ago #8567

  • Bevan
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Thanks both for your replies.

I'll check out the software then, just needed to be slightly convinced before going to the effort to track down a Windows computer. At this stage my system is Mac based.

I think the thing most in need of phase correction in my system might be the active 80hz XO, and the bass drivers natural roll off and whatever phase issues my new listening position up against the wall might be causing. John, when you say no way to separate room from speaker correction and that its either or... can I have either of these programs correct from only 80hz and bellow for room+XO phase and FR anomalies? My Kef LS50s are well enough behaved above that that I'm happy to leave them alone. I'm concerned after reading a post by someone who was not happy with the outcome after the software came up with 25 filters for what were also apparently well behaved speakers....

Looking forward to hearing some impressions re sonics. There were some guys over at Stereo.net.au that did a comparison between a number of Eq units and found them all sounding pretty much the same except for the DEQX which was noticeably better due to its added phase coherency/group delay feature, but sounded essentially the same as DCX/Minidsp when the playing field was levelled as far as what it was allowed to do. Which is promising.

Cheers
B
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Re: Newby questions re OpenDRC and AcourateDRC 6 years 6 months ago #8568

  • john.reekie
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Oh, I forgot to mention - FWIW I'm running AcourateDRC and rephase in a Windows 7 VM under VMWare Fusion.
Bevan wrote:
Thanks both for your replies.
John, when you say no way to separate room from speaker correction and that its either or...

I just want to clarify that I'm referring to AcourateDRC there. The OpenDRC is just a filtering engine, it will run the convolution with whatever filter that it's given. So, with AcourateDRC you make a single measurement and it generates a filter to try and match the target response. There's no ability to do separate "speaker" and "room" measurements and combine them somehow to make a single filter.
I think the thing most in need of phase correction in my system might be the active 80hz XO

rephase may be able to that although I have not tried.
can I have either of these programs correct from only 80hz and bellow for room+XO phase and FR anomalies?

Not that I know of... Bear in mind that the two programs perform very different functions, even though both generate an FIR filter as output.

I thought I had mentioned it but seem to have lost it - the frequency resolution of an FIR is determined by the filter length. Subwoofers are probably not where FIR filtering is at its best. You can try generating some hypothetical filters with rephase to see.
I'm concerned after reading a post by someone who was not happy with the outcome after the software came up with 25 filters for what were also apparently well behaved speakers....

Do you have a link? Sounds like operator error...

:)
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?
Last Edit: 6 years 6 months ago by john.reekie.
The administrator has disabled public write access.
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