Seeking Idiots Guide to multi-sub 2ch REW/Dirac Live calibration for miniDSP

[Smithg97]

As the title suggests I'm really hoping someone can provide a step-by-step idiots guide as to how to, once and for all, properly calibrate my miniDSP Flex Dirac Live version for a 2.2 music setup.

I've tried numerous times and either miss something or do something which later transpires is wrong (e.g. using MSO as I see now that Dirac enable miniDSP Flex is listed as incompatible) or follow a rigid process that I believe is correct and when it comes to the listening test sounds awful so therefore must have done something incorrectly!

I have the following hardware in my setup;
miniDSP Flex unbalanced with Dirac Live
Nord acoustics MP NC252 2ch power amp
Arendal 1723S THX bookshelf speakers (desk setup so quite near field)
SVS PB1000 Pro x2 subwoofers (placed about 9ft behind me close to the backwall with no option to relocate)
UMIK-1
I'd like to understand a full end-to-end process if someone is kind enough to draft one as i've seen high level bits and pieces online, or guides which become dated or don't account for nuance....etc what I'd really appreciate is full end-to-end process;

• Which mic cal file to use (given i have speakers in front, subs behind)
• Do i set XO first or later in the process? Should i high pass speakers or just low pass subs?
• For the routing matrix do i sent L+R channel both L+R subs or keep them separate?....etc
• Do i use REW to gain match & time and phase align subs and speakers, if so how and in what order? What options do i need to activate in REW.....etc - my current calibration sounds awful i think due to time alignment with subs being wrong so always hear a distracting boominess that sounds completely out of sync
• For the acoustic timing reference what is the correct way to use this feature to ensure time alignment is correct
• What stage in the process do i run Dirac Live calibration and how to ensure it improves sound rather than destroying any pre-calibration i've already done on subs....etc?

 

[john61ct]

Altogether this is the equivalent to several semesters' worth of a uni course.

How about compiling and posting a list of the learning resources you've found so far, so you are Contributing to the cause, helping others behind the learning curve from you?

To be honest IMO, miniDSP is very limited - both in FIR processing power, and compatibility with the more "open" tools out there.

Using a PC for convolving, at least for learning purposes, would let you access them, and pretty soon you will likely be doing better than Dirac.

IMO

 

[john61ct]

Which mic cal file to use (given i have speakers in front, subs behind)

How many different ones do you have?

Use the 0° one for when you are pointing the mic directly at the driver you are measuring.

Use the 90° one when pointing straight up to capture the room reflections

 

[Smithg97]

Altogether this is the equivalent to several semesters' worth of a uni course.

How about compiling and posting a list of the learning resources you've found so far, so you are Contributing to the cause, helping others behind the learning curve from you?

To be honest IMO, miniDSP is very limited - both in FIR processing power, and compatibility with the more "open" tools out there.

Using a PC for convolving, at least for learning purposes, would let you access them, and pretty soon you will likely be doing better than Dirac.

IMO

The alternative i'm considering is switch to Lyngdorf TDAI

 

[john61ct]

To me that is the opposite path to wanting to learn the topic. Maybe would be interesting if I had no time for the hobby but had lots of money.

I would start a different thread for your questions about that unit, or comparing it to the miniDSP.

 

[mps]

I have a MiniDSP SHD with two subs and umik1. I would also appreciate a guide. I first adjusted the phase on the subs for the smoothest frequency response and then mostly accepted the recommendations of Dirac live. Is there anything between that and several semesters of study?

 

[Smithg97]

The intent of this thread is to get a process guide that I can follow in order to get good results from the miniDSP failing which I'd then consider an alternative like the Lyngdorf

 

[kyuu]

If you haven't already, you might consider checking out @Keith_W's excellent free REW ebook to help you with taking measurements and using REW.

• Which mic cal file to use (given i have speakers in front, subs behind)

As the ebook says, if there is a 90-degree calibration file, use that and point the microphone at the ceiling. If the 90-degree is not available, then use the 0-degree one and point the mic between the L/R speakers.

• Do i use REW to gain match & time and phase align subs and speakers, if so how and in what order? What options do i need to activate in REW.....etc - my current calibration sounds awful i think due to time alignment with subs being wrong so always hear a distracting boominess that sounds completely out of sync

Use impulse/step response in REW to align the subwoofers with the main speakers. Check this post to get an idea of the process.

• What stage in the process do i run Dirac Live calibration and how to ensure it improves sound rather than destroying any pre-calibration i've already done on subs....etc?

Run Dirac Live last and curtain the correction to 500Hz (or lower).

 

[Smithg97]

If you haven't already, you might consider checking out @Keith_W's excellent free REW ebook to help you with taking measurements and using REW.

As the ebook says, if there is a 90-degree calibration file, use that and point the microphone at the ceiling. If the 90-degree is not available, then use the 0-degree one and point the mic between the L/R speakers.

Use impulse/step response in REW to align the subwoofers with the main speakers. Check this post to get an idea of the process.

Run Dirac Live last and curtain the correction to 500Hz (or lower).

Thank you Kyuu I will be sure to review this documentation, Keith_W has responded to me in other posts and clearly knows a lot more than I do. When you say curtain Dirac live you mean to say don't let it EQ below 500hz right?

 

[kyuu]

When you say curtain Dirac live you mean to say don't let it EQ below 500hz right?

No the opposite. Don't let it correct higher than 500Hz. After that you are well out of the modal and transition regions where making corrections based on in-room measurements makes sense.

 

[Mort]

• Which mic cal file to use (given i have speakers in front, subs behind)
• Do i set XO first or later in the process? Should i high pass speakers or just low pass subs?
• For the routing matrix do i sent L+R channel both L+R subs or keep them separate?....etc
• Do i use REW to gain match & time and phase align subs and speakers, if so how and in what order? What options do i need to activate in REW.....etc - my current calibration sounds awful i think due to time alignment with subs being wrong so always hear a distracting boominess that sounds completely out of sync
• For the acoustic timing reference what is the correct way to use this feature to ensure time alignment is correct
• What stage in the process do i run Dirac Live calibration and how to ensure it improves sound rather than destroying any pre-calibration i've already done on subs....etc?

1) 90 degree but it really won't matter as long as you are consistent
2) first, both
3) both usually
4) no
5) dirac live does this
6) all else equal, as soon as you do the crossover

 

[Mort]

The intent of this thread is to get a process guide that I can follow in order to get good results from the miniDSP failing which I'd then consider an alternative like the Lyngdorf

And stop asking for a process guide. It's sounds entitled.

 

[Smithg97]

And stop asking for a process guide. It's sounds entitled.

I didn't demand anyone do anything and I'm not entitled, I asked for help from people with knowledge in this area given the material online is fragmented, often dated or incomprehensible for the average hobbyist which is what I am. If someone is kind enough to share their knowledge (which is a large part of what this forum entails) then I appreciate them as I'm sure many others do. I could say to you "stop sharing your opinion, it's irrelevant to the topic of discussion and no one asked for it" but it wouldn't be helpful would it?

 

[john61ct]

The intent of this thread is to get a process guide that I can follow in order to get good results from the miniDSP

You are absolutely sounding entitled.

Imagine that the time of the actual experts here is worth a very high hourly rate.

You may not be "demanding", you may not "feel" entitled, but the way you approach asking for help will definitely have an impact on the quantity and quality of help you receive.

How To Ask Questions The Smart Way

Edit: Note that the CATB.ORG website is not itself a provider of help.

 

[Smithg97]

You are absolutely sounding entitled.

Imagine that the time of the actual experts here is worth a very high hourly rate.

You may not be "demanding", you may not "feel" entitled, but the way you approach asking for help will definitely have an impact on the quantity and quality of help you receive.

How To Ask Questions The Smart Way

Edit: Note that the CATB.ORG website is not itself a provider of help.

How do you think you sound?

 

[john61ct]

Like an old hand genuinely trying to help someone to get the most possible out of an incredibly valuable learning resource, when used correctly.

 

[Keith_W]

As the title suggests I'm really hoping someone can provide a step-by-step idiots guide as to how to, once and for all, properly calibrate my miniDSP Flex Dirac Live version for a 2.2 music setup.

I've tried numerous times and either miss something or do something which later transpires is wrong (e.g. using MSO as I see now that Dirac enable miniDSP Flex is listed as incompatible) or follow a rigid process that I believe is correct and when it comes to the listening test sounds awful so therefore must have done something incorrectly!

I have the following hardware in my setup;
miniDSP Flex unbalanced with Dirac Live
Nord acoustics MP NC252 2ch power amp
Arendal 1723S THX bookshelf speakers (desk setup so quite near field)
SVS PB1000 Pro x2 subwoofers (placed about 9ft behind me close to the backwall with no option to relocate)
UMIK-1
I'd like to understand a full end-to-end process if someone is kind enough to draft one as i've seen high level bits and pieces online, or guides which become dated or don't account for nuance....etc what I'd really appreciate is full end-to-end process;

• Which mic cal file to use (given i have speakers in front, subs behind)
• Do i set XO first or later in the process? Should i high pass speakers or just low pass subs?
• For the routing matrix do i sent L+R channel both L+R subs or keep them separate?....etc
• Do i use REW to gain match & time and phase align subs and speakers, if so how and in what order? What options do i need to activate in REW.....etc - my current calibration sounds awful i think due to time alignment with subs being wrong so always hear a distracting boominess that sounds completely out of sync
• For the acoustic timing reference what is the correct way to use this feature to ensure time alignment is correct
• What stage in the process do i run Dirac Live calibration and how to ensure it improves sound rather than destroying any pre-calibration i've already done on subs....etc?

Looks like I was tagged in this thread. Have you seen MiniDSP's step by step tutorial for AutoEQ? I realize it does not describe how to properly integrate a subwoofer. As luck would have it, I am currently working on a subwoofer integration guide for Acourate which will be given away for free. You can see progress here. It already answers some of your questions, e.g. whether your subs should be mono'ed, how to set the LPF for your sub, and whether speakers should have a HPF. If you are willing to wait a couple of weeks, the whole document will hopefully be ready.

In your case, because your subs are behind you, you do not want to hear the location of your subs. Therefore they should be mono'ed and the LPF set low enough so that there is no chance that the subwoofer itself or its distortion products audibly give away the location of the sub.

I can not answer any questions on Dirac since I don't use it.

This is a general outline of how to integrate your subs with REW:

1. Reset your MiniDSP so that all filter banks are empty.
2. Set LPF for subs and HPF for speakers in your MiniDSP.
3. Perform time alignment. My favoured way of doing this is to input the maximum delay for your main speakers (I think it's 30ms for MiniDSP) then sweep the subs and mains together. Examine the impulse response. You will see two peaks - the subwoofer peak arriving earlier, and the main speakers arriving later. Measure the difference between the start of both impulses and subtract 30ms.
4. Use REW's alignment tool. Input the delay you just measured, the fine-tune the delay to align the phase and remove as many dips as possible without worrying about the peaks.
5. Input these delays into your MiniDSP. Sweep all speakers and subs combined. Run this through REW's EQ function as per that link I supplied.
6. Load the biquads into the MiniDSP and take a verification measurement. You are done.

 

[Smithg97]

Looks like I was tagged in this thread. Have you seen MiniDSP's step by step tutorial for AutoEQ? I realize it does not describe how to properly integrate a subwoofer. As luck would have it, I am currently working on a subwoofer integration guide for Acourate which will be given away for free. You can see progress here. It already answers some of your questions, e.g. whether your subs should be mono'ed, how to set the LPF for your sub, and whether speakers should have a HPF. If you are willing to wait a couple of weeks, the whole document will hopefully be ready.

In your case, because your subs are behind you, you do not want to hear the location of your subs. Therefore they should be mono'ed and the LPF set low enough so that there is no chance that the subwoofer itself or its distortion products audibly give away the location of the sub.

I can not answer any questions on Dirac since I don't use it.

This is a general outline of how to integrate your subs with REW:

1. Reset your MiniDSP so that all filter banks are empty.
2. Set LPF for subs and HPF for speakers in your MiniDSP.
3. Perform time alignment. My favoured way of doing this is to input the maximum delay for your main speakers (I think it's 30ms for MiniDSP) then sweep the subs and mains together. Examine the impulse response. You will see two peaks - the subwoofer peak arriving earlier, and the main speakers arriving later. Measure the difference between the start of both impulses and subtract 30ms.
4. Use REW's alignment tool. Input the delay you just measured, the fine-tune the delay to align the phase and remove as many dips as possible without worrying about the peaks.
5. Input these delays into your MiniDSP. Sweep all speakers and subs combined. Run this through REW's EQ function as per that link I supplied.
6. Load the biquads into the MiniDSP and take a verification measurement. You are done.

Thank you Keith, I will try to digest this all at the weekend when I've got a few hours to spare and have another go at the calibration whilst also awaiting your guide to materialise as sounds like it could be just the thing I'm after!

 

[thcdru2k]

There is a lot of conflicting comments just listen to Keith_W

 

[Smithg97]

There is a lot of conflicting comments just listen to Keith_W

Haha yes I had this impression from other threads on similar topics