REW subwoofer alignment Video using MiniDSP

[Deleted]

Very helpful resources which may help utilize the freeware software REW and MSO for multiple subwoofer integration. 

In addition: 
www.minidsp.com/applications/subwoofer-tuning/tuning-multiple-subs
www.minidsp.com/applications/digital-crossovers/minidsp-2x4hd-application/282-2x4-hd-sub-integration
www.minidsp.com/applications/subwoofer-tuning/dual-sub-with-mso

Note: the instructionals utilize Minidsp equipment but I find the walk through Rew most helpful.  




And here's the next step which integrates into the mains:

[Germotiva]

yes I can only agree. when i tried it for the first time, the setup of my multisub was better.
i learned a lot from it and tested a lot with rew. and I was able to improve it further
🍻

[ttocs]

Thanks for posting that video. I watched it early last year and it was a great help in getting going with REW.

[jagman]

I found it very useful as well. I wouldn't be surprised if the majority of people on this sub use... multiple subs (pun intended).

[Deleted]

Later today will be my first time working w/ REW after weeks of reading/viewing instructionals!!!
I have a Minidsp 2x4HD and firmware/software upgrade to the Dirac Live model DDRC24. 
After I upgraded I decided why bother w/ Dirac Live at all if using REW? So I downgraded the firmware back to the 2x4HD. 

Please, if anyone has advice or wishes to chime in by all means feel free!

Steps with REW:
1) Config/setup hardware and load Harman Research +8db curve into REW. Once  I learned that house curves could be loaded into REW I decided there's no sense at all for me to use Dirac Live in a 2.2 channel system. 
2) Align both subwoofers into one virtual subwoofer by adding delays and building a subwoofer biquad filter and loading it into the 2x4HD. 
3) Align both mains
4) Integrate "the" subwoofer" into the mains using REW's "time alignment" tool. 

[Deleted]

Putting together a page here: www.disqus.social/2021/05/maximum-optimization-using-rew-and.html

Included are the instructional videos, Harman Research download sources, and parts lists. 

I'll be adding to the page w/ results throughout the next week. 

[Deleted]

Installing Minidsp:

For my parts list: www.disqus.social/2021/05/maximum-optimization-using-rew-and.html

SVS RCA in both 1 and 2 meters:



Minidsp currently playing w/ no filters in the analog audio chain.

Out 1: Left Main - Amplifier
Out 2: Right Main - Amplifier
Out 3: Left Subwoofer - Active Subs
Out 4: Right Subwoofer - Active Subs



Bluesound Node 2i streamer and SMSL M400 DAC:



Parasound Halo A31 w/ AcInfinity cooler: 





Now I'm just waiting for a 30+ ft USB extension cable w/ repeater to link my PC in another room to the Minidsp... 
Looking forward to firing up REW and let the tuning begin!

[Deleted]

2.2 Channel Summation using Harman Research +10db curve....
Took me forever to get going today but this is both mains and 2 subwoofers.
Measurement taken 9 ft in front of sound stage center MLP. 
My first time using Rew and my first screen shot graph using 1/12th smoothing:




Any suggestions?

[ttocs]

If you apply Psychoacoustic smoothing I think you'll find that above 100Hz the mean will be about 80dB, and below 100Hz it's more than 24dB hotter. That's a LOT! I would lower the subwoofer gain.

Otherwise, there's no bad huge dips or peaks, so, no big problems to deal with!

You might try measuring from about 15Hz and up instead of all the way down to 2Hz. Some subs do better around 20Hz when they don't have to "recover" from being walloped with ultra-low frequencies. It may give a more accurate result at and around 20Hz, at least that's what I learned with a couple subs I had before my current subs so I only measure down to 15Hz minimum.

[Deleted]

May 22, 2021 21:29:51 GMT -5 ttocs said:

If you apply Psychoacoustic smoothing I think you'll find that above 100Hz the mean will be about 80dB, and below 100Hz it's more than 24dB hotter. That's a LOT! I would lower the subwoofer gain.

Otherwise, there's no bad huge dips or peaks, so, no big problems to deal with!

You might try measuring from about 15Hz and up instead of all the way down to 2Hz. Some subs do better around 20Hz when they don't have to "recover" from being walloped with ultra-low frequencies. It may give a more accurate result at and around 20Hz, at least that's what I learned with a couple subs I had before my current subs so I only measure down to 15Hz minimum.

Thanks  for all your help brother. I generated test tones starting at 10hz to 300hz for subs and to 20,000hz for mains. Then as recommended applied the psychoacoustic smoothing. 

Here's both Tekton 4-10 subwoofers:



And here's the summation total of 2.2 channels after filters:



Not sure if I'm doing this "optimally" but I measured each speaker [mains and subs] individually and applied created biquad filters to each channel's outputs. Then, I began measuring summed response and created a summed biquad filter and imported it into the 2x4 HD's inputs. 

Anyhoot, this is the final result of doing so mind you to reduce the low frequency spl/gain to this point I have the subwoofers gained down -10db! In this following week I'll try a lesser low frequency Harman Research house curve. 

Question, that dip above 16,000khz .... is that normal? 
Edit: Just realized I had the "slow filter" on in my DAC....   next round of measurements etc I'll be sure to turn the slow filter off. 

Appreciate your help ttocs !

[Deleted]

Finally got the low frequency down to 10db

[ttocs]

May 24, 2021 10:54:22 GMT -5 @deleted said:

Finally got the low frequency down to 10db

Are these subs also used for LFE? If so, run REW using the LFE output and see if it makes LFE to be at +20dB above baseline instead of +10dB.

[audiobill]

How does it sound?

[Deleted]

May 24, 2021 13:01:23 GMT -5 ttocs said:

May 24, 2021 10:54:22 GMT -5 @deleted said:

Finally got the low frequency down to 10db

Are these subs also used for LFE? If so, run REW using the LFE output and see if it makes LFE to be at +20dB above baseline instead of +10dB.

No, the L and R are simply summed in the 2x4 HD:



And after a few more hours of tweaking:

[Deleted]

May 24, 2021 13:09:00 GMT -5 audiobill said:

How does it sound?

The sound stage is incredible in contrast to without REW. 
I've never heard a center phantom channel so focused. 
In the past I had problem where the phantom center wasn't focused enough or too focused where it didn't reach out to the mains. 
The soundstage goes past the mains in width and though I realize a phantom center is a psychoacoustic effect I'd swear up and down that there's a center speaker. 
A center, that is, without all that dsp processing and tunnel sounding effect. 
I'm  now sold on 2 channels!

[ttocs]

May 24, 2021 13:29:44 GMT -5 @deleted said:

May 24, 2021 13:01:23 GMT -5 ttocs said:

Are these subs also used for LFE? If so, run REW using the LFE output and see if it makes LFE to be at +20dB above baseline instead of +10dB.

No, the L and R are simply summed in the 2x4 HD:

Ok, I get it, this setup is only for the two channels. No worries then.

[audiobill]

Try pulling the bass lift down to +6db

[Deleted]

REW's  alignment tool is very nice and easy to use to integrate subs into the mains. The second video in the OP makes the process easy. Just sweep both mains playing.  Then sweep both subs playing. In the controls option choose alignment tool and place cursor at your subwoofer crossover point. Hit align slopes and phase and wallaa -  a delay will be kicked.  In my case at the 120hz crossover point the subs needed to be delayed 3.42 milliseconds which is roughly 3.4 feet in distance. 

The delay is a minus number but ya can put that number in the subwoofer delay settings in the minidsp as positive.

Sweep both mains and then both subs:



Select the Controls button option and choose alignment tool. Align slopes and phase at crossover point:



Input delays into minidsp:

[jbrunwa]

May 15, 2021 13:18:22 GMT -5 @deleted said:

Very helpful resources which may help utilize the freeware software REW and MSO for multiple subwoofer integration. 

In addition: 
www.minidsp.com/applications/subwoofer-tuning/tuning-multiple-subs
www.minidsp.com/applications/digital-crossovers/minidsp-2x4hd-application/282-2x4-hd-sub-integration
www.minidsp.com/applications/subwoofer-tuning/dual-sub-with-mso

Note: the instructionals utilize Minidsp equipment but I find the walk through Rew most helpful.  




And here's the next step which integrates into the mains:

Thanks for posting this along with your experience. I just ordered a minidsp 2x4HD and hope to solve the bass management issues in my system. Any additional advice is appreciated!

[Deleted]

Don't follow my process above in this thread. For one I wasn't using the acoustical timing reference during measurements. I'm still trying to figure out how to use the trace arithmetic tool and alignment tool, but man - the help I've received from Jtalden over AVNirvana has been incredible: www.avnirvana.com/threads/time-alignment-tool-question.9079/