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Subwoofer Calibration

Subwoofer Calibration
« on: April 24, 2022, 07:58:21 PM »
So, I recently reviewed a M&K X15+ subwoofer and absolutely loved it enough to keep it. It's the best subwoofer I've ever used in the 25+ years I've been involved with this hobby. In fact, it's the first sub that was able to handle the Edge of Tomorrow opening without any distortion at all at reference level (far too loud to listen for more than a few minutes). Anyway, in order to incorporate it with my current subs (SVS PC-Ultra, HSU VTF 15H MK-2, and stacked JL Audio F110s), I had to equalize some of its low-end output to play nice with the other subs. While I sacrifice some low-end output, I do get great response across my four seats in the theater. In my dream world, I get another M&K X15+ and just use dual subs....it would make calibration a lot easier, but is very expensive (the X15+ is $6K retail). 

Anyway, here are my before and after calibration readings plus some output graphs from some movies. Needless to say, the bass is pretty damn impressive. I implemented a house curve from 105-30 dB in order to get great bass output at less than reference levels. As you can see, I got over 110 dB on the Edge of Tomorrow Intro with absolutely no distortion. 

https://i.imgur.com/7e591N4.jpg
Subwoofer Calibration

https://i.imgur.com/AhpwQc6.jpg
Subwoofer Calibration

https://i.imgur.com/tNdiOol.jpg
Subwoofer Calibration

https://i.imgur.com/LW3FGKC.jpg
Subwoofer Calibration

https://i.imgur.com/Ja1gcUI.jpg
Subwoofer Calibration


Blu-ray Reviewer / Technical Writer
Sound & Vision Magazine

bmoney

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Re: Subwoofer Calibration
« Reply #1 on: April 25, 2022, 03:20:49 AM »
Very nice. One request. Can you change the frequency response to 5db increments. Will help see the whole picture 
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Nad t758v3 
7.4.4 diysoundgroup 1099's (3) 
Volt 6 (8 ) 
18" SI subs (4) 
diy 130" 2.40 spandex screen
minidsp 2x4HD
JVC rs600
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bmoney

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Re: Subwoofer Calibration
« Reply #2 on: April 25, 2022, 03:22:04 AM »
Also you shouldn’t need to sacrifice lowend to have it interact with your other subs. They should be complimenting each other. 
SadieMax 2,0 Build thread

Nad t758v3 
7.4.4 diysoundgroup 1099's (3) 
Volt 6 (8 ) 
18" SI subs (4) 
diy 130" 2.40 spandex screen
minidsp 2x4HD
JVC rs600
Lumagen radiance pro 4242
Nvidia shield pro
Emby NAS media player

Re: Subwoofer Calibration
« Reply #3 on: April 25, 2022, 08:28:10 AM »
Also you shouldn’t need to sacrifice lowend to have it interact with your other subs. They should be complimenting each other.
I somewhat misspoke. I could push it, but it would cause distortion in the "lesser" subs...does that make sense?
Blu-ray Reviewer / Technical Writer
Sound & Vision Magazine

Re: Subwoofer Calibration
« Reply #4 on: April 25, 2022, 08:53:02 AM »
Here's the chart with finer measurements. https://i.imgur.com/99uh9VM.jpg
Subwoofer Calibration
Blu-ray Reviewer / Technical Writer
Sound & Vision Magazine

AVSCraig

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Re: Subwoofer Calibration
« Reply #5 on: April 25, 2022, 09:03:45 AM »
I somewhat misspoke. I could push it, but it would cause distortion in the "lesser" subs...does that make sense?
That is the problem of not having 4 identical subs. 
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Re: Subwoofer Calibration
« Reply #6 on: April 25, 2022, 09:12:49 AM »
That is the problem of not having 4 identical subs.
Plus, getting the different subs to "play nice" with each other can be a challenge. My wife was ready to throw me out of the house after two weekend of hearing frequency sweeps :)
Blu-ray Reviewer / Technical Writer
Sound & Vision Magazine

Re: Subwoofer Calibration
« Reply #7 on: April 25, 2022, 10:01:12 AM »
Greetings,

All in all, nice work here Dave. I like what you did with the house curve. Have fun and let 'er RIP!!


Regards,
« Last Edit: April 25, 2022, 10:04:23 AM by Ralph P. »

Re: Subwoofer Calibration
« Reply #8 on: April 25, 2022, 10:13:56 AM »
Greetings,

All in all, nice work here Dave. I like what you did with the house curve. Have fun and let 'er RIP!!


Regards,
Thanks Ralph :)
Blu-ray Reviewer / Technical Writer
Sound & Vision Magazine

bmoney

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Re: Subwoofer Calibration
« Reply #9 on: April 25, 2022, 10:40:35 AM »
Here's the chart with finer measurements. https://i.imgur.com/99uh9VM.jpg
Subwoofer Calibration

Wow. Any smoothing on that graph?
looks great. Are all the subs vented or sealed. That’s really the only time they are really challenging. 
either way looks great. Have fun :)
SadieMax 2,0 Build thread

Nad t758v3 
7.4.4 diysoundgroup 1099's (3) 
Volt 6 (8 ) 
18" SI subs (4) 
diy 130" 2.40 spandex screen
minidsp 2x4HD
JVC rs600
Lumagen radiance pro 4242
Nvidia shield pro
Emby NAS media player

Re: Subwoofer Calibration
« Reply #10 on: April 25, 2022, 11:18:28 AM »
Wow. Any smoothing on that graph?
looks great. Are all the subs vented or sealed. That’s really the only time they are really challenging.
either way looks great. Have fun :)
No smoothing applied to the graph. The JL Audio and M&K subs are sealed, the HSU and SVS are ported. It took me hours and hours to "get it right" and I learned a lot of things along the way as well in regard to using a sine wave at a particular frequency to help with the time delay.

So let's say you have a dip at 42 Hz, you can play a sine wave at the frequency and adjust the delay in the sub until the dB measurement starts to rise. I would then find out the "end point" at that frequency (when it would start to dip) and know that the proper delay was somewhere in that range. What you'll find, is that if you maximize the output at 42Hz, you end up screwing something up in another frequency, so you need to make minor adjustments within that range and see how it impacts the other frequencies. Needless to say, it involves a ton of trial and error with REW and the MiniDSP, but is well worth the effort. 
Blu-ray Reviewer / Technical Writer
Sound & Vision Magazine

bmoney

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Re: Subwoofer Calibration
« Reply #11 on: April 25, 2022, 03:05:46 PM »
Ahhh. Mixing ported and sealed is a major no no. Shocked you were able to get tolerable results lol
SadieMax 2,0 Build thread

Nad t758v3 
7.4.4 diysoundgroup 1099's (3) 
Volt 6 (8 ) 
18" SI subs (4) 
diy 130" 2.40 spandex screen
minidsp 2x4HD
JVC rs600
Lumagen radiance pro 4242
Nvidia shield pro
Emby NAS media player

Re: Subwoofer Calibration
« Reply #12 on: April 25, 2022, 04:22:16 PM »
Ahhh. Mixing ported and sealed is a major no no. Shocked you were able to get tolerable results lol
It can be done, but it takes a lot more effort. At some point I'll go to all sealed subs, but I'm not at that point (yet). 
Blu-ray Reviewer / Technical Writer
Sound & Vision Magazine

Re: Subwoofer Calibration
« Reply #13 on: April 25, 2022, 06:28:16 PM »
That's a really nice result!

I'm guessing this is for your MLP?  Have you measured any other seats?  Maybe they don't matter.

If they do, you could try using MSO (Multi Sub Optimizer), since you already have a MiniDSP.  It could do all those calculations for you, and end up saving you time.

Scott

Re: Subwoofer Calibration
« Reply #14 on: April 25, 2022, 06:45:15 PM »
That's a really nice result!

I'm guessing this is for your MLP?  Have you measured any other seats?  Maybe they don't matter.

If they do, you could try using MSO (Multi Sub Optimizer), since you already have a MiniDSP.  It could do all those calculations for you, and end up saving you time.

Scott
I actually spent over 8 hours with MSO and hated the results. I calibrated everything to my listening position and it still sounds good in the other three seats (although not as good :D). I have a multi-purpose room that opens to two other rooms and I don't think MSO likes that type of situation. I was really hoping for better results, but it didn't turn out for me :(
Blu-ray Reviewer / Technical Writer
Sound & Vision Magazine

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