# Multiple subwoofer calibration



## juszat (Jan 11, 2015)

I recently moved into a house with a dedicated home theater room . I decided to add two more subwoofers to make it a total of 4( identical servo subs). My question is related to calibrating and integrating this 4 subs to the rest of the speakers . I have a processor with a Dirac room measurement built in . I have one sub out from the processor.
My question . Can I use Dirac ONLY to make the measurements , calibration and integration of the subs along with the rest of the speakers or should I add for example a Minidsp 2X4 and make a separate subwoofer calibration using REW and the 4 subs ( setting levels , phase and delay ) and then use Dirac for the final measurement and setting the target curve for the system as a whole ?


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## Da Wiz (May 8, 2019)

You should set levels manually on the 4 subs first by connecting 1 at a time to the processor and selecting the subwoofer level setting tone, set all 4 subs to produce the same volume level at your main seat. Then connect all 4 subs and run DIRAC. The point of multiple subs is to reduce the impact of room modes (cancellations that cannot be corrected). If you setup multiple subs running a single LFE channel, you really "have" to measure all of them at the same time. Calibrating them one at a time would be problematic as they may not "mesh" properly when all 4 are in use. More subs won't improve extension (low frequency limit). More subs will produce higher LFE SPLs but most systems rarely need louder bass in the room, but you only get a maximum of 3 dB more bass for each sub you add (assuming they are identical models with the same power amp). Of course you don't want to add 9 dB of bass when you add 3 LFE subs to a system, that's why you have to run DIRAC with all subs connected. Unless you have a huge room problem, I don't think you'll get a lot of benefit from adding DSP processing for each sub independently. As I recall, DIRAC is one of the few room correction systems that allows you to identify how many independent subwoofer outputs there are in a processor and DIRAC will then test each subwoofer independently AND then test all 2 or 3 or 4 subs TOGETHER and use the best combination of individual sub settings and "group" sub settings. Obviously, that only works if there are 2 or 3 or 4 independent sub outputs that the processor handles individually. With a single output shared by multiple subs, you have to take that extra level setting step at the beginning, then treat them like they are a single subwoofer. The vast majority of the time, your result will be fine.


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## AustinJerry (Apr 2, 2010)

I recommend a MiniDSP 2x4 to consolidate the subs prior to the Dirac calibration.

Here is a guide that explains the approach: 

MiniDSP 2x4 Set-Up Guide Latest Version.pdf


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## Sal1950 (Jun 8, 2016)

Da Wiz will get you a decent result but due to the subs still not being time aligned one may call attention to itself over the others.. To get really first class results you need to follow a path such as AustinJerry recommended.


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## Mazza (Jun 27, 2010)

Also worth a read...



Bass Integration Guide – Part 1


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