# MiniDSP...mono or stereo for dual subs?



## Bear123 (Dec 31, 2013)

I toggled back and forth between mono and stereo and did an in room FR sweep....the stereo setting actually resulted in a better FR and higher output at certain frequencies. What is the proper setting for integrating dual subs. I have been using mono up to this point but saw this and played with it. Just not sure what the correct setting is, and if stereo would not be advised for some reason. This makes me wonder if it is changing the strength of signal to the subs. In mono I noticed that I had to very nearly completely max the gain on one sub to get the level set the same as the other sub with the miniDSP in the signal chain. I suppose I should check to see if toggling to stereo is changing the output level of one sub or the other which could be resulting in the change in FR. Main reason I am asking is because if there is no detriment to stereo then I would like to use that for my basis for eq since the response is better.


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## ajinfla (May 10, 2009)

Hi Bear,

There really isn't a "proper" setting....and your settings depend on many factors, including XO frequency to mains, preferred content (music/movies), etc, etc.
I recommend stereo, based on my needs/preference.

cheers


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## Bear123 (Dec 31, 2013)

Thanks, this is great news indeed. Will make my eq come out much better, and wondering that I might even gain some headroom.


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## Wayne A. Pflughaupt (Apr 13, 2006)

There may be good reasons to go with stereo subs, but not based on that graph. There’s barely enough difference between the two traces to actually make an audible distinction.

Consider that any _actual_ stereo bass content will originate with the signal source, and will pass through the receiver (assuming it can be set up for stereo subs) to the miniDSP. However, for the measurement you took we can assume that the test signal was simply mono and split between the two channels. As such the two measurements should be virtually identical because mono or stereo mode won’t make a difference if the signal source is mono. You weren’t clear if you were using the AVR or miniDSP to “toggle between mono and stereo,” but the fact that the measurements are so different suggests that something is amiss in your signal chain. 

Regards,
Wayne


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## Bear123 (Dec 31, 2013)

AVR single subwoofer output---->miniDSP input 1, then output 1 and 3 to each of my subs. Toggling mono to stereo on "system settings" tab of the miniDSP under "sub output mode". I plan to check the output level of each sub separately after toggling this mode. If it is indeed simply bumping the output level of one of the subs, I may stick to that mode since one of the subs is at 100% gain in order to level match with the miniDSP in line. And I suspect that if this is the case, that it is the sub that I had to max out the gain on that has been bumped up(it fills a 40-60 Hz null of the other sub). Here is a better representation of the difference in FR. To me it is a very noticeable change as it completely fills one of the nulls and reduces the other. Compression sets in early with my current eq in those areas, so I am hopeful that I might pick up a few dB of headroom.


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## Wayne A. Pflughaupt (Apr 13, 2006)

Bear123 said:


> AVR single subwoofer output---->miniDSP input 1, then output 1 and 3 to each of my subs. Toggling mono to stereo on "system settings" tab of the miniDSP under "sub output mode".


 Ah. So basically this is a mono input signal split, not actually stereo. Looks like the Chinese lost something in the translation.



> I plan to check the output level of each sub separately after toggling this mode. If it is indeed simply bumping the output level of one of the subs...
> 
> Compression sets in early with my current eq in those areas, so I am hopeful that I might pick up a few dB of headroom.


Any increase in output level is merely the result of a boosted input signal. This does not increase headroom. It only means that the sub with the boosted signal will clip before the other one.

Regards,
Wayne


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## Bear123 (Dec 31, 2013)

Reasonable points Wayne, thanks. I suppose I can hope that the sub that did not receive a boost was clipping early. I will do some tinkering Monday to see if it is simply a matter of the signal being boosted to one of the subs. I will try to report back on my findings and any before and after graphs, especially if I gain any headroom from improving the response.


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