Go dual Subwoofers!

IWC Dopplel

Distinguished Member
Hi I run 3 sonus Faber Cremona subs that are aligned and level adjusted (not actually volume matched) and EQ’d across the seating area these are not ported but have two passive 12” drivers. The way I did this was to effectively match the levels of all subs for volume then look at the time alignment in theory and then with REW and I ended up with small differences between them (the delta will mean that say 4,4,6 will be the same and 5,5,7) then you move the ‘group’ to align with the Fronts/centre. Then I spent quite a bit of time looking at each sub and how they combine at the different seating position, then made some more individual tweaks to the EQ and volume of each sub at each seat to get the compromise to be the most efficient and further improve the curve.

I then added the 18 and looked at the alignment and SPL so I could blend the 18 in with the others. I looked at 20,25,30 Hz as the choice to align with the group of 3 and I had a dip at 25Hz, removed by adding a bit more delay of the 18. I also looked at where I should roll off the 18

Initially the curve looked great and 8ms was the best for the 18 in terms of technical combination, I then spent some time listening and preferred less delay, it was tighter and more coherent with less smearing, I settled on 1.5ms. It measured worse though with a small dip at 25Hz at 1.5ms

Listening to two channel I spent some time with the three SF subs and ended up moving from 3,3,5 to 3.4,3.4,5.5 after extensive listening and adding the 18 I moved much further and now this runs 1.3 ms, now I criticise myself here to question a fraction of a ms, really !? But I believe I can here this 0.2ms with a-b with the 18. Not life changing just marginally better I think.

Regarding rolling off I settled on the 18 going to 41 Hz(-6db) so really rolling of from mid 30’s, the 12” subs are flat to 70Hz then roll off. If I roll the 18 later then I need to bring down the volume of each of the three subs as they are all providing output from 17Hz, the 18 from 5Hz

I did a few EQs and recorded the figures to add more of the 18 and less from the 12’s so I could a-b with different settings and decided on the 41 Hz point and the blend with a few more db from the 18 and a few less from the 3 x 12's

All the speakers have the subs picking up the lower frequencies that are missed by the speakers running full range, I use a 10x10 mini dsp for this, just to do the bass

So really 5-17Hz is the 18, 17-25Hz is all 4subs, 25-35 all mains,surrounds and 4 subs, 35-70 all mains and surround and 3 12” subs, 70Hz+ just mains and surrounds

My L,C,R,SL,SR,are good in the 30-40 range, the rears are strong above 40, so I prefer to run all the 7 channels full range and just add what is missing (possible with the 10x10, as you have EQ on the input and output) I run parallel leads so the main channels are not corrupted by EQ and additional A>D D>A it’s just the low frequencies I align and EQ
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IWC Dopplel

Distinguished Member
By the way I tried rolling in the 12’s at say 20 as they struggle below there really, I had horrible timing issues and it sounded wrong. I have heard some say rolling off is easier to align than rolling on and off

All of my subs are open at the lower frequencies and roll off only. I only add BEQ to the 18 (BEQ Catalogue) and only add 50% of the recommended lift,


Active Member
Hi I run 3 sonus Faber Cremona subs that are aligned and level adjusted
Sounds a bit like Dirac Unison, all drivers full range working together but achieved the hard way.



Active Member
For dual subs, is a miniDSP always required, even if the AVR has dual subwoofer outputs and its own subwoofer EQ HT?

About Audyssey Sub EQ HT™​

Audyssey Sub EQ HT™ makes the integration of dual subwoofers seamless by first compensating for any level and delay differences between the two subwoofers and then applying Audyssey MultEQ® XT32 to both subwoofers together.

Mr Wolf

Well-known Member
Not "required" as such but it should give you the ability to get a smoother in-room frequency response and the ability to add a House Curve. Its level of benefit to you also depends on the subs - if they have built in manual PEQ filters then you could get get a measurement mic and tweak Audyssey's result manually to fine tune the FR (or do it in reverse and get Audyssey to polish off the FR that you've already tweaked with the PEQs). That may be enough for you - this method got my FR to within a 9dB window. A few months later I bought a MiniDSP which got it to within a 3dB window.

Personally, as a minimum I would buy a UMIK-1 microphone so you can at least accurately measure what Audyssey has done for you and go from there. You'll be needing one if you end up going the MiniDSP route anyway. It actually has many uses.


Active Member
Thanks Mr Wolf.

I've got a UMIK 1 already, and the sub is the SVS pro with the app for minor tweaks. Your post just helps justify me moving to duals! :D

I wonder if there will be any black friday deals coming...

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