multi sub pasive phase control

Hi,

I have a 15" subwoofer I built, using 25mm plywood (you can see the cabinet with the green grille in the image of my vintage system!) and I use this subwoofer amp BSBPV500

(they used to manufacture for REL in the early days I believe and they seem to know what they are doing ...a lot more than me!)

My brother with 3 Sonus Faber subwoofers like the sound of mine and tried the BK amp direct into the sonus subs bypassing the SF amp, and he and ended up with 3 replacing the integral amp with the BK. He uses digital signal processing to align his which I tried and did not get on with.

I made a 12" version of my 15" sub with the same brand of driver for a friend who borrowed my 15 and loved it, but his room could not put up with the cabinet size..

Anyway the preamble set's the scene for the question. When I make my subs I use a CNC shop on a full sheet of 25mm ply, and with the 12" I was able to get two cabinets out........so I have the chance to try a 2nd sub.

BUT I would rather not also invest in a 2nd amplifier if possible (which would give me independent phase control of each sub with the integral control on the amp). So is there any clever way to create a phase adjustment for the 2nd sub with a passive controller?

Thanks,
 

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The 0-180 degree continuously variable subwoofer "phase" controls use all-pass filters.
Passive, post amplifier all pass filters would be impractical due to the cost of components required- they would likely cost more than another amplifier, and would waste power.
 
What do you bean extreme? Seems pretty normal. I had 8 subs running at one time just for fun and 4 of them were push pull. I now just run four and I think it’s the sweet spot. Usually have 3 or 4 speakers in room to compare.