Different brand/model Sub(s) integration


I have an all analog setup, the speakers are 2 Tannoy Kensington and one REL s/510. 

I have a room mode at around 30Hz, that I can't fix regardless the REL's location. The only viable solution I can see is to add another sub, because the REL does not have DSP and no bass-trap can effectively absorb it.

Do I need to add another s/510 or I would be better off adding another brand with DSP so I can null the room mode? 

128x128astolfor

Hard to say astolfor. The ideal solution would be to get another s/510 and a stand alone two way crossover/room control unit like a MiniDSP. 

I think you need more than one sub, at least 2, the more subs will reduce your dead zone. Absolutely use a crossover with a high pass filter to your main stereo speakers. 

@fiesta75 I am going to get one more, but the question is do I need another s/510 or I can use another brand or model and smaller?