This comes up from time to time, so I thought I would share my current findings on using multiple subwoofers to get smoother and flatter bass. I use 6 B&W subwoofers, all are pairs of the same, with varying capabilities. I have 2x DB1's, 2xCTS15 and 2x CTSW10. Note this is all without any EQ to the system.
I have measured the results in pairs, to show firstly how bad things look but improve as more pairs are included and then time and phase aligned.
This is my pair of DB1's, they are located almost midwall along the longest wall sides of my room, on opposite wall sides. As you can see both subs measure fairly similar and the third graph is of both subs combined resulting in a 6dB gain.
This is a pair of CTSW15's they are located in the front room corners.
Finally a pair of CTSW10's.They are in the room rear corners. There is only one image as they both are driven off the same amp.
I have now taken the CTSW15's and 10's outputs
Resulting in this. I time aligned to CTSW10's to be the same distance as the 15's. This results in a corner loaded set.
I then took the 4 corner subs and added in the 2midwall DB1's.
Resulting in this
I then flipped the phase on the pair of DB1's to get a smoother response.
I then included the main floor standing speakers and used a crossover of 90Hz. 90Hz was used as it gives the best measured frequency response.
I then flipped all the sub phases to get the smoother blue output. I have not time aligned the main loudspeakers, so this step is a bit of a compromise as the splice at the 90Hz crossover results in a notch at the crossover.
Ideally I should time align the main loudspeakers, but that would mean I need to run another a/d and d/a step in the process and that would sort out the splice properly. Ironically referring to the above graph with the blue and red graphs, I prefer the red one.
Finally a waterfall of the sub response only.
I have measured the results in pairs, to show firstly how bad things look but improve as more pairs are included and then time and phase aligned.
This is my pair of DB1's, they are located almost midwall along the longest wall sides of my room, on opposite wall sides. As you can see both subs measure fairly similar and the third graph is of both subs combined resulting in a 6dB gain.
This is a pair of CTSW15's they are located in the front room corners.
Finally a pair of CTSW10's.They are in the room rear corners. There is only one image as they both are driven off the same amp.
I have now taken the CTSW15's and 10's outputs
Resulting in this. I time aligned to CTSW10's to be the same distance as the 15's. This results in a corner loaded set.
I then took the 4 corner subs and added in the 2midwall DB1's.
Resulting in this
I then flipped the phase on the pair of DB1's to get a smoother response.
I then included the main floor standing speakers and used a crossover of 90Hz. 90Hz was used as it gives the best measured frequency response.
I then flipped all the sub phases to get the smoother blue output. I have not time aligned the main loudspeakers, so this step is a bit of a compromise as the splice at the 90Hz crossover results in a notch at the crossover.
Ideally I should time align the main loudspeakers, but that would mean I need to run another a/d and d/a step in the process and that would sort out the splice properly. Ironically referring to the above graph with the blue and red graphs, I prefer the red one.
Finally a waterfall of the sub response only.
