Dipole sub......any takers

[kgveteran]

I never really understood Dipole subs. I want to do something different, and i have all the parts.....
Adire Tumults(4) QSC1450's(4) MiniDSP2x4, Omni mic to measure. Only thing i will need is a sheet of MDF......

The application is simple. This is an Airplay system for Pandora, itunes, Utube video's. Does the baffle height or width impact the FR, or is it all EQ....

[5th element]

If you want to try this then I would suggest reading up on the stuff found over at Linkwitzlab. There you will find details (among lots of other stuff) on the technical aspects of designing open baffle systems.

If you've got 4 sub woofer drivers, 4 channels of amplification and 4 channels of DSP available then the obvious answer is to go the multiple sub route. If correctly set up this will provide bass quality equal to and superior to that of OB bass, except you get the added benefit of vastly higher system efficiency. This translates into lower overall distortion for a given SPL and far greater bass extension for a given SPL. That and you can place the subs against walls, rather than needing to place the thing some distance into the room.

The basic principle behind multiple subs implementations is to build one main sub that has awesome output down to 20Hz and then have at least two more smaller subs placed about the room. The main sub does most of the leg work, but due to the effects of room modes you get suck outs at specific frequencies. The point of the smaller subs is to act as filler devices that are positioned about the room to excite the room in a different way to the main sub and fill in the gaps that the main sub left.

Usually one places the main sub in a corner behind one of the main loudspeakers with one of the filler subs placed in a corner along the back wall on the other side of the room to the mains and the main sub. The third sub can be placed pretty much anywhere providing it is distinctly different in location to the other two, say along a side wall.

Given what you've got available to you a nice idea would be to go with a dual opposed, push-pull system for the main sub, possibly going vented for greater extension if the drivers are suitably specified. Then make two smaller sealed subs, with a single driver each for the fillers.

[kgveteran]

Thanks for a great reply, i wonder if anyone lives with one of these systems.

[5th element]

Multiple sub systems? Lots of people do, myself included

I feel I should perhaps add a little more to this.

My sub set up consists of two XLS 10" drivers in a dual opposed sealed alignment, with then two single XLS drivers in separate cabinets positioned similarly to I just described. This is fed with UCD class D amplification and filtered with a DSP.

Prior to that the 4 XLS drivers were in two H baffle open baffle loudspeakers very similar to Linkwitz' old Orion bass module when he used the XLS 10" driver there. This sounded very good, but with all the talk of multiple subs being the way to address room modes, but to also keep mono pole efficiency and extension I figured I had to give multiple subs a go.

The fact I still have the multiple subs probably speaks volumes about which I think sounds better The main added benefit is that I get extension to below 20Hz, with THX spec SPL levels achievable down to 20Hz. That the OB could not do even if it tried.

[ThomasW]

We've discussed this subject numerous times so a search is a good option.

Linkwitz doesn't use dipole subs, his sub is a sealed box.

My experience with dipole subs led to abandoning them as a failed concept due to their inability to reproduce deep low bass. Even with the benefit of EQ they lack the impact of other alignments.

Years ago as a shootout I compared an IB sub with 4 drivers to an OB sub containing 8 similar drivers. They were setup in the same room and driven with the same electronics. One would think having the benefit of double the swept volume would give the performance edge to the OB. No so, the SQ was roughly the same, but the OB lacked the ability to dig deep and reproduce the lowest notes with the same impact as the IB.

Perhaps increasing the driver count even more would do the job, unfortunately that wasn't an option when I did the comparison