Multiple drivers in the same enclosure

[MJ Dijkstra]

Hi

I am looking for a bass enclosure for a hybrid electrostatic loudspeaker. The box will have a volume of around 80 liters.
It probably will be a closed system for maximum fidelity.

My question: will the bass extend much lower if I use 2 woofers (of the same kind) in stead of one?

Maybe I coukd get the same extension as with a port (vented enclosure), but without the 'problems'of a vented system.

Thanks for help, MartinJan

 

[Paul W]

Martin,
Greater in-room LF extension may come from a sealed enclosure because of the shallow roll-off of a low-Q box rather than 2x drivers. Sealed box volume for 2 drivers will be 2x one driver sealed; or nearly the same as 1 driver ported. 2x drivers increases headroom for lower distortion and could be designed for opposing force cancellation.

I'm guessing this will be a low enclosure with the drivers next to the floor used as a stand for your ESLs???

Though I really like dipole bass, I have been thinking about trying a sealed, extremely stiff, 2-driver bass enclosure with opposing drivers firing to the sides. Used below 200Hz, bipole cancellation would occur only to the sides, and even then well above crossover. Front and back enclosure walls would be curved to increase stiffness. Enclosure would be divided or braced diagonally so that neither driver has a flat wall behind it. Anyhow, just sharing thoughts...
Paul

 

[richie00boy]

If you add another driver into the box then it's like halving the volume. That results in F3 shifting upwards. You could throw more power at the two drivers to get around the same SPL as a single driver in a vented box, but generally distortion would be higher as there is much more cone movement, thermal compression of the voicecoils and high power demands.

This is why to make a small subwoofer needs good drivers and is expensive, and budget models favour vented boxes.

 

[MJ Dijkstra]

I'm guessing this will be a low enclosure with the drivers next to the floor used as a stand for your ESLs???

Paul

Hi,

Yes, that's what I had in mind. So I have a limited box volume.
From the answers sofar there seems little advantages of putting two drivers in the enclosure, so I will use only one. Probably I can use some electronic equalizing in the sub-bass. It seems the new martin logan summit uses some kind of equalizing to sqeeze deep bass out from a tiny enclosure. Maybe a larger enclosure with moderate correction will do the job?


Regards, MartinJan

 

[Cal Weldon]

Hi Martin,

If you are limited in your available area you can use two woofers, isobarically loaded ie: woofers cupped very closely together with a small enclosure for the viewable woofer. This way you see only one woofer but the one inside that you can't see acts like another engine on the train. The cabinet size is reduced because you get the same sort of depth from the woofer if the other one is pushing and pulling from behind. The only disadvantage is that you get a slight reduction in volume as the inside woofer is being used to push and pull and not actually be heard.

Here's a run down. Don't worry that it's in car audio, the theory is the same. Part way down the page, front to back alignment.

http://www.caraudiobook.com/car_audio_subwoofer_system/car_audio_subwoofer_system.htm