Subwoofers

KEN KREISEL DXD-12012 Dual 12" Push-Pull Subwoofer

ARTICLE INDEX

The Design

Most subwoofers on the market either use one or more drivers, mounted on front and rear, or on the front and sides, and they are all in phase with one another. That is to say, all the cones move outward towards the room at the same time and inward towards the inside of the enclosure at the same time.

The DXD-12012 uses a push-pull configuration that is back-sidefire-loaded. One driver is on the side, and the other is mounted inside the slot, facing into the enclosure. They are wired out of phase, but because of the reversed mounting of the driver in the slot space, they both move outward towards the room and inwards to the enclosure at the same time. The bottom driver is operating the same as if it was a bottom firing driver except that three openings (slots) direct the bass energy toward the rear wall and sides which control how the bass energy couples to the room and room boundaries, and also helps to produce a push-pull pressure wavefront when combined with the side firing driver. This assumes you place the subwoofer with the driver facing the side rather than facing the listening position, and this is its optimum setup.

The push-pull configuration does two things: (1) because the enclosure is sealed, cone movement pressurizes the room, and (2) because one cone is moving away from the basket (towards the room), and the other is moving in towards the basket (also towards the room, pushing air out of the slots), the result is cancellation of some of the distortion. The cancellation makes the subwoofer more accurate (low distortion) than conventional subwoofers.

Below are three animated GIFs that show the cone movement with a single subwoofer, the DUO (two subwoofers) and QUATTRO (four subwoofers). Click on the images to see the animation.

 

 

 The amplifier section contains two 375 watt Class D modules, one for each subwoofer.

The rear panel is shown below.

From the left, are two XLR jacks, the first one as the line-level input and the second as a pass-through for connecting multiple subwoofers. Next are the two RCA line-level inputs, the Variable Low-Pass dial, Variable Phase, Volume Control, a toggle to turn off the low-pass filter (if your receiver is doing the low-pass out to the subwoofer), the Auto On/Off, Always On toggle, and an LED indicating Standby or On.

Shown below is the QUATTRO-QUATTRO, which has 32 drivers and a total of 12,000 watts of amplifier power. Cost ~ $50,000.

Kreisel Sub