BassZilla Update: June 2006

Tip #54: by Dick Olsher


I was informed several months ago by Jerry McNutt, design engineer at Eminence,  that the Magnum line has been superseded by the Definimax. The DefiniMax 4015LF is the replacement for the Magnum 15LF and Eminence says they improved the motor by going to an extended core. In addition, the shorting ring is a bit smaller as the older design was overcompensated. The only survivor of the Magnum line is the 12HO, which is now designated as the DefiniMax 4012HO, but is unchanged except for cosmetics.

A number of you have already inquired about a replacement for the Magnum 15HO. Over the past three months I have been evaluating the new Definimax 15 inch woofer in the context of an open baffle dipole design (more about that in July), and in addition I am now recommending the use of the Eminence Definimax 4015LF woofer as the woofer of choice for the both the Diamond and Platinum BassZilla Editions when used with the following alignment:

Total internal volume: 4.72 cubic feet (same as current cabinet)

Absorptive Lining: thin layer on inside walls

Vents: 2 each, 4-inch diameter by 10-inch long to replace the current rectangular vent. These two vents should be mounted on the back side of the bass cabinet.

Predicted bass half power (F3) is 43 Hz and the box tuning (Fb) is 38 Hz.


My own cabinets tend to be forever prototypical in nature as I am always trying new things. However, as you can see from the attached photos, Bjørn Nilsens of Norway, has chosen an extreme construction approach. In addition, each speaker contains 40 kg of sand in 3 chambers. The bass cabinet weighs about 140 kg and the top baffle is about 30 kg. The bass cabinet is constructed of 30 mm plywood and the top baffle is a sandwich construction of 15 mm plywood and 16 mm MDF. There is also a layer of lead under the foam damping on the open baffle. All cabling is by Cardas. Note that the cabinet volume  has been increased the to make up for the dead space.