Revised MBOW1 3-Way

Revised Crossover for the Best Buy Insignia

Revised Crossover for the BR-1 Kit

Mod for Morel 403.5 3-Way


Revised Crossover for the Norh 9.0 Marble

The New Vifa Tower

Fixing the Polk RTi28

The MB20

The MB27

The Plop-in-the-Box

The Usher Two-Way

Revised Crossover for the Radio Shack LX550

Alternative Crossover for the Dynaudio Gemini

Crossover for the Revelator-RT1 Mini Monitor

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The Acoustic Research AR4x

A Tale of Two Cabinets

Tweeter Comparison

The RadioShack Minimus 7

JMLab Mezzo Utopia,
Tannoy Westminster,

Measurements for the Radio Shack LX550

Proac Super Tablette

Acoustic Research AR3a

Sound Dynamics RTS-3

Stock vs Modified Gemini

NHT Super One


Here is a variation on my MBOW1 that provides about 5 Hz more bass extension (down to 50 Hz) and a slightly clearer midtreble.  This version uses the Seas C15RLY treated papter woofer (H1216) instead of the GR Research M130 woofer.  The Seas unit runs about $48 a side, vs. $25 for the still excellent M130.  Other than revisions to the crossover, the two versions are identical from an assembly standpoint.  You just follow the cabinet plans on my MBOW1 page and use the Seas woofer instead of the M130.  It will fit in the same drill hole, and is also surface mounted, so there are no routing issues.  Some may prefer the look of the M130 in this application.  The flange is tapered to meet the baffle without any raised edge.  But the Seas edge does not cause any significant diffraction problems in either the woofer or tweeter response.  If you wish to purchase finished cabinets with pre-drilled driver holes, they may be obtained from Delmond Won: These cabinets are about 4" taller than the plans show, and provide a compartment at the bottom to house the crossover.  This approach is highly recommended in any event, since it's very difficult to squeeze all of those parts into the main interior space of the cabinet.  Delmond does excellent work (he runs a large cabinet-making operation), and would be happy to discuss pricing for custom finishes with you.  Here is the 1-meter on-axis response:

And here are the schematics.  You may adjust the highs to your preference by either increasing or decreasing the 6 ohm tweeter series resistor by an ohm or two.  Make sure you reverse the tweeter polarity as shown.  The little resistors shown in series with the woofer inductor and the final tweeter series inductor are not real--they are just the suggested dcr of the inductors.  All other resistors are really there.  You will probably have to order a .10 inductor for the last element in the tweeter circuit, and then unwind a little less than half of the wire.  The value is not critical.