The WB4 uses a nominal 4” paper cone wideband driver, in a mass loaded transmission line cabinet, that is tuned to a fundamental frequency of 40Hz. The driver is a Sounderlink Audio Labs model number DQ40TZF-02 - the round 4 ohm version. The price of a pair of drivers is about $70-90, depending on where and when you buy them. A pair of 4 ohm round frame drivers can be bought here for just over $70 shipped: https://www.aliexpress.us/item/2251832432918591.html
This is the least complex speaker we have designed, and it can be built for about $200; if you cut your own panels. If you buy our WB4 flat pack (available here), you can build a pair for about $400. They work very well on ~24” / 60cm high stands in a small to medium sized room - or on a desktop.
The cabinet is 6.5”W x 18”H x 13”D / 165mm x 457mm x 330mm and is made with 18mm thick material - either Baltic birch or MDF. Each finished WB4 speaker built with Baltic birch weigh a bit less than 17 pounds / 7.7kg. The corners are designed to have a 12mm x 12mm chamfer; but the MDF can be left square, if you choose. The chamfer also has an acoustic function of reducing edge diffraction. I can provide CAD files to make CNC cut files - the build manual includes drawings of the CNC version of the panels. It can be built with a table saw and plunge router, and/or with a CNC machine.
A strong benefit of a “folded” transmission line design is the internal baffles not only form the specific volumes and dimensions required for the correct tuning for the driver - they also form asymmetrical bracing for the cabinet. Less obvious is the fact that the internal air pressure in a TL design is lower than an equivalent sealed, or even a ported design. This greatly reduces the panel resonances - and this is possibly why the midrange and bass are more open and clearer. The driver has less of an “air spring” behind it, so it is more closely reproducing the music in the recording. The driver has an Mms of just 2.5 grams, and the quality of the midrange is excellent.
A transmission line speaker cabinet is a tuned “column” of air, that is folded behind the driver - it has lower distortion and greater bass extension that conventional sealed or ported designs. We used a program called Hornresp (short for Horn Response), and carefully matched the computer acoustic model to the cabinet design, using DataCAD.
We include an optional baffle step filter - see the XSim response graphs below. The sensitivity spec of the driver is 87.9dB. The minimum impedance is about 4.5 ohms, with a nominal value is about 6 ohms - see impedance graphs below. At a minimum, you only need binding posts, wire, polyfil, along with the cabinet; to build the WB4 speaker.
The manual includes drawings in inches and in millimeters, Also included are straight cut, and rabbeted, and CNC versions of the panels. I can provide the CAD files for these, if you want to build it this way. Sheet layouts are included, and the will be one quarter to one third of a 5’x5’ sheet left over, after cutting all the 9 panels for each speaker.
For folks who want to build the WB4 speakers - but do not have the tools to cut the panels, or do not want to cut them - we have flat packs available - they are 18mm Baltic birch, and you can decide to the chamfered edges (or not). The finish we prefer is Odie’s Oil, which is easy to apply.
The price is $250 per pair of flat packs, plus shipping via UPS - you can order it here.
The WB4 uses a nominal 4” paper cone wideband driver, in a mass loaded transmission line cabinet, that is tuned to a fundamental frequency of 40Hz. The driver is a Sounderlink Audio Labs model number DQ40TZF-02 - the round 4 ohm version. The price of a pair of drivers is about $70-90, depending on where and when you buy them. A pair of 4 ohm round frame drivers can be bought here for just over $70 shipped: https://www.aliexpress.us/item/2251832432918591.html
This is the least complex speaker we have designed, and it can be built for about $200; if you cut your own panels. If you buy our WB4 flat pack (available here), you can build a pair for about $400. They work very well on ~24” / 60cm high stands in a small to medium sized room - or on a desktop.
The cabinet is 6.5”W x 18”H x 13”D / 165mm x 457mm x 330mm and is made with 18mm thick material - either Baltic birch or MDF. Each finished WB4 speaker built with Baltic birch weigh a bit less than 17 pounds / 7.7kg. The corners are designed to have a 12mm x 12mm chamfer; but the MDF can be left square, if you choose. The chamfer also has an acoustic function of reducing edge diffraction. I can provide CAD files to make CNC cut files - the build manual includes drawings of the CNC version of the panels. It can be built with a table saw and plunge router, and/or with a CNC machine.
A strong benefit of a “folded” transmission line design is the internal baffles not only form the specific volumes and dimensions required for the correct tuning for the driver - they also form asymmetrical bracing for the cabinet. Less obvious is the fact that the internal air pressure in a TL design is lower than an equivalent sealed, or even a ported design. This greatly reduces the panel resonances - and this is possibly why the midrange and bass are more open and clearer. The driver has less of an “air spring” behind it, so it is more closely reproducing the music in the recording. The driver has an Mms of just 2.5 grams, and the quality of the midrange is excellent.
A transmission line speaker cabinet is a tuned “column” of air, that is folded behind the driver - it has lower distortion and greater bass extension that conventional sealed or ported designs. We used a program called Hornresp (short for Horn Response), and carefully matched the computer acoustic model to the cabinet design, using DataCAD.
We include an optional baffle step filter - see the XSim response graphs below. The sensitivity spec of the driver is 87.9dB. The minimum impedance is about 4.5 ohms, with a nominal value is about 6 ohms - see impedance graphs below. At a minimum, you only need binding posts, wire, polyfil, along with the cabinet; to build the WB4 speaker.
The manual includes drawings in inches and in millimeters, Also included are straight cut, and rabbeted, and CNC versions of the panels. I can provide the CAD files for these, if you want to build it this way. Sheet layouts are included, and the will be one quarter to one third of a 5’x5’ sheet left over, after cutting all the 9 panels for each speaker.
For folks who want to build the WB4 speakers - but do not have the tools to cut the panels, or do not want to cut them - we have flat packs available - they are 18mm Baltic birch, and you can decide to the chamfered edges (or not). The finish we prefer is Odie’s Oil, which is easy to apply.
The price is $250 per pair of flat packs, plus shipping via UPS - you can order it here.
The first graph is the in room response of the WB4 at 1 meter at about 15 degrees off axis.
The second graph is the WB4 impedance.
The third graph is the XSim graph with the baffle step filter in blue vs the driver only in the cabinet in gray.
The fourth graph is the XSim impedance with the baffle step filter in blue vs the driver in the cabinet in gray.
