Euraudio Origo floorstanding loudspeaker building description
The loudspeaker design and building directions presented below were published in good faith. Nevertheless the publisher assumes no liability either for the accuracy of information contained herein or for any loss or damages arising from the use of these pieces of information.
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THIS IS PRELIMINARY DESIGN INFORMATION!
The Origo loudspeaker has not been built yet. The plans are based on manufacturer data, and simulation with measurement data of similar drivers, therefore the crossover may need fine tuning. The first builder of this loudspeaker may get free help from the designer. Further information: help for DIY speaker builders.
Caution: The mechanical guidelines is not a detailed mechanical drawing. For example, only the outside lines of the enclosure walls are drawn, the wall thickness is not shown.
It's expediential to have the front enclosure panel prepared by using a CNC woodworking machine. It's rather difficult to make the countersinks for the speaker baskets at home. Of course it can be made using a router, provided you have the proper router bits, and a circle cutting jig. The internal edge of the midwoofer cutouts must be chamfered, at approx. 7 mm depth, as exemplified in the next image.
PVA wood glue, D3 type is recommended for gluing.
The back of the enclosure should be lined with 3 cm thick egg-crate foam, the sides with 2 cm thick normal foam. Only open cell (acoustic) foam will do. The foam blocks should be cut about 5 mm bigger than the distance they are to fill, so they will be snug in their place. Additionally, we'll use 9 dkg pillow stuffing material such as polyester pillow fill or long-fibre wool. Glue a few thin bamboo sticks across the bottom of the middle cross brace and place 2.5 dkg of the damping material loosely on them. Place the remaining 6.5 dkg material in the bottom of the cabinet. The damping materials must be fitted before gluing on the last enclosure side.
Please mind the polarity of the drivers.
The crossover can be mounted on the cross brace behind the mid-woofer or in the bottom of the cabinet. Components with 5% tolerance are recommended. The best solution for fastening components seems to be cable ties. Tie them to a thin (e.g. 5 mm thick) HDF plate and screw that plate to the inside of the cabinet. I haven't made a component layout or PCB plan, just solder components together across their leads or use terminal strips.
All inductors are air core. Don't fasten coils with ferromagnetic metal screws (e.g. steel), because they may cause some distortion. Don't place inductors close to the ferromagnetic metal parts of the speakers. To prevent crosstalk, place coils at least 10 cm away from each other or - if they are closer - direct their axes perpendicular and skewed:
The hard-to-come-by capacitor values can be attained by connecting more common values in parallel. By parallel connection, the capacitances are summed. In the circuit diagram of the crossover, the shown voltage of capacitors is the minimum suitable rating, you can also use capacitors with higher withstanding voltage. I recommend the Jantzen Cross Caps for this design. I don't recommend nonpolar (bipolar) electrolytic capacitors, I'd avoid even types designated for use in crossovers. Never use polarized (unipolar) elcos in crossovers.
Copper speaker cable of at least 0,5 mm2 cross-section or CCAW speaker cable of at least 0,75 mm2 cross-section is recommended.