Euraudio Essentia audiophile loudspeaker building instructions
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 Essentia loudspeaker has not been built yet. The plans are based on measurement data of the drivers in test cabinets, not in the final enclosure, so 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.
Please keep to the plan exactly.
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 basket rims at home. The internal edges of the midrange and woofer cutouts must be chamfered, as exemplified in the next image. They need approx. 3 mm deep chamfer.
PVA wood glue, D3 type is recommended for gluing. The internal braces are from 18 and 28 mm thick MDF. The cross braces must be glued to the walls with two-components epoxi glue.
Cover the internal walls of the enclosure with elastic adhesive that sticks well to wood, using a notched trowel in approximately 3 mm thickness. For example, the Mapei Adesilex G19 or a similar high-viscosity adhesive that dries to a rubber-like layer, can be used. If you are unsure, first test the glue on a piece of MDF. Push 0.8 cm felt sheets into the wet adhesive. As an alternative instead of the elastic glue, you can use a 2.5...3 mm thick self-adhesive bitumen damping sheets such as the Hanno-Protecto PF 830, the Amortson Bi 5A or the Sinuslive ADM. If you use damping sheets, don't cover the whole surface, keep a 3...4 cm space from walls and cross-braces. The back panel of the enclosure should be lined with the 0.8 cm thick felt sheets, plus 3 cm thick polyester damping sheets (Acoustilux). Available from Jantzen Audio. Cover the sides with one layer of 0.8 cm thick felt. Additionally, put 8 dkg pillow stuffing material such as polyester pillow fill or long-fibre wool in the bottom of the cabinet. The damping materials must be fitted before gluing on the last enclosure side. You don't have to put any felt or Acoustilux on the walls of the chamber of the midrange, just entirely fill it with polyester pillow fill or long-fibre wool.
I have not specified the type of the terminals. It is recommended to use gold plated terminals.
As you could have seen above, two crossover plans exist. Their frequency response simulated at 2 meter distance without box diffraction effects can be seen in the image below. Near field measurement curves were used, so the bass boost between 100 Hz and 1 kHz serves to compensate for the baffle step in the far field. What can't be seen in the image is that the No. 1 crossover (XO1) has lower group delay in the midrange.
Please mind the polarity of the drivers, which is different in the two crossover plans.
The crossover can expediently be mounted on the bottom panel of the cabinet. For this purpose the bottom panel of the cabinet must be made removable. 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, except for the ones with values higher than 2 mH. For the ferrite core inductors, please use the Jantzen components specified in the crossover schematic. 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 Standard Z-Caps for the tweeter section, and Jantzen Cross Caps for the other capacitors in the crossover. Neither capacitor should be electrolytic, including the capacitor in series with the midrange driver.
Copper speaker cable of at least 0.75 mm2 cross-section or CCAW speaker cable of at least 1 mm2 cross-section is recommended.
It is recommended to install spikes into the base of the cabinet.