Transcription of Humble Homemade Hifi
1 Humble Homemade HifiConcept Cabinet Crossover Measurements HomeL' Orfeo - design conceptThe L'Orfeo loudspeaker is designed to be a reference grade, two-way speaker kit based on very high quality components in acleverly thought out and easy to build enclosure. The relatively compact and slim shape of this floorstander should integrate intomany an interior, especailly when you consider that the finishing options are nearly endless if you build them yourself. The mainingredients are an 18cm Scanspeak Illuminator midwoofer combined with a large Mundorf Air Motion Transformer tweeter.
2 Bothwere chosen for their high resolution, low distortion and wide usable bandwidth. Furthermore the final system should have ahealthy 8 ohm nominal impedance so that the choise of a partnering amplifier is made easier. And last but not least, the overalltonal balance must be extremely neutral so that this loudspeaker can be used as a tool as well as a means to listen to a large,varied repetoire of Illuminator midwoofer from the Danish company Scanspeak is in every aspect an unusual design with it's open construction,the extremely long linear excursion and patented under-hung SD-3 (Symmetrical Drive)
3 Neodymium motor system, which due tocopper caps and its construction ensures very low distortion, adding the unique patented cones, low-loss linear suspension theresult is (if we are to believe Scanspeak): The Very Best Money Can Buy ! The L'Orfeo uses the Scanspeak 18WU8741T-00 papercone version which produces a remarkable combination of deep bass and midrange neutrality - ideal if you're looking for widebandwidth from a relatively small enclosure. I have found this driver to be very flexible and can be used in many cabinet typesranging from small, well damped closed boxes of about 15 litres up to large bass-reflex systems getting close to 40 litres and withonly a small amount of damping material inside.
4 The L' Orfeo bass-reflex cabinet has an internal volume of 35 litres but if yourspace is limited or the speakers have to be placed very close to a wall, it is possible to build the L' Orfeo as a (smaller) closed boxwithout any alterations to the crossover. More about the cabinet design in the next Mundorf AMT (Air Motion Transformer) Concert Model 2510c has very strong neodymium magnets and a low mass diaphragmfoil that together give high efficiency and fine microdynamics combined with remarkably high SPL while maintaining a very lowdistortion ratio. According to the german magazine Hobby-Hifi the AMT 2510c has some of the lowest distortion levels they haveever measured!
5 This tweeter is "holographically" precise in its depth, clarity, and transparent performance - very dynamic! Finallyit has a low-resonance chamber that is damped with multiple layers of felt. Internally the AMT is constructed with Mundorf'sSilver-Gold wire and terminated in gold-plated banana sockets for easy connection with the supplied plugs. Basically this all boilsdown to an excellent tweeter with extremely high resolution without ever getting "edgy" or usServicesComponentsL' Orfeo So the L'Orfeo loudspeaker uses one of the best midwoofers and one of the best tweeters available today.
6 The art is to combinethese two, using high-grade crossover components, very pure internal wiring and a clever cabinet concept, to a seamless andcoherent unity in a package that should please a large potential audience. As mentioned earlier, the choise of cabinet finish willgive you the possibility to match them to your personal budget and interior. The L'Orfeo is available as a complete DIY kit includingevery part down to the last screw except for the cabinets. Seeing as labour is the most expensive part of any product, you cansave a lot of money if you build the cabinets yourself.
7 The loudspeaker is designed in such a way that all the panels arerectangular and can be glued together with butted joints - so there are no difficult angles to cut and only the tweeter is part of this website may be reproduced in any form without written or e-mail consent from the author. The designs are free to use for private DIY-purposes only, commercialuse is strictly prohibited. Copyright Humble Homemade Hifi 2000 - 2012 Humble Homemade HifiConcept Cabinet Crossover Measurements HomeL' Orfeo - cabinet constructionFrom the outside, the cabinet of the L'Orfeo looks rather standard issue, but inside it is a totally different story.
8 Instead of anormal cross-braced rectangular enclosure, this loudspeaker uses a unique diffusor type of woofer loading. This internal diffusorhas several major advantages: first of all it creates an irregular shape that breakes the back wave produced by the woofer. Thisminimizes the amount of delayed energy that (in more coventional designs) is reflected back off the rear wall and travels throughthe thin paper cone of the midwoofer, "smearing" the original clean signal that is fed to the woofer. The second advantage is thatthe cabinet width and depth vary internally so the strong standing waves that you usually get between two parallel surfaces arebroken down into several smaller and therefore less harmfull ones.
9 Third item is that the varying panel thickness (minimum 22mm/ maximum 88mm) and density (constrained-layers) helps reduce panel-borne resonances, flexing and vibrating energy that travelthrough a panel of constant thickness. Advantage number four: all these extra panels help to make the whole construction "dead"and heavy, again reducing unwanted excess energy radiating from the cabinet. All these advantages together result in a very quietcabinet that also needs only a minimum of damping material inside and therefore adds to a "live" and dynamic approach to my knownledge this type of Internal Cabinet Diffusor is a world premiere has not been used before, so if you see it popping upin other loudspeakers in the future, be sure to remember that you saw it first at Humble Homemade Hifi!
10 :-) The only dampingmaterial inside these loudspeakers is some bonded acetate fibre that is placed in the Internal Helmholtz Absorber that is positionednear the bottom of the cabinet, between the main volume and the crossover compartment. This absorber volume works like areflex-port in reverse. The volume, port diameter and length are tuned to act like a sort of "black hole" for a defined frequency -namely that of the standing wave between the top and bottom panels of the cabinet. The main volume is completly free from anytype of damping material! One last important thing about this design: all the panel dimensions and positioning of the panels are based on the Fibonaccisequence of numbers.
