A different approach to the Oris Reference (BD-Design)

by madprofessor , 27777 Ganderkesee, Germany, Wednesday, November 14, 2007, 09:35 (6007 days ago)

A different approach to the Oris Reference System:

2005, at the High End Show in Munich, I had the opportunity to hear several good rigs – a Kharma/Wavac, a Avalon/Pass and a Lumen White/Ayon chain. All impressed me with the way of reproduction, they did. All had in common, that they used the Thiel ceramic chassis. Unfortunately all lacked a bit of dynamics. So my idea was to use spherical horns in front of the Thiel chassis. But I didn´t find a solution for the bass, till I found the page of bd-design.
The bass-system of the Reference Ultra seemed theoretical the perfect match.

Now the system is completed. Using the alloy.-profiles from Bosch-Rexroth gives the opportunity to get the single systems exactly adjusted for phase response at my listening position. Also that way, tweeter and midrange can be mechanical decoupled from the whole structure ( for the tweeter I use a small, heavy box, which rests on springs, the much more heavy midrange unit sits on spikes.)
The bass-cabinet looks from the outside like a simple box, but inside there are no parallel walls, by building double walls. The outside is 35mm multiplex. The inside walls create some spaces, which are filled with sand. Than the cabinet is lined with a special alloy-foam, which has two merits: Sound reaching the rather big cabinets is not reflected by a smooth plane and resonances, maybe still existing in the cabinet, are mostly absorbed. I couldn´t measure no of the typical cabinet resonances, with an accelerometer.
Of course the cabinet is a matrix-construction.
Also to avoid reflections, all the horns and other cabinets are covered with 40mm acoustic foam. That gave a real audible improvement in inner detail and room reproduction.
The alloy-profile structure has 4 wheels for easy placement in the right position. After that is found, the whole structure is placed on 3 Absorber-Spikes from Alto Extremo.

The system measures very well. The difference between the two bass-chassis is basically not existing. At that price, they are a real bargain. The Thiel chassis were ordered as tightly matched pairs.

The amplification of the system is a diy-class A solid state amp with a 18dB passive filter in front for the bass and a SET-amp (at the moment a 845-based diy unit, but soon to come a GM70 based better version) for the midrange/tweeter section. The midrange/tweeter section has a passive x-over, without any level matching resistors.

The sound? It´s allway subjective – so I just say, that I´m very satisfied!
I know, optically there are much nicer systems, but I wanted sonically the optimum , so I avoided all the nice looking surfaces…

Thanks to Bert for providing the Horns and bass-chassis and for all his advice!

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