Orion; the plan

The construction of the Orions can be quite easy if you buy all the components and parts but you can also choose to buy the plan set only and do the rest yourself. This is one of the many appealing characteristics of the Orion but the drivers of the loudspeakers are very expensive. We were planning to expand our living room so I knew I had some time which ended up being over four years. As I wasn’t in a particular hurry I decided to do everything myself. This included designing my own circuitry and making my own cabinet from self-made panels. The trouble was that I had no experience in either electronics or woodworking so I knew I was in for a learning curve than might become uncomfortably steep! I decided not to be held up by these distracting facts.

Fortunately, the Orion is an active speaker. This means that the amplified signal from your receiver is not sent to your speaker to be distributed by a filter in the speaker for the low, mid, and high-range drivers; the signal is first split into one frequency range for each driver, amplified separately for each driver, and only then sent to the speaker with one speaker cable per driver. You could see the subwoofer as an active speaker as they nearly always have their own amplifier, but that is merely a self-powered speaker; there is not frequency filtering going on (a low-pass filters perhaps). Articles on the advantages of active verses passive systems can be found on the net and I’m not qualified enough to start lecturing. A clear disadvantage of active speakers is the cost of the amplification.

An active system needs to first filter the signal between that part of the receiver that processes your signal and the horde of amplifiers. There isn’t a single piece of equipment that can do that, so you need three; the incoming signal is handled by the so-called pre-processor, you then use the filter and the amplification is performed by separate amplifiers. Most audio systems have the filtering in the speaker; the pre-processor and amplifier are joined into a single receiver, or two ‘separates’, when you have two pieces of equipment performing the same function. Audiophiles will argue that such a system of ‘separates’ is superior to a receiver, but if you put separates into a new single casing nobody will know, right? Most receivers can work as a pre-processor, having the pre-amp out connectors for low-voltage signals to be amplified later, but then you won’t be using the amplifiers in the receiver which is wasteful. A dedicated pre-processor, without amplifiers, is typically twice as expensive as a receiver or more. This is probably due to the cost of leaving out the amplifiers. Then you need to amplify four channels per speaker; normally you need only one.

Separate amplifiers can be bought everywhere but I wanted to be prepared for a 5-speaker setup, meaning 20 channels and that is an absurd number for normal home systems. Fortunately I was able to buy a stash of Rotel RSP-1077 amplifiers, fitted with 7 channels of 100 Watts each, more than enough for the Orions. Next to being very small, they are also very efficient. These Rotels use the Bang & Olufsen ICE amplifier modules that B&O use for their own active speaker. I now have 21 channels, leaving one channel unused, using the space of a some stereo amps. I don’t really need to have 100 Watts standing by for each channel except for the bass drivers, but there aren’t many multi-channel amplifiers with lower power outputs.

NEXT

Introduction
The plan
Design changes
Signal processing
The listening room
Production
Listening