Ortho Acoustic WAW Part 1.

Note: This series of posts was initially titled "Ortho Acoustic Concrete" but I had to give up on the concrete part so it has been renamed to "Ortho Acoustic WAW".

I was planning for my next build to be a retake on my 3WC. I wanted to increase the volume to at least 45 liter (55-65 would be even better). I wanted to get the tweeter up to around 90 cm above the floor. And I wanted to make it all passive. Sounds like a regular floor stander right? I am sure it would sound great but it would probably be a quite boring build. My first thought was to make the cabinet out of concrete to make it a bit more interesting. But a full size floor stander turned out to get quite heavy in concrete. I was also playing with the idea of something omnidirectional. Loads of ideas but nothing actually worth building...

So I got concrete and omnidirectional but this is where my next build would take a totally different direction. I decided to buy a new screen for the projector and I only took visuals into account not the audio. The new screen turned out quite big and it was also moved out a bit in the room. The screen is not acoustically transparent making it interfere with any speaker with a height of 70 cm or more (god damn it and I brought this on myself)! The next event that made me think was when my neighbor (a younger HiFi nerd with perfect hearing) uttered - "these are the best speakers you have ever built". He was listening to vinyl through my latest WAW-build. OK, We’ve had some wine but still, it was unexpected and it made me think of these WAW as something more than just a quick hack out of leftovers.

A new concept started to take shape in my mind. First of all omnidirectional speakers can be really interesting but what I aimed for was more semi-omnidirectional, like the Ohm Walsh 2 (I love the look of that speaker). But unfortunately something like that would interfere with my new screen. So something low that can be placed up against the wall and is semi-omnidirectional. What I, as a Swede, instantly came to think of was the Carlsson OA-50 and OA-52.

The paper Carlsson Ortho-Acoustic Loudspeakers: Design and Performance Principles is highly recommended read for the ones not familiar with Carlssons work or his Ortho-Acoustic ideas. I can also recommend the thread The Advantages of Floor Coupled Up-Firing Speakers at DiyAudio and Linkwitz Labs page about "Controlled Directivity" loudspeakers.

So my next build will not be a remake of my 3WC, it will be a remake of my some kind of WAW instead. I will take cue of several of Carlssons designs. The up-firing bass from the early OA speakers, like the OA-5. The "low box against the wall" concept of the OA-50 and OA-52. I will try to combine these elements into something that hopefully will work with the concept of my some kind of WAW.

It will be semi-omnidirectional like the Ohm Walsh 2. I will make the box out of concrete. The tweeter and mid-bass of the OA-50 and OA-52 will be replaced by the W5-2143 running full range and the sub-woofer element will be up-firing like on the OA-5. I do not know exactly what it will look like yet but something along the way of this 3D mock-up (that I made to figure out if the elements would fit on the baffles or not):

All set for the next build; concrete, ortho-acoustic, semi-omnidirectional WAW. OMG what have I got myself into?