This project has been a long time coming, and I hope it can be of interest to some of you out there. I’m happy for all comments, views, questions and suggestions.
As long ago as back in 1984, I came across an article in Hifi News & Record Review about Wharfedale’s Option One research project. Their chief engineer G P Millard investigated the possibility to use dipolar speakers to increase the sweet spot area for stereo listening. This opened my curiosity towards dipolar speakers.
Born and living in Sweden with a burning interest in sound reproduction, you will likely come across the late great speaker designer Stig Carlsson and his unconventional designs. He pioneered a lot of work on how the speakers should be designed in order to interact with a normal living room to create a believable lifelike reproduction of recorded sound, together with the likes like Roy Allison, Peter Snell, Jim Thiel, Harold Beverage and others.
He named his principals ortho acoustics and has been a huge inspiration to my own designs. And since the HNRR article in 1984 I have also been experimenting with dipolar applications to these ortho acoustic design ideas.
A number of incarnations have seen the surface since 1984, some realized and some just ending up as great ideas for the round archive. Then family and career came in between. Eventually this specific revision of my designs was initiated in 2009, when a faulty amplifier (my own modification) literary put the preceding version on fire in its premier listening session. A very sad day in my DIY life, but good things eventually came out of it (I think).
My vision for these speakers was to build a design which interacts positively with the acoustical attributes in a normal living room, in order to create a balanced and lifelike reproduction of a recorded sound - a believable gestalt of the original event. As in the article from 1984 I also wanted to use the dipolar directivity for time intensity trading in order to increase the sweet spot area for believable soundstage reproduction.
My aim was to create a speaker with an even frequency response both for the direct and reflected sound using conventional placement in a normal living room, with controlled directivity and integrated damping to suppress early reflections from influencing the direct sound but still to illuminate the room for a lifelike apparent source width and sensation of envelopment.
The design prerequisites:
- Dipolar speaker using dynamic drivers
- Should work as intended with conventional placement in a normal living space
- Discreet design, i.e. family acceptance
We eventually agreed on a design with approximate dimensions of 12x12x34 inches. Which created a lot of folding and puttering on my behalf, but in the end I had an idea of how they should look and how they should be built.
Discreet external design.
The inside in cross-sections.
That gave me place for two 10” bass drivers in a W-baffle, one 8” midrange unit on an angled baffle with two 1” tweeters on top in dipolar fashion. My idea was to build the whole chassis in layers of routed MDF boards.
Then you end up with a lot of details like this.
The original intention was to use a professional workshop CNC-cutting all these details, but that plan fell through. So I ended up working with my own hand router (a lot). In hindsight a bad idea. Plain too many hours spent and too much router dust for recommending to anyone else - you are warned. Next speaker will have to be of a different design.
Driver selection fell on:
- two Acoustic Elegance Dipole 10 for bass
- a Seas Excel W22NY001 as midrange
- the Scanspeak Illuminator D3004/660000 and D3004/602010 as tweeters
That would make it possible to reach 110 dB @ 1 meter within linear excursion limits for the intended crossover frequencies and given baffle dimensions.
To be continued.
As long ago as back in 1984, I came across an article in Hifi News & Record Review about Wharfedale’s Option One research project. Their chief engineer G P Millard investigated the possibility to use dipolar speakers to increase the sweet spot area for stereo listening. This opened my curiosity towards dipolar speakers.
Born and living in Sweden with a burning interest in sound reproduction, you will likely come across the late great speaker designer Stig Carlsson and his unconventional designs. He pioneered a lot of work on how the speakers should be designed in order to interact with a normal living room to create a believable lifelike reproduction of recorded sound, together with the likes like Roy Allison, Peter Snell, Jim Thiel, Harold Beverage and others.
He named his principals ortho acoustics and has been a huge inspiration to my own designs. And since the HNRR article in 1984 I have also been experimenting with dipolar applications to these ortho acoustic design ideas.
A number of incarnations have seen the surface since 1984, some realized and some just ending up as great ideas for the round archive. Then family and career came in between. Eventually this specific revision of my designs was initiated in 2009, when a faulty amplifier (my own modification) literary put the preceding version on fire in its premier listening session. A very sad day in my DIY life, but good things eventually came out of it (I think).
My vision for these speakers was to build a design which interacts positively with the acoustical attributes in a normal living room, in order to create a balanced and lifelike reproduction of a recorded sound - a believable gestalt of the original event. As in the article from 1984 I also wanted to use the dipolar directivity for time intensity trading in order to increase the sweet spot area for believable soundstage reproduction.
My aim was to create a speaker with an even frequency response both for the direct and reflected sound using conventional placement in a normal living room, with controlled directivity and integrated damping to suppress early reflections from influencing the direct sound but still to illuminate the room for a lifelike apparent source width and sensation of envelopment.
The design prerequisites:
- Dipolar speaker using dynamic drivers
- Should work as intended with conventional placement in a normal living space
- Discreet design, i.e. family acceptance
We eventually agreed on a design with approximate dimensions of 12x12x34 inches. Which created a lot of folding and puttering on my behalf, but in the end I had an idea of how they should look and how they should be built.
Discreet external design.
The inside in cross-sections.
That gave me place for two 10” bass drivers in a W-baffle, one 8” midrange unit on an angled baffle with two 1” tweeters on top in dipolar fashion. My idea was to build the whole chassis in layers of routed MDF boards.
Then you end up with a lot of details like this.
The original intention was to use a professional workshop CNC-cutting all these details, but that plan fell through. So I ended up working with my own hand router (a lot). In hindsight a bad idea. Plain too many hours spent and too much router dust for recommending to anyone else - you are warned. Next speaker will have to be of a different design.
Driver selection fell on:
- two Acoustic Elegance Dipole 10 for bass
- a Seas Excel W22NY001 as midrange
- the Scanspeak Illuminator D3004/660000 and D3004/602010 as tweeters
That would make it possible to reach 110 dB @ 1 meter within linear excursion limits for the intended crossover frequencies and given baffle dimensions.
To be continued.
