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Re: black gates in parallel

Posted by Robert Karl Stonjek on December 24, 2001 at 13:19:43:
I realised that you were trying to be funny. Just thought there might also be some truth in the humour.
There have been some articles on open baffles in Speaker Builder. The first speakers I designed (1990-1) were all open baffle. I experimented with closed baffle but with both phases projecting forward (one or more speakers in phase, one or more out of phase). BOSE speakers had a similar concept (901s) but using â€˜direct and reflectedâ€™ sound.
I even came up with a theory that there are two types of sound wave. Basically a â€˜line of bricksâ€™ model. The brick represented the compressed part of the wave, the space between the low pressure. I asked what happened at the interface between brick and space.
I asked if one can actually reproduce (and thus control) the interface sound. I called the interface sound the transverse wave, and the brick model sound the compression wave. I reasoned that transverse wave could be actively produced using three speakers in a single baffle with the middle speaker reverse phase (all projecting forward).
Open baffle is another way of controlling transverse wave. If you donâ€™t control the â€˜Tâ€™ wave then you get a rough, hard edge to the brick. If you produce only â€˜Tâ€™ wave, then it has no strength.
I later figured that the slope of the â€˜Tâ€™ wave in an ordinary speaker is related to some intrinsic parameter of that driver/cabinet, possibly the resonant frequency, but also the cone radiating area. I reasoned that using two drivers to cover the same frequency range but making the two drivers/cabinets as different as possible while maintaining efficiency and frequency range should minimise the harshness of the â€˜Tâ€™ wave by spreading it across two drivers.
Then I forgot about the philosophy (as it is not provable) and concentrated only on the â€˜Virtual Speakerâ€™ concept. But the sound was better from the first experimental, and having built all those open baffle/dual phase things I could recognise the sweet â€˜Tâ€™ wave straight away.
I mention this for your own amusement only. I wouldnâ€™t dream of trying to stand by such a theory ~ too much philosophy for what is essentially an engineering forum.
P.S. I know you're having fun with the HTML tags, but in future, could you leave the background white? That textured background makes reading a bit more difficult. Thanks.
You're just jealous :)
Kind Regards,
Robert Karl Stonjek