rkeman Messages: 78 Registered: March 2010 Location: Florida
Viscount
The compression drivers used in most of the Pi Speakers offerings have rapidly falling output above 17kHz or so. Has anyone ever used a supertweeter (e.g. Fostex T90A) to extend the response to above 30kHz?
Wayne Parham Messages: 18835 Registered: January 2001
Illuminati (33rd Degree)
I have done that, and it does add "sparkle." But I don't like the fact that there's no-way to get summing right through the 90°x40° pattern. The wavelengths are too small and the distances between sound sources too great. So the top octave is a mess.
That said, it's dense interference up there. It's not like it forms discrete modes large enough to detect. They're all tiny little pockets of energy modes, with the direct sound being just like the reverberent field. So it's not like the interference is audible.
Still, I'd prefer to use a compression driver that reaches higher into the top octave than to use a supertweeter. There are some drivers with beryllium diaphragms that reach above 20kHz.
rkeman Messages: 78 Registered: March 2010 Location: Florida
Viscount
The Radian 450BEPB-8 is certainly a consideration, but still runs about $500. Looking solely at the specifications, do you believe it has a reasonable shot at being compatible with the 3Pi/6Pi crossovers without substantial modification? The aluminum diaphragm Radian also looks linear to over 20kHz and costs only about $190.
Wayne Parham Messages: 18835 Registered: January 2001
Illuminati (33rd Degree)
In most cases, compression drivers are pretty similar, with breakup and HF rolloff being the two things to watch for. So for the most part, you can swap 'em around by just matching voltage sensitivity with R1/R2 values. But as always, the devil is in the details. You just can't really know for sure 'til you bolt it on and measure it.
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