New waveguided tweeter from SB Acoustics

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That dip in the high frequency response is why I use 3/4" domes on my waveguides. I haven't found a way to reliably avoid it. I've tried phase plugs, to no avail.

Ring radiators avoid it, but ring radiators have less displacement than domes. (Because a ring has less area than a circle.)
 
What mid to mate with - a 4"er @3kHz? Same problem with SEAS DXT
SB26STWGC-4-graph.jpg
 
I'd argue that it was people like Geddes and Danley who introduced the idea of using waveguides into the home audio market.

I can distinctly remember the 90s, when any "hifi" company who dared to use a waveguide or horn was basically laughed out of the industry.

Horns and waveguides were commonplace in the pro and studio market, but they never really made any headway in the "hifi" community until the 21st century.

In a nutshell, we're not seeing a lot of hifi tweeters with waveguides because their use has only been accepted recently.

I was a fan of horns, going all the way back to the 90s, because they were commonplace in car audio.
 
-not much of a waveguide.. and there have been commercial designs like this over time. ex. Infinity's Prelude and most of Triangle's line.

I think it's as much an aesthetic-thing as anything else.. people expect their tweeter to provide a smaller diameter on the baffle: so the diameter is small.

-go larger and you start having to cut-into the waveguide to get closer "source-to-source" placement.

I *think* however that elliptical waveguides (small or large) are a much newer concept commercially (..and arguably at all), and help with getting the source's a bit closer.


..this driver might be interesting in-relation to being placed into a larger waveguide (..in that it might have a freq. response that's more accommodating to this). ..and the "ST" range is one of those rare tweeter's that provide excellent detail (..so long as spl isn't to high).
 
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That dip in the high frequency response is why I use 3/4" domes on my waveguides. I haven't found a way to reliably avoid it. I've tried phase plugs, to no avail.

Ring radiators avoid it, but ring radiators have less displacement than domes. (Because a ring has less area than a circle.)

It would seem with power handling limitations, the 3/4 dome is the ideal waveguide candidate.
 
Does anyone know what specifically causes the dip at high frequency and why a 3/4" solves it? I assume the 3/4" pushes it above 20kHz, but I'm curious where it comes from.

Edit: Looks like it's at the frequency that corresponds to a 1 inch wavelength. Still not sure why it shows in waveguides and not non-waveguide tweeters though.
 
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They are avalaible
I paid 60 euros each
I should get my hands on them next week.


Interesting, and thank you. That (assuming an exchange without more markup to USD) favorably less than the Wavecor waveguide tweeters and this seems like it would be of at least equal, perhaps moderately higher quality. I wonder when they'll show up at retail in the US or at Solen in Canada?
 
Does anyone know what specifically causes the dip at high frequency and why a 3/4" solves it? I assume the 3/4" pushes it above 20kHz, but I'm curious where it comes from.

1) 13,500Hz is one inch long

2) when two sources are one half wavelength out of phase, they cancel each other out. (Destructive interference)

3) One half of a 13,500Hz wavelength is 1/2" long

So, it's simply geometry: as your radiator gets larger and larger, you start to get peaks and dips that are caused by it's geometry. For instance, the TIP of a one inch tweeter is nearly one half of a wavelength out of phase with the EDGE of a one inch tweeter, above 10khz.

There's a few ways to fix this:

1) use a flat diaphragm

2) use a diaphragm that's "flattish." For instance, if you look at JBL and Infinity domes, you'll notice they're flatter than Dynaudio domes. This is because JBL uses waveguides.

3) Use a smaller diaphragm

4) Use a ring

5) Some combination of the above

Most of JBL's studio speakers have switched from a one inch throat to a 0.625" throat, for the reasons that I describe, and they're driven by a ring radiator.


Edit: Looks like it's at the frequency that corresponds to a 1 inch wavelength. Still not sure why it shows in waveguides and not non-waveguide tweeters though.

Rippletanksource2.gif


With no waveguide, the radiation is spherical

When you put a waveguide in front of a source, the walls of the waveguide bend the wave if the wave is smaller than the diameter of the waveguide.

For instance, picture a waveguide that's two inches wide. 6,750Hz is two inches wide. This means that *everything* above 6,750Hz is going to get bent by the walls of the waveguide.

If that makes sense, than you can see why there's a lot of reasons to bring those walls in closer, by using a smaller tweeter.
 
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