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In Reply to: RE: Avantgarde Horns posted by Mr_Steady on October 26, 2014 at 07:40:42
I didn't consider the Community M4. It's an interesting driver.
"I'm being serious. If the AG 5" 300hz horn sounds good and meets it's advertising, then brother we all need one. You just couldn't copy the horn. Your right, it's the custom driver too"
Playing in hornresp, I can't seem to get any regular driver to model to 104dB/watt in free space. If I model half space, then I can sim 104dB to 300Hz in a AG sized horn - AG is possibly including some room gain in their specification. That would be reasonable for a speaker intended for small rooms / near wall placement.
The image is one simulation of the B&C 8PE21 8" Midrange Speaker, in free space, 10watts input, crossover as shown. That looks like acceptable ripple, ~107dB output, -3dB at 300Hz, from 0.25mm of cone movement. It shows HF rolloff early, but that's a limitation of hornresp, as discussed in the link
I'm sure some horn genius could tweak it to perform better than that.
My point: 300hz from a modest horn doesn't seem like an impossible goal, or one that requires a magic driver. If it were me, I'd still build it a bit bigger though :)
Follow Ups:
For the benefit of the reader;
300hz being important, because Bell Labs said it was.
Big speakers and little amps blew my mind!
Ah, it's always the input parameters that stop me dead in my tracks. LOL
Hollowboy, you the man. Do you have a rule of thumb for how much bandwith to add on the high end? It must have been buried deep in that article.
Damn right it's an interesting driver. There is nothing else like it. Instead of simming 110db at 10 watts, it would be milliwatts.
It's a good thing HR models the low end, because that is where action is. People always worry about the highs in horns, but the bottom is critical.
Can't make the numbers match? Everybody always tries to fudge the low end with horns. You and me too. It's universal. All speaker manufacturers fudge their efficiency numbers. It's universal. It's only the hobbyist who will put up with the huge weight/size gain from not fudging, but that's why our systems sound better too. Sometimes.
"My point: 300hz from a modest horn doesn't seem like an impossible goal, or one that requires a magic driver. "
Modest is in the eye of the beholder isn't it? More seriously, I accept your point. It's that you just don't see any. In fact I would have to say the AG may be the first. That's why I'm sceptical. Doesn't mean it's not true.
I hope you create the horn you want.
Jamie
Big speakers and little amps blew my mind!
A driver that could possibly be used to clone the AG horn: RCF MR8N301
Their spec sheet shows 107dB / watt* on a horn, bandwidth of ~500Hz to 3kHz.
Their horn is tiny (very short, 35*40cm mouth) for close spacing in arrays. An bigger horn (an AG sized mouth, but shorter) should extend the LF down to the driver's Fs (with -3dB just under 300Hz).
The RCF phase plug seems to be built for efficiency over bandwidth (like type 2 in the link). Type 1 or 3 from the link might extend the HF a little, but possibly not worth the effort as 3.5kHz looks like the most you'd ever get.
*when I model the raw driver (half space, as they measure in a "hemispherical" environment), I get the same 102dB efficiency at max, but I get less gain for the horn. Maybe I'm doing something wrong.
Hey HB,
I wrote you a nice reply Friday, and hit the wrong button and lost it all. Let me get over being sick with myself, and I reconstruct it.
J
Big speakers and little amps blew my mind!
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