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In Reply to: RE: Avantgarde Horns posted by Mr_Steady on October 22, 2014 at 19:36:24
A 5" exit compression driver would be crazy expensive, I think. I'd also expect a high end compression driver to be a little more sensitive than 104dB. By comparison, the TAD 4001 is small (voice coil "only" 100mm), gives 110 dB/watt and cost is $6000 a pair.
"The M1 is a 130 mm (5 in) midrange driver with a 75 mm (3 inch)
dome especially developed for the Uno and optimized for a large,
linear excursion"
This sounds like a well chosen / built conventional driver rather than a compression driver. The pic on the brochure looks like a regular driver.
Not that this is a bad thing - I'm thinking of making something similar myself*. When I punch the data for a normal pro 4.5" driver on a Uno Fino sized horn into Hornresp, I get something that models well - no ripple. It needs 3.5 watts to hit 104dB and -3dB point is 340Hz. 1mm displacement gives 113dB.
The Uno Fino claims better efficiency and a lower rolloff, but these claims seem within reason, given that their driver is specialised for horn loading, whereas I was modelling a standard driver.
*have ordered but not yet received the drivers, so still at the modelling / theory stage.
Follow Ups:
I think you may be right about the driver. The "large linear excursion" phrase is the tip-off. The efficiency comparison is also correct.AG is well known for using the Community M4 driver, which is a 4" exit CD that uses a carbon fiber diaphragm. I saw 5" and CF and figured it was a modified M4. I priced the M4 years ago, and it was not prohibatively expensive. Half or less the price of your cited TADs. Problem is nobody but community makes a horn for a four inch comp driver. Hope you like their horn. That's where AG comes in. The M4 has a FR of 200hz to 4000hz. There is a lot I could do with that if I was a horn designer/manufacturer, which I'm not, and never will be. I guess I assembled my own system.
Many times I wish I had learned HornResp. McBean must be a bloody genius. The Spherical horn profile happens to be my favorite. It's in my system now, because it sounded the best. It is a very capable profile. It does a lot of things right like loads well, but isn't too long. I will take your word about your sims. It does surprise me. 300hz is low. It's 45"/1.15m wide. That's big. On the wavebox site you see horns that are at least 36" wide with 10" drivers.
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. Having said that, your sim resulted in 340hz. I can tell you from persoanl experience, that the difference in the mid horn world between 300 and 340hz is all the difference in the world.
Check out the picture. It was just released. Autotech is real good at cutting down their horns. 2,4,4.5,5,bigger. It's all possible. If you were Johnny on the spot you could sim it, and tell us how short the horn would become, or we could just ask Jacek. I would love to see that green and red soundwave plot Hornresp generates. The one that shows the SW leaving the mouth. I just noticed. This horn is only 31" wide. That seems small. Hmmm.
The one thing I don't get about AG, and the one thing I have against them is; Why did they keep the stock carbon fiber diaphragm on the M4? Community makes mylar diaphragms for their other drivers. AG has the money to make a mylar diaphragm happen. I would bet my system it would make it sound better. Also, if AG did sell this horn and driver standalone, I wouldn't pay their price.
Jamie
Big speakers and little amps blew my mind!
Edits: 10/26/14
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 :)
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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