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In Reply to: try this posted by nl on February 24, 2007 at 18:58:57:
" Try at least a 6db/octave filter (input capacitor on your power amps) and see if it helps. If that seems worthwhile, I'd try for at least a 12db/octave filter."I have done this already. The Lowthers get an amp with a frequency response from 120 Hz to 40 KHz, 6dB/octave slope on the low end. There is a 0.01 uF teflon capacitor in front of the input 133K ohm resistance. It sure helped, but not quite enough. I might be able to add in another pole there, but I don't think that'll solve the real problem, which is described below.
>I would imagine that a properly highpassed Lowther in an Oris Horn would have quite a bit of headroom, enough to pretty much blow the doors off a typical living room. <
It will play very loud on minimal power. It's amazingly loud, but not always clean. There are resonant notes in the whizzer cone that breaks up and causes huge +10 dB or more peaks (above and beyond what is the correct level) at high volume levels. This is not really the "shout" that is most complained about, but now it is the resonant break-up of the cone in different modes. It also can still shout, however, depending a lot on temperature of the room, of all things. If it's cold in the room such as it is in this winter time, it shouts more easily, oddly enough. I once mentioned it before, I can't believe anyone would be happy with a Lowther not front loaded and running full range. It would be shouting at relatively moderate levels to me.
I am trying to be able to get through musical crescendos near 105-110 dB at 1m when loud high-pitched music is playing. I have recently begun to enjoy these kinds of things, except for that blasted blast in the ear by a picolo or violin at ffff on certain notes, and not all notes, mind you. Avantgardes were good about never doing that kind of thing. But they were also not as transparent, either, at moderate levels.
Kurt
I think horns can be a bit frustrating trying to get it all. You get so close, and then it's not quite enough because of some peculiar thing. But maybe I just haven't found the right one yet.
Follow Ups:
As far as alternative systems go, if you like the Lowther's directness, you might try something like a 10" driver designed for horn loading. B&C makes one available at Parts Express. You can bang together a "flower petal" type conical horn without too much strain, or even a basic rectangular conical horn. These go to 100hz on the low side and then add something like a bullet tweeter for the 4K+ range. I'm guessing something like this would retain many of the attractions of the full-range approach (crossovers below 200hz and above 3000hz), but give tremendous dynamic range. Plus, you could do it all for $600 or so.
Well, if you notice some improvement with a 6db filter then I'd certainly go with a higher-slope filter and see if it helps! 12db/octave seems to be the minimum for horn-loaded applications. If you have a 6db filter at 120hz and you want 110db peaks, then you're asking the Lowther to vibrate at 104 db at 60hz totally unloaded. I would a) raise the XO point to 150hz, and b) see if you can add at least one more pole somewhere for 12db. Within a tube signal chain there's usually something somewhere that you can try. Or, just stick an additional capacitor on the Lowther itself. It might not sound good but you'll be able to tell if there's progress to be made in this direction.For those kinds of high levels, I'd try a 18db/octave filter at 150hz before pitching the Lowthers out completely. With a little creativity you can probably introduce three poles somewhere in the amplification chain without being too intrusive. Or, borrow an adjustable electronic crossover and see what happens. It'll kill the tone but you'll see if the driver acts better at high levels.
Some subwoofer amps have a line-level highpass output. Of course it'll sound like doodoo but I'd try it if you have it, and see if that "overdriven" sound goes away.
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