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Posts: 353
Location: Knoxville
Joined: February 2, 2001
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Interesting. And to think, 500Hz was almost a standard among large format 2-way systems of yesteryear. An example would be the John Hillard system, either side of his fireplace. "Where to cross?" has been a discussion spanning at least 2 decades. I don't think there is an easy answer. Pretty much depends on the system. But, in this thread, I suppose we are discussing a horn based system. Now, how many horns is the question (?) 3 horns plus low bass? 4 horns? 2 horns plus a mid-bass, and a low bass?
****Which decade do you wish to keep intact?****
Maybe we can keep two decades intact. Let's say we follow Bill's guideline:
"The 350-800Hz range should be avoided for crossing over, as that's where time and phase issues are most easily heard".
Seems to me, this is a reasonable recommendation. I'll add my opinion, to his recommendation. This *just* my opinion, and not a carved-in-stone rule. Compression drivers really don't like to be pushed very low. An 800Hz lower limit, even for a 2inch seems fair. That sets our decade at 800-8K. Now what do we use? A 600Hz horn? This leads into a discussion of what type of crossover topology to use. That, in and of itself, is an entire devoted discussion. The one octave over-lap rules comes into play. In that case we need a 400Hz horn, but then that leads to the question of where does beaming start at the top end of the decades' range? We also need a horn to cover the lower of the decade sections: 80-800Hz. That's another tough one. It's better to cover that range with a straight horn. But, then we get to where we are using an eighty hertz horn only down to 80. Now what? DSP to the rescue? Sorry, even as I type this, I realize there seems to be more questions than answers.
It might just be that a 4-way is just too complex. And I say this as a 4-way guy. In a previous system, that I had up, which was horn based, I used a very large round horn for my "main" horn. A 6 inch throat with an eight inch wizzer cone mid. 250Hz-6K, sometimes even trying to stretch it to 8K. Super-duper tweeter on top; ppsl mid bass; infinite baffle low bass. Although a superb system it was still a compromise. Lots of criticism directed towards that system, by guest listeners. They said lack of ultimate resolution, because I was not using a compression driver for mid-range. Now see, this goes full circle of what this thread is about. If I adopted a compression driver , I would have to change horns. Best I had was a 400Hz horn. But then, I'd have to stretch the ppsl up to 500Hz. It was already a push, to get it to operate in a linear fashion, to 250Hz.
In all my previous years of "listening" to crossover points, none sounded as good as the 250Hz point. Provided the mid-range was big enough to keep up. Whether it could keep up, depended on what I used for mid-bass, or just plain bass.
In the years past, there has been plenty of discussions like this. Much of it was in what I call the hey-day. The 2nd installation of the Golden years. Circa the year 2000, plus or minus 5 years or, so.
Do a search for Sierra-Brooks horns, and you will see quite the color commentary.
Oh, one more thing. If you have not seen it, look for the Joe's system in Brooklyn. By Steve Guttenberg, "Meet Joe" (and his amazing system)
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