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In the Forum: Audio Discussions
In the Thread: The loudspeakers for a powerful SET

Post Subject: Coddling One's Inner NerdPosted by Paul S on: 7/3/2010

The new parts I needed to build the new crosovers arrived about a week ago, but I have been otherwise busy (for a change...), and now I've managed to get sick, so I am still only mentally toying with the project. I will try to work in some bread boarding, at least, this weekend. Anyway, here is what I actually ordered parts for: For the 15" Audax PR380M2, I decided to start with 1st order low pass at 200 Hz (for a 300 Hz XO). This will be an octave higher than it's crossed now, and I'll also be relaxing the slope from the present 3rd order XO. Again, the idea is to add weight in that range. I will also add a notch filter at this driver's 1,500 Hz resonance peak (better safe than sorry...), even though that big motor effectively stifles HF on its own. For the Reps, I will high pass it at 6 dB at 400 Hz (ie., 300 Hz XO),and I will use a 2,200 Hz notch filter for its peak. Present Lowther high pass is 200 Hz, 2nd order. The Lowther-alike Reps will be allowed to run as high as it wants, without its whizzer, and the Audaphon ribbon will come in at about 8k Hz, but 3rd order, rather than it's present 2nd order high pass near 15k Hz. Here, the idea is to sluff "HF" (and quell HF noise). Although all this should allow decent phase relationships (once I flip the ribbon's leads...), who can be sure of these things ahead of time? This ribbon does have a built-in circuit that keeps its own impedance constant, however, which is way cool compared to the wild swings of most ribbons, which make figuring XOs for them extra tough.

I'm presently hatching a plan for a straight-to-the-point "separate" ULF that some purists here are probably going to sniff at.

But, first things first...

Paul S

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