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KP-301 KP-3.0B Crossover


Dave A

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Apart from individual component values that may or may not differ from those in the schematic above, it looks like you've additionally got a 1st-order low-pass (which would phase the squawker signal back 45° for a total of +45° from input) as well as overload protection on the squawker.  Can you sketch out a diagram?

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10 minutes ago, glens said:

Apart from individual component values that may or may not differ from those in the schematic above, it looks like you've additionally got a 1st-order low-pass (which would phase the squawker signal back 45° for a total of +45° from input) as well as overload protection on the squawker.  Can you sketch out a diagram?

Here you go.

KP 301.pdf

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Near as I can tell from this angle it looks like a match to the diagram.  So it's a 2nd-order low-pass on the squawker.  From what I can see it appears as though the order of red / black on the right (long barrier strip) is reversed on the two-position strip.  I'd leave it alone so long as everything's routed correctly, unless you wanted to jumper that two-position strip to the long-strip input pair and run only one set of wires in to the crossover, maybe (don't think I would, though).

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1 minute ago, glens said:

Near as I can tell from this angle it looks like a match to the diagram.  So it's a 2nd-order low-pass on the squawker.  From what I can see it appears as though the order of red / black on the right (long barrier strip) is reversed on the two-position strip.  I'd leave it alone so long as everything's routed correctly, unless you wanted to jumper that two-position strip to the long-strip input pair and run only one set of wires in to the crossover, maybe (don't think I would, though).

I have left it alone since it does work and sounds good. I was just wondering about the complexity of it all and thinking the more stuff you add in would that possibly degrade the sound?

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1 hour ago, Dave A said:

I have left it alone since it does work and sounds good. I was just wondering about the complexity of it all and thinking the more stuff you add in would that possibly degrade the sound?

 

For what it's worth I agree with Dean, pretty simple, really.  Except maybe for using both a resistor and an autoformer on the mid.  12dB/12dB/18dB is a little ambiguous.  I don't know what the convention is but I'd say 12dB/12dB 12dB/18dB.

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Didn’t even notice the .pdf. Looks like a 24dB/octave midrange. The autoformer has too much inductance to actually be doing anything (other than introducing phase shift). The series resistor behind the autoformer is attenuating and manipulating the impedance before it gets to the input tap. The resistor in parallel with the polyswitch is the tweeter protection. These are all uneducated guesses. 

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I'm sticking with 12 up and 12 down on the mid looking at that PDF, Dean.  Assuming the tap numbers actually mean anything on the auto, coming off at 4 out of 5 ain't going to be much voltage drop.  Obviously they had something in mind and they do this for a living, but seems a lower tap would do the same thing as a series resistor with a higher tap (or a different value resistor allowing elimination of the autoformer).  That's if there are actually multiple taps available for use on that unit, don't know...  The only autoformers I've had much experience with changed pretty-high voltages to mediumly-high voltages for use in manufacturing.

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On 3/8/2019 at 11:49 AM, Deang said:

It’s a stupid feature that customers want, so the company caves and adds it - because if they don’t, then it’s something the competition has that they don’t. It’s marketing, not engineering.  

Famous words, uttered to me by PWK himself in 1985.

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