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MWM power question

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@Chief bonehead   Roy... I've picked up some MWM  cabs w/K43 woofers in them. Do you think I  can power them safely with a Crown amp only rated for 4 or 8 ohm loads? Not at home but in a small venue setting.

 

Thanks

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Bruce, here's an input impedance plot for an MCM1900, which crosses at 350 Hz from the MWM (K-43 woofers) to the MSSM (in four-way operation):

 

824189212_MCM1900InputImpedancePlot.JPG.171043d437396d78b8647d53ad050076.JPG

 

Chris

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Everyone has said this would be fine and those plots seem to agree. I guess I won't sweat it. Not like I need to be straining the amp anyway. It won't be at rock concert levels. My quest has always been the older literature for the K-43 shows them as 8 ohm speakers, but they definitely are not.

 

Thanks Chris

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IIRC, the K-43s are wired in parallel in the MWMs.  The Thiele-Small parameters for the K-43 on the forum is showing a 6-ohm nominal input impedance.  That would otherwise make the MWM input impedance 3 ohms--nominal.  But the Z-magnitude plot above shows a higher minimum than the nominal calculated value from T-S parameters. 

 

I like to see Z plots, not "nominal" values, which to me have no meaning.  The concept of impedance implies a function that changes with frequency--not a "nominal" singular value.  If you look at the complex plane impedance of a 1980s-era Klipschorn (from the Richard Heyser Audio magazine review in 1986), it shows that "nominal" has no real meaning for the Khorn:

 

Richard C Heyser KHorn Review impedance plot fig 3.jpg

 

I was encouraged to see that the MCM1900 Zin plot was much better behaved.  If you've had older Khorns or La Scalas, I would be a lot more worried about amplifier stability under high loads with them (using the supplied passive crossovers).  Tri-amping Khorns/La Scalas, or biamping MWMs and some other HF horn and compression driver would typically increase stability over passive network crossed loudspeakers.

 

Chris

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