Can I safely do this to a pasive cross-over?

  • Thread starter Thread starter mixsit
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M

mixsit

Well-known member
I have a JBL D-120/075/N2400 passive monitor.
What I want to do is move the 12" speaker connections from the low-out of the crossover to the full-range x-over input terminals. This would leave the low freq. terminals disconnected (and un-loaded?) and allow me to dial the 075 in or out as needed.
This could be a nice fix for a switchover to and from electric and acoustic guitar cab duties -if it's feasible.
Thanks in advance.
Wayne
 
You should be able to wire up an simple on-on switch to do that. I think I'd wire it a bit differently, so the other components were disconnected when you want to use the woofer as full-range. In that case the crossover would be completely out of the circuit when you used it as a cab.

Oh, one more thought, the crossover design might have a Zobel circuit on the woofer. Instead of wiring one side of the switch directly to the woofer, you might tap into that point of the crossover which is often after the filter circuit.
 
Yes I see. I would like to go the other way though if it's safe.
(One factor is I'd get to try it tonight in about an hour... :)
Wayne

I just realized -I might still have an old 100 watt/10 ohm resister I could string in there.
Hmm
 
mixsit said:
I just realized -I might still have an old 100 watt/10 ohm resister I could string in there.
Hmm
Click to expand...

I don't think you'd need a resistor. The impedance should be stamped on the woofer, and I doubt it's much if any less than 8 ohms. It's more typical to pad a tweeter as they commonly have higher sensitivity than the woofer.
 
Well I seem to have gotten an all clear from a nice gentleman at the Lansing Heritage site, looks like I'm good to go then.
Thanks Mshilarious.
Wayne
 
mixsit said:
So as to not be spreading any bad info, here's an up-date and correction. There's a reason for not doing this.
http://www.audioheritage.org/vbulletin/showthread.php?t=7056
I got away with it last night but may have just been lucky..
Wayne
Click to expand...

Right that's what I was saying: wire up a switch to take the crossover out of the circuit.

Regarding the "open circuit crossover warning" bit, something seems odd about that analysis, because if the filter circuit provides no resistance at the crossover frequency, then I don't see how adding a parallel load prevents a short circuit. I would guess the open circuit is designed to provide the same resistance at the crossover frequency as the driver :confused:
 
mshilarious said:
Right that's what I was saying: wire up a switch to take the crossover out of the circuit.

Regarding the "open circuit crossover warning" bit, something seems odd about that analysis, because if the filter circuit provides no resistance at the crossover frequency, then I don't see how adding a parallel load prevents a short circuit. I would guess the open circuit is designed to provide the same resistance at the crossover frequency as the driver :confused:
Click to expand...
Might the load and x-over combine for an even impedance? I'm really just guessing here..
Wayne
 
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