McIntosh MC901's internal active crossover & speaker's internal passive crossover

A biwirable speaker provides a separate path for lo and hi frequencies, but they are still joined electrically at the xover.

@Cleeds In my experience that’s’ almost never the case, but I have seen it happen. Almost all speakers I’ve seen with 2 sets of inputs and external jumpers separate the crossovers internally.  Otherwise, why have jumpers??

You can easily check this in a couple of ways. Remove the jumpers and plug in the woofers. See if anything comes out of the tweeter.

Next, do an impedance check between hot to hot and ground to ground. Should be infinite.

The one case I remember being posted about the speaker only had ground shorted internally. Normally this would be OK unless your amp was fully balanced.

erik_squires

Almost all speakers I’ve seen with 2 sets of inputs and external jumpers separate the crossovers internally.  Otherwise, why have jumpers??

Agreed, biwiring doesn't make much sense and neither do the jumpers. When you biwire, you do not send the full amplifier output to the tweeter, do you? Of course not, you'd blow the bugger out. It still goes through the speaker's x-over. It's easy to verify with a DMM - just check for continuity. Spendors used to be wired that way, IIRC, and it always puzzled me.

@cleeds

What you are missing in your understanding is that the filter sections for each driver are independent in the classic, parallel crossover.

When the external straps are removed the individual high and low pass sections remain in place but the crossovers should not (and usually are not) have any be connected internally.

An external crossover would of course be additive to the internal crossover so it's not quite as good as having a purely external crossover, but it's workable.

Still, the risk of connecting two amps to the same bi-wire speaker is only present in rare cases when they join the grounds internally, and a balanced amp is used. 

Best,

Erik

@cleeds Wrote:

Agreed, biwiring doesn't make much sense and neither do the jumpers. 

I agree! Bi-wiring is a joke.

Mike