Can a crossover change the ohms of a speaker?

[ace_800 5,000+ posts]

OK kind of a strange senario. I have a set of Boston Pro60 running off a Zapco 360.4. Once in a while the amp would go into protect. When the right rca was not plugged in it would not go into protect. Just touch the RCA to the input and it would go back into proctect for a few second at a time then turn back on for a second. I was told to send the amp in for repair, came back clean. No problems. Reinstalled it, worked great for about 2 months, started up again. I check the ohms from the speakers and coming out ot the crossover. Left side- tweeter @6.0, speaker-@3.4-3.6 at the crossover the same, and at the output to amp @3.5 roughly. Right side- Tweeter @6.0, speaker @3.4-3.6, at the crossover same. Heres the kicker. When the amp was going into protect I checked the crossovers showed the same at the inputs from the spakers and tweeters, but the right crossover output was fluctuating from under 1ohm to 3.6ohms. When it was working normally the ohms showed around 3.5ohms. So I guess the crossovers going bad???

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[helotaxi 5,000+ posts]

Sounds like the case.

 

[Speedyd718 10+ year member]

hey man my zapco did the same exact thing when i had a set of comps bridged to it. i think that the amp is sensitive to running below that 4ohm bridged resistance. that's all i could come up with when talking to zapco (i sent mine back too).

 

[helotaxi 5,000+ posts]

BTW, were you checking the resistance of the speakers at the crossover while still hooked to the powered on amp? If so, that is what was causing the variation in resistance. Also, resistance isn't an accurate indication of amplifier load. 3.4 ohms measured with a DC ohmeter will most always present an amp with a load in the 4-6 ohm range.