COLIN WONFOR: Zero autoformers; how to measure impedance please

Colin Wonfor

Dear Colin, Zero autoformers; how to measure impedance please? I got a pair of Speltz zero autoformers recently but when I measure the total impedance, my multimeter sees only 0.4-0.6 ohm no matter what I do. It seems the multimeter could only read the DC resistance from the autoformer itself but not the total impedance of the speakers and the autoformers. Is this normal? It's blowing my amp into protection mode. I read somewhere something about using these with solid state amps that has excess offset voltages but I have no idea what that means…. HELP! Thanks.

Oh dear , Having now seen their web site and read their explanation I am not sure what the heck they are doing. The Graph is not defined, and the Tech Spec is nothing.

Now then, DC can and often causes Transformers a problem, so I suggest you block the DC, try and measure the DC with no signal in the Amp. If it’s high –lets say over 100mV – then we need to revisit this problem. Also note which terminal has the +V reading OK then come back with info please. Meanwhile, you could try Orelle XTC DC-blocker 230v audiophile power cord

Thank you for the question.


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