# How to isolate ground on DIY active crossover?



## Spasticteapot (Mar 5, 2007)

I'm cooking up a DIY active crossover for another project, and was wondering how I might adapt it for automotive use. I'm afraid I'm a bit stumped - short of using input and output transformers (expensive!) or a fully isolated switching power supply, I can't see how one would go about it.


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## lycan (Dec 20, 2009)

if transformers are too expensive (and the good ones, with good low freq performance, indeed are), then you might consider a classic balanced input stage ... which can easily be used with single-ended RCA signals/cable as well.

One opamp per input, plus 4 resistors.

Also called a "differential-to-single-ended converter". This simple circuit "observes" the input as if the input is differential, meaning that the input "common mode" ... or input ground reference ... is ignored. The circuit then re-references your signal to the local ground.

It's a great "isolator", particularly if you're already building an active xover ... you'll already have the opamp power supplies handy


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## envisionelec (Dec 14, 2005)

Something like this.












R5 is probably not needed AND R2 and R3 should be 15K, as well.


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