opamp output - how to make its impedance higher?

[peskywinnets]

ok, so an opamp output impedance is low, but how can I make it higher so that it s output wouldn't load down passive guitar pickups? The end goal here is to integrate an extra active piezo pickup preamp output into a guitar's traditional switching scheme

[nigelwright7557]

I think you mean input impedance.

Make the guitar coil output go into the non-inverting input.

[peskywinnets]

No I don't!

I want to mix the active output of a piezo pickup preamplifier (low impedance), into a guitar's high impedance wiring scheme.

The low impedance of the opamp output will load the pickups down...so was just wondering if it's simply a matter of putting a large resistor in series with the opamp output to help align the output impedance of the piezo preamp with the passive pickups.

[nigelwright7557]

OK with you now.

One way is to just put a resistor in series with the output of the op-amp.

Or use anotehr op-amp to buffer and mix the two signals.

[Xoc1]

I would probably link in a high value variable resistor - say 100k or more to start with, and then adjust the pot until its a reasonable match. Then measure and subsitute a fixed resistor.

[peskywinnets]

Originally Posted by nigelwright7557

OK with you now.

One way is to just put a resistor in series with the output of the op-amp.

Or use another op-amp to buffer and mix the two signals.

but this would then make all the guitar's pickups 'active' (which changes their tone due to their output being low impedance)

looks like a series resistor is the way to go.

Cheers.