Guitar Gear Forum

...FX loop. What are the rules to follow ?
Example: ZOOM G7: input 1 Mega ohm, output 1 KOhm
Randall RG75: FX loop send 1 KOhm, return 100 Kohm.
What do you think, is it OK ?

High input impedance and low output impedance are pretty much the usual in audio gear, I wouldn't worry about it. It does have an effect on the sound but there's no rules to follow other than use your ears to decide whether two pieces of gear work together. It's exactly the same on a pedalboard where loads of low impedance outputs are connected to high impedance inputs in a row.

The thing to watch out for is the actual level of the signal - instrument vs line level, and whether the line level is -10 or +4dbu. That's the part that trips people up when using loops and effects.

Here's a good page about impedance mismatches I found (it's about using guitar fx with synths but the principle is the same):

http://www.submodern.com/slowburn/?p=93

tl:dr:

Your big worry with an impedance mismatch is when you have a (relatively) high impedance signal going into a (relatively) low impedance input.

ie. the opposite of what you have.