Originally Posted by Mark Nye
I just did one the other day where the engineer took two signals: the DI from my STL900 and a signal from a Palmer speaker simulator that we ran off of the STL speaker out. The result was sublime.
In another session I did a few weeks back, the engineer wanted a direct signal and nothing else. I convinced him to take my STL DI in addition to whatever DI he was using (make/model escape me at the moment). He ended up going with the STL signal alone and thanked me for my suggestion.
Just a quick note here for users of any of the class D amps... most of these are operated internally in BTL (bridge tied load) mode and should not be used with any of the conventional direct boxes. The problem is that there is no ground referenced signal going into the DI so a special, fully isolated from ground connection must be used. There are a few specialty DIs that offer this but most do not. Also, pin 1 must never be connected to the sleeve or speaker minus terminal because excessive fault current can then flow down the shield of the snake and into the mixer's ground bus. The wiring (including circuit board traces inside the mixer) is not capable of sustaining this current and very costly damage can occur to the snake and/or mixer.
I really discourage doing this without getting confirmation from the manufacturer of the DI that it provides safe isolation from BTL sources, and there's adequate isolation between pin 1 and everything else.