Patching a mixer into existing PA

[rtrice]

A church I'm working with has a Mackie Onyx 3280. They are meeting in a high school auditoreum and want to tie the Mackie into the house system. Last Sunday they attemped this by coming right out of the house amplifier with 2 xlr cables into 2 inputs in the snake that I assume went to the main outputs of the Mackie. They could not get any gain out of the house even though the amp volumns were all the way up. There are other components in the amp rack but I'm not sure what they are. Should we have patched in somewhere else? Can anyone give me some options or the best way to patch our console into an existing sound system?

Thanks,

Robbie

[agedhorse]

Why would you want to patch your mixer outputs to the Mackie's main outputs? You run the risk of damaging either their console or yours. You would want to connect to their amp (or speaker processor/crossover/eq) inputs.

 

Rule #1: Never ever assume what's on the end of a cable if you can't physically verify it.

 

Rule #2: If you don't know exactly what you are doing, rule #1 applies even more strictly. If you can't clearly identify what the equipment in the rack is or how it's connected, you shouldn't be touching it.

 

Rule #3: If you manage a house installation, keep everything under lock and key and out of reach of folks who will help themselves to "reconfigring" your equipment without knowing what they are doing, potentially damaging your equipment.

 

Rule #4: ALWAYS transformer isolate any line that has the possibility of phantom power appearing on your outputs. Never assume that the other end of the line is "safe".

 

Rule #6: You are generally better off going into a mixer's channel inputs with the pads on, gain (trim) down and phantom turned off if possible. Transformer isolate your outputs and set the board faders (channel and master) to nominal "unity". You may need to ground lift pin 1 at the source (your mixer) to avoid ground loops.

[Ear Abuser]

Maybe better to go in through the house system line or mic input. You'll want to put an isolation transformer between your system and house system to eliminate any chance of ground loops.

If there is a balanced line level input to the house mixer, that should give you more gain. You could go into a mic level input on the house mixer if you have a mic level out on the Mackie (some of their boards do, not sure about the Onyx).

A passive direct box could work to get you to a mic level signal from a line level .

[rtrice]

Thanks for the advice. Points well taken agedhorse. I'm not in the habit of walking into a venue and reconfiguring their system. We have been very careful not to change anything or just start plugging things in where they don't belong. I know how easy it is to fry something. The good news is we got our board patched in properly and everything worked great. I appreciate it.