AXB-VOL3 tripping my amp?

vegastech

I'm using an AXB-VOL3 to control my rotel 2ch amp. After about 2-5 minutes of running at a fixed volume, the amp trips out. It only seems to happen when I have the VOL3 pushing the audio to it. I wired my standard RCAs into the vol3's in+ and ground terminals for both the inputs and outputs.
Is this the right way to wire it, or do I need something connected to in-?

Andrew G Welker

What you describe is an unbalanced to balanced audio connection. Typically, you connect both the shield of the cable and the black wire to the ring or - connection of the RCA and the red wire to the Tip/center/+ connection on the RCA. Then, on the balanced side of the connection, you connect Red to +, Black to -, and shield to the ground.

ericmedley

Andrew G Welker wrote: »

What you describe is an unbalanced to balanced audio connection. Typically, you connect both the shield of the cable and the black wire to the ring or - connection of the RCA and the red wire to the Tip/center/+ connection on the RCA. Then, on the balanced side of the connection, you connect Red to +, Black to -, and shield to the ground.

Another thing to be careful of is that the output of the AMX box is +4. If you're using the RCA unbalanced on the amp, it's level is -10.

the act of grounding out the - pin lowers the overall level of a plus 4 output to somewhere around -2 ~-4 depending upon the impedence of the circuit.

So, your levels are still not matched up. They are fairly close so most things don't care too much. But, with a higher quaility peice of gear it could be clipping on the input. This is especially bad on hi-fi gear (not guitar amps) You may have to cheat the output of the Vol box down a bit to compensate.

I have had to build in a limit on AMX vol boxes in programming to assure that this never happens. I think I ended up limiting the output level to something like 190 or 180 in AMX level.

vegastech

So you're saying that if I just run a jumper from the ground terminal to the - terminal for the input and output on the vol3, I will have issues with the MAX ouput on the vol3? So I CAN do it, and as long as I limit the max level on the vol3, I should be ok?

ericmedley

vegastech wrote: »

So you're saying that if I just run a jumper from the ground terminal to the - terminal for the input and output on the vol3, I will have issues with the MAX ouput on the vol3? So I CAN do it, and as long as I limit the max level on the vol3, I should be ok?

Yes,

If you have an oscillascope or volt meter that can read db or 100ths of a volt you can figure out down to the gnat's eyelash what value you'd need.

run a 1k sine tone through the vol box and slowly tweak the level until you get the voltage down to -10db.

Or, you can just 'ear-ball' it. Play some music and tweak the volume until you start to hear clips. then back it down. Whatever level your end up at should be around the max level.

vegastech

Yup, that did it! I'm just not used to running unbalanced to balanced...but hey, as long as it works, right?