Wiring Neutrik Connectors

[joemichaels]

I purchased Neutrik NCJ5FI-S female combo connectors (XLR & TRS) for the input (box) end of our snake. The Neutrik connectors are balanced as is the snake cable.

I soldered 1/4" balanced (stereo?) male jacks to the mixer end of the snake.

After wiring them, XLR inputs (such as a mic) work fine. But I get a horrific buzz and no discernable signal when I plug an unbalanced guitar or mic jack into the connector.

Can someone tell me what I'm doing wrong?

I read somewhere that I should tie pins 1 & 3 together. Does this mean that the 1/4" line won't be balanced?

Are 1/4" balanced and stereo male jacks the same thing? Or, does that have something to do with it. (The mixer only has six XLR inputs, the rest are 1/4" -- hence the decision to use them.)

Grazi!

 

[esun127]

You now have direct experience with connecting balanced and unbalanced signals... don't do it.

Balanced and Stereo signals are not the same thing. They both use the exact same cables, but are completely different when in use.

In balanced cables, a single signal goes through the "+" and "-" terminals/conductors. In XLR plugs, these are pins 2 and 3, and in 1/4" TRS plugs, these are tip and ring. The ground (shielding) connects to pin 1 or the sleeve.

A stereo cable does not have "+" and "-" terminals. It essentially acts in same way as two independent unbalanced cables. Pins 2 and 3 are separate signal cables, or if your using TRS, the Tip and ring are separate. Pin 1 or the sleeve are still the ground.

If you tie pins 1 and 3 together, you will get rid of the "-" terminal by make it part of the ground, which WILL fix your problem. It basically turns the cable into an unbalanced cable.

I assume you're tieing the pins on the XLR plug that goes into the input box of the snake, right? Your snake itself is fine... it's just that it only accepts balanced signals, which is the same with pretty much all pro snakes.

I also assume that you're plugging some type of instrument directly into the mixer. If you were to get a preamp/DI box for the instrument that is being plugged in, it should solve this probelm too as most good DI boxes have balanced outputs.

 

[skippy]

The combo connectors are XLR-TRS combos. So XLR pin1 is shield/sleeve, pin 2 is tip (hot), pin 3 is ring (cold). If you plug in a TS connector (guitar cable or high-Z mic), you will automatically short ring to sleeve (or pin 3 to pin 1). And yes, in that case it very definitely will be unbalanced.

You aren't actually trying to run the guitar's instrument-level pickup outputs back to the board, are you?

There are three possible sources of trouble. One is that the 1/4" TRS inputs on your mixer bypass the mic pres altogether (that the assumption is that mic level signals will always be XLR, and anything on a TRS connector is line-level). If that's the case, then you will probably get very little signal to go along with your noise. The next is that you have a ground loop between whatever is on stages (presumably, a guitar amp line out?) and the board- and that will definitely give you loads of noise. And last (and least likely) is that your mic preamps lie when they say that they are balanced, and they are really single-ended preamps that use pin 3 as their input- in which case you're dumping all that ground noise into the pre.

What mixer are you running, and how long is your snake? I can already say that you are going to have trouble running high-impedance single-ended signals over a long snake: your signal-to-noise ratio will suffer, as will the high frequency components of the signal (the cable capacitance will kill your highs).

I'd recommend putting male XLRs on 6 of the snake lines at the mixer end, and always dedicating them to mic use. The other runs can remain TRS, but should be dedicated to line-level use (preamp outs and the like). If you have high-impedance unbalanced mics, I'd recommend using a high-Z/low_Z balancing transformer at the stage box end, so that the long run is both balanced and low impedance. And for guitars, you lust absolutely have to use some kind of a preamp onstage, and use another of those balancing transformers to convert the single-ended signal to balanced (if your pre does not have a balanced output).

The bottom line is that you must avoid running single-ended, high-Z signals through a snake. It'll cause you much more grief than it is worth...