Connect carillon to PA

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Connecting the output of Chime Master carillons to PA systems for inside sound is easy once you determine the type of input you are connecting to. Dealing with impedance mismatches, ground loops, and running cables a long distance, are addressed here.
The best way to connect any instrument to a PA system with a professional mixing desk with balanced inputs is with a "direct box."
Running long wires to connect to a PA with unbalanced inputs is generally a bad idea, but you may achieve acceptable results by following the balanced cable approach.

Carillon Outputs

Rack Mount Millennium, Platinum and Six-SS

Both quarter inch jacks on these systems are tip-sleeve unbalanced outputs. The reason the inside jack is unbalanced is because it drives the internal monitor speaker amplifier when there isn't another plug in it. Plugging a cable into the Inside jack disables the front panel speaker. Always use a direct box or pair of matching transformers to extend the connections to a PA with these systems.

Din Connector

Balanced audio output is available on pins 2 and 3 of the DIN-4 jack (the pins closest to the notch). Unless otherwise labeled, this output has a high-pass filter because it typically is used to drive a remotely located tower amplifier. It also is not affected by the carillon's monitor level controls.

Pin 1 has a switched 12V through a 220 ohm resistor to enable power to the amplifier and Pin 4 has a 220 ohm resistor to ground (for enable current only). We provide cables to connect these DIN plugs to QSC amplifiers with 15-pin D connectors for balanced audio and power switching. Junction boxes with 4-pin DIN male and female jacks and screw connectors can be used to extend a 2-pair shielded cable to remote amplifier locations.

Pinout as viewed from the rear of the carillon chassis:
1 - 12VDC positive switched (right top pin)
2 - Audio Hot (right bottom pin)
3 - Audio Cold (left bottom pin)
4 - Power supply GROUND (left top pin)
Barrel - Chassis GROUND

Rack Mount Six-CD and EZ-Bells

These systems have a high impedance pseudo-balanced output with a 330 ohm resistor from the op-amp output to the Inside jack tip, another 330 ohm resistor from ground to the ring, and the sleeve is grounded to the chassis. It is recommended that a balanced line input from the mixer be tied only to the tip and ring, leaving the shield connected only to the mixer input ground.

The Tower output jack is fully balanced on these systems.

Oak and Plexiglass Millennium and Six-CD

The Six-CD systems had a 4.7k resistor isolating the tip of the Inside jack from the Tower jack. Always use matching transformers (or direct box) when connecting to these systems beyond 25 feet.

Mixer Connections

Close Unbalanced Line Input

A line input on a mixer that is located next to the carillon system can be connected with a quarter inch unbalanced cable. In some instances the mixer will have an RCA type input jack. For this reason, when a customer requests we include a cable for connection to their PA system, we supply a cable with a quarter inch plug on one end, and an RCA plug on the other end, with an RCA to quarter inch adapter.

Distant Unbalanced Line Input

When an audio signal is sent any distance beyond 25 feet, it should be connected through a balanced cable. The PA outputs of the Chime Master carillon are not balanced. An RCA input on a PA is always unbalanced. Quarter inch input jacks on a PA may be balanced or unbalanced. Use transformer adapters at each end of the balanced cable (2-conductor plus shield with standard XLR to XLR microphone cable of the required length) as follows.

Plug the quarter inch to quarter inch cable from the PA output of the Chime Master to a Hosa MIT-129 (or similar Radio Shack 274-017) transformer adapter, and plug the female XLR plug from the balanced cable into the output of the adapter. The other end of the balanced cable has a male XLR plug that goes into a Hosa MIT-435 (Radio Shack 274-016) that has a male quarter inch plug on it. Plug the MIT-435 into the quarter inch jack on the PA. For a PA with an RCA input, use Hosa GPR-104 adapter with a female quarter inch jack to a male RCA plug.

Note that these adapters do not attenuate the line level signal enough to feed a microphone input. These adapters are available for around $20 each.

Parts can be obtained at a local music store or online from Sweetwater.com

Hum

The primary cause of hum is a ground loop. The audio equipment is grounded at its outlet, the carillon at its outlet, then if the shield of the cable is connected at both ends, current starts flowing through it, causing hum. For best results, always connect the shield at the input (mixer board) end.

Make sure that inline matching transformer cables do not come into contact with the chassis of equipment or to electrical boxes and conduits.

Balanced Microphone Input

Sometimes the mixer will only have a microphone input using an XLR connector. In this case, a direct box with a line input is recommended. The box takes care of converting unbalanced to balanced and high to low impedance. It will also reduce the gain of the signal (through the Line input jack) so it doesn't overload the microphone preamp in the mixer. Place the direct box next to the Chime Master carillon and run a balanced cable (two conductors and shield) the distance to the PA mixer.

Decent direct boxes are available for less than $50. Always choose a passive transformer-isolated direct box that does not require batteries or phantom power. The input jack should be plastic and isolated from the chassis ground.

Links

• Sound System Interconnection - Rane discusses avoiding ground loops and cable pinouts
• Sweetwater Sound Direct Boxes - Good and Cheap - Better Quality