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Church Sound and Video Advice > Audio Tips > AC Hum


We are getting AC Hum on our sound or recording system - How can we fix this?

 
When audio and video sources are interconnected, sometimes a ground loop is created which causes AC hum. This usually occurs when the devices are connected to equipment in different locations. In order to correct this problem, the grounding on the audio lines needs to be decoupled.

AC Hum Elimination16 Minute Video about AC Hum & Buzz cause and elimination - includes explanation of Balance & Unbalanced signals and Ground Loops.

The AGDC2 is an Audio line level decoupler. It completely electrically isolates (both signal and ground) the input source from the destination, thus eliminating the coupling which causes AC hum on sound systems. The AGDC2 is a two channel unit which can be used for stereo or two fully independent sources.

Inputs and outputs are 1/4" TRS Phone jacks. They will accept either balanced or unbalanced connections. They will even convert from one to the other. For example, you can connect a unbalanced CD player output to balanced line input on a mixer using these units.

 

Price and Data Sheet

If you need RCA inputs or outputs, add the A256 adapters.

The AGDC2 is a professional unit using high quality Neutrik connectors and housed in a thick steel case to eliminate RFI and EMI interference.

Typical applications include:

- Computer feeding video to projector and audio to mixer
- DVD player feeding video to projector and audio to mixer
- Mixer feeding audio to DVD recorder
- Equipment connected to mixer, located elsewhere (musical instrument, Computer etc.)
- Mixer output feeding to remotely located amplifiers
- Mixer output feeding to powered monitor speakers

The inputs and outputs are interchangeable, so it doesn't matter which connection you use for input or output. If you plug in a TRS cable, you can get a balanced connection. If you plug in a 2 conductor phone cable you will get unbalanced.

We sell a wide selection of cables which enable you to use this device in any application. We even make custom cables if you require them.

Links:

Application Examples

Instruction Sheet

Price and Data Sheet

Here are some Application examples :

 

Parts & Prices

AGDC2 > Audio Line Level 2 Channel Ground De-coupler.

 

Click on image for larger view.

Below are examples of Cables which Alectro Systems makes to go with the AGDC2 (or any other application you may have). Typical lengths are 3 and 6 feet, but most of them can be made in any length desired.

CABTRS > !/4" Phone Tip Ring Sleeve (Balanced) Cable.

Since most mixers have Balanced line inputs, this is the most common cable used to connect the AGDC2 output to the Line Inputs on the mixer.

Click on image for larger view.

CAUTS > 1'4" Phone Tip Sleeve (Unbalanced) Cable.

This cable is commonly used to connect the output of the AGDC2 to an Unbalanced Line Input on a mixer, or to connect the 1/4" Phone Unbalanced output from an audio source to the AGDC2.

Click on image for larger view.

CADXMTRS > 1/4" TRS Phone to 3 Pin XLR Male (Balanced) Cable

This cable is often used to connect the Output from the AGDC2 to an XLR Input on a recording unit, equalizer or amplifier.

Click on image for larger view.

CADXFTRS > !/4" TRS Phone to 3 Pin XLR Female (Balanced) Cable.

This cable is often used to connect from a Balanced XLR mixer Output to the AGDC2.

Click on image for larger view

CAMINTS > Mini Phone to 1/4" Phone Mono Cable.

This cable is typically used to connect an audio Output from a Computer to the AGDC2, or the Output from the AGDC2 to the audio Input on a Computer.

This cable combines Left and Right into Mono.

Click on image for larger view.

 

A505 + 2) A256 > Mini Phone to 1/4" Phone Stereo Cable - 6 foot only.

This cable is used to connect the Output from a Computer to the Input of the AGDC2 in Stereo, or the Output from the AGDC2 to the Input of a Computer in Stereo.

You need 1) A505 plus 2) A256 adapters, each sold separately.

Click on image for larger view.

 

CAUTSRCA > 1/4" Phone to RCA Cable.

This cable is used to connect the output from a DVD or CD Player to the Input of the AGDC2. It is also used to connect the Output from the AGDC2 to the audio input on a DVD or CD Recorder.

Two cables are required for Stereo.

Click on image for larger view.

CAUTSRCA + A500 > 1/4" Phone to Dual RCA Cable.

Add the A500 adapter to the ASITSRCA cable to combine a Stereo RCA input or Output into Mono Phone.

Each sold separately.

Click on image for larger view.

A256 > RCA to 1/4" Adapter.

This allows you to plug an RCA Cable into the AGDC2 Input or output.

 

 

 

 

 

 

 

 

 

 

 

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