Inputs Versus Outputs and Signal Flow

-Input- The term seems self explanatory but when wiring a system with a ton of cables, things can get confusing.  

XLR Inputs

  • XLR inputs either have three little holes that make a triangle shape
  • The three little holes an XLR cable fits into is actually referred to as a female port.
  • There are two types of XLR inputs
    • combination jacks are both XLR and 1/4″ inputs combined into one input
      • by looking closely the 3 XLR ports are also shown on the combination input
    • Regular XLR inputs which have 3 female ports that make an upside down triangle shape

XLR Outputs

  • XLR Outputs are always 3 pin male
  • This can be found on the bottom of a mic or a mixer main output
  • EX: on the bottom of a mic there are three pins.  That means that when someone sings into a mic the singer’s voice comes out of the three pins on the back of the mic, then through a cable and into a mixers female mic input


1/4″ inputs and outputs

When learning about 1/4″ in and outputs it is important to know that both are female ports.  This can be confusing so keep an eye out for how the 1/4″ port is labeled.  To better understand the terminology associated with each output make sure to follow up with the layout of a mixer blog post, coming soon!

1/4″ Inputs

  • 1/4′ inputs are female
  • Generally unbalanced
    • meaning the 1/4″ cable needs to be mono or in other words TS
      • if the cable is balanced or TRS there may be signal loss due to the connection points on a TRS balanced end versus a TS mono end


1/4″ Outputs

  • 1/4″ outputs are female
    • read the label associated with the 1/4″ port and make sure the output is labeled as an output
  • Most are balanced and unbalanced
    • a TRS cable can be used or a TS cable
  • Always use a balanced cable if possible
    • TRS cables help remove buzz and hum from coming through the speaker



Signal Flow

Is where the input source starts and the path it takes step by step until the final destination of the output source.  Essentially how inputs and outputs work together to achieve an efficient audio system.

Understanding signal flow is the most important building block to becoming an audio engineer.  A great example of signal flow is thinking in terms of a singer.  The voice of the singer comes from their diaphragm, out of the singers mouth, into the microphone, from the microphone to the microphone cable, then from the cable into the mixer, through the preamp section, and eventually out of the mixer, then through the speakers.  This is a very simplified explanation of the signal chain when simply connecting a mic to a mixer.  There are several key points that the signal travels through and understanding how sound travels will payoff.  Knowing how to trouble shoot, being able to detect a problem at a moments notice, and coming up with unique routing designs all stem from signal flow. 

Below is Signal flow charted out to depict the complexity of even the most simple connection.

This example elaborates on the steps in signal flow a singers voice takes to come through a mixer and out of a speaker.

  1. The voice of the singer comes from their diaphragm
  2. Out of the singers mouth
  3. Into the microphone,
  4. Through the microphone
  5. To the microphone output
  6. Into the mic cable
  7. From the cable into the mixer
  8. Through the preamp section of the mixer
  9. Through the insert section
  10. The eq section
  11. The auxiliary section
  12. The effects send
  13. The panning section
  14. The mixers routing options
  15. Channel volume
  16. Then out of the main mix output of the mixer
  17. To the speaker input
  18. Through the speakers volume control
  19. Then the speakers amp
  20. Then finally out of the speakers


This 20 step process is a great checklist to have ingrained in your though process when having any issues or trying to come up with unique ways to manipulate routing designs!

-This concludes this blog post! Keep an eye out for the next one, Layout of a Mixer.



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