What are balance input impedence

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    Balance Input
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Discussion Overview

The discussion centers around the concept of balance input impedance, particularly in the context of audio and power circuits. Participants explore the implications of input impedance on voltage and current transfer, as well as the significance of balance in audio systems.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant mentions that input impedance is designed to achieve a desired transfer of voltage or current between devices, highlighting different requirements in audio, power, and RF circuits.
  • In audio circuits, it is suggested that a 'good' input impedance is significantly higher than the output resistance of the source device to maximize voltage transfer.
  • Another participant notes that in power circuits, the ideal impedance focuses on maximum power transfer rather than voltage, indicating a different approach compared to audio applications.
  • In RF circuits, it is proposed that impedance must be matched to avoid power loss and signal reflection.
  • Balance is described in the context of audio systems as the equality of power output from speakers to maintain a realistic sound stage, though some participants express confusion about the term "balance" as used by the original poster.

Areas of Agreement / Disagreement

Participants express differing interpretations of the term "balance" and its relevance to input impedance, indicating that multiple competing views remain regarding its application in various contexts.

Contextual Notes

There is uncertainty regarding the original poster's intent with the term "balance," which could refer to various concepts such as balanced versus unbalanced transmission lines or matched impedances. This ambiguity affects the clarity of the discussion.

dhool3053
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lm doing an assignment regarding resistance may caused an error in the magnitude of the output voltage.
 
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You can't possibly expect a productive reply based on a post like yours can you?
 
input impedance refers to an impedance value designed or set to result in a desired transfer of voltage or current to one device/circuit from another source.

For instance, in audio circuits 'good' input impedance usually means that as seen from the terminals where another output device is to be hooked up to it, the effective resistance of the input circuit of a device is 100 or more times the internal resistance seen backward at the output terminals of the source device. This ensures that little current flows, but maximum voltage transfer is achieved between the source and input of the next device.

In power circuits, the ideal impedance is based upon maximum power transfer or maximum efficiency of power transfer, *NOT* maximum voltage. Here quality of the signal is not important but direct transfer of energy is the key idea. So here, you might find that the internal impedance of the input circuit is only a bit higher than the output terminal internal resistance.

In RF (radio frequency) circuits again the goal is slightly different. Impedance must be exactly matched between source and sink so that there is no residual reflection or waste of power or loss of signal.

Balance usually refers to equality of power or centralized perceived direction of sound in a stereo or quadraphonic (or 5 way) speaker system. It results from roughly matching the overall power output from each speaker so that a stereo image is maintained and the sound is evenly distributed to the listening area and results in a realistic illusion of the original sound-stage.
 
Last edited:
Averagesupernova said:
You can't possibly expect a productive reply based on a post like yours can you?
You have a point: my response was productive, but will it be understood by someone who can't string a sentence together?
 
Nam_Sapper said:
You have a point: my response was productive, but will it be understood by someone who can't string a sentence together?
Nice writeup Nam. The OP's use of the word "balance" confused me, so I waited to try to reply. I couldn't tell if he meant balanced versus unbalanced transmission lines, or matched impedances or whatever. (I didn't even think of the audio multi-channel balance angle...) Hopefully your answer helps him.
 

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