- Apr 11, 2011
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Hello everyone, this happens to be around my tenth post on the forums and I wanted to give back some basic information to thank you all for the helpful tips and advice I've received while browsing the threads.
The Basics of "Z" (or impedance):
To begin, the "Z" is really just a symbol for what we call impedance. Precisely defined, impedance is the total opposition to an alternating current by an electric circuit, equal to the square root of the sum of the squares of the resistance and reactance of the circuit and usually expressed in ohms. Without getting into the physics and mathematics behind impedance in an electrical circuit, impedance is the collective resistance to an electrical current.
How is impedance measured?:
Impedance is measured in Ohm's (named after Georg Simon Ohm), the basic unit of electrical resistance. Most electrical devices operate on a Low-Z current.
What is considered Low-Z?:
Devices considered as Low-Z typically have an impedance of up to around 600 ohms.
What is considered Hi-Z?:
Devices considered as Hi-Z typically have an impedance of over 600 ohms to thousands and even tens of thousands of ohms.
Why does it matter?:
When recording sound, certain microphones and guitar pickups are considered Hi-Z, which in turn means they have a higher voltage. This will generally mean they have a higher signal and therefore a superior "signal to noise" ratio. This means that when the source impedance is equal or higher than the input impedance, the signal will deteriorate causing a poor frequency response.
Balanced vs. Unbalanced:
A unbalanced cable contains a center conductor and a shield. While the shield is essential to the cable, the audio signal travels on the center conductor. The shield absorbs any electrical interference that may have otherwise reached the center conductor.
A balanced cable contains two impedance balanced conductors guarded by a shield. The shield provides a defense against interference because the audio signal does not travel down the shield.
In conclusion:
It is important to know what equipment of yours is Hi-Z and Lo-Z as well as if your cables are balanced or unbalanced. I had hoped this clarification would show the differences and give you (as the engineer) a look into why things happen the way they do (such as buzzing and humming). Although this may not have explained when to use what, I will hopefully add a Part II that will accurately describe that.
Thanks again to everyone on the forum, I appreciate your ongoing support and love of music.
Cheers.
The Basics of "Z" (or impedance):
To begin, the "Z" is really just a symbol for what we call impedance. Precisely defined, impedance is the total opposition to an alternating current by an electric circuit, equal to the square root of the sum of the squares of the resistance and reactance of the circuit and usually expressed in ohms. Without getting into the physics and mathematics behind impedance in an electrical circuit, impedance is the collective resistance to an electrical current.
How is impedance measured?:
Impedance is measured in Ohm's (named after Georg Simon Ohm), the basic unit of electrical resistance. Most electrical devices operate on a Low-Z current.
What is considered Low-Z?:
Devices considered as Low-Z typically have an impedance of up to around 600 ohms.
What is considered Hi-Z?:
Devices considered as Hi-Z typically have an impedance of over 600 ohms to thousands and even tens of thousands of ohms.
Why does it matter?:
When recording sound, certain microphones and guitar pickups are considered Hi-Z, which in turn means they have a higher voltage. This will generally mean they have a higher signal and therefore a superior "signal to noise" ratio. This means that when the source impedance is equal or higher than the input impedance, the signal will deteriorate causing a poor frequency response.
Balanced vs. Unbalanced:
A unbalanced cable contains a center conductor and a shield. While the shield is essential to the cable, the audio signal travels on the center conductor. The shield absorbs any electrical interference that may have otherwise reached the center conductor.
A balanced cable contains two impedance balanced conductors guarded by a shield. The shield provides a defense against interference because the audio signal does not travel down the shield.
In conclusion:
It is important to know what equipment of yours is Hi-Z and Lo-Z as well as if your cables are balanced or unbalanced. I had hoped this clarification would show the differences and give you (as the engineer) a look into why things happen the way they do (such as buzzing and humming). Although this may not have explained when to use what, I will hopefully add a Part II that will accurately describe that.
Thanks again to everyone on the forum, I appreciate your ongoing support and love of music.
Cheers.
