What is hiss?

[bhcarpenter]

Out of curiosity, can anyone point me to an explanation of what causes hiss in an audio signal? Like is it RF interference/byproduct of an amplification stage/something else?

Honestly, I’m not really sure what I’m asking. It seems like there are some interesting things to learn though.

 

[Betty Wont]

Cattos and Sneks

 

[bhcarpenter]

Found the culprit.

 

[mybud]

Hiss is related to leakage from a faulty or misbiased (maybe Ge) transistor, a leaky electro cap, what have you. This noise (random electrons) is then amplified as it enters the audio path. Try a noise gate maybe if it’s bothersome. PPCB’s Muffler is a nice choice. Peace to all cats and their families. We have some too

 

[bhcarpenter]

This noise (random electrons) is then amplified as it enters the audio path.

Aha! I think this is the answer I was looking for. Thanks

 

[Chuck D. Bones]

Hiss is white, or broadband noise. It can come from any number of sources including all of the ones listed above. It is also an inherent property of electron flow. Any component that has resistance generates thermal noise. This includes resistors, semiconductors, capacitors, inductors, even wire. Semiconductors have other other noise generation mechanisms that are a consequence of semiconductor physics. Semiconductor manufacturers can tune their processes to minimize, but not eliminate noise. That is why some transistors and opamps are described as "low noise." The pickups and pots in a guitar also make thermal noise.

 

[fig]

I'm not sure, but if one partakes of too much it can result in fits....very....hissy fits....*groan*

 

[BuddytheReow]

Hmm, but how can we keep it to a minimum?

 

[jimilee]

Hiss is white, or broadband noise. It can come from any number of sources including all of the ones listed above. It is also an inherent property of electron flow. Any component that has resistance generates thermal noise. This includes resistors, semiconductors, capacitors, inductors, even wire. Semiconductors have other other noise generation mechanisms that are a consequence of semiconductor physics. Semiconductor manufacturers can tune their processes to minimize, but not eliminate noise. That is why some transistors and opamps are described as "low noise." The pickups and pots in a guitar also make thermal noise.

This. As explained to me by an audio engineer, one source is when the gain, input, is set higher than the volume, or output.

 

[Chuck D. Bones]

Hmm, but how can we keep it to a minimum?

It's a challenge. We use low-noise parts. We chose the impedances carefully. We don't build in any more gain or bandwidth than we need.

 

[bhcarpenter]

Hiss is white, or broadband noise. It can come from any number of sources including all of the ones listed above. It is also an inherent property of electron flow. Any component that has resistance generates thermal noise. This includes resistors, semiconductors, capacitors, inductors, even wire. Semiconductors have other other noise generation mechanisms that are a consequence of semiconductor physics. Semiconductor manufacturers can tune their processes to minimize, but not eliminate noise. That is why some transistors and opamps are described as "low noise." The pickups and pots in a guitar also make thermal noise.

Thanks @Chuck D. Bones! That’s enlightening