What, Exactly IS hiss?

[Doctor Varney]

I realise this sounds like a bit of a dumb question. Why, it's that "Ssssss" noise on your audio of course!
But what is the cause? Hum, in my case, is usually caused by some equipment which is causing vibration, I suppose. So what is hiss?

Edit:
Seems obvious for me to assume, it may come from using mediocre equipment in many cases - but what exactly would you say is the main factor(s) in such equipment that might be generating this sort of noise?

Thanks in advance

Dr. V

[ashcat_lt]

A lot of the "hiss" we hear nowadays is sidebands and harmonics of EM signals flying through the air. Any one of these signals might come up as a whine or buzz, but when combined with all the other signals randomly bombarding a circuit any any given time it sounds like broadband noise.

Much of it is also "thermal noise" - literally the sound of the atoms in the conductor bouncing or vibrating around and taking their swirling field of electrons with them. It's the sound of brownian motion. Everything has this going on, but large resistors in series with the signal path are usually the worst contributors in audio circuits.

Course then there's "tape hiss" which is the sound of randomly oriented magnetic particles on the tape itself. Those of us who have abandoned that legacy format have said "goodbye and good riddance" to that particular waterfall...

...But in its place we get dither noise, which is (or should be) added to a digital signal any time a change in bit-depth happens. It's usually nowhere near as loud as any of the others, but it gets added at various stages in the process, and can sometimes end up adding up to a noticeable amount.

[Doctor Varney]

Very informative, ashcat_It. Thank you very much.

[CMB Studios]

there's no single Error...

signal path, electricity current, bad wires, bad connectors, bad plugs, under or over powered components.... all can cause unwanted noise and the science behind them are all different

[Doctor Varney]

Thanks, CMB.

So - is there anyone here who can say for definite there's no hiss or extra background noise of any description on their recordings (their quieter recordings).

a) If no, do you use software to remove it? Is noise removal an accepted part of your workflow?

b) If yes, then presumably your environment is good - but what would you say is your optimum combination of mic and pre-amping structure used for recording quieter material?

Since I came straight into home recording, with zero experience of the professional world, I'm trying to get a sense of what can be reasonably expected when setting up your own little studio.

I appreciate if the question sounds a bit like "How long's a piece of string" - but generally speaking - I mean, (vintage tape issues aside) do professional engineers also have to deal with noise - however slight? Or is it more the mark of an amateur?

I also appreciate that you might say a loud distorted guitar wouldn't matter so much - and then loud passages of music can hide any hiss in the quieter tracks. I'm more interested in what sort of acceptable benchmark/ threshold you would have for noise/ hiss, etc... and how you personally deal with it.

Cheers

Dr. V

[grimtraveller]

How long is a piece of string ?

Twice as long as half.

[Doctor Varney]

Twice as long as half.

Cheers! Very handy equation, that. I will have to note it down, for future reference...

[grimtraveller]

Cheers! Very handy equation, that. I will have to note it down, for future reference...

For years, I had to endure a colleague, when he wanted to be awkward and not think through an answer, saying "how long is a piece of string ?". Then years later, I said the same thing to this 11 year old called Ben. It was, to give credit where due, him who said "Twice as long as half". Apart from me, he's the only person I've ever heard actually answer the question and I got it from him. I was so impressed that I used the question and answer in the lyric of a song {"Varuni's bag"}.
I never did get to say it to my former colleague. By the time I heard it from Ben, we'd 'lost' {more appropriately 'never even entertained the falseness of maintaining'} contact.

[Doctor Varney]

Excellent!

[CMB Studios]

professional mixes do not have noise (or at least not audible noise) ... to follow my first comment... find where the noise source comes from and fix it... could be a cable, could be an input... could be dirty power... could be a lot of factors.