Why does old video so often have hum?

[brassplyer]

The subject line pretty much says it - an example below. The hum is clearly audible in the first few seconds and in quieter moments throughout.


https://www.youtube.com/watch?v=fsDcwQeNznc

[cholla]

My best guess is the "hum" comes from the device used to create the recording.
I know some old tube radios had a hum.

[themaster1]

Ground loop
https://www.youtube.com/watch?v=einxGsiuwso

[Kakujitsu]

Has to do with the audio amplifier in the equipment and the wall outlets used. In the US it's called 60 cycle hum.

[cholla]

While I agree ground loop hum may be the cause that the older videos have this hum.
If the hum is already recorded into the video it will be there no matter what you do.
You might be able to use something like Audacity to filter it out some.

Now if almost any video you play has this hum then ground loop hum is the likely cause.
The using the same outlet may help.
The real solution & cure is to have only one ground for the whole building.
This is easier with a house.
This helps no matter what outlet is used because they only have one ground to go to.

Many times the second ground source is the cable connection for TV & Internet.
The company installs its' own ground rod.
Then the coax adds this ground when a TV and/or a receiver is connected.
This is often missed because this ground is not through an outlet.

If this is the problem you need to ground the cable companies coax to the same ground your electric service is grounded to.

[timtape]

The linked concert appears to have been a pro shoot but remember this is a remote live location recording at a high school...

Yes there's audible hum in one of the tracks but it's much harder to achieve a first class production with no mistakes when recording live in a remote location rather than in a fully equipped pro television studio. Possibly the hum was not noticed due to lack of a dedicated on location soundproofed audio monitoring room. They may have been forced to monitor the audio in a noisy crowd. It's also possible the hum was introduced when the tape was digitized.

Here's a short clip of the YT live audio recording you linked to *before and after* my attempt to reduce the hum with a software audio Dehum tool. Note most of the hum in this live location recording seems to be only in the audience applause track only, not the stage sound track. For best effect listen on a decent stereo speaker setup.

But generally speaking pro video recordings going back well before this 1985 one didnt have audio hum problems.

[hech54]

Go to a Joe Bonamassa concert. He uses nothing but vintage tube amplifiers....humm and buzz for days.

[pandy]

Such imperfections are outcome of lack of proper knowledge, technology limitations and external conditions.
Lack of knowledge is obvious - for example 40 years ago there was no practical knowledge about many important things, nowadays almost everyone is familiar (in some way) with them.
Technological limitations is also quite obvious - 40..50 years ago there was no technology we observe now.
External conditions are still valid for today - sometimes it is difficult to meet all necessary conditions to avoid ground loops or other audio related problems with live events - that's why it is way easier to achieve high quality audio in recording studio.

[timtape]

From about 1950 so called "balanced lines" were used in the pro broadcast and recording studio industry to reduce or eliminate audio noise. Again, the vast majority of pro recordings did not have significant hum. More likely the hum the OP hears is mostly from amateur live recordings.

Here's a rare pro live location recording (1969) of a famous artist which has some 60 Hz hum but only at the end of the song where only the artist is speaking and the hum is audible. It's not really bad. You may only hear it with good speakers or headphones.

https://youtu.be/m5aGUEhtYwo?si=dPRU31Q_2Ve4p6xE

[johnmeyer]

Why does old video so often have to hum?

Because it can no longer remember the words.

My 6-year old granddaughter got a joke book for Christmas yesterday, and that was one of the jokes