System upgrade (part 2)

I just watched the whole video and yes, perhaps the HD versions of the recordings have had dither applied to manipulate background noise into being less audible by putting the higher noise floor parts in less sensitive regions of our hearing and the lower noise floor parts in the regions of highest hearing acuity.

The hiss on the old recordings will always be there although it is probably being 'gated' i.e. the level is being automatically reduced in quieter passages. That can create a noise tail where you notice the noise as the note fades. In the manual equivalent You can probably hear places where a noisy track a hissy or humming guitar amp is faded up as that instrument starts to play and then dipped down as the notes finish.

Digital restoration can do wonders with old records as you can fix clicks and sample the noise signature for a modern version of noise gating. The problem with tapes is that the noise floor isn't constant as most tapes have noise reduction that has been encoded on the tape like DBX and Dolby. It would be easy to decode if it were fixed pre-emphasis (i.e. treble boost to be reversed on playback) but it's usually dynamic encoding with compression of signal range onto tape and expansion to reverse this on playback. With Dolby there is a treble emphasis that varies with signal level, really clever for improving signal to noise on that machine but challenging years later. In 'remastering' my old band recordings and demos I found Dolby B and C is really hard to decode now on different equipment. The decay in magnetic signal and physical deterioration of cassette tape doesn't help.

Anyway it's worth remembering that many classic albums were recorded quickly to be issued fast in an era when the 'warts' were lost in the record surface noise and vinyl roar. The remasters we hear now will only be as good as the original tracks, albeit after some digital restoration.

I would have been out but it's still raining here! Please ignore the numbers and enjoy the music as you suggested.

Cheers Jon. The rushed recording suggestion makes sense to me. All the songs I found that are guilty of the loudest hiss seem to be from the 60/early 70s (although many others I have from the same time period are fine). From memory all of my pre-60s music are relatively hiss free too, whether remastered or not. It's a shame that some of the biggest hits of that period could have so easily been mastered better. Shortcuts on the way to making a quick buck I guess.