Learned something new today and it isn't good.


I have been in this crazy hobby for over five decades and thought I knew most of the basic information regarding audio quality.

That was before this morning.

Today I learned about the practise of applying "pre-emphasis" to CDs that was around during the late '70's and early '80's. Apparently this practise was developed as a way of reducing the signal to noise in digital audio. The problem is this was a two-part process and required the CD player to have a "de-emphasis" capability to allow the disk to play properly. Without the application of de-emphasis, cd's would sound "bright".

My question would be, "Does everyone else know about this?"

If you do, "How do you deal with it?"

I still listen to CDs and this is not something I need in my life.

128x128tony1954

This has nothing to do with noise or noise reduction. Why does that keep getting repeated??

It was a necessary step to deal with the natural operation of early DACs.

One of my colleagues sent this. It is not light reading but the concept seems easy to understand.

https://www.analog.com/en/technical-articles/equalizing-techniques-flatten-dac-frequency-response.html

I read about this years ago and now am using a Audiolab 6000CDT. Before the 6000, I was using an Oppo and never noticed anything saying something was emphasized or deemphasized, so I just ignored that about one in a hundred disks sounded a bit bright.

@erik_squires 

Thanks. Nice to get a response that is based on actual research and facts, as opposed to a lot of guesses and hypothesizing.

Researching information about any topic.

Wasn't that what Google was for, before they tried to take over the world?

 

The other thing that is kind of along these lines was HDCD decoding. I don’t know of any (and I haven’t searched) ripping software which would detect and expand an HDCD Redbook 44.1 / 16 to 44.1/24 so I ended up writing some hack based on old Microsoft C code.

HDCD was also weird in that sometimes the HDCD flag was on, but no HDCD features were actually used.