[Ham Sandwich]

The Ham Sandwich guide to pre-emphasis

I had to learn about ripping CDs that have pre-emphasis a few months ago when I bought an original issue C2K version of "The Wall". I ripped it and played it and it didn’t sound right. Played it on a home stereo system and it was good. Played it on the computer from the DVD drive and it sounded wrong. Played the rip and it sounded wrong. What was going on? So began my journey.

CD emphasis was implemented in order to get better linearity in the high-frequency range given the capabilities of old school A/D and D/A converters. The CD gets mastered with pre-emphasis and a flag indicating pre-emphasis is present. At playback the DAC applies de-emphasis. Pre-emphasis adds a high-frequency boost. De-emphasis applies a complimentary high-frequency cut to get the signal back to flat.

There is a good explanation of CD emphasis in an article at audioXpress OnLine. The article is in their PDF archive. Direct linking to the PDF file doesn't work so go to the PDF archive and search for "A De-Emphasis Test CD" by Gary Galo.

Ripping a CD bypasses the DAC in the CDR drive and since it is the DAC that is responsible for applying de-emphasis, the de-emphasis doesn't get applied unless the ripper software does it.

A few older rock CDs from the 80s have pre-emphasis. A larger number of classical music CDs from the 80s have pre-emphasis and some classical releases today continue to have pre-emphasis. If you have a collection that includes classical music you likely have a few CDs with pre-emphasis. In my collection of classical music I found that most of the BIS recordings had pre-emphasis, a few of the Delos recordings had pre-emphasis, a Deutsche Grammophon and a Telarc had pre-emphasis.

How to rip a pre-emphasis CD the easy way

iTunes does the right thing and automagically applies de-emphasis if it detects that you are ripping a CD that has the pre-emphasis flag. It is the only ripper that I know of that does that automatically for you.

But there is a downside to that easy way. Apple's de-emphasis process causes a loss of soundstage or stereo separation. I compared a rip of Pink Floyd's "The Wall" done with iTunes (version 8 for Windows) and a rip processed manually using SoX to do de-emphasis, and the version done by SoX sounds better. So the easy way isn't going to do for those who want the best possible sound quality.

How to rip a pre-emphasis CD the hard way

Both EAC and dBpoweramp can tell you if a CD has pre-emphasis. EAC has a column on the far right hand side in the UI. You'll likely have to scroll over to see that column unless you have a large monitor and the EAC window is expanded. Unfortunately that column is hidden for most people and easy to miss.

dBpoweramp also has a column that tells you if a CD has pre-emphasis. Unfortunately that column is not displayed by default. You have to manually add that column to the UI. Right-click on the column display and select the "Track Technical" field. That will add the column that will tell you if a CD has pre-emphasis.

Unfortunately both EAC and dBpoweramp may tell you that there is pre-emphasis, but they don't make that information obvious or alert you that you are about to make a rip that won't sound correct. I saw a forum post by the developer of dBpoweramp that the next version may include a process for de-emphasis. We can hope.

The easiest workflow I came up with is to use EAC to create a CUE file
1) Rip the CD using EAC to a single WAV and CUE file
2) Process the WAV file with SoX to apply de-emphasis
Use the command: sox "foo.wav" "foo_deemph.wav" deemph
3) Edit the CUE file in a text editor to point to the foo_deemph.wav file
4) Load the CUE file in Foobar2000
5) Select the tracks from the CD, right-click, and select Convert. Convert to FLAC or your favorite format.

SoX is a command line program. It is available on SourceForge: SoX - Sound eXchange

To run SoX you will have to know the basics of how to change directories and run programs in a command prompt window. If you are a command line geek you can add the SoX files to your path. If you don't know what a path is you can copy the sox.exe and cygwin1.dll files to the directory where the WAV file is.

The EAC Ripping Guide has a page on pre-emphasis. The guide also uses SoX. But the process described can be simplified. The current version of SoX for Windows no longer has problems with file names that have spaces. So the section in the guide about renaming the files to remove spaces can be avoided.

Ripping to a single WAV and a CUE file also simplifies things. The single WAV file means there is only one WAV file that needs to be processed with SoX. The CUE sheet contains the basic tagging information like album and tracks so when you load the CUE file in Foobar2000 you'll get basic tagging info done when you convert the tracks to FLAC. Only one file to process and automatic tagging of the converted files.

The EAC Ripping Guide links to a command line tutorial to help those who are not familiar with running commands from a command prompt.

And a little something so forum searches can find this thread
pre-emphasis de-emphasis preemphasis deemphasis preemph deemph

 

[Orcin]

Great post! Very interesting... I did not know about this. I need to check my version of The Wall and some of my other CD's.

If dBpoweramp automates this workaround process in a future release, that will be a good reason for me to switch from EAC.

 

[fishpatrol]

Is there a database that lists releases that use pre-emphasis? Do I need to put every disc in the drive to find out?

 

[Ham Sandwich]

Quote:

Originally Posted by fishpatrol /img/forum/go_quote.gif Is there a database that lists releases that use pre-emphasis? Do I need to put every disc in the drive to find out?

I'm not aware of a database of CDs that have pre-emphasis. I did do a rough search in the hopes of finding one online. I ended up having to rescan all of my classical CDs to check for pre-emphasis. I took a best guess for my rock CDs and only checked a few there were from the early 80s. Didn't find any other than "The Wall".

The rock CDs should be fairly obvious if the have pre-emphasis that hasn't been removed. They will sound very bright, especially in the cymbals.

Classical music is a little more difficult to pick out. Classical music doesn't have a lot of cymbals and other high frequency energy where the effects of pre-emphasis are most noticeable. What you have to listen for in classical music are things like violins that are more edgy than they should. If you're listening to a classical piece for 10 minutes and you get the feeling that it is too bright or edgy, it might have pre-emphasis.

I have two 30 second clips from "The Wall". One with pre-emphasis and one that has been processed with de-emphasis. The differences are obvious.
pre-emphasis and de-emphasis clips

 

[fishpatrol]

Wow, the difference between the two is a little frightening. Crap, another thing to hunt down.

 

[synfreak]

Hi!

This, and the HDCD decoding probs, are the most bothering things you might come across when you start to archieve/rip a big CD collection ...

I really hope that spoon is implementing a good de-emphasis plugin into dbpoweramp soon (as he did with the HDCD decoder). That would help to save some time and a pig pile of hassle for the future.

There is an other proggy out there from a german fellow (Lautsprecher Homepage von Thomas Ahlersmeyer) that does also a good job.
If you want to try it, go directly to the download here:
HAUPT

Cheers
Harald

 

[MadMan007]

I both thank and curse you for making this thread. Thanks because I wasn't even aware of this even though I went over directions for EAC closely I missed this and I never open the window wide enough heh, and curse you because now I'm going to have to go check my CD rips...I've got over 700 but I'm still not done.

btw does this depend upon the pressing? I mean, might a new pressing of The Wall not have this issue? I'm wondeirng when this is added in the recording and production process.

 

[Ham Sandwich]

It depends on the mastering since pre-emphasis is applied during the mastering. Any pressing made from that master will have pre-emphasis.

Budget classical CDs would be some to look at. Budget classical CDs typically don't remaster and just use the old masters. If those old masters were made back in the days when pre-emphasis was more common you'll be more likely to have a "new" CD that has pre-emphasis. So check any budget classical CDs, and check anything by the label BIS.

And yeah, I had to go through all of my ripped CDs and check for pre-emphasis too.

I keep an archive of CUE files of my pre-emphasis CDs. The CUE files are made with EAC so they include the PRE flag which indicates the track has pre-empasis. The archived files are unprocessed (no de-emphasis has been done). This is so that if SoX comes out with a better algorithm I can re-do the de-emphasis. Doing the de-emphasis digitally at 16-bits also means there is the possibility of clipping. SoX will warn you if there is clipping. You may want to have SoX convert the files to 24-bit during the de-emphasis processing to avoid the possible clipping. For now I've kept everything at 16-bits.

 

[Cla55clown]

I know this is an old thread, but thought I would revisit it anyway. Is this still the easiest way to de-emphasize albums that have pre-e? I came across an album that has this (as told to me by EAC) and was looking for an easy, up-to-date solution. I'm using the latest version of EAC (v1.0b3) and JRMC17. 

 

[Ham Sandwich]

I still find the above method with SoX to be the easiest way to handle de-emphasis.  I haven't done a listening test since I wrote the guide to test if iTunes is now doing a better job than it was.  If iTunes has improved then iTunes may be a good option for some people.