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EAC changes the EQ [moderation: only via pre-/de-emphasis], EAC alters sound
TheFodge
post Oct 28 2005, 04:05
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I'm no expert, but I have concluded that EAC in some instances alters the original CD sound when it converts to a wav file. I'm no expert so I can't fully explain why, but I have ears and am sure this is happening. I noticed this when ripping Santana's Beyond Appearances. EAC transforms it by greatly exagerating the high end --- this is very real!!!!!! I have experimented with this CD and noticed that when iTunes converted this CD to a wav file it was much more accurate sounding as compared to the original CD (believe me I am no fan of iTunes which is why I use LAME). So I compared the two different wave forms using a wave editor (e.g. Nero Wave Editor or Cool Edit Pro) and what I found was that the iTunes wav file displayed more narrowly than the EAC wav file. I know EAC is supposed to be an exact copy blah blah blah but can someone explain what's going on here. It may only be an issue with the songs on this album (a sampling of other CDs yielded what appeared to be identical wav forms from EAC and iTunes) but the songs on this Santana album create noticably different wav forms and it has me wondering if this differential exists elsewhere. Anyone?

I HAVE RESOLUTION TO THIS PROBLEM!!....HERE IT IS.
Thanks to all those that posted. This problem only relates to older CD's which were recorded using a now obsolete method called pre-emphasis. If the "Pre-emphasis" column in EAC says YES when you have a CD inserted, then this situation exists. (I didn't even know that the "Pre-Emphasis" column existed in EAC as it was hidden on the far right and I had to shorten the title column in order to see it). I now know to check this column.

If a CD has pre-emphasis, I simply will use iTunes to convert it to a wav and then convert that wav with LAME. EAC was not performing the de-emphasis needed to bring the equalization back to normal but iTunes makes this adjustment.

Thanks again for everyone's help. I once again feel comfortable using the EAC/LAME as my ripper of choice.

This post has been edited by TheFodge: Oct 29 2005, 00:10
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Tahnru
post Oct 28 2005, 04:09
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Ouch.

If you would please, would you go into EAC's settings and check to see if it is set up to normalize the audio files as it rips them? Also, you might consider using Accuraterip in conjunction with EAC to give a high degree of confidence that the tracks you have ripped are perfect / flawed.

http://www.accuraterip.com
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TheFodge
post Oct 28 2005, 04:28
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QUOTE (Tahnru @ Oct 27 2005, 11:09 PM)
Ouch.

If you would please, would you go into EAC's settings and check to see if it is set up to normalize the audio files as it rips them? Also, you might consider using Accuraterip in conjunction with EAC to give a high degree of confidence that the tracks you have ripped are perfect / flawed.

http://www.accuraterip.com
*


I do not have Normalize checked as an EAC option nor is it checked in iTunes. I should have mentioned that in the original post.

This post has been edited by TheFodge: Oct 28 2005, 04:41
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boojum
post Oct 28 2005, 04:54
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You might ant to submit samples and proof. "Sounds better" just does not work on this board and will get you heaps of scorn. cool.gif


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Societal Eclipse
post Oct 28 2005, 06:15
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Screenshots?


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TheFodge
post Oct 28 2005, 12:45
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QUOTE (boojum @ Oct 27 2005, 11:54 PM)
You might ant to submit samples and proof.  "Sounds better" just does not work on this board and will get you heaps of scorn.    cool.gif
*


I understand what your saying but this is not a subtle difference in sound and besides as I said I can see the difference in the wave forms. I will try to submit some screenshots later when I get more time.
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ShowsOn
post Oct 28 2005, 13:00
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Is it possible that you are listening to CDs using an analog connection for playback, and then once they are ripped you are listening to the WAV files directly as digital.


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Cyaneyes
post Oct 28 2005, 15:06
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QUOTE (TheFodge @ Oct 27 2005, 11:05 PM)
greatly exagerating the high end ---  this is very real!!!!!! 


QUOTE (TheFodge @ Oct 27 2005, 11:05 PM)
It may only be an issue with the songs on this album (a sampling of other CDs yielded what appeared to be identical wav forms from EAC and iTunes) but the songs on this Santana album create noticably different wav forms and it has me wondering if this differential exists elsewhere.  Anyone?
*


When you open EAC with the Santana CD inserted, what does the Pre-Emphasis column say?
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TheFodge
post Oct 28 2005, 15:49
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QUOTE (ShowsOn @ Oct 28 2005, 08:00 AM)
Is it possible that you are listening to CDs using an analog connection for playback, and then once they are ripped you are listening to the WAV files directly as digital.
*


The way I first noticed this was because my LAME encoded mp3 sounded like it had way too much high end. So I conducted a direct comparison between the LAME mp3 and the CD, both played through a very good analog system. Upon further investigation, I concluded that it was not the LAME encoder that caused the drastic difference in the sound. Instead, I noticed the differences in the wav files when ripping with EAC and iTunes. When I rip the iTunes wav file using LAME and play it through my analog system, it sounds identical to the CD played through that same system.

Again, once I noticed this difference I compared other CDs wav files as ripped by these two programs and they looked identical. So I am still baffled by the clear difference noticed in this one CD and wonder if it is somehow impacting other CDs in a less noticable fashion.
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Cyaneyes
post Oct 28 2005, 16:04
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I'm almost certain the issue is pre-emphasis. I see the album was originally released in 1985. Is your CD an original? Many early CDs were pressed with pre-emphasis.

The question is whether the pre-emphasis tag should be there or not. If pre-emphasis is supposed to be "yes", then the treble-boost is the intended and "correct" sound. iTunes and probably most other hardware these days might not detect it, as it's an antiquated feature of the redbook specification.

However, it's also possible the pre-emphasis flag is not supposed to be there.
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Axon
post Oct 28 2005, 16:11
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If preemphasis is there, shouldn't it be attenuating the high and and boosting the bass? So it almost sounds like iTunes and your CD player are doing the right thing, and EAC isn't.
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Cyaneyes
post Oct 28 2005, 16:18
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QUOTE (Axon @ Oct 28 2005, 11:11 AM)
If preemphasis is there, shouldn't it be attenuating the high and and boosting the bass? So it almost sounds like iTunes and your CD player are doing the right thing, and EAC isn't.
*


I was afraid I had that backwards tongue.gif

Axon's right. I was thinking of the boost on the recording side. Either way, I still think it's the issue.
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TheFodge
post Oct 28 2005, 17:00
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QUOTE (Cyaneyes @ Oct 28 2005, 11:04 AM)
I'm almost certain the issue is pre-emphasis. I see the album was originally released in 1985. Is your CD an original? Many early CDs were pressed with pre-emphasis.

The question is whether the pre-emphasis tag should be there or not. If pre-emphasis is supposed to be "yes", then the treble-boost is the intended and "correct" sound. iTunes and probably most other hardware these days might not detect it, as it's an antiquated feature of the redbook specification.

However, it's also possible the pre-emphasis flag is not supposed to be there.
*


Thanks Cyaneyes. Yes this CD is an old one.
I had never heard of pre-emphasis till your post. I am not home right now, so I can't check the CD yet, but I just did a little research on that topic and agree that my problem appears to involve pre-emphasis. As you highlighted from my original post, it has two of the symptoms: 1)only noticed on this CD and, 2) greatly exagerates the high end.

I still am a newbie with this topic so I don't fully understand your present reply. All I know is that EAC and iTunes are presently ripping this CD differently. So, I'm assuming that one of these programs is not properly adjusting the wav file for this pre-emphasis setting. I am still unsure which program is handling it correctly. It is possible that the manufacturer intended that the CD be very heavy on the high end in which case EAC is converting it correctly and my CD player is not recognizing the flag and playing it without the high-end emphasis. On the other hand, the iTunes may be handling it correctly and my CD player is properly recognizing the flag. I don't know enough yet to be sure which it is. (Off hand my guess is that iTunes is handling it correctly because the EAC rip just sounds way to high...but this is a personal preference judgement).

My present crude understanding of this topic leads me to believe that iTunes is properly carrying out the deemphasis process when converting to a wav file. This deemphasis process is taking the place of what would be performed by the CD player when playing a CD with the flag. Any thoughts
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JeanLuc
post Oct 28 2005, 17:58
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QUOTE (TheFodge @ Oct 28 2005, 03:05 AM)
I'm no expert, but I have concluded that EAC in some instances alters the original CD sound when it converts to a wav file ...  I noticed this when ripping Santana's Beyond Appearances.  EAC transforms it by greatly exagerating the high end ---  this is very real!!!!!!
*


If I were you, I'd get myself some flame-resistant clothing ... laugh.gif

If EAC performs an error-free rip of an audio CD (that isn't HDCD-coded although EAC keeps the HDCD info - but software players don't get along with it), the resulting wav file will be 1:1 with the original track on CD.

Pre-emphasis could be the reason (especially if it happens only on one CD) but I always thought that EAC would carry out de-emphasis properly ...

This post has been edited by JeanLuc: Oct 28 2005, 18:00


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Drenholm
post Oct 28 2005, 18:18
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Screenshots and short samples of the different extractions would be useful for the purpose of investigating your claims.
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KikeG
post Oct 28 2005, 18:44
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I wouldn't be so sure about EAC (and most rippers) carrying out deemphasis.

Edit: deemphasis at the digital domain is a lossy process, in the sense that some of the low-level signal of the pre-emphasized ripped signal will be lost in the process of deemphasicing. Not that anything audible will be lost, if done properly. It could be lossless only in case of the deemphasicing process resulting in a final 24-bit deemphasized rip that kept all of the original 16-bit data.

This post has been edited by KikeG: Oct 28 2005, 19:42
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TheFodge
post Oct 28 2005, 19:20
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QUOTE (JeanLuc @ Oct 28 2005, 06:58 PM)
If I were you, I'd get myself some flame-resistant clothing ... laugh.gif

If EAC performs an error-free rip of an audio CD (that isn't HDCD-coded although EAC keeps the HDCD info - but software players don't get along with it), the resulting wav file will be 1:1 with the original track on CD.

Pre-emphasis could be the reason (especially if it happens only on one CD) but I always thought that EAC would carry out de-emphasis properly ...
*


Here's my latest research on this topic.
EAC may indeed be performing an error-free rip, but apparently in the case of these rare CDs manufactured with pre-emphasis, the resulting wave files contain the pre-emphasized wave forms along with a flag which is supposed to inform decoders that deemphasis is needed during playback. But, because this emphasis/de-emphasis process is obsolete, most decoders don't apply de-emphasis. Therefore, listening to the file without deemphasis will not be a true reproduction of the intended sound (which is why it is very heavy on the high end). So, it seems the best way to rip these CDs is to apply the deemphasis in the ripping process in order to ensure that the playback signal is returned to a linear (non-emphasized) frequency response.

So, it seems that iTunes is taking care of the de-emphasis process in the ripping to a wave file. I have not heard whether or not there is an EAC option which can also perform this function.

Go ahead and flame me just because EAC may technically be generating a perfect rip. The fact of the matter is that EAC gave me a file that sounded like crap. Thanks to everyone in these forums that help resolve problems like this because learning and having good music is what it's all about!
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Cyaneyes
post Oct 29 2005, 03:38
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Wow.. very interesting to me that iTunes would know to apply the deemphasis curve and EAC wouldn't. I can't find any option in EAC relating to preemphasis other than the column displaying the yes or no flag. I just wish I had a disc with it so I could test myself.

Did a little googling and found a post on another forum by our esteemed Pio2001 that includes a very helpful link. http://club.cdfreaks.com/showpost.php?p=400909&postcount=23

If you have access to a good parametric EQ, you could try applying the deemphasis manually yourself.

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Pio2001
post Oct 29 2005, 23:26
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I had completely forgotten that I posted this !

Anyway, the best way to copy such a CD is to use EAC's wave files, and set the emphasis flag to "yes" on the copy. This way, the copy will be faithful to the original.

I checked four programs
EAC ( http://www.exactaudiocopy.de ) and Feurio ( http://www.feurio.de ) allow to set the emphasis flag to "yes" on a copy.
Nero and Plextools Pro don't.
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TheFodge
post Oct 30 2005, 02:10
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QUOTE (Pio2001 @ Oct 29 2005, 06:26 PM)
I had completely forgotten that I posted this !

Anyway, the best way to copy such a CD is to use EAC's wave files, and set the emphasis flag to "yes" on the copy. This way, the copy will be faithful to the original.

I checked four programs
EAC ( http://www.exactaudiocopy.de ) and Feurio ( http://www.feurio.de ) allow to set the emphasis flag to "yes" on a copy.
Nero and Plextools Pro don't.
*


I don't think you understand what was going on here. I should have made it clearer in my updates/replies that my Santana CD was flagged as having pre-emphasis. Also, I conclude that EAC will make a copy that is faithful to the original (without me changing any settings because EAC did recognize the flag and I believe would carry that forward to a copy).

Again, the Santane CD had already had the Pre-emphasis flag set as "yes." As such, my CD has wav files that are "Boosted" and need to be de-emphasised for playback. I believe that EAC copy the wave files with the boost and will carry that pre-emphasis flag over to a copied CD. And even though this flag was only used on CDs manufactured a long time ago, it seems that most CD players will recognize the flag and perform a de-emphasis of the EQ on playback.
My problem related to the conversion of such a wav to an mp3. Even though the wav and mp3 may still carry the flag, most decoders won't recognize it and thus the playback is not de-emphasized, therefore it's high end is exagerated. For example, I think that computer programs such as win-amp will not recognize the flag, even on a wav file, and therefore if you play any pre-emphasized files on your computer it will exagerate the high end. Similarly, I came to notice this problem on my iPod.

To get around this playback problem when ripping these now rare CDs, it seems the best solution is to use software to convert the file to one that is no longer pre-emphasised. I have found that iTunes will do this.

So in response to your suggestion, EAC appears to properly recognize the pre-empasis flag, and will properly carry it forward to a copied CD. There is no need to change it unless the original CD was not correctly flagged...which is probably an even more rare case. I came across another post that described how to change an incorrect flag with EAC by adding "FLAGS PRE" to the cue sheet. See:

http://www.stevehoffman.tv/forums/archive/...-10981-p-3.html
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dreamliner77
post Oct 30 2005, 02:21
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IIRC, the fhg encoder allows for encoding of files with pre-emphasis. I would image that this would "de-emphasize" the mp3 files.


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TheFodge
post Oct 30 2005, 03:15
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QUOTE (Cyaneyes @ Oct 28 2005, 10:38 PM)
Wow.. very interesting to me that iTunes would know to apply the deemphasis curve and EAC wouldn't. I can't find any option in EAC relating to preemphasis other than the column displaying the yes or no flag. I just wish I had a disc with it so I could test myself.

Did a little googling and found a post on another forum by our esteemed Pio2001 that includes a very helpful link. http://club.cdfreaks.com/showpost.php?p=400909&postcount=23

If you have access to a good parametric EQ, you could try applying the deemphasis manually yourself.


*


Hey Cyaneyes, thanks again for your help. It goes without saying that you were right that my Santana Beyond Appearances CD had the Pre-emphasis flag. Your graph clearly shows that if de-emphasis is not applied, the high frequencies would be heavily exaggerated.

I have since found another of my old CDs, Pink Floyd The Wall, to contain pre-emphasis. I have a newer remastered copy of the same album that does not have pre-emphasis. So, I made a comparison of 3 wav files: one from the old CD ripped with EAC, one from the old CD de-emphasized by a rip with iTunes, and one from the newer CD. I looked at the waveform and spectral views and found the old one ripped with EAC was clearly heavier on the high end while the other two were virtually identical. This is conclusive proof that iTunes is applying de-emphasis in the rip process thus reshaping the wav file to the form in which it was intended for playback.
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rutra80
post Oct 30 2005, 05:01
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Now it would be nice to have a free tool that can properly apply de-emphasis on WAVs securely ripped by EAC.
BTW, I noticed that LAME has -e switch (marked as obsolete) which only flags MP3 as pre-emphasised (it doesn't apply de-emphasis to WAV - expects decoder to do the job). More details in the docs.

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Donunus
post Oct 30 2005, 09:25
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What version of EAC are you using? Wonder if this issue is fixed with the latest version of EAC
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TheFodge
post Oct 30 2005, 14:17
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QUOTE (Donunus @ Oct 30 2005, 04:25 AM)
What version of EAC are you using? Wonder if this issue is fixed with the latest version of EAC
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I have been using V0.95 beta 2 from June 1, 2005. I just downloaded V0.95 beta 3 dated 8/26/05 and do not see any new extraction feature that would perform the de-emphasis.
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