CD quality differences

I am in the middle of a DIY speaker project. Which means I have been doing more critical listening lately.

I've noticed on more than one disc that I listen to, there are differences in recording quality from song to song.

These are not "greatest hits" discs. Has anyone else experienced this, or is it just in my head?
Absolutely. Mastering engineers try to iron out some differences from studio sessions and mixing but it is rare that it can all be reconciled to a totally consistent quality level. Live recordings are a little more consistent but rarely of high quality.

Check out Sheffield Labs direct to disc stuff (originals were vinyl but now available in CD) - these are consistent.

Also check out Steve Ferrone Fur Farm More Head (Live) for a terrific recording with great consistency throughout.

It's all in your head!

Just kidding, there are differences. Lots of reasons, here's some.

1. Different recording engineers producing the songs on the same CD. The recording engineer will use his idea of how the song should sound, then his ear to put that sound on the CD. If you've ever played in a band, you know how important finding a good soundman is, his ear can make or break you sometimes. Jonnell Mosser has a CD where one song has a compressed soundstage while the next one opens up and spreads out.

2. The artist wants the songs to sound a certain way, perhaps to add a mood. Some artists might want a particular song to sound like it's from a different era. The Eels make a few songs that sound like they're off of an old scratched record or that they're being played on an old gramaphone.

3. The original songs were recorded at different times and on different machines, then transferred to a machine for CD production. The timing clocks may not match up perfectly, that's why a CD recorded on a home computer might sound better when it's played back on that same computer.

I see that you sold your JM Labs/Focal speakers, what'd you get to replace them?

I've experienced it.

On many albums the different tracks are recorded in many locations across a long time period. During mixing and mastering the engineer will attempt to smooth the differences, but if the original recordings are too different then this will be clearly audible on a decent hifi.

Different tracks may have been recorded on 2" 24 track analog, others on ADAT, and with different mics in different rooms, with more or less competent engineers, monitoring with different speakers.

I've found it very common on a band's first album, because there are often a couple of tracks recorded earlier, perhaps when funds were less scarce, and the remainder recorded when the record deal was landed with a major label. Jamiroquai's first album is one example.
You are not imaging things! There is considerable variability in sound quality across discs. I hear it all the time.

As for different quality within a disc, I've not really experienced this unless an artist adds a very old recording to the mix for prosperity.

HD video is the same with lots of variability. It's just something that comes with these entertaiment products.
Listen to "Sledgehammer" and "Big Time" from Peter Gabriel's "So". There's no doubting these cuts were recorded, mixed, or mastered differently than the other songs.

Different studios, instruments, recording equipment, and musicians are also contributing factors to what you are hearing.
I've noticed this difference most on anthology or greatest hits CDs. The earlier stuff sounding harsh and nasty (probably early solid state recordings) while the more recent stuff starts to sound better. Recently heard this on a Roxy Music CD and a Bruce Springsteen CD. The difference from beginning to end is quite dramatic on both CDs.
Experienced this recently while listening to "East West" by the Paul Butterfield Blues band. "Never Say No" is a markedly superior recording to the other tracks on this generally well-recorded album.
There is a thread on here about better remasters of some Stones CD's.  I think it is the 2002 abkco one.  I am replacing my 1980s Stones CDs with those.

But note that these are all based on alterations in the studio of the sound from the original masters, not on whether the CD spec. is deficient in some way.  There is a lot of smoke and noise from those claiming the latter is not adequate, but no double blind listening tests show higher bit rates, 1-bit etc. etc. sound better.
So true. Disappointing,along with the fact that even the absolute phase was not consistent from song to song (due to processing). It seems many with a great ear for music are so into the music that don't hear,or perhaps listen for, sound quality.