Thanks for your replies everyone. Here's what I've done:
(The exact title I'm referencing here is The Jeff Beck Group, Rough and Ready (quad mix) on SACD, Sony Music # EICP 10005.)
Rough and Ready is one of my old favorites. I was always a big Jeff Beck fan, and this was one of the first (stereo) LPs I bought as a lad. I think it was also the first quad release I ever heard, hanging out at the local stereo shop as a nerdy teen. I could never afford a quad setup back in the day, so I was excited to hear about these old Beck quad albums being reissued on SACD - I even bought an SACD player just to hear them!
Unfortunately, this title has some problems. I'll do a brief description of each, and what I did to correct it here. Then if anyone needs more info on how I arrived at these figures, or more detailed instructions on how to use Audacity to fix things, just holler.
(As mentioned above, the following assumes that you've ripped the SACD to a PCM file format suitable for editing in Audacity.)
1. The first 2 tracks were mastered at the wrong speeds (too fast). Compared to the original stereo release:
Track 1 ("Got The Feeling") needs to be slowed down to -3.336%.
Track 2 ("Situation") needs to be slowed down to -6.586%.
(Be sure to use the Change Speed effect, and not Change Tempo or Change Pitch.)
2. On the first few tracks (but not all), the Left Front channel is delayed from the others by approx. 1 millisecond. This doesn't sound like much, but it's just enough to blur the soundstage. Most noticeable is how it it puts the front "phantom" center channel out of focus; on some tracks it also has the same effect on the front-rear cohesion. To fix this:
On Tracks 1 thru 5 ("Got the Feeling" thru "I've Been Used"), delay every channel except the Left Front by 1 millisecond, or .001 seconds. (I used the "Insert Silence" feature in Audacity to do this.) This will bring the channel timing back into focus, restoring a nice clear phantom front center image in particular. This is important because:
3. In my opinion, the "derived" center channel on this mix was a mistake, and should be deleted. For one thing, it's nothing more than a low-level mono mix of all 4 quad channels! This alone would make it pointless, but there's more: The channel time delay error described above happened at some point upstream from this mono mix, so it has created a comb-filtering effect that can often be heard fairly clearly as a false, hollow tone in the sound. And because it's already "baked into" this mono mix, there's no way to fix it. My solution:
Delete the center channel on all tracks. Just click the Mute button on the center channel. Then when you go to re-export the project, it will show up as only 5 channels instead of the original 6.
For me, the above changes have taken this quad mix from unlistenable to the definitive version of this Jeff Beck classic. I hope others will find this information useful as well.
- Jim