This is the next title in my quest to look at all the Sony SACDs sourced from quadraphonic masters. When I was doing the conversion from SACD to PCM to load up in my DAW I had a vague recollection that I'd had issues with the bass on this disc, and sure enough almost 13 years ago (!) I started a thread here about this title called
Jeff Beck - Blow By Blow ...where's the bass?
Reading through the old thread, it plays out almost identically to the thread about the recent Opeth Blu-Ray, which had a couple of out-of-phase channels, both in terms of what I was experiencing (muddy/ill-defined bass guitar, lots of bass drum) and what other people were saying (people with full range speakers claiming it was fine). So the first thing I did once I had the album loaded up was look at phase correlation, and sure enough the front left and front right channels are out of phase with the rear channels (and the LFE track). See here:
You can clearly see the peaks (arrows placed for convenience by yours truly) for the front channels oscillate in the opposite direction as the rear speakers, which is a definitive visual indicator of phase issues. The LFE track (not pictured) oscillates the same way as the rear channels which tells me that it's the front channels that are the problem. Once you invert the phase on the front channels, all 5 channels are in phase and voila, there's the bass I was missing.
It's also worth saying that I think the phase issues were created during export. The LFE, being derived from the 4 main channels, would have been a phase cancelled mess if the original tracks were out of phase but it isn't. What I think happened is somewhere along the line, this mix went through an analog stage and the front left and front right channels were wired out of phase. I also think this went throught an ADAT (PCM stage) which I'll explain after this. It went one of two ways:
original tapes (in phase)
-analog connection, in phase-> DAW (to generate LFE & phantom center)
-digital connection-> ADAT (PCM)
-analog out, front channels wired out of phase-> DSD workstation to generate SACD master
or
original tapes (in phase)
-analog connection, in phase-> ADAT
-digital connection-> DAW (LFE/center generation)
-analog out, fronts wired out of phase-> DSD workstation to generate SACD master
The reason I think there's an ADAT generation in there somewhere is that spectral analysis shows frequency response cuts off abruptly at 22kHz. ADATs were the industry standard from the early 90's to the early 2000's for digital multitrack - they were 8 discrete channels, and first generation models were 16bit/48kHz and later models were 20bit and selectable 44.1/48kHz. I obviously don't have any conclusive proof, but I believe the 22kHz frequency cutoff makes it most likely this is a 20 bit/44.1kHz ADAT transfer - perhaps this was done initially with a view towards being a source for a DTS CD (which are 44.1/20bit) release that never happened. I just can't see them newly digitizing the master tape at 44.1kHz with SACD release in mind. Here's the spectral analysis:
So to sum up:
Front channels out of phase (accounts for my bass issues)
Sourced from a 44.1kHz master (accounts for some complaints about 'average' fidelity)
If you're re-authoring this in PCM with corrected phase, you can delete the center channel as it's just a mono sum of the front left & right channels
13 year old mystery solved. Feeling mildly smug today.
:chill
