Preferences change, and that is part of the subjective part of the auditory system, and that's an added complexity. Tones I thought were
good for bass 20 years ago I hate now!
To match two recordings, even with the same bass over thirty years you would need to:
1. Ensure that loudness is the same to within about 0.5dB.
2. Ensure that the strings are the same. Manufacturers may make the same model of strings now, but they might vary slightly between now and 30 years ago
3. Ensure that the dynamics of the playing are pretty much the same as before (see 1)
4. Ensure that all the elements in the recording are the same (exactly the same equipment all measurable via test equipment to exactly to the same tolerances)
5. Ensure the playing is the same (same notes, etc).
6. Ensure that the 30 year old recording has not degraded in any way. I.e. it would need to have been digitised via very good A/D 30 years ago
If you have good ears (and I have no doubt you do) you are probably more sensitive than most to the issues from 1 to 7. Your good ears are probably a hindrance as you might be picking up on a difference in something in the recording chain that is not the bass. If the old recording has got ever so slightly muffled over the last 30 years you might prefer the new one. If there is a standard set of reference tones on the recording that could be adjusted for. There are so many possible variables in a recording that it would make it hard to pin down what might be causing a preference for one recording over another.
For just the audio side I think you'd need to create a bass playing robot and have it play a selection of old and new basses behind a curtain and do a large listening test of a hundred or so people (enough to have a good chance of statistical significance depending on the other test parameters). Even for new and old recordings of a bass it should be done double blind, ideally.
So you know pretty much all the criteria in your post are met. The tracks in question were immaculately produced by Ken Scott who also engineered or produced David Bowie, Elton John, Supertramp, The Beatles (White), Jeff Beck, Stanley Clarke, Billy Cobham, Mahavishnu Orchestra, Dregs, Missing Persons geeeeeez, the list goes on.
The tracks were recorded at A&M Studios or Chateau Recorders in Hollywood and of course were treated in a first class, state of the art manner all the way.
Ken taught me how to record the PRS, his theory being that you never compress the bass, but only limit the peaks. He was a fanatic when it came to keeping the dynamic range of the instrument intact and NOT squashing it.
He used an LA2A at the time, and I use Summit Audio now. Ken always used EQ on the Rickenbacker, but used none on the PRS. He loved the combination of the nine position "Dial a Brew" (as he called it) rotary switch and Rickenbacker treble pickup.
Stanley Clarke was recording at the same studio and Ken introduced us - Stanley mentioned that I could use any of the basses he left laying around. I grabbed his Jazz Bass one night and Ken wouldn't even let me plug it in! He pointed back to the PRS and smiled.
I suppose it could be an illusion but the bass just seems to sound deeper and woodier somehow to us after 35 years. Not just me.
Thanks for checking it out and for the kind words. There is a ton of songs all over YouTube, many with no accompanying video content that fans have put up. Just go to YouTube and search on "Happy the Man".
PS: There is a Happy the Man thread on TB which has a tiny bit of recent traction:
http://www.talkbass.com/forum/f19/happy-man-165157/
And I just noticed there is a TB thread on Ken Scott here:
http://www.talkbass.com/forum/f30/ken-scott-abbey-road-ziggy-stardust-917749/
BassHappy
www.innertainment.net