Well, I went & dug out some of my old vinyl from that period. Burgers is a gatefold, with pics. The only bass shown is the last Starfire.
I have a couple of Casady articles by Dan Schwartz saved on my computer; the relevant passages are: ...Burgers, recorded in late ?71/ early ?72... and For an instrument that had so much energy, time and money invested in it, Jack's Alembic doesn't make too significant a mark in his recorded catalogue, appearing on one Hot Tuna album, the final Airplane album, and some Kantner-Slick collaborations.
Jack , according to Dan, got the bass in early 72 and used it for about 3 years until it dropped on pavement. So, my revised assessment is that it's on Phosphorescent Rat, not Burgers.
It is pictured on the back of 30 Seconds Over Winterland - whether he used it on the last studio album, Long John Silver, copyright 1972, is doubtful, I think. Sunfighter is 71, so it's not on that, leaving Baron von Tollbooth and probably Manhole as the the other 2 albums that he would have used it on.
So listen to 30 Seconds, Baron von Tollbooth & Phos Rat - you'll have a range of approaches done on Alembic #1.
I stand to be corrected.
Frank