LKL & LKS Tape Numbers
Mono vs. Stereo.
At Contemporary, each master tape, once assembled, was assigned a tape number. For an LP, that means two tapes: one per side.
Mono full-track tapes for 12-inch LPs were assigned LKL 12-xx numbers (xx is the variable).
Stereo two-track tapes were assigned LKS xx numbers.
LK = Lester Koenig.
The latter L in LKL = LP (long play). Which explains why 45rpm 7-inch singles don’t have it (LK 45-xx) while 10-inch LPs, all of them mono, DO have it (LKL xx numbers, with no 12).
The S in LKS = Stereo.
These numbers are easy to find, printed on every center label and stamped/etched in all metalwork prior to October 1984. Here it is in practice, on mono and stereo copies of The Arrival of Victor Feldman:
Tape numbers for the two sides of an LP were assigned together, and were thus always consecutive (eg. Arrival of Victor Feldman’s stereo tape numbers are LKS 103 and LKS 104). This meant assignments were doled out in even pairs (2 for a single LP or 4 for a double LP), so every side 1 received an odd number and every side 2 received an even.
The mono and stereo numbering were entirely separate sequences. A title’s mono tape numbers were always much higher than the stereo, because stereo recording (1956) and stereo tape assembly (1957) didn’t arrive until mono tapes had ascended to the high double digits. The two sides of My Fair Lady were the first stereo assemblies, LKS 1 and LKS 2. Its mono tapes are LKL 12-93 and LKL 12-94.
Contemporary stopped recording to mono tape in 1958 or 1959 (thereafter using stereo masters to cut mono LPs, examined on the next page, the 50-50 line). After this point, mono and stereo numbers were both assigned to the same single pair of stereo master tapes. In this period (1959 to 1966), mono and stereo tape numbers advanced in tandem, as an equal amount of mono and stereo numbers were handed out (changes in that balance did happen, though, resulting from belated stereo assemblies and outliers like mono-only compilation title M3584).
The final known mono tape numbers belong to M3616 Here and Now (1966). Those two sides are LKL 12-409 and LKL 12-410, with matching stereo numbers well behind at LKS 273 and LKS 274.
From then on, only stereo tape numbers were doled out.
Fast forward to 1983 and the final title released under Koenig ownership: S14010 Peter Erskine. Its tape numbers are LKS 375 and LKS 376.
So, 17 years of stereo-only production allowed stereo tape numbers to catch up considerably against mono… but they never made up the lead mono had gained back in 1955 and 1956.
Looking at this — the full Contemporary Records discography — you can see the stereo tape numbers making their best effort to catch mono. Another two years and they would have made it.
You can also see the direct relationship between catalog number and master tape number, which is not surprising. But let’s look at the ruptures in that pattern.
The mono sequence reveals oddities in the late 3500s and early 3600s with oddly low LKL 12-xx numbers. This seems like old vacant tape numbers assigned to new titles. The outliers in the stereo sequence are the more interesting story to dig into.
Stereo Outliers and the Chronology of Intent
‘The Belated Twelve’
Looking at the graph above: the blue trendline closely traces the separation between Stereo Records (1958-1959) and Contemporary stereo (1959+). Every title south of the line (up to 3560) was released on Stereo Records, and everything north of the line was recorded before or during the Stereo Records era but was not released on the sublabel. The titles inside the red ellipse are the second category, and are a familiar set:
3526 | The Curtis Counce Group
3536 | Concerto for Clarinet and Combo
3538 | Presenting Red Mitchell
3539 | You Get More Bounce With Curtis Counce!
3545 | All Night Session! Vol. 1
3546 | All Night Session! Vol. 2
3547 | All Night Session! Vol. 3
3549 | The Arrival of Victor Feldman
3550 | Harold in the Land of Jazz
3551 | Something Else!!!!
We can talk about these ten titles as a unit. (yes, the header said Twelve… we’ll add two more to this in a bit.)
Each title in this dectet breaks from the release pattern of their recording era. Their stereo LP debuts were all delayed several years, sometimes more than a decade. (See Mono & Stereo and Label Color & Design to dissect the indicators for that release dating.)
Meanwhile, their LKS tape numbers give us totally new insight into the chronology of intent. The stereo tape reels for these titles were edited and assembled long after the mono versions. However, the delays between mono and stereo assemblies are not constant between these titles, and the timings of tape assembly don’t line up consistently against the eventual stereo LP releases. These gaps are fascinating! They offer tiny rare glimpses into — perhaps — the market variables that fed decision-making for these stereo LPs.
You may have no idea I’m talking about. Let’s try to get more specific.
First, let’s visually divide this belated TEN (not yet twelve) into two families:
Stay with me. Keeping intact the families above, let’s stretch our view and chart titles up to 3616 (the last mono title).
Removing the trendline, we now expand the PURPLE group to include two more titles: 3558 Andre Previn Plays Vernon Duke and 3560 Swingin’ the 20s. This is how we get to the Belated Twelve:
Okay, let’s see if we can estimate when green and purple groups of tapes were assembled.
Helpful to us will be the 50-50 line: by Spring 1959, Contemporary was recording to stereo only, then using those two-track stereo masters to cut both stereo and mono LPs. Several mastering engineers have touched on this, including Bernie Grundman while holding the tape box for Art Pepper + Eleven (recorded Mar-May 1959) in front of the camera in 2022.
As stated earlier: after Contemporary switched to unified master tapes, each tape would be assigned a stereo LKS number (A side of Art Pepper + Eleven was given LKS 89) and a mono LKL number (the exact same tape is also LKL 12-259). We can see this illustrated with the 1961 tapes for 5006 Sounds Unheard Of:
So we have a ballpark estimate for the 50-50 line sometime before or around Spring 1959. How does this help us?
Well, with tapes being assigned stereo and mono numbers at the same time, the sequence of new tape numbers (after this 50-50 line) should advance in tandem.
With one tape assembly per side, we can then pinpoint that moment of assembly sometime between recording and release. So, recording < assembly < release. Using releases definitely recorded after the 50-50 line, we can use their tape numbers to point to general windows of time when specific assembly occurred.
Now, in our LKS tape numbers graph, remember that the Y axis = tape number, and we know tape numbers were assigned sequentially, so we can assume a direct correlation between tape number and when a tape was assembled.
So to figure out when the Belated Twelve stereo tapes were assembled, we have to look at later recordings with adjacent tape numbers to the belated twelve and derive from their windows of time the same windows for the Belated.
As below:
So, the stereo tapes for the PURPLE group were assembled and cataloged in sequence in 1959. Three of these titles would be released in stereo in the next few years: S7551, S7558, and S7560. The other half wouldn’t be pressed in stereo until the mid-late 1960s (S7549, S7550) or early 1970s (S7539).
The GREEN group of six titles sees their stereo tapes assembled much later, in 1961 or 1962 — and their stereo fates were even worse than those of the purple group. None of the green titles received stereo release until the mid-late 1960s (S7526, S7545/6/7) or early 1970s (S7536, S7538).
Still with me? Great. So we’ve talked about the 50-50 line being somewhere before Spring 1959. Can we be more specific?
Yes, maybe, but let’s take a page break. Next up: The 50/50 Line and the End of Mono Recording