A list of known ELEX / Hohner / Excelsior K1, K2, K3, K4 serial numbers. These seem to come as 2-part numbers, but it’s not clear what the parts are. Maybe batch and serial?

(For details of the instruments and revisions see here. The rn for revision+number is my addition, not part of the original model numbers.)

No numbers known for a K3 yet. It’s possible that this serial number system was introduced after the K1r1s began production.

So long as we regard the parts as separate (or assume a zero-padded second part), the known numbers seem to be in a continuous sequence across the revisions, and between the K1, K2 and K4, and across all brands. The same system seems to have been used for at least some other ELEX instruments at the time ^[1] but it is not clear whether the other models used the same actual sequence. Unless this point can be clarified (by finding a number collision between models) it will not be possible to use the numbers to estimate production volumes. (The later EK 2 and EK61 had four-digit serial numbers, so are not part of this sequence.)

I’m not sure whether some of the numbers stamped are 1s or 7s, but on balance of probabilities, I’m assuming 1s. Without that assumption the distribution of numbers becomes very unusual. (16 out of 18 numbers below 200 and the remaining 3 over 700.)

Unless otherwise noted, these are all Hohner-branded.

From which, so far, the only available conclusion is that the K4r3 blacktop was probably introduced before the K1 and K2 blacktops.

One possibility which occurred to me some time ago is that the String Orchestra models might have been prototypes used for trade shows when ELEX were looking for distributors. The recent appearance online of the Silvertop String Orchestra K2, paradoxically, makes this seem more likely, because:

1. its pedalboard connector, and probably tuning trimmer, are on the underside, unlike either the (single oscillator?) r1 or r3, and
2. it has a different colour scheme than the other String Orchestras, which would be more likely in a demonstration model

— but also makes it seem less likely because:

1. it comes later in the sequence here than most of the K1r2s, and
2. pictures of its circuitry show 1976-dated chips, which does not match the original release date of 1975 — but these could possibly be replacements;
3. its power rating is 16W, lower than some K2r1s, implying later, more efficient circuitry. (See appendix.)

It might still come earlier than the K2r1s, but this is not yet known. If so, the String Orchestras should probably be renumbered in this revision scheme to r1, with the existing r1s becoming r2, but I’d want to see more evidence first.

(This hypothesis could by disproved by a discovery of String Orchestra marketing materials, or perhaps proved by a mention of one in a 1975 trade show review, if any such records exist anywhere.)

Appendix: Power ratings

The power ratings given on the K1 and K2 models vary for unclear reasons.

K1r2s are either 25W or 16W rated; later revisions (only one example of each) seem to be 10W. This may imply some under-the-cover changes in the r2.

Earlier r2s didn’t give a power rating and I haven’t yet seen labels for r1 or r3, but the 12/1 oscillators change was the r3/r4 step.

K2r1s are either 25W or 16W. At the time of writing I haven’t seen any interior shots; the difference leaves the possibility open that some early ones may have used twelve oscillators (like the K1r1–r3 and at least some K3s) rather than a single oscillator and divider chip like r3. Some r1s clearly have a single external tuning trimmer; but this isn’t visible in photography of others, so I can’t rule it out. However, it seems unlikely that there would have been space for an oscillator bank as well as the ensemble effect boards. (The K3 had the oscillators but not the ensemble effect.) It is also possible that the power difference was due to a change of TOG chips, as some early ones used a higher voltage supply. If either of these turn out to be true it will constitute another revision.

The silvertop K2r2 is rated 16W and has a single oscillator and pitch trimmer (seemingly with external access on the underside rather than the back).

K2r3s may be either 16W or 10W but they all seem to have single external pitch trimmers.

I haven’t seen any K3 plates. All K4s with visible plates are 14W.

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