The other day I stumbled on a revision that Bill made to the Centaur PCB after the changes he mentioned in the Premier Guitar interview. In the interview, the changes he talks about can easily be identified with R1B and R14B on the PCB. But he never addresses R1C, a 100k shunt resistor at the output. I had assumed that he had added R1C in the ’95 revision and he either forgot about it, or didn’t think it was significant enough to warrant mentioning. Going through some gutshots, I noticed that the PCBs immediately after his 95′ changes had vertically oriented output resistors, where most of the later PCBs have them horizontal. This means he made a third revision later on, most likely to add R1C. So we have a 3rd version of the Centaur PCB, with R1B and R14B, but lacking R1C.
Going over known units, we can get a general idea of what serials have what PCB (these serial ranges are not exact):
|Rev1 – ’94||001-300||?|
|Rev2 – adds R1B and R14B||300-800||S001-S200|
|Rev3 – adds R1C||800-3858||S200-S3922|
These serials are rounded off to the nearest hundred, except for the highest ones that are known. I don’t know of a single Silver with a rev1 PCB, but they may exist, as S001 isn’t accounted for. The fact the Silvers with rev2 PCBs exist show that Silvers were being produced alongside Golds in the early days, though in much smaller numbers. My data on Silvers is much more tentative, as most are horsieless with rev3 PCBs, and the fact that the changes are bunched up in the earlier serial numbers means I need more info on those units. Changes in Golds are more spread out, and so a nice spread of data gives us a clearer picture than what we can see with the Silvers. Assuming a total of 8000 units (in reality, it’s most likely a little less with no 4000 range serials attested), we can get an idea of how common the various Centaur versions are:
|Rev1 – ’94||3.75%||?|
|Rev2 – adds R1B and R14B||6.25%||2.50%|
|Rev3 – adds R1C||40%||47.00%|
We can do the same thing with Horseyman:
|Closed Tail||1-1800||S001 – S400|
|Open Tail||1800-3000||? – ?|
|None||3000-3858||S400 – S3922|
Horsieless Silvers are the most common. I know Open/Short Tail Silvers exist, but don’t know any serials for them, hence the question mark. Again, these numbers are very very tentative and have a lot of rounding going on.
The important thing to keep in mind is that whether or not a Centaur is Silver or Gold has little to do with what’s inside. There are no Silver/Gold circuit differences. But there are three different versions of the circuit, and 87% of all Centaurs have the rev3 PCB, which all klones are based on as well. The differences are minor, and only R14B should be audible. My experience is that swapping it in and out of the circuit doesn’t produce any audible effect, despite what Bill was going for.