Max Wrote:Your personal opinion (AFAIU):
At the very beginning - IYO in the mid to late 70ies - ODR #0060 started its life in an unmodified empty 3rd generation style (toggle switches) ODR chassis with a circuit and with parts (Centralab 500KL treble pot, Piher carbon film resistors e. g.)
I never made any mention of the chassis being “3rd Generation” as I don’t necessarily subscribe the generation taxonomy that has been developed here. My opinion is that the chassis was fabricated sometime in later 1970’s...more like the 1978 to 1979 timeframe. Back in those days, to make a chassis like this it would have to have been stamped out on punch-press. The tooling to punch the flat was extremely expensive as it was all fabricated on traditional, non-CNC machine shop equipment. My opinion is that the original dies for the ODR chassis had the rectangular slots for slide switches. These same dies were likely modified for the round thru-holes for the mini toggles early on. The chassis fabricator surely had a minimum run and Dumble would have been forced to purchase this amount of ODR chassis on the first run. I believe Dumble had the fabricator modify the original stamping dies possibly after the first batch of chassis were made (converted from rectangular switch slots to round thru-holes). If you have had these two different ODR chassis to study in person, you will find they are dimensionally identical to one another. There are only two differences. (1) The aforementioned switch holes and (2) the side gussets. The side gussets as found in #0060 have formed reliefs for better mounting screw clearance. With the non-relief gussets found on some ODR chassis…the mounting screws get pretty close to the gusset and steel being harder than aluminum can cause cutting into the gussets. This is why he implemented this change. But if you study those examples that exist, you’ll find that the #0060 chassis was originally designed to use all the boards, jacks, relay, etc. from the earliest versions of the ODR. The modifications made to #0060 are actually fairly extensive and many new holes were punched and drilled to make the amp as it is today. Many hours went into building #60 due to the many hand operations required to make everything “fit”. This very well may explain why no other ODR has surfaced with a similar layout/circuit.
And yes, given I found evidence that the #0060 chassis had a Centralab RV4 Treble pot installed at one time…my suspicions are that it had the 500K Treble pot along with the 250K Mid (CTS) and 1MEG Bass (CTS) pots in the tonestack. It also had the singular, long black pre-amp board, The CalRad Relay and the FET board situated at the of the chassis (not the front as found on #0060 today).
Regarding the Silk-Screening of the various Dumble chassis I’ve seen in person. My opinion is that he might have been setup to do silk-screening in-house or he had access to someone who could screen for him. I doubt it was the same vendor that stamped, bent and welded up the chassis for him. You have a lot of flexibility with silk-screening so the many changes you see employed over the years are easy and inexpensive to implement. Back in the 1970’s your options for metal decoration were limited as metal lithograph or rotogravure were prohibitively costly unless your volumes were substantial. That’s why most every guitar or bass amp chassis from the era was silkscreened…as it was a cost effective method of metal decoration. Actually, it still is though it is become less and less common with all the options available today.
At some later point in time Alexander Dumble modified the original chassis in order to prepare it for the implementation of a nearly completely new circuit similar to the circuit and with the kind of parts (Sprague Q-Line carbon film resistors e. g.) shown here
Given the actual amplifier (#0060) shows substantial evidence of having the early style FET, the early reverb jacks plus the RV4 pot installed…it tells me that it was indeed built out like an early ODR. It also likely was delivered to Jackson Browne at this point. Given the low sequential serial number that is consistent with two other known ODR’s #0058 & #0059 that were built for and belonged to JB…it was surely originally made within close proximity (Maybe a year) to these other two ODR’s. The amp went back to Dumble who decided to modify it. I have no idea how many iterations of modifications it went through, however, it clearly is far removed (circuit and component wise) from an early ODR.
Then - again at some later point(s) in time - Alexander Dumble updated this circuit to its current ("skyline") specs, similar to the specs of the circuit shown here (of course with the exception of the reverb circuit of ODR #0060): Correct? If so, then let's compare your personal opinion with
Max, I have no clue of the timing or the iterations. All I know is that it surely was an early ODR as described previously and eventually, it became what it is today. I do know that there are many parts that date to 1981 in the amp (including the can lytics) but the newest part in the amp is the Texas Instruments solid-state voltage regulator. So I know it could not have been fully completed before 1982. The white jacketed coax would seem to date it deeper into the 1980’s though this I’m not really confident is the case…but maybe…hard to say for certain as there is no circumstantial evidence to pinpoint when it was completed unless Jackson Browne recalls…which is doubtful.
So our personal conclusions and opinions in regard to the timeline for the chassis-mods you describe and in regard to the specs of the first original circuit of ODR #0060 are (and perhaps will stay) different…
But IMO in regard to the topic of this thread (OD-50WX #006X) it doesn't matter very much, if your or my speculations in regard to ODR #0060 are correct or if we both are wrong. Or do you think, that our different personal opinions concerning ODR #0060 are of great importance in regard to the OD-50WX #006X topic?
The relevance to the #006X ODS revolves around the serial number on the chassis. #0060 (Not an ODS but clearly using the same master serial number range as the ODS) most logically would have been stamped prior to the #006X being stamped? Right? It is somewhat obvious that the ODS #006X was built in 1979. How many amps a year was HAD actually producing in 1979? Great question…nobody really knows but we do know he was still in Santa Cruz and he did have Jack Smith helping him from time to time. Was the ODR #0060 stamped and left unused for years? I do not think so. I think it was built just like #0058 and #0059 were and delivered to JB. It came back to HAD at a later point in time and got modded. How many times did he mod it? Nobody but he or JB know for sure. But the better question is does JB care? I doubt he does
Best Regards,
GPD
