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In Reply to: Help needed Identifying Conn organ 12au7s posted by anumber1 on September 27, 2004 at 18:31:58:
Alan,I've only used "absolutely" in the subject to encourage others to have a look- and argue!
My thought is that the tubes in your photo are both Sylvanias- one black plate and one grey plate/square getter. Sylvania did use both that green and yellow printing at various times.
As you probably already know, these tubes were relabelled for use in older elctronic organs from the Conn Co. I have a few 12AX7s labelled by Hammond Organ and these are black plate, square getter tubes also made by Sylvania- and very nice.
All the organ labelled tubes I've seen have been either Sylvania (80%+) and a few RCA. For some reason it seems Sylvania somewhat cornered the organ tube business.
Cheers,
Follow Ups:
Alan Gallacher
Born to Tinker!
Conn used many Sylvania & RCA clear top 12AU7 with a mix of 6V6 or 12V6 plus some 6L6 power tubes.
Baldwin used mainly Raytheon to the mid 1960s with most having RCA 6L6GB & 6L6GC power tubes.
Hammond used RCA & Sylvania in the early to mid 1950s with 6V6 power tubes. Hammond also favored Sylvania 6SN7 more than RCA in the 1940s. In the 1960s Mullard or Amperex were favored with 6BQ5 power tubes.Organ manufactures spent plenty of time rolling tubes for best sonics. They also requested best of production run tubes plus close matched power tubes for push-pull. The close matched power tubes were marked with a color usually white or orange on the keyed base pin (octal socket). Low noise selected 9-pin preamp type tubes in critical circuits could have many different colors for identification.
Tube organs have an interesting history, but I never read the specifics of design & production in the manufactures factory.
Jimmy,Thanks for the additional information about the tube mkers relabelled or organ use. I had only seen Sylvania and RCAs labelled for organs, with a couple of Mullards for less common types, but of course Raytheon and others were used.
Based on my organ tube purchases, it rings true that organ makers chose the models carefully and then selected the tubes. The 8 "Baldwin"*** 12AX7s I have are all quite close and all 16 triode sections are probably under 10% in variation. They must have selected crefully to have adjacent notes on the organs be consistent in timbre and output.
***I mistakenly wrote "Hammond" organ for some 12AX7s I have, but these are "Baldwin"!
The organ tubes I have are all nice. I look for organ labels as well HP or Textronix becasue of these companiies' selectivity. I have 4 Textronix RCa cleartop 12AU7s and the 8 sections are about 2% apart! HP too in particular chose very nice models for their instrumentation tubes- I have HP labelled: Amperex 12AU7s, RCA cleartops, and Amperex 6DJ8s.
I think tube organs really got going post WWII when the miniature triodes were available and I've actually never seen an electronic organ made before the early 1950's. It would be interesting to know more about it- there must be many books on the subject! Of course, the digital/sampling/synthesizer/MIDI revolution is perfect for organs and organ technology today has jargon heavy enough to sink ships! I subscribed to the Allen Organ Owners newsgroup and those fellows were plugging laptiops into three manual organs like the pit crews do to Formula One cars..
I'm not sure there were SE organs, but I think Theremins were SE!
Cheers,
After testing 1000s of tubes, I notice the same close tolorances regarding dual triode tube section to section matching. Additionally, the power tubes usually are close matched as well.Many pre 1950 organs used 6SN7s instead of 12AU7 & 6SL7 instead of 12AX7. With the low 80 to 120 volts plate in most applications, the tubes seem to last forever & especially so with larger tubes such as 6SN7s..
Hammond also used 6SJ7 and 2A3 push-pull as noted in some ebay Hammond amps...
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