Conn Organ Conversion

[ALBATROS1234]

Just snapped up a Conn 426 from Craigslist and I have a few questions. Since I already have a fully operational Hammond M3 this one is getting gutted. I have been looking for a schematic to download which would be nice to have so I don't have to spend time tracing wires to figure it out and not really wanting to pay $25 for a service manual download for something I will be changing around but it still would be cool. If someone has one please email me.
     This thing has 57 tubes, 45 of which are 12AU7a (Sylvania) and only 12 were bad so it's a score regardless for $50. The amp oddly uses 4-12V6s with what looks like 2 output trannies(stereo?) this is peculiar because the speakers are 1- 12" Magnavox made alnico with a beefy voice coil and magnet, plus a 5" field coil pointed sideways into the volume pedal compartment (another reason why a schematic would be nice.) I imagine the huge p.t. only has a 12volt and 5-volt(5U4) filament, windings because all tubes are 12volt. In theory If I so desired, I should be able to do pairs of 6-volt tubes in series right. By this I mean send the 12-volt feed to a pair of 6V6s which the filaments of those 2 are in series. Is this done? The 12V6s tested pretty weak.
     Also, one of the tubes is a yellow label Sylvania 12AX7 short plates with a painted red tip like it the top point was dipped in red paint. It is one of the few tubes not labeled Conn and tested on the high end of NOS. A net search gave differing reasons and most talked about European tubes having the red tips sometimes. Is this a Euro tube even though it is marked Sylvania made in USA. how can I figure out what it is? I have read that sometimes companies bought/swapped tubes and re labeled them. What does the red tip mean? Low noise, Mil Spec? Thanks in advance for your responses and assistance.

[thetragichero]

your assumption of only 5v and 12v low voltage windings is likely correct. yes you can wire the filaments of two 6v6 in series to use the available 12v (i have done this with a baldwin power transformer). you can always pump a small ac voltage into the power transformer primary and measure the secondaries and determine what you have with some maths. stereo output transformers makes sense. either save em for 2x6v6 projects to throw in a 2x6l6-type ot (this is what i would do) or look into something fun with stereo amps (i have a hankering to build riff on the ampeg echo twin, running the reverb off of one of the output transformers)
sounds like a good score! i've picked up 20-25 organs (solid state and tube) and only ever paid for one of the old hammonds, my first (i usually mention that my payment is that i won't charge them to haul it away). sometimes i only get some speakers and a reverb tank, sometimes it's enough stuff to build two amps (like the hammonds that have a separate chassis to run the reverb off of). the garbage men must hate me when i have four empty organ husks at the curb (it's a shame even the 50s organs are just veneer on junk wood or pressboard; i'd love some old wood to build guitar bodies from)

[1blueheron]

Just snapped up a Conn 426 from Craigslist and I have a few questions. Since I already have a fully operational Hammond M3 this one is getting gutted. I have been looking for a schematic to download which would be nice to have so I don't have to spend time tracing wires to figure it out and not really wanting to pay $25 for a service manual download for something I will be changing around but it still would be cool. If someone has one please email me.
     This thing has 57 tubes, 45 of which are 12AU7a (Sylvania) and only 12 were bad so it's a score regardless for $50. The amp oddly uses 4-12V6s with what looks like 2 output trannies(stereo?) this is peculiar because the speakers are 1- 12" Magnavox made alnico with a beefy voice coil and magnet, plus a 5" field coil pointed sideways into the volume pedal compartment (another reason why a schematic would be nice.) I imagine the huge p.t. only has a 12volt and 5-volt(5U4) filament, windings because all tubes are 12volt. In theory If I so desired, I should be able to do pairs of 6-volt tubes in series right. By this I mean send the 12-volt feed to a pair of 6V6s which the filaments of those 2 are in series. Is this done? The 12V6s tested pretty weak.
     Also, one of the tubes is a yellow label Sylvania 12AX7 short plates with a painted red tip like it the top point was dipped in red paint. It is one of the few tubes not labeled Conn and tested on the high end of NOS. A net search gave differing reasons and most talked about European tubes having the red tips sometimes. Is this a Euro tube even though it is marked Sylvania made in USA. how can I figure out what it is? I have read that sometimes companies bought/swapped tubes and re labeled them. What does the red tip mean? Low noise, Mil Spec? Thanks in advance for your responses and assistance.

I think I have a schematic posted in a previous thread on a Conn the same or very similar to yours.  It also has 4, 12V6 tubes.

I think what you will find is that there are actually multiple amplifiers on the same chassis.  One was for the low frequencies, and one for mid/highs or "voices".  The Field coil speaker was a unique take on a tremolo system rather than having an oscillating speaker or a Leslie like many competitors had.

Like you, I scored a ton of very nice 12AU7's a a handful of 12AX7's  I think that was the organ I also found a bunch of neon bulbs in.  Let me search for the thread and if I can find it, I will post a link to it.  In my case, the chassis is still in a pile under my bench.  A half finished project.

[1blueheron]

Is this the same beast you are working on?

https://el34world.com/Forum/index.php?topic=23884.msg256917#msg256917

[ALBATROS1234]

No, 1blueheron that is the one which also has 6L6s mine just has the 4-12V6s with a 5U4, a 0A3, and 2-12AX7s. I appreciate you taking the time to post it, and I will use is as a loose guide. I may try to give away the husk after I strip out what I want, the keys, and buttons are in great shape and all of the tone generators probably work, would be a good parts organ for someone because I have seen people posting other places that they were looking for the buttons for these type Conn
 because the writing wears off.
 Tragichero, Yes, I noticed the top is particle board, my hammond is plywood at least. I thought maybe I would disassemble this one and use the sides and front which are plywood for a cab since it already has the speaker baffle made. If you were local, I have some cool wood I scavenged from a 200+ yr. old building in the French quarter, New Orleans. They were tossing a bunch of hand sawn cypress (and other things) in 4' to 5' pieces which are various thicknesses of 1 5/8" to 2". I took one board with all straight grain which was virtually quarter sawn cut it in 3 lengths and made a badass body blank. This was passed through a planer until it was the standard 1 3/4" probably do a tele body. some of the boards are only 3/4" to 1 1/4" I fantasize about making an archtop with F holes but will probably end up as book shelves.

[thetragichero]

i know this is veering off topic, but when i took the built in cabinets out of what was my studio (but will be something else once the house sells) i noticed that the doors had a nice grain to em (beats me what type of wood) so i glued two halves together (since the doors are not a single piece but tongue-and-groove slats glued together, the back is rotated 90 degrees so that hopefully they'd stay together with changes in temperature/humidity...we'll see when the PODS container with all our stuff makes the trip from florida to upstate new york) and made a body to go with a particularly nice birdseye maple mighty mite neck (which i've had on a number of strats and a jazzmaster before ultimately selling them) and p90 i had wound for a different guitar project and ended up with this for my first guitar build:



all in all came out nicely, although the pickup positioning isn't great for the high e string. still the only guitar i'm playing at church since the rest are packed away
here's the ongoing build thread if you're interested. haven't finished the bass since other priorities have been taking up my time: https://guitarnuts2.proboards.com/thread/8957/gonna-make-guitar-body-cabinet

[sluckey]

Very pretty. I think the wood is Elm.

[tubenit]

Thanks for sharing the guitar project! Turned out quite nice. I think Sluckey may be right that it's elm. If not elm, my next guess would be ash.


with respect, Tubenit

[thetragichero]

now that i look at elm, it definitely seems as such
i fully support upcycling old wood/organs into things that are currently useful (sure an old hammond *looks* cool but is such a niche instrument and you can get damn close with a laptop and midi controller. just be careful because a few of the organs i've  picked up have had mercury switches in em)