Great Transformer and Some Good Tubes Too

[J57LITTLE]

I came across an old Lowrey LS organ that no one wanted. Before it went to the curb I was able to pull out the tubes and transformers. The output transformer was pretty small, but this organ has nearly 50 tubes, so the power transformer is substantial.

Since I could find no information on the web regarding the Schumacher P6414 transformer I had to ring it out myself. The attached is what I came up with. The 12.6V circuit would have minimal value, but since it has a center tap it could provide a lot of filament power (and that's apparently what it used to do since the 12V circuit was divided and powered a boat load of filaments. Additionally, there's a separate 6.3V circuit (E2E, but also has a 3.15V center tap), so even more filament power. The 5V circuit was powering a 5U4G rectifier, so it has to be rated at at least 3A. The primary circuit was tied to a 3A fuse, so an overall 3A rating seems to be about right. Even better, the high power circuit was putting out 710V (E2E) with circuits tied to the center tap at 355V each. This could be a very useful (if large) transformer!

I was able to salvage a 5U4G rectifier, two 6V6GTA's and four 12AX7's. There are many more tubes, but none of the others have much value these days - mostly oscillators and tone generators.

So while no one may be interested in restoring a Lowrey home spinet organ, the parts inside could be the beginning of a great new guitar amplifier! I believe a 6VG double-ended system driven by a 5U4G could turn out well. If I drive a 12-inch speaker pulled from an Allen organ and re-coned, I'm thinking bass guitar amplifier. We shall see!

 

[nerdorama]

There are many good power tubes that use 12.6v filaments. An organ uses enough small tubes that it could surely power a pair, maybe a quad, of power tubes at 12.6v. A diy build can always add an aux filament transformer.

 

[Mdpaudio]

I got a great PT, choke and a couple of PP outputs from a Hammond on eBay. Really nice PT but the outputs were so so.

 

[gadget73]

center tapped 12.6v works just fine for 6v tubes, just have to balance the load out on both sides. One side of the heater of each tube to ground, the other to a heater supply.

Or as mentioned there are plenty of 12v tubes too. The 1625 comes to mind, its basically a 12 volt 807, which is more or less a top-cap 6L6GC. Officially the screen ratings are much lower, but they have been used with good success in UL setups with voltages well beyond official ratings. Stick 12SN7's in front of that and you have an easy 12 volt Williamson amp.

Output traffo probably useful for guitar use. Those have limited frequency range so you don't need a massive lump of iron that can do lows that will never be needed.