Baldwin organ model 40

[Mars-Hall]

Recently had the opportunity to scavange the power section from a Baldwin Model 40 organ.  First off, I was pleased to find a Magnavox 12" alnico speaker dated to 1955.

Looking at the iron, trying to decipher if it will make a good guitar amp build.  The power section currently has a pair of "coke bottle" 6L6 power tubes and a 5U4G rectifier.  The trannies have 512 manufacturer codes but none of the lists I see online have it.  The iron looks comparable in size to what you would see on a 100 watt Marshall.

These photos are not of mine but are the same.  Mine are in better shape.

[Platefire]

  Almost all of those organ amps got their AC voltage and preamp signal from a seperate section of the organ through that octal conector. So basicly what you got is the power amp section without the preamp and no AC voltage hookup to your power transformer. I think the easyist way to make a guitar amp out of it is install a three conductor power cord, fuse and power switch to replace where your AC power is coming into the chassis from the octal plug. You would have to determine which of the two wires in the cord from the octal plug was powering the power transformer(PT). Hook your incoming AC power to that. That would get AC power to it.
  Then you need a preamp section that would include an input jack, volume pot, tonestack pot and a preamp tube. I would recomend a tweed princeton input and preamp model fender 5F2. You would have to install a 9 pin socket for a 12AX7 right in front of the power tubes closer to the front and tap into the AC heaters wires and DC from the Phase inverter tube for your 12AX7 power. So you could install an input jack, 1 meg volume, 1 meg tone on front right in front of your new 12AX7 socket. One of the wires of the cord with the octal plug is for preamp signal from the organ. You would have to locate that wire to where it ties into the Phase inverter tube and that is where your 2nd stage ouput of your new preamp tube would connect to the existing power amp.
  Also you would have to locate the output transformer(OT) taps and wire in a speaker jack on back side opposite your new input and controls. This is just a very basic plan of how you could make it work. Not an easy conversion for the fainthearted for sure. First I would want to get some AC power to it to make sure the transformers were good before you invest to much time into it. So if you still had the organ preamp section that the octal cord plugs into with the power cord you could maybe hook it up and test it. You would need a speaker hooked to put a load on the output transformer. A multi meter check of DC voltage output from rectifier would be a good indicatior PT is working. Static through speaker would be a good indicatior OT is working. Should you decide to accept this mission, to protect the innocent, this message will self destruct in 5 seconds. Platefire

[RicharD]

Look at that big honkin choke!  Reverse engineer it.  You can make a fine guitar amp from it.  Like Plate says, you'll have to add a preamp and safety up the AC.  Given the state of the chassis, I grab the iron and tubes and abandon the rest.  Since the number on the transformers are stamped in ink, I'd betcha that's a stock part number and not an EIA code.  1955.... probably UTC, Stancor, NYT, or Triad.  Who cares, that's schweet stuffs.

[eleventeen]

You have roughly the same conundrum I do while pondering the potential guitarization of the below-pictured CONN organ chassis, though I admit yours looks like it would be a lot easier. In my case, the power transformer is set in from the end of the chassis enough so that it eats up a lot of chassis room. It's a through-chassis type, like yours. But my OT is also through-chassis type and would presumably leave its own rect hole. If I wanted to reclaim that room while using the same PT and OT, then I would have to re-cut the rectangular hole in the chassis, and I think that would weaken it quite a bit. Yours is at least at the end of the chassis. But if you ponder further, you'll see that you would most likely have to move stuff around quite a bit. I think yours would be easier than mine but still no walk in the park. Yours looks like it could accomodate a turret board and controls and a row of preamp tubes.....just barely, in terms of front-to-back room. Your chassis is also taller, in its narrowest dimension, than my Conn. Like at least 2" tall whereas the Conn is kind of squat. One looks at yours and wonders why the PT is at one end and the can filter caps are at the other end. Doesn't seem like a best practice, nor is it an issue if you are going to rip them out.

The executive decision has to be made at the outset how much metalwork you plan to do and whether you can get the parts installed in any kind of workmanlike fashion. If you don't care how the end result looks, then fine. If you wanted an ugly chassis you could experiment on, fine. But to put a lot of work into something just to make it work and then have it look cruddy isn't exactly encouraging. What I'm saying is that if you could buy a Mojo chassis and have many of holes pre-drilled/punched, or a Hammond chassis and end up with something that looks nice, either for under $100, that would be my personal preference. Rather than struggling for 5 or 6 or 8 hours and ending up with something ugly.

I could see yours working. The consensus of the forum was that my Conn would be stinky and I became convinced of that view. Yours could work, I am just trying to clue you into some potential problems before you begin trying to reuse the chassis. As far as the trannies are concerned, go for it.  

[DummyLoad]

hey richard, you remember that big honkin' baldwin that we salvaged that had the bad OT? it kinda looked like this one, only ours had 2 5U4GB & 4 6L6G. you remember, the weird-o PS? the choke is in series first filter and the center-tap ties between them. difference here is ours had 2 5U4GB & 4 6L6G. from what i can make out from the pics, it looks like this one shares the same topology only with a single recto a one pair of 6L6G.

link to orig. topic below... PS schema there too...

http://www.el34world.com/Forum/index.php?topic=11056.0

--DL

[Platefire]

Organ amps are not a good conversion format for guitar amps. Old PA amps or hi fi amps are a lot easier to convert. Believe me, I've converted a lot of amps and its really easier in the long run to build new from scratch. Plus when you do that, you can build something really usable taylored for your spacific needs. Platefire

[RicharD]

ayup.... now I remember.  That was an odd PSU but it did encourage some thinking.

[Mars-Hall]

My idea is to scavange the iron from this chassis and use them for a build.  Just what build, I do not know yet.  I think it would be a lot easier to get a new chassis to build from.  Hopefully these transformers have "common footprints" or at least close to minimize modifications.

From what I understand the organ was working but had some dead keys.  I have all chassis', with some very interesting looking tone caps.  I'd like to repurpose as much as I can for this build. 

My first instinct was to make some kind of tweed Fender clone but A Trainwreck clone would be nice as well. 

[kagliostro]

Eleventeen I was thinking that the chassis in your image was something about a radio apparatus (also if the variable cap is in a strange position), do you know which was the purpose of that air variable capacitor on the chassis ? which function in an organ ?

Thanks

Kagliostro

[eleventeen]

Hi Kagliostro; I do not know the specific function of the variable cap on my Conn chassis because I bought the amp just as the amp....I did not strip it out of a complete organ. I would guess it was part of either a tone circuit, a "swell" circuit, or perhaps a vibrato speed circuit...but I do not know for sure. Those are just guesses. I agree, it is a strange part to have on an amplifier!

[kagliostro]

Anyway thanks

Kagliostro