Salvaged 2xEL84 organ amp w/ gutshots

[benoit]

I bought an organ from a thrift store several years ago for 15 bucks. This was long before I became interested in tube amps. It sort of worked at the time but I had no use for it so I gave it to a friend, whose garage its been sitting in ever since. Tonight I realized it might have some potential as a starting point for a project.

Its pretty much solid point to point. Lots of micamold caps, a few spragues, some "good-all" and some sangamo. Big mallory cap can. RMC ceramics. Power cord is two-prong, so that'll definitely have to go. Has anyone ever heard of any of those brands, besides the spragues and mallorys? There's also a delay unit running a pair of 12ax7s. If I get some time I'll maybe try to get a schematic drawn up for these guys.

Possibilities for this thing? The tube layout is awkward, based on what I've seen from other amps. Maybe a PTP ghia? Not enough 12ax7s for a wreck..

Anyway, here are some gut shots

[benoit]

more guts

[mhuss]

Any 18 wattish thing, 18watt, AC15, Ghia, etc. I'll bet you could punch a hole in the chassis and add another noval tube without straining the PT.

--mark

[muchxs]

Baldwin? Baldwin used a lot of those green Sangamos.

Where are the oscillators? There should be another chassis with more tubes on it.

If it's what I think it is you should have easily 200ma on the high voltage and 7.5 amps on the filaments. Don't take my word for it, though. Count 12AU7s. Every three 12AU7s use an amp of filament.

[benoit]

Baldwin? Baldwin used a lot of those green Sangamos.

Where are the oscillators? There should be another chassis with more tubes on it.

If it's what I think it is you should have easily 200ma on the high voltage and 7.5 amps on the filaments. Don't take my word for it, though. Count 12AU7s. Every three 12AU7s use an amp of filament.

All the twin triodes are marked 12ax7, but it comes out the same for current needs.

I'll have to go back and look at the organ again. I pulled everything I saw tubes on. If there are more they're hidden very well. I'm hoping I can find a schematic, just out of curiosity.

[muchxs]

Baldwin? Baldwin used a lot of those green Sangamos.

Where are the oscillators? There should be another chassis with more tubes on it.

If it's what I think it is you should have easily 200ma on the high voltage and 7.5 amps on the filaments. Don't take my word for it, though. Count 12AU7s. Every three 12AU7s use an amp of filament.

All the twin triodes are marked 12ax7, but it comes out the same for current needs.

I'll have to go back and look at the organ again. I pulled everything I saw tubes on. If there are more they're hidden very well. I'm hoping I can find a schematic, just out of curiosity.

There should be an I.D. tag on the back of the organ. At least find out what brand it is, what brand and model would be a bonus.

[benoit]

It is a baldwin, so says a tag on the delay unit. It's an orgasonic, as I recall (its been sitting in a friend's garage for a good while and other than last night I haven't seen it in years so I dn't remember a lot about it). I'll try to swing back there sometime and get a model number. I don't care a ton as I'm probably just going to gut and rebuild anyway.

Ben

[billv]

Interesting - there should be a tone generator section with a bunch of 12au7 (older ones used 6sn7). This is IIRC but based on examining another Orgasonic a while back.

[muchxs]

If the power supply is early '60s Baldwin you probably have enough current for an EL34 amp.

[skyboltone]

My recommendation is to gut the sucker, save the iron, and install it in a fresh chassis and make the amp of your choice.

Hammond used a lot of 375-0-375 trannys with something like 260 ohm secondary impedence. This makes for lots of sag. Do the standard test for turns ratio/primary impedence on the OT and build accordingly. Hammond frequently uses only single tap secondarys on the OT, making match ups kinda weird for well known builds. Still, there's lots of room for fudge factors I'm told.

[benoit]

I might indeed but the chassis has 4 noval sockets so it's going to be a pair of 84s. I think I'm going to do the CG thing. The PTP layout is going to be tough as I've never had to do my own layout before, esp not real ptp.

The organ is a baldwin model 72, by the way, SN is 72P-30373-B9.

I looked again last night and did not find anything more with tubes besides the 2 12ax7 delay unit and the main amplifier.

[LeftyStrat]

I look at the pic "4.jpg" and think that if HAD built his amps point-to-point he wouldn't have to use any goop. People would just keel over dead trying to figure out the schematic.

[skyboltone]

I might indeed but the chassis has 4 noval sockets so it's going to be a pair of 84s. I think I'm going to do the CG thing. The PTP layout is going to be tough as I've never had to do my own layout before, esp not real ptp.

The organ is a baldwin model 72, by the way, SN is 72P-30373-B9.

I looked again last night and did not find anything more with tubes besides the 2 12ax7 delay unit and the main amplifier.

PTP is easier! Very few long leads. If you do end up with a longer signal lead for some reason know when it comes time to trouble shoot that the long leads are the first suspects. The organ chassis is set up for low gain, hence close tube placement etc. Remember that your guitar amp will need more space between components to remain stable.

[benoit]

skybolt, i missed your first post in this thread, I think I must have been typing when you sent it. I think you're probably right about saving the iron. I was just hoping to cut corners pricewise because I want to build and don't have much cash. I'll test the iron, see what I really have, and go from there.

Ben

[p90freak]

Resurrecting an older thread.

Are polystyrene Good-All caps good for anything? This one appears to be polarized (but not sure). It is only rated at 200v, so that rules out most coupling applications.