Baldwin Organ Power transformer?

[Blair]

Hi guys,

I'm still in the build process with my Bogen MO-200 amps, but recently stumbled across a few old baldwin amps at a friend's house. They are this one:

http://i650.photobucket.com/albums/uu22 ... an0009.jpg

Thanks Mark! it's your photobucket.

Anyway, the power transformers dwarf the ones in the Bogen amps. The bogen amps used a doubler, but have a filament winding good for about 15A.

The Baldwins have, based on the schematic, only about 4A riding on the filament winding, but have a plug that has a filament out in it. Plus they only provide B+ for 4 power tubes. Why are they so freaking huge?!

I was considering buying these from him to drop in place of the Bogen power iron to get a more useable B+ of roughly 450V for 6550s.

Thanks!

Blair

[nyazzip]

not sure but maybe the PT also supplied B+ and filament juice to other outboard/peripheral devices(effects/reverb/motors for "leslie" speakers/lamps). i can't quite make out the schem but it looks like a lot of nodes say "to pedal"

[Blair]

That's what I am thinking. There is no way they put a transformer that big on there to power a pair of pp amps.

If the umbilicals went to what I have seen on other organs, there are 25-40 6SN7 or 12AU7s also being powered. That would make more sense.

Blair

[EWBrown]

My old (dead) Schober organ had 67 12AX7s init, plus a few other assorted twin triodes. Hefty power supply, big 350-0-35 power trannie, 5U4GB rectifier, big filter choke, and a separate 6.3V, 14A filament transformer.

No amps, reverbs, just line level output. Back in the 60s we used an Eico HF-20 to drive an AR One. Sounded pretty goodback then.

/ed

[battradio]

Hi Blair
The B+ on the Baldwin PC45's was rated at 360 ma ,
but was most likely a bit conservitive .

[Blair]

Thanks,

Minus the "safer" B+ I could get with a FWB choke input using the Baldwin transformers, the bogen will likely be rated for higher current? It powered 8 X 8714s, but I'm not sure how they were biased.

Mark, did the amp you converted to 6550 PPP have any PS sag when pushing 100w?

Blair

[Blair]

I ended up buying the Baldwin amps anyway. I got a good deal including the essentially new RFT EL34s.



So, now I need to figure out what to do with these. I have access to a pair of ST-70 output iron for $50. That might be a good swap.

Blair

[nyazzip]

...i see a 50w Marshall guitar amp clone !

[Blair]

There are two, but the only thing I know how to do with a geetar is swing it like a bat:)

It would be easy to swap the output iron on these to make them a little better.

Blair