Help Identifing Amplifier

[VivianCampbell]

I picked this up at an Estate Auction. No Idea what it is supposed to be. Has what looks like an ANU and has a Hadley 6694 Transformer. Is only about 13" wide and has a marbleized paint job and a cast iron handle. Only has a 1/4" jack input. No knobs. I'd guess it is from the 30's or 40's. Anyone seen this before? Thanks.

[nashvillebill]

Its a Oahu, I personally don't know anything about them but Google came up with a ton of hits.

[VivianCampbell]

1947 single ended lap steel amp.

I was able to use the name to find that this a 1947 single ended lap steel amp.

[nashvillebill]

Cool, that looks like it could be really nice!

Don't even THINK about plugging it in as-is "just to try it out", I'd wager every capacitor in there has deteriorated just from old age. They could fail catastrophically if you throw any juice to the amp, which could make a terrible mess to say the least.

There's other folks here that are far more knowledgeable than I am about restoring these old amps from 70+ years ago, hopefully they'll chime in.

[Steve Conner]

The speaker is missing its cone, for a start. (maybe mice ate it?)

With some sympathetic restoration I'm sure it could be pretty good. I saw a thread somewhere on the board about a similar looking amp, sold under the Dickerson brand:

http://music-electronics-forum.com/t17692/

http://www.charlestonarea.com/Dickerson/index.htm

[Brad1]

Love those old Mother-of-Pearl amp cabs. I had an old blue Magnatone about like that once. They liked to match the amp cabs with the lap-steel finish.

Looks like you have a field-coil speaker in there? That would put it very early '50's or before.

Here's a quick search find for the amp with guitar....

1935 Oahu Lap & Amp Pearloid Set > Guitars : Lap, Pedal & Table | Gbase.com

Notice it looks like they may have changed the speaker and put an output transformer on it...can't really tell. Or, maybe it was a slightly later model where they quit using FC speakers?

Anyway....they are pretty cool. I have an old Kalamazoo about that size in excellent condition. Just like the one following, except mine is near mint:

1940 Kalamazoo amp

With that funky speaker, it scares me to push it much, though.

BTW...what's at the other end of that brown zip cord from the speaker? Looks like the black one is the AC cord...

Brad1

[52 Bill]

Love those old Mother-of-Pearl amp cabs.

More often referred to as MOTS - Mother of Toilet Seat.

[Bruce / Mission Amps]

The FC speaker amps all still use an output transformer.
The field coil, built into the speaker, is used to make an electromagnet, replaced by permanent magnets in later years.
EM Electro Magnet
PM Permanent Magnet
CM Ceramic Magnet
The high voltage from the power supply B+ rail is using the FC as a "choke" and the current flowing in the coil, from the current flowing in the tubes, makes a magnet so the speaker will work.

I did a refurbish on an old Gibson EC150 last fall with an EM 12" filed coil speaker and had the folks at Orange County Speakers re do the speaker for me.
It sounded terrific.
You don't need to though... any speaker the same size at about 4 to 8 ohms will work fine, you just need to reroute the two high voltage wire going to the filed coil (speaker), over to a 4-10hy choke at around 100ma (or so) instead
and mount the choke on the cabinet, chassis or some other convenient place like the speaker basket.

[VivianCampbell]

Thanks to everyone for their input.

In one day I went from knowing very little regarding this amp to a wealth of knowledge. It is very cool but I really am not a collector of stuff this old, so I will probably just sell or trade it. Thanks for the warnings and suggestions.

[Brad1]

The FC speaker amps all still use an output transformer.
The field coil, built into the speaker, is used to make an electromagnet, replaced by permanent magnets in later years.

Of course, Bruce sets me straight. My old Kalamazoo DOES have one mounted on the speaker. Been a while since I peeked back there.

I didn't see one on VivianCampbell's amp, and just noticed that brown cord, so just thought I'd bring that up. Still wondering what's at the other end of that brown cord. Wonder if someone just tried to run that to another speaker from there?

Brad1

[VivianCampbell]

Brown Cord

The Brown Cord is a Power Cord, so it terminates in a standard 2 prong power cord. Once again thanks for all the help.