Magnatone speaker (field coil) with tubes?

[glebert]

Saw a CL ad for this and have never seen or heard of this. From the wire harness I will assume this is a field coil speaker, and the ad says the tubes are rectifier tubes. Any idea what kind of amp used this? I think this Magnatone is different than Estey guitar amps.

[52 Bill]

The Gulbransen name is the real clue here. This is an organ speaker, the Magnatone name has nothing to do with the guitar amp company.