Zenith 701 - Just Got It

[Jeffhs]

Originally Posted by Bob E.

Some areas of the US were 50 Hz until the late 40's, and some rural areas (and places with Edison power) were DC early on. I have a Magnavox "Concerto" phono from 1936 that is listed as 117 Volts, AC or DC. It has five tubes (two 25L6, two 25Z5 and one 6C5 with the heaters in a series string...no transformer so it doesn't care about the incoming power frequency! I also have a Mills jukebox from the same year, and it also has the ability to run on DC. It uses 2A3's for outputs, though, and I haven't looked the schematic over yet to see how it does the job on DC. I think there are some connection re-configurations you have to make.

--Bob

A phonograph that operates on AC or DC? I can see the amplifier running equally well on either source since series tube strings will operate on either type of power, but I'd think DC power would burn out a synchronous phonograph motor in no time flat, as soon as the motor was switched on.

[jeyurkon]

Originally Posted by Jeffhs

A phonograph that operates on AC or DC? I can see the amplifier running equally well on either source since series tube strings will operate on either type of power, but I'd think DC power would burn out a synchronous phonograph motor in no time flat, as soon as the motor was switched on.

I don't know if it does, but it could have a governor controlled DC motor. I have a Concord reel to reel tape recorder that works that way.

John

[Bob E.]

Originally Posted by Jeffhs

A phonograph that operates on AC or DC? I can see the amplifier running equally well on either source since series tube strings will operate on either type of power, but I'd think DC power would burn out a synchronous phonograph motor in no time flat, as soon as the motor was switched on.

Jeyurkon has it exactly right. It is a fairly large (for a table-top phono) brush motor with governor speed control. Not only that, it is geared down appropriately and spins the platter from the spindle! I.E. direct-drive existed back in 1937! I was suitably impressed. This thing also has a fairly impressive speaker (Magnavox, of course), an 8" electrodynamic with an aluminum voice-coil...take that, JBL! If you are in the south SF Bay Area, I will be showing it off in my upcoming Antique and Vintage Radio show on Feb. 21 in Santa Clara.

--Bob