Hoffman Amplifiers Tube Amplifier Forum

Other Stuff => Your other hobbies => Topic started by: Blueboozer on April 27, 2021, 10:30:46 pm

Title: To Field Coil or Not to Field Coil
Post by: Blueboozer on April 27, 2021, 10:30:46 pm
I just invested a months pay in a 1940’s Sparton 7-46 PA ($60). My original intention was to steal it blind and see what kind of amp I could build with 2 6F6’s in push pull configuration and what I think are 7A7 pre’s (I can still do that and check out the tones). But after firing it up I think I might just restore it. It makes noises and all the tube filaments are lit. It has an old field coil equipped 10” speaker in it.  So my question is, should I go with the current speaker or try to find an OT to match the 6F6’s and go with a more modern speaker?

I think I’m going to turn it into a twilight zone radio. Wire an audio source that plays big band and use it to puzzle the kids. “It’s stuck in WWII and only plays Big Band”
Title: Re: To Field Coil or Not to Field Coil
Post by: PRR on April 28, 2021, 12:42:00 am
Only you can answer those questions.

That's a particularly nasty "phase inverter".
Title: Re: To Field Coil or Not to Field Coil
Post by: Blueboozer on April 28, 2021, 12:44:44 pm


That's a particularly nasty "phase inverter".

I was assuming that was the function of the 7B6. Not what I’m used to seeing. Will take some noodling…

Title: Re: To Field Coil or Not to Field Coil
Post by: Blueboozer on April 28, 2021, 07:26:55 pm
 :think1:
Title: Re: To Field Coil or Not to Field Coil
Post by: Blueboozer on April 28, 2021, 10:45:30 pm
Shows my ignorance. A phase inverterless push-pull amplifier.

I didn’t know there was such a critter.

Found this in the DIY forum - looks strikingly familiar

Title: Re: To Field Coil or Not to Field Coil
Post by: Willabe on May 06, 2021, 02:26:56 pm
I think I’m going to turn it into a twilight zone radio. Wire an audio source that plays big band and use it to puzzle the kids. “It’s stuck in WWII and only plays Big Band”

 :l2: