Hoping for help on what I have -- guitar amplifier?

[heapes]

Hi all,
First off, I know this amp is really rough. I paid $10 for it at the Florida Flywheelers Swapmeet last year. I figured I would have $10 worth of fun taking it apart which I have. I came to this forum hoping that someone might help be determine the age and manufacturer of the amp. I am also curious of what would have been it's use. It has no tone controls like a guitar amp typically would. Is it likely for guitar, mic, harp, etc? I love learning to do things I know little about and this qualifies for me. I thrive on basket case restorations. Should I do more than throw this amp away? Thanks in advance and I can post more pics and add info if needed. I am fairly certain the speaker is not original.
Stephen

Ps. Sorry about the sideways pictures

[Justin Thomas]

A guitar amp of this vintage may NOT have any tone controls. I'd guess early 50s, probably earlier. The nice part is, it seems to have a power transformer? Are there any numbers punched/stamped into the end bell of the transformer? You'd be looking on the black piece, above all the laminations. Another place to look might be the back of the volume pot - same thing - any numbers stamped there?

Otherwise, all we can go on is the make of the parts, and those resistors are pretty darn ancient! Some of those parts I've never seen in person before!

Justin

[heapes]

A guitar amp of this vintage may NOT have any tone controls. I'd guess early 50s, probably earlier. The nice part is, it seems to have a power transformer? Are there any numbers punched/stamped into the end bell of the transformer? You'd be looking on the black piece, above all the laminations. Another place to look might be the back of the volume pot - same thing - any numbers stamped there?

Otherwise, all we can go on is the make of the parts, and those resistors are pretty darn ancient! Some of those parts I've never seen in person before!

Justin

Thanks Justin, I never noticed it before but the transformer is made by Thordarson out of Chicago and has stamped T 13R11 9A3. I will do a web search to see if I can find any info on it. There is nothing on the volume pot that I can see. The Tubes are from left to right: tung sol 524, 6f6, 6f5, and sylvania 6J7. I searched these tubes a while back and found some info indicating that these tubes were used in the early '30's. All help appreciated. Stephen

[Justin Thomas]

Yeah, those numbers make no sense to me! Now I'm curious, too...

Justin

[nickb]

Could that be a 5Z4 rectifer 5Z4, Tube 5Z4; Röhre 5Z4 ID2219, Full-Wave Vacuum Rectifier rather than a 524?

[heapes]

Yes, 5Z4. As a pharmacist I can read doctors handwriting all day long but cannot read my own. Thanks

[Richard]

You ever get so used to reading crappy writing that when everything's straight and square it hurts your eyes?

[g1]

Yes you should do more than throw it away.
Agree it looks like something from the 1930's.
And the covering reminds me of something like the Gibson EH style, which is from that era.

[olddawg]

Yes you should do more than throw it away.
Agree it looks like something from the 1930's.
And the covering reminds me of something like the Gibson EH style, which is from that era.
[ATTACH=CONFIG]40433[/ATTACH]

My guess is that it is an extension amp for a film projector. But... Could also be a lap steel amp. What's odd is that it has that old Utah alnicol speaker. With that tube compliment I would expect a field coil type of speaker. Another guess is that it was converted to use that speaker long ago. Maybe in the 50s. Is it line level input or instrument level input?

[DrGonz78]

My thought was the amp is from the 30's too. I looked up a few radios that had those same exact old box shaped Aerovox Hi-Farad Dry Electrolytic Condensers and only one's that looked like your pics were from about 1935.

Edit: Also the simplicity of the chassis amp reminds me a little bit of Webster Electric Company. Kinda like the look of this chassis...

https://www.flickr.com/photos/museum...sic/3326081171

[nickb]

Yes you should do more than throw it away.

Indeed. Resist the temptation to plug it in just see to see if it works.

It looks like it has been stored somewhere rather damp and that could have affect on insulation. Also the electrolytics are very likely to be bad. Draw a schematic first and carefully bring it up. It sounds like your are familar with the procedures of being up an old amp. Oh, and change to use a 3 wire cord and earth the chassis.

[heapes]

My guess is that it is an extension amp for a film projector. But... Could also be a lap steel amp. What's odd is that it has that old Utah alnicol speaker. With that tube compliment I would expect a field coil type of speaker. Another guess is that it was converted to use that speaker long ago. Maybe in the 50s. Is it line level input or instrument level input?

This is great. I am hooked and want to do more with it. After searching lap steel amps I come up with an early Magnatone Lap steel amp that has the same covering minus the stripes, same shape and size case, and same grill cloth. If I am seeing the speaker screw heads correctly they look the same too which is an odd double slot head (similar to a Phillips head but shallow and all the way accross. The speaker has certainly been replaced.
So, any suggestions on a resource for getting started repairing this thing? I need a book that would guide me through the process. I feel certain that I would have too many questions to ask on a forum. That would be a bother to everyone. I am no dummy but my knowledge on audio electronics is limitted. I did heavily modify my Gretsch g5222 Electromatic amplifier a while back but I had good detailed instructions. Thanks all.

[g1]

Which model magnatone and can you post the schematic?
Don't worry too much about too many questions, as long as you are willing to consult references that may be recommended along the way.
Some threads here are very high tech, some are for people with very limited experience or electronics background. Everyone learns something from all of them.

[heapes]

Which model magnatone and can you post the schematic?
Don't worry too much about too many questions, as long as you are willing to consult references that may be recommended along the way.
Some threads here are very high tech, some are for people with very limited experience or electronics background. Everyone learns something from all of them.

They don't list the model number and all I can see is the forward view of the case. It's actually on Magnatone's website on the home page as one the the historical amp's. I see a lot of similarities with that picture. As for a schematic, I will have to research how to draw the schematic. There are an awful lot of resistors and caps in this chassis.

[eschertron]

There are an awful lot of resistors and caps in this chassis.

...and things that look kinda like resistors that might be caps, and vice-versa. This will be a history lesson for sure, maybe more like an archaeological dig. Keep us posted on your progress, and as G1 says, don't be afraid to show and tell.. and ask. Many here will learn from your endeavor. I know I'm looking forward to it!