Trashed Hi-Fi + extras score

[JJGross]

I was coming back from the post office today and right before I get home I spot an old console TV with something else behind it out for trash pickup. I slowed down and the other thing turns out to be an old hi-fi, I'm guessing from between WWII and late 50s by the woodwork style and other clues like a SW band in the radio, wooden knobs, 'Magic Eye', etc. I pulled all the tubes from it right there and came back with a screwdriver and wire cutter later to pull the chassis.

Tubes are:
1x Sylvania 6E5 'Magic Eye'
1x Sylvania 7Q7
1x Tung-Sol 6S8GT
1x RCA 6SK7
1x Sylvania 6SK7
1x RCA 6SG7
1x RCA 6SJ7
1x CBS 6SJ7
1x CBS 6V6GT
1x RCA 5Y3GT

* and in a box in one of the compartments a box marked 'spares' with:
2x Thomas Organ 12AU7
1x CBS 12AX7
1x RCA 12AU7A (in an original box)
1x RCA 0A2 (in an original box)
1x Amperex 12AT7 (in an original box)



I have a Sencore TC28 I'll be testing these with.

I also grabbed the speaker from it, a 10" with the transformer mounted on it.

Maybe not a real valuable haul, but I'd think between these and the chassis complete with transformers I should be able to build a nice low wattage blues grinder guitar amp. I didn't grab the whole thing because it looked like there were 50 years of home-made fixes to the wiring, all done with tape. The woodwork was also not in really good shape so I pulled all the vintage hardware off it and brought that home too. I figured it's life as a home hi-fi are past. Maybe I can give it another chance as a guitar amp.

Any ideas about what kind of amp circuit would make best use of these parts? Maybe a Champ or Princeton or something along those lines? Possibly something with slightly more power? Any ideas are appreciated.

I'm just glad I could keep this out of the local landfill. If I can actually make something usable out of it - bonus!

Also, you should see all the domino & bumblebee caps and other vintage parts in the chassis. All P2P terminal strip construction with cloth wires. Not a single piece of plastic in sight. Like a little museum of technology. I didn't see any transistors, but I didn't start digging through the wires on the roadside. The few date codes I spotted on tubes are from 56 or so, but the radio itself looks older than that.

Cheers,
- JJ

[bob p]

good stuff for a champ, but i don't know if the radio tubes will be much help in a guitar amp.

alnico speaker?

did you grab the PT?

[JJGross]

Originally Posted by bob p

good stuff for a champ, but i don't know if the radio tubes will be much help in a guitar amp.

alnico speaker?

did you grab the PT?

I thought a Champ would be in the ballpark. Would a Princeton be pretty much the same thing except for the tone control? I figure if nothing else whatever little $ I scare up for the radio tubes on ebay I can put back into other parts. I've built a ton of effects and have fixed a few amps including my SF Twin, but never built one from scratch (I know about the safety requirements involved, discharging caps, etc.).

I'm not sure how to tell what the magnet is made of. It's not real big and has a frame around it if that matters. I not only got the power transformer, I grabbed the entire chassis. The only things I left behind were the cabinet, the boxed frame antenna and the record player.

Some pics are up at http://s233.photobucket.com/albums/ee255/BubbaKahuna/
The salvaged amp pics are the first several in the album.
After that it's just other junk I have. ;D

Cheers,
- JJ

[bob p]

i'm out of luck -- photobucket is down for maintenance now.

regardng your princeton question, yes the tweed princeton is just like a champ with a tone control. great circuit to start as your first build. the later princetons were push pull amps.

i havent' seen the photos yet, but i'm wondering if you have a really old speaker that may not have a permanent magnet. some of them had field coil magnets that had little transformers mounted on the speaker frame.

[52 Bill]

Bob, nice call!
I looked at the photos and it looks like a field coil speaker. There isn't a clear shot of the side of the frame, but there are cardboard/paper forms showing and some wires as well.

[JJGross]

Looks like the magnet on the speaker isn't a magnet unless it's powered up. I took a pair of pliers and tried to feel a pull on any part of this thing and nada. The frame on the rear of the speaker has what looks like a large cardboard bobbin with windings around it and covered in paper, and it does indeed have a small transformer mounted on the speaker frame. I'm guessing this is more accurately an electro-magnet, not a real magnet. The code on the transformer mounted to the speaker frame is 711-66004-1. The hookup going to the amp has several wires with a big phenolic plug that looks a lot like a tube base.

I've seen Princeton amps guts in amps before and the transformer in this thing would dwarf them. In fact, it's not much smaller physically than the main PT in my SF Twin, bigger than the one in my HRDx. Since it ran the amp in the hi-fi as well as an AM-FM-SW receiver + the turntable, I'm guessing it'll power a small guitar amp just fine. If size matters in iron, this thing should have some real whollop!

I've seen the schematics and layouts of the various clones at the Weber website, but I'm not familiar with all the individual revisions they go by. One I saw looks very promising with my parts, a 5C1A - that would be a Champ? That particular layout & schematic at Weber @ https://taweber.powweb.com/store/5c1_layout.jpg and https://taweber.powweb.com/store/5c1_schem.jpg has no tone control, but uses both the 6V6gt and 6SJ7 I have here. The similar build at https://taweber.powweb.com/store/5f2a_layout.jpg has a tone control and it looks very simple. The Weber schematic also has instructions for using the 5Y3gt rectifier (which I have in my 'score pile') so it looks like I have pretty much everything I need for the big stuff - all from a junked hi-fi. Sweet!

I'll be pestering you all for more stuff as the tear down and subsequent build progresses. I also belong to a loose 'club' of sorts called the Madison Area Amp & Effect Builders Club. I'm sure they're gonna get sick of me in the next couple months. ;D

I'm thinking my first project should be to pull the PT and see what it actually puts out on each winding. If it's no good, I don't have much of an amp here.

Cheers,
- JJ