Need Help Identifying This One

[Kasanay]

Hello,
I picked this amp up a few months ago and noticed it has no ID marking on it.



Id like to take a crack at restoring/ rebuilding this. The tubes are: 35Z5GT, 12AV6, 12AU6 and 50L6.
The closest I can find is an Alamo Fiesta or Alamo Capri.

Any help would be greatly appreciated.


Thanks,
Joe Y

[Steve A.]

Looking at the tube numbers I'd guess that the filaments are wired in series to 110vac. FWIW the tolex reminds me of Silvertone amps.

[Kasanay]

So, I pulled the guts out of the amp and I found this hand written information inside:

I searched around and found an amp called the Lindell Tremolo Deluxe that looks like a variation of the amp I have. It has the same panel layout and the width and depth dimensions are a match.
Now if I could just find a schematic.

[g1]

Be aware this is what is referred to as a "widow maker" amp and is not considered safe to use without the installation of an isolation transformer.

[The Dude]

Looking at the tube numbers I'd guess that the filaments are wired in series to 110vac.......

Could be. It does look like there might be a PT in there, though. Easy enough to tell. Pull a tube and see if the other filaments still light.

[The Dude]

This might be close. If so, yes- series filaments.

[g1]

If the filaments are on the PT secondary like that then you are fine.
If memory serves, sometimes they have a PT but run the series filaments directly off the line, which I still consider a safety issue, even if it's not exactly a widow maker.

[Kasanay]

I'm tracing out the circuit. The filaments are all series wired straight off the mains (35+50+12+12=119).
I'll post a copy when I get it finished up.
Then I'll get after the safety issues and re-capping.

Thanks,
Joe Y

[olddawg]

I'm just curious. Is a 50L6 just like a 6L6 with a 50v filament. Are these amps similar to a Princeton in sound or is the B+ too low? I assume they just use a voltage doubler on the line voltage?

[Justin Thomas]

Nope, 200V plate & 10W dissipation... 35L6 is similar...

Piggers.

Justin

[olddawg]

Nope, 200V plate & 10W dissipation... 35L6 is similar...

Piggers.

Justin

Yeah... I didn't compare the spec sheets. Lazy I guess. It just made me wonder.. for the NOS tube buffs. These line string filament output tubes were in everything from TVs to stereos to table radios in the 50s and early 60s. There's a ton of them out there still for cheap. It wouldn't be terribly difficult to build a safe modern amp using them. Like your 35L6. Half wave rectifier off the line and two filaments in series for a PP amp with DC filaments. Then run everything else off a cheap PT with an applicable 12vac and B+?

[Kasanay]

Thanks for all the great advice!
I have been considering adding a 6.3V transformer and switching to all 6V tubes (6x5GT, 6AV6, 6AU6 and 6W6GT). That way, the existing power transformer would take care of isolating the B+ voltage and the added 6.3V tranny would do the same for the heaters.
Of course I'll still add a fuse and change the cord to a three prong.

I took a shot at drawing up a schematic of the amp (I used Paint). It's a work in progress and I hope to finish it in the next couple days.
Here's a peek:

[g1]

You still have to add a transformer, then change all the tubes over.
Why not just add an isolation transformer and run the entire amp off that?

[Kasanay]

You still have to add a transformer, then change all the tubes over.
Why not just add an isolation transformer and run the entire amp off that?

I haven't decided how I want go with this amp yet. One reason for switching to 6V heaters is because I have a bunch of these tubes (NOS). I also have a 6.3v tranny. So it wouldn't cost anything.
How big of an isolation transformer would I need if I did just add one to drive the amp?

Thanks,
Joe Y

[g1]

Well, if you have all the parts you need, then that's different.

I think a 50VA unit like the triad N-68X would be more than sufficient.