40’s National: Dobro Enters the Resto Dojo

[Luthier Vandros]

Here’s the beginning. What am I getting myself into here? The owner bought this with the matching lap steel. he was nice enough to Kick the rats out and give her a cursory cleaning, so I’m grateful. This will either be a massive money pit/stalled project or one cool Resto.

 

[Luthier Vandros]

Whoa momma. This may be a ‘42 Concert Model 400. Looks like it has two preamp circuits. The mic channel looks grid biased.

 

[ce24]

Keep us informed….cool amp.

 

[Dan German]

 

[Telekarster]

I love these old National amps! Kickin' myself for not pickin' a couple up back in the day. Good luck on it man! Looking forward to how it turns out!

 

[Luthier Vandros]

Thank you! Owner said he was able to play it until the power cord crumbled lol! I’ve been able to bring back the color in the cloth covered wiring within the chassis, but the harness that connects the field coil speaker to it will take some work. I’m really grateful to be able to do this kind of work. This amp is super interesting and, aside from a few radio restos, is the oldest guitar/mic amp I’ve had on the bench. Really humbled.

I love these old National amps! Kickin' myself for not pickin' a couple up back in the day. Good luck on it man! Looking forward to how it turns out!

 

[ce24]

This is a webster chicago 1949 5 w. Amp i restored…..great sounding little amp.

 

[Luthier Vandros]

This is a webster chicago 1949 5 w. Amp i restored…..great sounding little amp.

THAT is a really cool amp!

 

[Luthier Vandros]

The only source of info on this amp I've been able to find: http://judyboxamp.blogspot.com/2012/02/overhauling-national-dobro-mystery-amp.html

 

[Jon Snell]

I had one in for restoration a few years ago;
The guitar pre amp, pentode, is wired as a triode and the mic is pentode for extra gain.
Here is a copy of the controls and catalogue page.
Strange how one never forgets the colour code of solid carbon resistors from a long time ago.

 

[Luthier Vandros]

Good progress today. Waiting on one cap can and have to whip up a power cord, then I can test. All the caps tested as either shorts or were almost double their uf ratings.

 

[Luthier Vandros]

Update: Amp sounds stellar through the mic input, as usual! Almost no background noise after revising grounding scheme. Cheers!