1957 National Dynamic Archtop Electric Mandocello Conversion

April 05, 2017

1957 National Dynamic Archtop Electric Mandocello Conversion

A customer of mine had begun lusting for an acoustic mandocello -- and an electric one. We discussed options, realities, prices, conversion problems, and also what was really needed. The instrument in question would be used in studio and the selling point of a mandocello is its low-end paired courses, so we boiled the desires down to an "easy modification" -- a mandocello minus its top A string course -- just 6 strings. That means just about any guitar (within reason) can be used. I'd been chatting with him about how I like the old National Stylist necks, and he spied this Kay-bodied National archtop on the web, bought it, and sent it here.

This guitar probably started out as a National Dynamic electric with a pickguard-loaded pickup, volume, and tone controls... though that was all missing when this arrived. The '56 Dynamics had the electronics installed that way but the '57 ones I've seen had them installed on the body. I'm guessing that this one was either an early '57 or very late '56. The serial says '57, though, per the usual lists. The body is Kay-supplied and entirely ply -- though they used thin stuff and, acoustically, they don't sound too shabby.

Bracing was loose and the frets needed a level/dress, but after that the "conversion" was pretty simple -- a new saddle for the adjustable bridge, a new bone nut, and general setup work. Since the body was never cut for a pickup or controls, I had to also cut a hole for the new Alnico-magnet P90 pickup and drill holes for the volume and tone controls. A new Switchcraft jack sticks out of the side and vintage-ish chickenhead knobs complete the 1950s look.

The mic placement for the acoustic section in the above clip, by the way, is in front of the bass-side f-hole. I find that's usually the best placement for an archtop as it doesn't block my arm from playing properly.

Check out those strings! I wanted the C to sound really good, so the gauges are nickel-wound 70w, 38w, 28w -- taken from a double set of GHS baritone guitar strings. I have it tuned to an open CGC in the soundclip, but CGD for fifths voicing would also be just fine.

The frets are smallish and low -- per normal practice for Nationals at the time. I lucked-out on the neck shape, too, because this has a medium-sized C/V hybrid shape to the rear but a 1 5/8" nut width which makes the string spacing more comfortable. It was actually nice to have a wide nut (for 3 courses) on this instrument because the pairs could be spread farther apart and thus keep them from rattling against one another (something I don't like about most production mandocellos).

The P90 isn't anything fancy but it does sound excellent. The pickup itself is set back from the strings a bit so it sounds a little cleaner than most P90s, though as you hear in the clip -- when driven it has a delicious rumble.