I've always wondered what resonator guitars were all about, so when my friend Peter told me he was thinking of buying one, I asked him to explain. This is what he said: "Remember that crappy Epiphone Airstream Guitar you had? Well, if Airstream had ever built a guitar it would really have looked like this National Tricone - which was first produced in 1927, with an all-metal body and Chrysler building styling.
Before electric guitars, resonators were the loudest guitars you could buy.
The tricone has three metal speaker cones (resonators) inside instead of the usual soundhole - like the one on the right, which goes under the bridge. They give that metallic, buzzy slide sound associated with Son House and the other Delta Bluesmen. These days, resonators walk a tightrope between redneck naff (yes, they’re used by Country players and yes there was one on the front of 'Brothers In Arms') and blues cool, but I'm going to shell out sooner or later.
Alternatively, if you can't afford £1000 or so to buy a classic National like this and you're happy to cut holes in your favourite acoustic, you can buy a resonator conversion kit on eBay. Alternatively, cheap resonator copies cost from £150 upwards."
Thanks Peter. One thing I noticed is that some of these guitars are designed to be played in the lap, so have unfinished square necks - so if you're bidding on eBay, make sure you know which you're getting...