The Danforth Standard Digitrola

I’ve been working on this sculpture for a while at TechShop and at home. It’s taken a long time but I’m finally finished and wanted to share it with you.

Video of it In Action

Here’s my build-journal of sorts.

I started out with a vague idea of making a digital Victrola. I thought about making an iPod dock attached to an old horn but quickly abandoned the idea for a couple of reasons: it’s been done already (!) and it didn’t satisfy my artistic goal. In a nutshell, my artistic goal was to use this piece as a means for abstracting the listener/viewer from time by creating a whole that shouldn’t-be using parts that could-be.

So, as with any build, I sought out my hardware first. I knew that I would have to design the aesthetics of the chamber around the horn hardware. I dragged my son down to High Point to a swap meet organized by the Carolinas Chapter of the Antique Wireless Association. It was February or March and freezing. Luck provided me with a Magnavox radio-speaker horn in decent physical condition but terrible surface condition. I bought it for $20.

A quick proof-of-concept set up and I moved on to the next step: refinishing.

I sandblasted the entire horn and cleaned it up all its original paint. It was sad to see the Magnavox logo go but I was happy that it was going to see new life.

I sent the horn off to Anderson Silver Plating in Indiana. This is a place that specializes in restoring brass instruments so I knew that it would be right up their alley. I elected to have the horn brass-plated on the inside of the bell and lacquered on the back. This isn’t too far distant from the appearance of a period piece, actually. The plating and lacquering process took several months which I used to build the rest of the piece. Lets start with the box.

The box / sound chamber is made of a stunning single piece of Marado (Bolivian Rosewood). This piece is sturdy due to the use of 4/4 stock that I milled down to 3/4”. I made the box using miter joints so that the grain of the wood would flow all the way around seamlessly. This is the same technique that I teach in the Basic Box-Making class at TechShop. For the top I inlaid a solid inch-thick piece of the same Marado for two reasons: to provide a sturdy base for the heavy horn and volume control knob and to provide a solid mounting point for the driver underneath. I didn’t want this piece to reverberate.

Once I discovered the day after building the box that I am DEATHLY allergic to Marado I finished the bottom with home-made walnut molding. Live and learn. It actually looks very attractive and it will darken over time anyway.

Now for the hardware. I decided early on that I wanted the hardware to be very deliberate and ornate. There’s only one thing you can DO on this piece (adjust the volume) so I decided to make the volume knob very weighty and attractive. I have a theory: Quality = Price * Weight. I knew that I had to make the volume knob heavy!

The knob was turned from a solid 2” diameter slab of brass. I faced the top and bottom and then drilled a hole halfway through the middle. Next I milled a brass rod (about 3/4”) very slightly larger than the hole I drilled in the top and squished the two together permanently in the arbor press. Finally I mounted the entire assembly in the lathe again and cut the knurling. Knurling is hard. The very last step was to polish the top so I used my 3M graded-micron polishing paper and oil to give it a mirror finish.

The volume knob’s post was drilled so that I could slide it over the arbor on a volume potentiometer. I had to mill and tap a hole so that I could secure the knob to the potentiometer. No picture, sorry.

The top is thick enough that I could have just crammed the horn into a hole and had it stand up straight. I didn’t like the transition very much though. I tracked down a cast-brass door knob escutcheon ring at House of Antique Hardware in Oregon. This piece only had a 21/32” collar so I had to expand it to fit my horn. Back to the lathe!

The last piece of hardware to make was the brass bushing for the power cable. I made that on the lathe out of a 3/4” piece of brass rod.

Once the box was assembled and fitted I installed the guts: a Gilderfluke SD-25 MP3 playback board / digital amp, driver, and a volume control potentiometer. I created a walnut standoff for the driver and laser-cut a cork gasket to install the driver directly beneath the hole for the horn. The walnut box and gasket ensure that the maximum amount of sound energy is focused out of the horn rather than into the box.

I visited my friend Tom (The Radiomonger) at his workshop hoping to score some vintage fabric-wrapped wire. It used to be that copper wire was insulated with cloth and I think that this is really attractive. I wired all of the audio wiring using this wire but opted to use modern teflon-jacketed (and cloth covered) wire for the power connection.

So there you have it… The Danforth Standard Digitrola.

Complete Flickr Set
Now I’m going to make an HDTV. I just ordered the LCD screen. :-D

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