Few pieces of vintage audio gear from the turn of the century (the previous one) inspire the kind of devotion that a Leslie speaker does. Sure, there are plenty of pieces that are rarer or more valuable, but the Leslie speaker has such a big following because of its uniqueness of physically moving sound around a room. Two rotating devices in the speaker physically direct the sound around the cabinet with musician-controlled speed, and this sound remains extremely difficult to reproduce faithfully without the moving components. But originals are enormous and meant for organs, so [Eric] built a 40% replica with a few modern touches for his guitar.

The build starts with a CAD model, where [Eric] works towards making the most accurate enclosure for his speaker as possible. The CAD model heads out to a CNC machine which can care most of the details into the wood, and he eventually is able to finish it, although it took a few tries with stains and paintbrushes of various types. For the speakers themselves, he’s using modern versions including modern brushless motors to drive the rotating elements. Like the original speaker, the high range of sound is sent through a rotating set of horns, of which one is only a counterweight, and the low range is directed out of the bottom of the cabinet through a large rotating drum. Both rotating elements here are 3D printed, and with everything put together and wired up [Eric] has a much more portable, faithful recreation of the original Leslie speaker.

There are some upgrades in the wiring too, which makes it work better with a guitar rather than for an organ. It’s also much lighter, and was a hit when he took it to let a few other guitarists to play as well. It’s not the first time we’ve seen the Leslie’s movement recreated for guitar, but it is the most alike to the classic 1930s-era speaker we’ve seen so far.

The Hammond organ is an early form of electronic– or perhaps electromechanical– musical instrument. It solved the very real problem of organs normally being the sort of thing you built into a cathedral, allowing a similar sound to fit into a piano-like form factor. Their workings are a so simple that it’s hard to wrap your head around it actually working– which is why [Uri Tuchman] built one on YouTube. Also for a gift exchange, but we’re not Santa, here– we’re here to learn, and [Uri] does not disappoint.

[Uri]’s organ is a bit smaller than what the Hammond corporation was putting out back in the day, just one hand-cranked octave– and it lacks the distinct spinning speaker in favour of plugging into any old guitar amp. It’s enough to get the idea across. Each of the twelve keys acts as a simple switch, wired to a pickup made from a coil of wire around a steel rod– much like a magnetic pickup on an electric guitar. The pickup faces the tone wheel, which is the part that feels like magic: the tonewheel spinning past the pickup acts exactly like the steel string vibrating in an electric guitar, its ferroelectric motions inducing a tiny current. The tonewheels smooth teeth are spaced to create sine waves at the frequencies corresponding to each key, so it has to be exact. That’s why while the rest of the brass-and-wood build is [Uri]’s beautiful craftsmanship, the iron tonewheels are CNC’d.

Aside from the amp it is plugged into, there are no electronics here. There’s nothing to double or otherwise alter the frequencies: one key means one tonewheel– twelve for this build– and if the RPMs are off everything is out of tune. Good thing [Uri] made it hand-cranked! Well, it is for a gift exchange. Maybe it’s a white elephant sort of thing, because we can only imagine that making it much harder to play. On the other hand, [Uri] demonstrates some neat effects by varying the RPM at the end of the video, so perhaps that’s a feature.

As nice as [Uri]’s work is, Hammond Organ Company filmed the construction themselves, back in the day if you want to see the true quill. Alternatively, you can get more of [Uri]’s craftsmanship with this square guitar.