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Amplitude Modulation

I recently purchased a Sangean HDR-141 compact HD Radio receiver after the local station that broadcasts baseball decided to move their AM/MW2 station (and most of their FM stations) exclusively to digital HD Radio broadcasts. In their announcement, they established that the time was right now that 20% of their audience was equipped to listen. That’s… an astonishingly low percentage, especially given that the technology was approved as the U.S. digital radio broadcast format over fifteen years ago. I, myself, was able to find one acquaintance capable of receiving HD Radio (in their car), and this receiver only handled FM.

Adoption has seemingly been low in the other direction as well. Though the airwaves near me seem flooded with broadcasts, the only HD Radio content is coming from the aforementioned station. Part of this is almost certainly because the standard itself is patent-encumbered bullshit from iBiquity3 instead of an open standard. Transmitting requires not only the encoder, but licensing fees directly to iBiquity. The public-facing language is very vague on the HD Radio website, but receivers also need to license the tech and I imagine if this was free they’d make a point of it (and there’d be more than three portable HD Radio receivers on the market).


The Classic Sound of the Moog Ladder Filter (external)

Great little article from nearly a decade ago about Robert Moog’s filter that shaped the sound of synthesizer music. Oddly enough, while the article mentions some of the Moog module’s prices, it doesn’t actually mention the price of the ladder filter. Having been researching lately exactly what Tangerine Dream would have been working with at any given moment on Phaedra, I happen to have the 1969 Moog price list (PDF) in front of me – $730 for the full-fledged 904 Voltage-Controlled Filter. That’s about $4,900 dollars today, nearly ten times as much as Moog’s current ladder filter. Bonus link: Robert Moog’s patent number 3,475,623: Electronic High-pass and Low-pass filters employing the base to emitter diode resistance of bi-polar transistors (PDF).


Field recording with the Tascam GT-R1

Field recording of found sounds is a rather crucial aspect of the sort of sound design that interests me. Diving deep enough into this area, one will inevitably wish to experiment with contact microphones. Contact microphones are unlike ‘normal’ microphones in that they don’t really respond to air vibrations. But they are quite good at picking up the vibrations of solids (or, in the case of sealed hydrophones, liquids) that they’re attached to. This is a lot of fun, but there’s one problem – due to an impedance mismatch, they aren’t going to sound very good when connected to a normal microphone input. Compare this matched recording with this recording from a standard mic input.

The typical solution will be to go through a DI box or dedicated preamp. For a portable, minimal setup, this is far from ideal. I figured at some point, someone would have had to have come up with a portable recorder designed with sound design in mind, and containing inputs suitable for a range of microphones. I came up empty-handed. Then it occurred to me, this is really the same problem that guitar pickups have – they need a high impedance (Hi-Z) input for proper frequency range reproduction. Perhaps a portable recorder for guitarists exists. It does, and let me just say that the Tascam GT-R1 makes an awesome little field recorder.