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.

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.

Aside from the (14″ TS) Hi-Z input, the GT-R1 has a built-in stereo mic pair, a 18″ TRS mic input with optional ~2.2V plug-in power, and a 18″ TRS line input. The mic preamp has three levels of gain available, and both the mic and Hi-Z inputs are attenuated by means of an analog dial on the side of the unit. The built in mic pair sounds good and is quite sensitive. Gain on the Hi-Z input could stand to be a bit higher for contact mic purposes, and all inputs could stand to be a bit cleaner, but these are rather trivial compromises for such a versatile handheld recorder.

For the most part, the UI is very easily and intuitively navigated. A large record button is surrounded by a red LED ring that blinks upon first press to indicate that the recorder is armed, and then of course goes solid as the second press begins recording. Input switching requires a hop into a menu, where related settings (gain, mic power, monitor) also conveniently live. Unlike Tascam’s current multitrackers, audio is recorded directly as WAV files onto the SD card – no clunky export process. Likewise, if I edit any of these files on my computer and save them back onto the card, the GT-R1 will play whatever WAVs are tossed on the card1.

Speaking of multitracking, since this thing exists to casually record guitar sessions, it actually has a minimalist multitracking ability. Once the recorder is armed, the user can opt to start a blank recording or overdub the active recording. These overdubs go into new files, the active file is not overwritten. I’m not sure I’ll ever really need to use this, but it’s neat that it’s there and easily accessed. Another neat guitar-centric tool belied by the device’s voice-recorder appearance is looped playback with custom in/out points. Points are easily set during playback (for precision) or while paused, and then playback will loop until the points are cleared. Aside from a rhythm section and some basic effects that I’ll never use, there is one additional nicety due to the unit’s primary function: the ability to shift playback speed and/or pitch. This combined with the looping affords me a lot of flexibility if I just want to plug the output right into my Eurorack.

Negatives? Well, to start, you’re stuck with that ~2.2V plug-in power mic input – no 48V phantom-powered XLRs here. That’s pretty limiting as far as external mics are concerned, although fortunately there seems to be a bit more of a market for plug-in power mics what with amateur DSLR videography taking off2. The unit is inexplicably bright red, which I guess makes it faster, but not terribly appealing. The biggest drawback, I suppose, is that the GT-R1 has been discontinued, and used prices seem to be all over the place. Any other quibbles are quite minor – the use of mini instead of micro USB, digital monitor level controls, and the somewhat sluggish startup time. Not dealbreakers by any means.

I got my GT-R1 for under $100, which I think was a steal. It’s been serving me really well, and I would pay more if I ever had to to replace it. The two audio samples in the first paragraph were recorded on the GT-R1, in the Hi-Z and mic inputs respectively.