Tony Visconti, Brooklyn-native, has been a fairly constant presence behind the glass of Bowie's work records among others. He's produced, mixed, engineered and / or played on the following Bowie records: "Diamond Dogs" (1974)," Young Americans" (1975), ""Heroes"" (1977), "Low" (1977), "Lodger" (1979), "Scary Monsters (and Super Creeps)" (1980) "Heathen" (2002), and "Reality" (2003). And of course, he mixed (some of) Iggy's "The Idiot", which Bowie produced.
In email exchanges with Visconti where I have asked about some of the details from the Idiot sessions he's been kind to reply, but cannot recall the details of what the gear he used, which is understandable. However, he also stated, "I use the same gear as all engineers do, the same mics, pres, consoles, etc. The way I use them is really my own business." My first reaction was puzzlement, "Why would someone protect some recording technique that is over 30 years old?". Well, back in 1977 after the release of "Low" engineers were clamoring to figure out what Visconti had wrought, and he wasn't telling then either.
Visconti's main secret behind the sounds of "Low" and "The Idiot" lies in the Eventide Harmonizer. I should say this is also a success for Thibault because he states that the Château was the first studio in Europe to have an Eventide Harmonizer. [Memories are fuzzy, we may never know who used it first and where] The Harmonizer is a real-time pitch-shifting device that one would typically use to fabricate vocal harmonies. In the hands of Bowie, Visconti and Thibault this device was used to pitch drum sounds DOWN. It's effect is more pronounced on "Low" but can be heard on "The Idiot" as well (remember both albums were recorded pretty much simultaneously at the same studio).
Here's Visconti talking about the Harmonizer in the context of the "Low" sessions:
Before we recorded the first piece, I had to get sounds from each instrument, and in the case of the drums, one for each drum. I immediately set up my Harmonizer and decided to use one of the coolest tricks I’d discovered before I’d left London. I sent a feed from the snare drum mic to the Harmonizer, I dropped the pitch by a semi-tone, and then I added feedback of this sound to itself. In simple terms it means a very deep snare sound that keeps cascading downwards in pitch; the initial impact had the ‘crack’ but then the ‘thud’ never seemed to stop, and, not only did it go on at length, but it got deeper and deeper in pitch, kind of like the sound a man makes when he gets punched in the stomach – ‘ugh’. Everyone was amazed.
David scratched his head and said, ‘I agree it’s an amazing effect, but I’m dubious whether we’ll use it.’ But as we grew more familiar with it – we eventually loved it. Of course, it made the final cut and it has since been regarded as one of the most revolutionary drum sounds ever created.
The harmonizer's effect can be heard quite clearly on "Funtime" where the snare sounds like a descending "Dush" sound.
The Eventide Harmonizer was designed by Eventide's Anthony Agnello. The Harmonizer H910 offered pitch shifting (±1 octave), delay (up to 112.5 ms), feedback regeneration and more from a $1,600 box. Users found all sorts of applications, ranging from regenerative arpeggios to bizarre sound design effects to lush guitar or vocal fattening. The first customer—New York City’s Channel 5—immediately put an H910 to work, downward pitch shifting “I Love Lucy” reruns that were sped up to squeeze in more commercials.
Frank Zappa put one in his guitar rack. Engineer Tony Platt used it for the memorable snare sounds on AC/DC's Back in Black. Eddie Van Halen had a pair (set to either 18-cents sharp and 18-cents flat with a 12ms delay on one side or +12c/-15c/18ms) as part of his trademark guitar sound. Tom Lord-Alge’s setup for Steve Winwood’s soulful vocals on “Back in the High Life” also employed two slightly detuned H910s (one sharp/one flat) with an 18ms spread. The twin Harmonizer effect was so popular that Eventide recreated it as the “Dual 910” program in the H3000 UltraHarmonizer that followed it a dozen years later.