Dallas Taylor (Twenty Thousand Hertz) just dropped another fantastic video, “How Hamilton Is Mixed Live on Broadway,” with Justin Rathbun, Hamilton’s front-of-house sound engineer at the Richard Rodgers Theatre. Rathbun, who’s been with Hamilton for ten and a half years, details the show’s incredibly complex audio setup, from the board programming to the speakers.

(One amusing detail: the El Gato Stream Deck used to control the 14-plus computers has a bank of buttons with various messages programmed in. Along with the expected responses (“OK,” “Copy that,” “LOL”) was “I need a drink.” I chuckled.)

Two things blew my mind.

One was line-by-line mixing. Rathbun raises and lowers faders on a per-line basis to hide breaths, eliminate cross-mic pickup, and “keep the sound as clean as possible.” It requires deep familiarity with the show and the performers, along with intense concentration to adjust in the moment to minute performance changes. Seeing Rathbun’s fingers flit across the mixing console was like watching a virtuoso musician at work.

The second was cue-based audio delays. To start, millisecond delays are introduced into the audio output to ensure aural consistency throughout the theatre, explains Rathbun:

Our approach is that the sound coming off the stage should arrive at the seat at the same time as the sound from the speakers is also arriving at the seat.

These delays are needed to account for the speed of sound. Pretty standard fare in professional theatre productions. Then things get wild:

In addition to that, we are also using channel delay during the show on a per-cue basis. We are changing the delays on every particular microphone, depending on where they are on stage.

So for instance, we can look at “Hamilton A” and we can look at our delay time, right? So right now he is at a 5-millisecond delay time; so he’s up stage standing behind the chair; when he walks down stage—so I have a cue here that says “Ham sits”—he will walk down stage literally two and a half feet, and this delay time is now going to change to “2”; we wanted to get the same timing between what’s coming out of his mouth and what’s hitting the audience at the same time. We have timed it out to that close.

Rathbun’s pride in this level of detail is quite evident—and deservedly so.

This is the latest in Taylor’s Hamilton sound series, and they continue to delight me.

See Also: “Where Hamilton hides its mics,” featuring Anna-Lee Craig, the show’s A2, who “walks through the signal chain from transmitter to mixing console, the transition from head-worn mics to booms for the women’s ensemble, and what it means to be the mechanic changing wheels while the bus keeps rolling.”