Using JC LeMay’s 11 sample calculators will help you solve conversion riddles regularly encountered in music-making and sound design
by Jon Chappell
Quick, what’s the delay, in samples, for a guitar sound hitting a mic that’s touching the speaker cabinet grille compared to the ambient mic that’s placed 30 feet away? Even if you know that sound travels roughly one foot per millisecond (because you’ve learned that sound travels 1,100 feet per second), it still takes you some time to wrap your head around converting milliseconds to samples. Not to mention multiplying two double-digit numbers.
That’s where calculators come in. It’s not because you can’t do the math, it’s just that it’s too time-consuming. Understanding the concepts are important, but once you do, you don’t need to do everything laboriously and manually. That’s why we have power tools, even if we’re experienced carpenters and mechanics. We know what we want to cut or fasten, and the decision is left to us, but we let our tools do the legwork.
And so it goes for computing music and sound. It’s all based on physics: Musical tones are frequencies, which are standardized (e.g., the A above middle C is 440 Hz) and measurable. Frequencies are sound, which has a fixed rate of speed (assuming normal atmospheric conditions). There is a relationship between pitch and frequency and EQ and frequency (such as 100 Hz and 10kHz). There is a relationship to tempo (measured in beats per minute on your metronome, DAW or drum machine) and absolute time, which is measured in minutes, seconds and milliseconds. Music is sound, music is frequency, and music occurs over measurable time. Just like electricity needs both voltage and current to be realized into power (which includes time), so does music need frequency and time.
But music and sound are also convertible, and going from samples to milliseconds and vice-versa comes up all the time for live and recorded sound situations.
For example, calculating the delay time parameter on a digital delay to produce a certain rhythmic effect requires that you know both tempo and milliseconds. If your tempo is q=120 (or 120 beats per minute), and you want to set your delay to spit bit eighth-note triplets for every quarter note you play, you have to do some calculating. In this case, a quarter note comes twice a second (so that in a minute’s time—60 seconds—you’ve racked up 120 of them). That’s 0.5 seconds or one every 500 milliseconds. If you divide that by 3, you’ll get 0.167. That’s the millisecond readout you’ll dial in to your delay time to produce three evenly spaced triplets within a .500 frequency (quarter note).
If this all sounds like too much work, well, it is. That’s why many delays now include onboard “calculators that simply give you a setting that reads: q=8, q=8(x3), q=16, etc. Look how the TC Electronic Nova Repeater handles it (Fig. 1):
Fig. 1. TC Electronic's Nova Repeater does the onboard calculating of tempo to milliseconds for you, offering you the results in musical terms.
That’s just one of many calculations that you can use to solve compositional and arranging problems.
A great resource that will help with this and other useful conversions is found on the Deep Sound website by JC LeMay. Actually, LeMay has assembled a single web page with 11 different calculators for sample rates and lengths, bpm and tempo, time-stretching and pitch-shifting, beats and measures, transposing, drum loops, and other musical uses (see Fig. 2).
Fig. 2. JC LeMay offers several different calculators, depending on the musical conversion task at hand.
What I like are the detaield text explanations on why you would a particular calculator. In fact, you might get a musical idea just by reading the description. It wouldn't be the first time a tool inspired a vision (rather than the other way around--having a vision and employing a tool to realize it).
Since these calculators are web-based, as long as you have an internet connection, you can calculate any of the little conversion riddles encountered in your music-making. Bookmark it in your browser and on your mobile device’s home page.
And by the way, the answer to the opening riddle is 1,323 samples. That’s 30 feet times 44.1 samples, and the amount of delay between the close-miked signal and the distant-miked signal. Go figure—er, calculate.
Jon Chappell is a guitarist and the Senior Editor of Harmony Central. He has contributed numerous musical pieces to film and TV, including Northern Exposure, Walker, Texas Ranger, All My Children, and the feature film Bleeding Hearts, directed by actor-dancer Gregory Hines. He is the author of The Recording Guitarist: A Guide for Home and Studio (Hal Leonard), Essential Scales & Modes (Backbeat Books), and Build Your Own PC Recording Studio (McGraw-Hill), and has written six books in the popular Dummies series (Wiley Publishing).