It’s About Time – Notable Productions – 1994

More spring cleaning has unearthed some very dusty music magazines and old photocopies of long since forgotten technical papers from the distant past. This one seemed too good to not share.

“We’ve all heard it said that being in the right place at the right time can make or break a career in music.  Nowhere is this more important than in your musical performances.  The difference between a great player and a good one can often be reduced to timing. Timing is what gives music that special funky flow that people want to groove to.  The error might be as small as a few milliseconds, but those milliseconds determine whether people want to dance or even listen to your music.

When music is rhythmically right, it just feels good.

It’s always been difficult to judge where your rhythms are placed relative to a mechanical click. Or at least for most of us…. Stories of Donald Fagen’s ears perceiving millisecond differences and voicing his disillusionment with MIDI gear are well documented and are what legends are made of. Most producers and engineers I know would love a tool that would show players where they fall relative to the click.

MIDI’s Murky Pathways

The desire for accuracy and the ability to measure it are also crucial in MIDI production. In a studio, there are countless causes of timing delays and errors that affect the music in small and large ways. We are falsely led to believe that when we play something and record it, we will hear that performance played back without rhythmic alteration. Admittedly, MIDI gear is a major perpetrator of these delays.

At the smallest level, MIDI itself can only communicate about one Note On per millisecond. A good sequencer can read the differences in your performance as closely as one millisecond per note.

Practically speaking, however, a serial cable is incapable of sending two notes at the exact same time: one note must follow the other by at least one millisecond. More often than not, you are sending multiple events in the hope that they will play simultaneously, but they don’t. Plus, events scheduled for simultaneous playing will appear one tick apart, in random order. One way to solve the random-order problem is actually to spread simultaneous events by one tick in your sequencer.

So far, we know that the accuracy is hampered by the speed of the serial communication and the quantity of notes simultaneously played. This problem is compounded by other MIDI data communicated at the same time, further slowing this process and making playback even less consistent. Many of you have seen your computer slow down when burdened with many complicated activities. This same problem plagues some sequencers’ metronomes when reproducing a complicated MIDI performance. This can be true for both computer sequencers and drum machines.

The problems don’t stop with sequencers, however. Once our MIDI data has left the serial cables, they arrive at a MIDI interface. These interfaces can create more delays as they translate information from serial to MIDI.

Finally, the data arrives at the MIDI modules. Guess what? More delays! Not only do different modules differ in the speed at which they produce audio from your MIDI data, sounds within a module vary in the time it takes them to be produced.

What’s a Few Milliseconds Between Brothers?

So what do we do about these millisecond differences? And how can we possibly guarantee that two MIDI notes will occur at the exact same time?  Here’s the product pitch: a tool that sent me scurrying to find all the faults with my own production studio.

Jeanius, a company in San Antonio, has provided the recording world with a tool to simplify the judgment and analysis of all these time errors.  It is called the Russian Dragon (RD-R and RD-T), named for its ability to accurately perceive if your audio is “rushin’” ahead or “draggin’” behind a reference source you supply. The idea for the unit came from Audio Engineer/Designer Marius Perron and his drumming brother, who had always wished they had a mechanism to judge how closely he was playing to the sequenced tracks. Marius made the prototype to remove both guesswork from the sessions and tension from not knowing who was right. The unit gave honest feedback to the drummer, the engineer, and the producer.

Description: The Anatomy of the Russian Dragon

The Russian Dragon is available in a small rack-mount version (the RD-R) and a less expensive tabletop version (RD-T). I opted for the rack-mount model.

The RD-R is an uncomplicated single-space rack-mount unit with 1/4-inch inputs on the back and the front.  The top input (channel 1) is used for the reference and the bottom input (channel 2) is used for the other audio event you will judge to be dragging (slow), rushing (fast), or dead on (what Jeanius calls “snake eyes”) relative to the reference.  The unit features an input level control and four LEDs for visual confirmation of audio and amplitude adjustment.  A large row of 25 coloured LEDs indicates the timing differences from a tenth of a millisecond to 99 milliseconds. The LEDs are adjustable in 1-9  millisecond increments  as set by a selector knob marked “ms per LED.”  A trigger LED indicates the presence and duration of the two signals. The duration is adjustable by a “Mask Control.” By increasing the length of the Mask Control, you can eliminate accidental re-triggering of the timing LEDs.  This allows the unit to ignore delay characteristics or extraneous sounds that would make analysis difficult.

A polarity check button for each input ensures that the shape of the transient wave forms start with positive (above the zero crossing point) sections. Polarity is checked for two reasons. First, the sensor that reads the beginning of the audio event is triggered when the signal goes above the zero threshold. So, a signal with a rarefaction at its entrance would not trigger until later in the wave form, when it moved above the zero crossing. Second, two out-of-phase drums, with similar transients, combined and aligned by this unit would produce a cancellation or thinning phase effect, which is probably contrary to the Mother-of-God drum sound you were looking for when you aligned six snare samples.

Testing: Let’s See Who’s Been Naughty or Nice

The minute I took the RD-R out of its box, I wanted to test the delays present in my studio system. It’s as if your ears have been bionically upgraded to distinguish millisecond differences.

Not all of the equipment in my eight-track MIDI studio is spanking new. But since good used gear is widely available, the Russian Dragon is especially valuable because it can measure the accuracy of used as well as new equipment. There is little documentation of MIDI delays in my older pieces (some of which create classic sounds which I still consider vital). Adaptable and precise, the Russian Dragon measures reaction times, consistency, and sync ability in software and hardware sequencers, metronomes, sync boxes, digital delays, and MIDI modules.

What’s the MIDI Module Delay Time?

I wanted to know how long it takes for audio to come out of my MIDI modules when they were programmed to play fully quantized quarter notes in sync with the Macintosh click. You’ll see that the delays range from 1 to 5 milliseconds. Keep in mind these are ideal circumstances – the units are only playing monophonic quarter notes and nothing further is being asked of the sequencer or the MIDI unit. Hardly a realistic challenge, but still there are measurable differences. The differences themselves are inconsistent. I’ve indicated where it varied from note to note by as much as 2 milliseconds. Again, these may seem like small amounts of time. But when added together, they are perceivable and they change randomly.

Device vs.        Device         Mode         Output         Drag (ms)

Mac spkr          Akai S1000           sample mode         mix out         4-5

Mac spkr          Akai S1000         program mode         mix out         5-6

Mac spkr          Akai S900         sample mode         mix out         3

Mac spkr          Akai S900         program mode         mix out         2-3

Mac spkr          Yamaha RX-5         pattern mode         mono out      5

Mac spkr          Yamaha RX-5         pattern mode         rim out         4-5

Mac spkr          Roland TR808         NA         main out         2

Mac spkr          Roland TR808         NA         rim out         1-2

Mac spkr          Emu SP-12 Turbo     sequence mode         mix out         2-4

Mac spkr          Emu SP-12 Turbo     sequence mode         rim out         3-4

Hardware and software-based sequencers were the next subject for analysis. All I really tested was the consistency of the metronomic pulse put out by these units.  Given more time I’d test start inconsistencies and sync influences.

These units also exhibited inconsistencies in their start-up time.We found that the tempo that each called 160 BPM varied — as well as the consistency between quarter notes. As a drummer, I’ve always wondered why some metronomes seemed easier to follow than others.  I often attributed it to how I felt on a given day or the sound of these units. With the Russian Dragon, I learned that metronomes can be as moody as I am. To this end, I tested a more complicated sequence as well as just a quarter note pulse.

The findings are validating for the drummer in me . . . but upsetting for the producer in me. There was an 8.4 millisecond difference between the RX5′s 160 BPM and the SP12′s 160 BPM. The quarter note test showed fairly stable tenth of a millisecond resolutions among the SP12, TR808, and RX5 sequencers. The surprises were the David and Goliath performances of the Macintosh SE/30 with Performer 4.2 and the Boss Dr. Beat metronome. The Macintosh was inconsistent 1 millisecond, and the Dr. Beat held “snake eyes” at better than tenth of a millisecond stability for minutes on end. The Mac and all of the drum machines suffered when many drum parts were added to the playback.

The TR808, an analog drum machine, could not be measured for tempo accuracy because it has no digital readout. Strangely, it was not less consistent when parts were added. But its tempo did slow down. Its determination to be consistent might be attributable to the 16-note resolution capacity of its sequencer.

Conclusion: Everything is Not always on the One

Notable Productions’ timing is kept by Daniel C. Cantor and Mark Weltner, whose mission is to seek out new timing errors and remove them. We’d like to thank Marius Perron at Jeanius for creating the Russian Dragon and providing us with the unit and information. Thanks also to fellow time delay sleuth Robert Poor at Opcode R&D Systems for his box of info and his enthusiasm. Finally Notable owes Kathy Wolff a heap of thanks for her split-second editing.

RD Keith CohenRD Rack

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