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Analog and Digital DAW Synergy

5/1/2011

Fig. 1
Pro Tools makes it easy to add external hardware: Choose an insert, and tell it which buses you want to use as audio I/O. In this screen shot, a Chapman Stick track is being fed through a Line 6 PODxt via I/O bus 5.

Analog versus digital? That’s so 1999. It’s been said the only rule in recording is that there are no rules, so cast off those prejudices and pick the right tool for the right job.

SOME PEOPLE still debate analog vs. digital, but the realists have moved past that— their only debate now is, which analog to combine with which digital. The answer can be as simple as capturing to tape to take advantage of its particular “sound,” then immediately transferring the tracks to a digital system before tape wear, stretching, or other gremlins start their inevitable attack.

Or the answer might be more complex, where a studio becomes a case study in “mix and match.” Most DAWs let you insert external hardware as inserts, just as you would use a plug-in; you can even insert a tape recorder, and process the audio through that. But if you don’t have a tape recorder to get “that” tape sound, then maybe a tape emulation plug-in is just the ticket—why not take advantage of the manufacturers who’ve probed, prodded, and analyzed to find out the essence of analog mojo? And while it’s hard to find something more analog than a great guitar, you might want to use sophisticated digital pitch-shifting to add a “virtual vibrato tailpiece” to that vintage Les Paul you would never modify.

So yes, cast those prejudices aside and pick the right tool for your needs. Which tools, you say? Keep reading—we’ll review some gear that offers analog/digital synergy, as well as provide some useful tips.

TIP The DAW/ Hardware Connection

Everyone has a favorite piece of analog hardware— that classic vocoder, a tube preamp, a dust-encrusted wah pedal. These can all be productive members of your digital world if you have an audio interface with some spare audio ins and outs.

Many modern DAWs simplify the process of adding external hardware either by including “dummy plug-ins” that act like effects plug-ins but route audio from your DAW to an audio interface output, or by letting you specify audio buses within an insert (Figure 1). But really, any DAW with aux buses can do the job—here’s how.

1. Create a bus that feeds an unused audio interface output (mono or stereo, depending on your hardware and track requirement). The send to this bus should be pre-fader.

2. Assign the track you want to process to this bus, and turn down the track’s main fader so the unprocessed track doesn’t feed the DAW’s mixer.

3. Patch the audio interface output fed by the bus to your external hardware’s input.

4. Patch the external hardware’s output to an unused audio interface input.

5. Assign an input from your DAW’s mixer to this interface input. This track now carries the sound as processed by your external hardware.

Sounds simple, but there are a few “gotchas.”

• Match levels carefully. If your processor is a guitar stomp box (which is optimized for lower levels), you’ll likely need to cut the bus output level way down, and bring the output back into a mic preamp so you can get enough level going into the DAW.

• Going through extra stages of D/A and A/D conversion will cause a delay. Some DAWs will “ping” the routing, calculate the delay, and compensate by delaying other tracks so that everything lines up.

• Record a click if there’s no automatic way to compensate for delays. Simultaneously record a single, sharp click (e.g., clave) to a track that’s not being processed and to the track that’s going to be processed. Record the processed sound to a track rather than using the effect in real time (a good idea anyway, as once recorded you’ve freed up those interface ins and outs), then line up the clicks on playback.