Analog/Digital DAW Synergy Roundup

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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.

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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.

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.

  • 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.
  • 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.
  • Patch the audio interface output fed by the bus to your external hardware''s input.
  • Patch the external hardware''s output to an unused audio interface input.
  • 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.
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Not Just Virtual Tape—A Virtual Tape Machine

Did people like analog tape recorders because of tape stretch, alignment issues, head wear, window splices, demagnetizing, rewind/fast forward times, high-frequency self-erasure, head “bump,” wow, flutter, oxide sheds, and replacing capstan motors? No. They liked analog tape recorders because tape is a signal processor. For proof, feed in a sine wave higher than -–20dB, and listen—yes, you''re hearing distortion that only increases as you hit the tape harder.

So now Universal Audio, keepers of analog mojo in a digital world, have done the right thing by divorcing the sound of tape from the mechanics of tape—I didn''t have to clean the plug-in''s heads once!

First, does it sound like tape? Second, what kind of tape does it sound like, how was the deck calibrated, what was the tape speed, was the bias tweaked for minimum distortion or minimum noise, etc.? To that end, UA has modeled the recorder''s entire signal path, and includes adjustments for both the repro and sync head high/low EQ, bias, high-frequency EQ (pre-emphasis), NAB or CCIR response curve for 7.5 and 15ips (30ips invokes the standard AES curve), and the option to add hum and/or hiss.

The front panel includes controls for tape formulation (four types, including 3M 250 and Ampex 456), IPS (7.5, 15, and 30), tape calibration standard (four choices, from +3dB to +9dB), and input/output controls to trim the distortion. Interestingly, there''s a button to calibrate these according to Studer''s original specs as you change tape speed, formulation, or EQ, but half the fun is tweaking the trims yourself. You can even switch the “input” among bypass, input electronics, sync head, and repro (playback) head.

A new option, “Gang Controls,” is brilliant. UA presumes you''ll be instantiating a lot of A800s within a project (however, an equally valid application is eschewing multitrack and inserting the A800 in the master bus to give the sound of mixing to tape) so when you adjust any control in any instance, the same control in all other instances matches the new value.

Having logged multiple thousands of hours with multitrack analog tape, and knowing how to align and calibrate them, I was curious if UA “got it right.” Simply stated, they did. Bull''s-eye.

But remember that this requires a UAD-2 DSP board (or the Satellite external DSP farm for the Mac)—sorry, UAD-1 owners. The latency also seems significant, but as I see this mostly for mixing, it isn''t much of a problem.

Universal Audio has specialized in imparting analog qualities to digital audio with their plug-ins. Their projects have become increasingly ambitious (e.g., Manley Massive Passive), and the A800 is arguably their most ambitious yet. What makes this emulation particularly successful is because it''s not just about the tape—but gives equal weight to the elements accompanying it.

TIP: Tape Sound With Real Tape
So maybe you can''t afford a 2-inch 24-track just to get “the tape sound.” Although there are some fine tape emulation plug-ins (such as the Universal Audio Studer A800 reviewed in this issue), if you don''t want anything but the real deal, here''s how to get reel—I mean, real—tape sound.

  • Comb the online classifieds for a two-track recorder with separate record and playback heads.
  • Find tape for said recorder.
  • Read “The DAW/Hardware Connection” section above to find out how to treat the tape recorder as an external effect.
  • Send the signal you want to “tape-ify” into the recorder input.
  • Set the recorder output to monitor the playback head (i.e., repro mode, not sync mode).
  • Load tape, put the recorder in record mode, and roll tape.
  • While listening to the tape recorder output, set the input record levels for the desired amount of “crunch.”
  • Once levels are set as desired, return to the track''s beginning, and start recording the tape recorder output into a DAW track.

As mentioned regarding using external hardware with DAWs, you''ll get latency—but it''s the mother of all latency, due to the delay between the point when the signal gets recorded at the record head and the point when it moves past the playback head. This varies from machine to machine, but it will likely be below 100ms at 15 ips. You''ll need to slide the recorded track from the tape output forward in time by this amount of delay to have it line up with the other tracks. As mentioned previously, a click reference can be tremendously helpful.

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Tubes Meet Code—And Audio Wins

Everyone knows that tubes add “something” to a signal, especially when overdriven. It''s not just about distortion, but a complex combination of the Miller effect (an electronic phenomenon that affects high frequencies), a natural sort of compression, and a unique input/output transfer curve.

Deluxe Buffer2 was created to give the designer''s Line 6 POD a bit more of that tube “oomph,” which it does. In a way, it''s “sonic caulking” that fills in some of the holes of purely digital signals. The circuit is textbook basic, with no input or output transformers (part of the “tube sound” in some pieces of gear); what you get is purist tube processing.

However as the online audio examples show, saturation is good for far more than guitar processing and re-amping—like roughing up the sound of a tonewheel organ. As another example, I set up a drum loop from the Discrete Drums library in Sonar, and used the External Insert option to insert the Deluxe Buffer2 as a “hardware plug-in.” The biggest advantage of this approach is that you can trim the level going into the Deluxe Buffer2 to tailor the amount of distortion, then boost (if needed) on the way out to maintain unity gain. There was definitely a “sweet spot” with drums that gave punch without losing detail—in my setup, this happened when I dropped the input by about 7dB. Pushing it to 0 gave a much crunchier sound: If the first sound was vintage R&B, the second was punk.

Just for kicks, I also used Sonar''s “Tube Leveler” plug-in, tried to match characteristics as closely as possible, and compared the results (also included in the online audio examples). Frankly, the Tube Leveler does an amazingly credible tube emulation—yet I could still hear quantitative differences between the two. These were most apparent with lower input levels; heavier distortion minimized any differences.

Construction uses point-to-point wiring, to the extreme that some parts are supported only by their own leads, rather than being soldered to lugs on terminal strips. In a studio context this wouldn''t be an issue, but I''d be concerned about subjecting it to the rigors of serious road travel. Besides, you want to keep it in your studio—clients will love the “future retro” look. Also note that the internal power supply (no wall wart!) uses a toroidal transformer, which minimizes hum.

Deluxe Buffer2 isn''t cheap, but it adds that boutique preamp vibe and sound to your studio. Granted, there are plenty of other ways to insert a tube in the signal path—and some DSP-based emulations, while perhaps not exactly the same, are extremely close to the “real thing.” But when only real tubes will do, Deluxe Buffer2 is a simple, classic design that works its particular magic on many more sounds than just PODs.

TIP: Physical Tubes Meet Virtual Cabs
You love your guitar amp…we understand. There''s something about a glowing tube pushing a speaker that has a certain magical quality, but what happens when you want to split off to a different cabinet, create some nifty stereo imaging, or even run your bass into an 8x10 bass cab that you don''t have?

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Fig. 2 Waves'' GTR has been edited to bypass the preamp/amp section, while leaving the stereo cabinet module active, in order to apply the virtual cabinet to a physical preamp''s signal.

Unless you have unlimited physical cabinets, amp sims are a great answer if your tube amp has an effects loop. The loop send will be post-preamp, but pre-power amp; patch the send into your computer''s audio interface, route the input to your guitar sim, and bypass the sim''s preamp so that the amp send goes directly into the simulated power amp and speaker combination (Figure 2). From here on, the sky''s the limit: Feed multiple cabs, spread them in stereo, use a bass cab for bass—you get the idea.

Even better, plugging into the send doesn''t interrupt the signal flow with most effects loops, so you''ll be able to mike the cabinet while you''re feeding the amp sim. There may be some timing issues, as the miked sound will be a little delayed compared to the direct sound because the mic is a finite distance from the speaker. Nudging the sim sound a bit later in time can solve this; delay it in tiny increments until it sounds “right.”

The same principle can work in reverse: Use the amp sim''s effects and preamp, but feed the out into a beefy power amp/cabinet, and mike it.

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A Virtual Vibrato Tailpiece? Yes, But It's More Than That

Pitch-shifting guitar signals isn''t new; just ask anyone who bought a DigiTech Whammy pedal ten years ago. But time marches on, technology improves, and DSP gets faster and more accurate—which brings us to the Bomber, a truly polyphonic (yes, you can play chords), pedal-controlled pitch shifter.

Some guitars, like a Fender Strat, are born with a vibrato tailpiece while others, like Gibson''s Les Paul, aren''t. But now, thanks to the Bomber, all of my guitars have a vibrato tailpiece—it not only bends up and down, but is actually more like the electronic equivalent of Ned Steinberger''s TransTrem, which provides an equivalent amount of pitch shift for each string.

The rear panel has ¼-inch phone input and output jacks, a control for setting levels, and a mini-USB port to allow for updating the pedal software. A wall wart provides power.

On the top panel, a sturdy, substantial pedal presents a decent-sized target. One footswitch handles bypass, while another selects the pitch-shift interval (down is 2nd, 4th, 5th, octave, two octaves, and “dive bomb”; up is 4th, 5th, octave, and two octaves). There''s no “shortcut” to step through the intervals, but you don''t have to hit the footswitch repeatedly—if you hold down the footswitch, the pedal cycles through the intervals. When it lands on the desired interval, release the footswitch.

But not this one, which is why it''s being reviewed. Of course, the less transposition, the more realistic the sound; I found pitching two octaves up useful only for sweeping—you wouldn''t want to leave it there and just play. However, as long as you stay within an octave, the sound quality holds up.

There are two catches, though. The reason why the Bomber works so well with guitar is because it''s optimized specifically for guitar—although bass worked reasonably well if I played high on the neck, anything else I tried through the Bomber, particularly if it had high-frequency content, sounded as bad as the guitar sounded good.

The other caution is that the Bomber needs to precede any effects. Bomber through distortion sounded fabulous; distortion through Bomber didn''t.

In the studio, matters get even more interesting—this box isn''t just about playing live. I split my guitar into two DAW channels, one with an external insert feeding the Bomber followed by AmpliTube 3, and the other channel going through only AmpliTube 3, set for the same program. The two paralleled tracks sounded almost identical—except, of course, the one with the external insert could do all the pedal dive-bombing tricks. Playing the two against the other allowed seriously novel effects—I could do things like play guitar, then magically slide chords down an octave against the straight track.

If you don''t play guitar or bass, forget about Bomber. But if you do, you''ll get quality, polyphonic pitch-shifting that''s happy to feed effects racks, be paralleled with other effects, and turn your pitch into a rubber band.