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Waves TRACT Plug-in

by Steve LaCerra • in
  • May 2019
  • Road Tests
• Created: May 8, 2019

Waves’ TRACT (Time and Response Auto Correction Tool) plug-in is designed to facilitate sound system tuning and alignment. Do we really need another audio analysis program? Well, TRACT is not your typical analysis software. It works in conjunction with Rational Acoustics‘ (rationalacoustics.com) industry-standard Smaart software. Smaart performs the audio measurements. TRACT imports the measured data from Smaart in real-time, captures the data, analyzes it and generates a FIR correction curve. TRACT can be used with Waves MultiRack and StudioRack (Native or SoundGrid), eMotion ST or LV1 mixers and most DAW software. When combined with MultiRack and your choice of audio interface, TRACT can be used with just about any analog or digital console.

TRACT employs two types of measurements via Smaart: single-source and dual-source measurements. An example of a single-source measurement would be a traditional RTA, where the mic is the only signal fed into Smaart. A transfer measurement utilizes two sources: a reference input (pink noise fed directly into Smaart, for example) and a measurement input (a mic listening to pink noise played through a P.A. system, for example). Compare the two signals, and a transfer measurement can reveal differences in frequency response, phase and delay time. Smaart’s Application Program Interface (API) enables streaming this data into TRACT in real time, along with control information such as start, stop, noise generator on/off, etc. Data is captured and analyzed, and TRACT automatically generates a correction curve. TRACT also provides the option of manually adjusting up to eight bands of IIR parametric EQ.

‡‡         Would You Believe?

TRACT can be used without Smaart as a high-quality EQ, but you’ll need a Smaart license (v8 or Di v2) to take advantage of its functionality. If you don’t own Smaart, Waves offers a bundle comprised of TRACT plus Smaart Di v2. The main difference between Smaart v8 and Di v2 is that Di v2 is a two-channel, single-device system whereas v8 supports multiple channels via multiple audio devices. TRACT’s learning curve is profoundly impacted by one’s familiarity with Smaart, so I suggest you work with Smaart and TRACT for a few hours before trying to configure the system under pressure at a sound check. It’s important to note that you must turn on API in Smaart or the two apps will not communicate.

I used TRACT running under MultiRack for live shows, and briefly in the studio as a DAW plug-in. My trusty MOTU Traveler served as the audio interface. I typically routed Main L/R, subwoofer and (sometimes) front fill outputs from a variety of consoles into the Traveler, then from the Traveler to the drive lines.

Running TRACT requires opening Smaart, enabling the API and configuring the I/O. Once this has been done, most of the work can be addressed within TRACT. When you open TRACT, click on the Smaart Connection Panel, then click the refresh button to acquire an IP address. The Connection Panel will indicate Smaart Di Found. Pressing Connect opens communication between the two programs.

A Remote Control Panel on the TRACT screen provides quick access to important Smaart parameters, such as activating the signal generator, choosing a measurement type, stopping or starting analysis or accessing various views. Making a change to any of these menus in TRACT is reflected in Smaart (with the exception of changes to the Views menu). RTA can be displayed as a continuous line, bars ranging from 1 octave to 1/48 octave resolution or spectrograph. Once the Measurement menu is set, press the start button to bring TRACT to life.

‡‡         Put to the Test

The first measurement I made was a single-source RTA using miniDSP’s UMIK-1, which includes a calibration response curve that most measurement software — Smaart included — can import, increasing accuracy of the measurements. I generated pink noise from the console and measured the resulting response in Smaart using the UMIK-1 as the input source.

While Smaart buzzed away in the background, TRACT was showing RTA in its own window. Clicking Capture takes a snapshot of the curve displayed in TRACT at that instant, and as TRACT supports multiple Captures, I could move the mic and perform Captures at up to eight different locations. You can click on one (or several) Captures in the Smaart Connection Panel to view or merge them. Merging captures keeps the originals and creates a new Capture with a Merge designation. Selecting one of the Captures, click “FIR” and TRACT generates the correction curve and applies it to the bus where TRACT is inserted. You can capture spectrograph curves, but cannot merge these, nor can you select them as a source for creating the FIR correction curve.

The results from TRACT were surprising. I’ve heard more than a few auto-correction systems and most of them stink. The results may look like a smoother EQ curve, but I find the phase shift to be unacceptable, causing audio systems to sound EQ’d. Not so with TRACT. I heard and saw the differences in the resulting curve but the audio didn’t sound like a 12-year-old got a hold of a 31-band graphic for the first time. It sounded musical. What a concept!

Next, I tried doing transfer measurements. The reference signal was pink noise routed directly to one channel of Smaart. The measured signal came from a measurement mic listening to that same pink noise played over the P.A. system. TRACT (actually the MOTU Traveler) was inserted between the Main L/R outs of a Mackie DL32S console and the drive line inputs. Playing the noise and capturing traces resulted in a more accurate FIR compensation curve than the single-source measurement — no surprise there. TRACT missed one or two small bumps in the response so I used the manual IIRs to try and fix them. One of the bumps was repairable and the other was a room anomaly that simply could not be corrected. IIRs can be set to a variety of curves including Bell, Tilt, Cut, Flat-top (plateau), Shelf, Cut or All-pass. The Flat-top, Bell and Tilt curves are fully parametric. Cut offers Linkwitz-Riley or Butterworth filter characteristics. The Shelf can be set to high- or low-shelf, and the All-Pass is designed to apply changes in phase response.

Waves’ online tutorial on TRACT was very helpful, and I used it as a guide to phase-align an aux-fed subwoofer output to the mains in a theater system, a fairly typical arrangement with top boxes flown on either side of the stage and subs centered in front of the stage. TRACT’s delay finder expedited the process, automatically finding the delay between the full-range cabinets and the direct-fed signal (again pink noise) and then the subs. Fig. 1 and Fig. 2 show the before/after graphs for this process. Notice in Fig. 2 how the purple traces are almost overlapping near the crossover point (around 125 Hz). Delay time can be set in mS, feet or meters, in whole numbers; I’d like to be able to dial in finer adjustments.

At a different venue, I used a similar arrangement to time-align front fills to the mains. The Find Delay and Insert Delay functions calculated the amount of time it took pink noise to arrive from the mains. Playing pink noise through the front fills and clicking Find Delay revealed the difference between the mains and the fills. TRACT displays this as the “Delta” value. Clicking “Apply Delta” sets the front fill output to this delay time, aligning the fills to the mains. Sweet and simple.

‡‡         Ready for TRACT?

Having heard more than a few misaligned P.A. rigs, the value of TRACT becomes obvious. The time coherence when aligning front fills to mains was excellent, accurate, and transparent. I didn’t hear separate boxes — I just heard the P.A. Phase alignment of subs to full-range boxes was even better — it felt like the subs became part of the full-range array, without that feeling of “the full-range boxes are here but the low-end is coming from over there.” The bottom-end became solid, forceful and coherent with the full-range P.A. — a great improvement in the system sound. TRACT is an eminently useful tool for anyone tuning a P.A. and is $399 well-spent.

At a Glance

A Smaart Enhancement

TRACT interprets analysis data from Smaart in real-time, and can automatically generate FIR EQ curves, phase/time-alignment correction to compensate for room acoustics irregularities and physical differences in speaker deployment. As such, it’s an eminently useful tool for anyone tuning a P.A.

PROS

  • Effective, automated sound system EQ, phase and time alignment
  • Smooth EQ section
  • Easy-to-use graphic interface

CONS

  • Steep learning curve for those unfamiliar with Smaart
  • Standalone operation requires Waves MultiRack

FEATURES

  • Automatic frequency response correction and time-alignment
  • Works with any P.A.
  • Can be used as a high-quality, stand-alone EQ
  • Sub zoom allows critical view of low frequencies while phase-aligning subs
  • Eight user-adjustable IIR filters
  • Captures up to eight measured response snapshots
  • Variable RTA bar graph resolution
  • Captures may be merged for “averaging”

STATS

Price: TRACT, $399; TRACT bundled with Smaart Di v2, $799

Manufacturer: Waves

More info: www.waves.com

 

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