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Add the character of analog tape and electronics to your Pro Tools HD sessions


Add-On for existing HD users: $495; included / bundled with all new HD TDM system purchases. http://www.avid.com/US/products/HEAT/features


By Phil O'Keefe




HEAT (which stands for Harmonically Enhanced Algorithm Technology) is a add-on for Pro Tools HD TDM systems (Mac and PC) that is designed to add "analog color" to your Pro Tools audio tracks. It isn't a plugin per se; it is applied to the entire session, as opposed to individual tracks. It doesn't stop at just "tape emulation"; it also emulates some of the coloration that is normally associated with vacuum tubes, as well as analog console signal paths; including transformer coloration.


RTAS is not supported. The DSP requirements vary with the amount of audio tracks in the session, as well as the sample rate. You get about 30 mono tracks per HD Accel chip at 44.1 / 48kHz, and 14 at 88.2 / 96kHz. For non-Accel HD chips, those numbers drop to 12 at 48kHz and 5 at 96kHz. Unlike some "tape emulation" plugins, HEAT is applied to all audio tracks in your session; although it can be bypassed on a track by track basis if desired, doing so does not free up any DSP resources. Disabling a track does not lighten the DSP load, but it does allow you some control over which tracks will be processed.




HEAT uses an iLok USB Smart Key ($40 - $50 additional, depending on which version you purchase; an iLok is not included, but most HD users will already own one) for copy protection / authorization, and the typical iLok registration process applies. I find the proceedure fairly straightforward and easy to use. If you purhase online directly from Avid, you just download and install the software. For those who buy the retail box, installation is via a DVD. Box purchasers need to enter an activation code at Avid's website to generate an iLok licence, which can then be downloaded directly to your iLok. Online purchases through Avid's site generate the iLok authorization automatically, without the requirement of entering an authorization code. Either way, you'll need to download the license to your iLok copy protection key at www.ilok.com in order to use HEAT.




HEAT is activated by selecting the Options / Activate HEAT or by clicking on HEAT's "on / off" button in the mix window display. (Fig. 1) The actual controls are pretty basic - there's an on / off switch, a Drive knob and a Tone knob and a master Bypass switch in the master section, as well as a Pre (pre-inserts) and Byp (bypass) button for each individual audio track in the session. That's it - simple, fast and elegant. It works only on audio tracks; unfortunately, it has no effect on busses, aux returns or virtual instrument tracks. You can get around this limitation by "printing" your effects and virtual instruments to audio tracks, or bussing them to a record enabled audio track with input monitoring enabled, but it would be nice if you could apply HEAT to these sources without having to take these extra steps.


HEAT On Off Fig 1.JPG


Figure 1: Enabling HEAT can be done from the Options Menu, or the HEAT Mix window on / off button, which are indicated with red arrows.




How much HEAT should you use? As with most audio tools, that will depend on the desired results and your personal preferences. HEAT processing is non-linear, and the results will depend on the track levels as well as how far you turn the Drive knob. It is also level and program dependent, so the settings you use on one song my be "too much" or "not enough" for the next one. Each track, as well as the HEAT master section, contains a glowing "meter" (Fig. 2; indicated with the red arrow) that gives you an idea of how much processing is going on from moment to moment. As you watch this meter, you'll notice it glowing more brightly as signal levels increase, and dim as they fade.


Turning the Drive control counter-clockwise from the center position introduces odd order harmonics that are similar to what you get when using analog tape. The highs and transients (note attacks) "soften" a bit, and the bottom and midrange frequencies fill out in a almost "three dimensional" fashion. As you increase the rotation of the drive control (turning it further counter-clockwise), the effect becomes more dramatic as additional harmonic content is added to the signals and they become subtly more saturated and compressed; especially on peaks.


Turning the Drive knob (Fig. 2) clockwise from center still gives you the odd order harmonics, but also adds in even order harmonics, similar to those created by vacuum tube based electronics. The result is a more "aggressive" and even "livlier" sound than when using the Drive knob in the counter-clockwise settings. You still get the warmth and fullness in the low and mid frequencies, but the sound also is brighter and more open overall.


HEAT Controls Fig 2.JPG


Figure  2: The HEAT Master and Channel controls are simple, but very effective.  The red arrow indicates the "meters", which glow brighter with  increased processing.


In addition to the harmonics, there is definitely some soft clipping and related compression going on, as well as saturation on peaks and loud signals. I believe this is an important part of the secret to HEAT's appeal. Human ears like those subtle shadings and distortions that tape and analog electronics add to recordings, and while you may not always notice them directly, you'll often notice it when they're not there. This "lack of coloration" (distortion) is a common complaint about digital recording systems. As with tube and tape based systems, the effect HEAT provides is adaptive and varies with signal level. The Drive knob settings give you some control over this too, although occasionally I wished for a drive knob on each individual channel of the mix so that I could add "more" to things I wanted to really color by "slamming hard". I got around this by inserting a CraneSong Phoenix plugin (designed by Dave Hill, the well-respected audio designer and the guy who is also responsible for creating HEAT) and using that to add "more" to individual tracks as desired. HEAT, by itself, is not really capable of heavily distorting and compressing things, so keep your favorite dynamics and distortion plugins handy for distorting and compressing vocals, drums and other sources that you really want to grundge up.


The master section also features a Tone control. As you might expect, turning it clockwise tends to brighten things and counterclockwise darkens things, but there's more to it than just simple EQ. It actually changes the way the processing occurs; adding and subtracting not only brightness, but also detail, in a non linear manner that interacts with the Drive control settings. As Avid claims in the well written HEAT manual, it actually changes the amount and character of the harmonic content. This can come in very handy - for example, if you crank the Drive knob fully counter-clockwise, you can add some of the detail back to the sound by turning the Tone knob clockwise a couple of ticks, without losing the extra compression and saturation you get at higher Drive settings. The two controls - Drive and Tone - are very interactive, and it will take a few minutes of playing with them in various settings to find how they interact and to get the best settings for your particular material, but once you get the hang of what they are doing sonically, adjusting them is very fast and intuitive.


The Master Bypass button allows you to quickly turn the processing on and off in order to hear the effect of the processing at the current settings in direct comparison to the unaffected sound. After using HEAT for a few minutes, the first time I hit that Bypass button, the result, quite frankly, was shocking. It was as if the mix "collapsed" and flattened out. The extra dimension HEAT adds to the sound is extremely attractive, and once you try it, you may very well decide you don't want to mix without it. I know I did.




If you're looking for the exact sound of analog tape, and you're a hard core analog purist, then HEAT may not totally satisfy you. It's not that it falls short - it actually does an incredible job of emulating the medium and hardware that it sets out to simulate - but the lack of analog tape hiss may give it away, even in a double blind listening test. If you're predisposed to think negatively of any digital recording medium or analog emulation, go in peace and stick with tape... but if you can keep an open mind and set aside your preconceptions, you owe it to yourself to give it a listen; especially if you work with Pro Tools on a regular basis.


HEAT is an incredibly valuable tool. It has similar sonic benefits as Dave Hill's outstanding CraneSong Phoenix plugins, but with far less muss and fuss in terms of ease and speed of use. In fact, compared to other "tape emulators" I've tried, it is by far the quickest to use and easiest to get stellar results with. True, other emulators may allow you to adjust tape speed and bias and countless other details, but if you're a busy professional, you'll appreciate HEAT's no fuss approach and very obvious sonic benefits. It provides the "warmth" and dimensionality and character that helps to "glue" tracks together in the mix, without making things muddy or indistinct. It's not easy to describe, but definitely easy to hear... and since Avid offers a free 30 day trial, you can easily give it a try on your own material. Download HEAT and decide for yourself - I think you'll agree that it's definitely the hot ticket add-on for Pro Tools HD.


System Requirements:

Pro Tools HD TDM 8.1 or later with sufficient available DSP chips for the amount of tracks in your session.
iLok USB copy protection key and available USB port. ( http://www.ilok.com
Internet access for software authorization and registration.
DVD Drive (if installing from the installer disk).

Test system:

Pro Tools HD2 Accel 8.1
Athlon 64 4200 X2 PC with 4 GB RAM 
Windows XP SP3.

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