I'm sure you've read countless interviews and reviews in Tape Op mentioning how analog gear can impart "depth," "weight," "sheen," or that elusive "glue" to a track or a mix. Much of the time, these discussions revolve around the classic preamps, EQs, and compressors of the '50s, '60s, and '70s. In the past few decades, many of these vaunted processors have been modeled as plug-ins – adding more attestations and remonstrations to the inexhaustible analog versus digital debate. Meanwhile, indie plug-in developer Shane McFee (Kazrog) worked closely with composer/producer Devin Powers (Powers Music) to model the individual transformers that are integral to the sound of those lauded pieces of gear. The result is True Iron, an AAX/VST/AU plug-in that lets one route audio through emulations of six different transformers that are found in vintage devices made by Ampex, Urei, Neve, Rhode und Schwarz, Siemens, Neumann, and Telefunken.

When F. Reid Shippen [Tape Op #125] and I visited Devin Powers at one of Devin's studios last year, I saw a fraction of the golden-era gear he owns, including the most impressive collection of tube limiters I've seen (or even knew existed in one place). Devin also walked us through his back rooms, while explaining the virtues of the specific transformers he has stockpiled and showing us his custom multichannel transformer interfaces that inspired this plug-in. I wish I had a video of the tour to share. Instead, I suggest downloading the True Iron user guide from the Kazrog website to read the history of the transformers modeled in the plug-in.

History aside, how does the plug-in sound? As Reid opined to me, "True Iron works exactly like vintage transformers work. Sometimes it's meh, and sometimes it's magic – and when it's magic, it's really magic. It's night and day on this new Kenny Chesney record." This is coming from a guy who has an enviable gear collection, including several pairs of bare transformers wired to his patchbay for outboard processing. On the other hand, I don't have any experience with audio transformers outside the context of recording or mixing through the transformer-equipped gear. But I can agree with Reid's sentiment. As with most audio processors that I love, I know quickly when True Iron isn't sonically appropriate for the project at hand; but when it is, it's easy to find its sweet spot without much fiddling.

The UI is simple to use but deceptively deep. The main controls are a six-position switch for transformer choice, a Crush knob for gain, a Strength knob for saturation/nonlinearity, and a wet/dry Mix knob. Smaller controls let us toggle Crush x2, Unity/Boost level, Morph even-harmonic saturation, and DNA advanced modeling.

While setting up the initial mixes for the new album by Chris Brokaw Rock Band (Come, Codeine, Lemonheads, Drop Nineteens, Juned, etc.), it was a challenge to find "space" for the many layered guitars and an electric bass that was rich in distortion. Meanwhile, the vocals were sounding too pristine in comparison. As Chris noted, the mixes weren't gelling. (This wasn't for a lack of analog. The songs were tracked using API, Avedis, and Hamptone preamps. Additionally, the drum mics were recorded through original Empirical Labs EL-7 FATSO Jr. [#24] channels; the guitar and bass amps through TL Audio compressors; and the vocals through Retro Instruments and Highland Dynamics processors.) I tried various plug-ins on the vocals and instruments, and I patched in several analog processors on the mix bus. After Chris mentioned that the vocals were still not sitting well in the mix, I instantiated True Iron on the track. It took less than a minute of turning the Crush and Strength knobs, while cycling through the six transformers, to realize we'd found the right effect for Chris's vocal. We settled on the Haufe V178 transformer, which adds a broad harmonic sheen at lower volumes, but pushes heavily into the lower-order odd harmonics when driven hard. Like magic, Chris's voice gained heft when it needed to, without me having to add (or ride) the level. On Claudia Groom's vocal, we chose the UTC O-12, which emphasizes all of the even-order harmonics; but from the odds, only the third harmonic becomes conspicuous when the transformer model is driven to saturation. This extra "sugar" worked perfectly for Claudia's beautifully sung vibrato. On the mix bus, I applied the Western Electric 111C, which seems to have the biggest sweet spot of all the models, where it adds even-order harmonics before it reaches a steep ramp-up of the third harmonic into wooly distortion. Adding Drive subtly and blending wet/dry, I was able to repaint some of the lower-midrange muddiness that I hadn't fully eradicated from the mix, into upper-midrange depth, without losing any weight in the mix. At this point, the mixes were gelling, and the vocals were sitting properly, but I found one more use for True Iron. In front of various delay and reverb plug-ins, I placed the UTC HA 108X, which emphasizes the third harmonic from the get-go. As you turn up Drive, it gets extra thick with odd-order harmonics. For each delay and reverb, I tweaked the amount of Drive and wet/dry Mix in True Iron to vary the texture of the effect.

While setting up True Iron on these mixes, I appreciated that the plug-in offers a dedicated delay-compensated bypass that switches between in/out modes with a volume ramp, facilitating A/B'ing when the current setting is subtle or transparent enough that a pop caused by jumping from in/out state would hamper comparison. On the other hand, I grew tired of looking at a large skeuomorphic rendering every time I opened the plug-in, and I eventually switched to the generic editor view offered in Cubase. (At least the UI scales on high-DPI monitors under Windows OS – something that most plug-in publishers haven't figured out yet.) Also, the plug-in's bandwidth is only 22 kHz. Even if your session is at 96 kHz or 192 kHz, any audio processed through True Iron will be down by 3 dB at 20 kHz. (If you use the wet/dry Mix knob, the dry signal will pass through at full bandwidth.)

Transformers distort the signal – plain and simple – but sometimes, that distortion is magic, especially when the harmonic energy of a track or song is redistributed in a musically dynamic way. True Iron is capable of doing this, without any complicated controls or difficult-to-decipher meters getting in the way. Granted, the plug-in isn't appropriate on everything, and it isn't a panacea for poorly recorded tracks; but I bet you'll find many instances where it will bestow some of the desirable traits associated with analog gear – depth, weight, sheen, and glue – to your mixes.

Tape Op is a bi-monthly magazine devoted to the art of record making.

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