$3,000, heritageaudio.com The original Fairchild is an ultra-rare valve compressor designed in the 1950s, famed for its flattering, gluey saturation, having risen to prominence when the Beatles used it in the studio. The Fairchild’s genius is in its Vari-Mu circuit, where compression occurs inside the valves themselves

$3,000, heritageaudio.com The original Fairchild is an ultra-rare valve compressor designed in the 1950s, famed for its flattering, gluey saturation, having risen to prominence when the Beatles used it in the studio. The Fairchild’s genius is in its Vari-Mu circuit, where compression occurs inside the valves themselves, with a progressively higher ratio as the signal peaks over the threshold – hence ‘Vari’ in the name. Despite the increasing ratio, a relatively leisurely attack means that transients rarely sound squashed, while the overloading valves reveal pleasing even harmonics. READ MORE: Korg Nu:Tekt NTS-4 is a small mixer with big ideas Fairchild has launched a recreation of the original unit in recent years. You can buy a new one for $30,000, but expect to pay an extra $10,000 if you find a vintage one. It’s no small investment. In 2021, Heritage Audio created the Herchild 670. This emulates the dual-channel Fairchild for $10,000, using 22 new-old-stock valves and an array of transformers. It has a similar retro appearance to the original, with a mammoth 6U case, VU meters and large knobs, all of which evoke a bygone age of recording. Two years later, the brand squeezed the essence of a Fairchild into 500-series format with the Grandchild 670/500 at around $2,000. With far fewer tubes, it still sounds sublime, and its stereo design makes it perfect for mixing or on-the-go mastering. This breakthrough gave Heritage the idea for something in-between. The latest Herchild builds further on the success of these two earlier models, offering a sound that’s in the ballpark of the Herchild 670, but at one-third the price. This feat has been achieved by using fewer tubes and transformers and, not happy to stop here, the feature set even exceeds the full-blown 670 by adding per-channel make-up gain control. I’m left wondering where the catch is. Image: Press Unleash the beast! The 670N’s form factor is close to the Herchild 670, but with a case shrunk down to 5U. The rear panel is uncluttered, with pairs of XLR ins/outs and a socket for the external power supply. Despite the shrinkage, the 670N still feels huge in my compact workspace; I’d need to be really set on the Fairchild sound to commit to this over similar 2-3U compressors. Furthest left on the front panel are illuminated VU meters that monitor gain reduction, followed by a bypass switch. Next are two large, soft-detent dials. Input Gain attenuates the incoming signal to control how hard the compressor’s input is driven, while AC Threshold increases gain reduction as the knob is turned up. The ‘turn up for more’ approach for both dials simplifies the process of control-setting. DC Threshold adjusts the compression response curve, ranging from soft knees for smooth vocals and mastering through to harder knees for slamming drum room mics. SC Filter sets the side chain frequency, and it’s surprisingly flexible. Not only does it feature the usual lower-frequency areas to stop pumping when mix-bus compression is triggered by kick drums, it also covers other troublesome areas. The uppermost settings, 1k, 3k, and 5k, help remove hi-mid harshness, sibilance and excessive high-frequency presence from drum overheads and cheap condenser mics. Really neat. Four operating modes offer loads of flexibility and are accessed via the AGC dial. IND is dual mono, where the two channels are fully independent. LINK is used for stereo operation, where compression is applied equally to both channels, and then there are two equivalent modes for LAT and VERT where the channels are encoded/decoded to mid/sides instead of conventional left/right stereo. Finally, there’s an output dial per channel—the aforementioned added bonus—which is especially helpful for gain staging in IND mode and for manipulating stereo wideness in LAT/VERT. Image: Press Mastering with the Herchild 670N Mastering is the most compelling use case for the Herchild for me, since Vari-Mu compressors excel early in the chain to even out levels and add sustain and gluey tube vibe. Oh, and the 670N would look impressive in a table-style mastering console; its large and tactile controls just beg to be used. The flexibility in stereo linking modes also makes the 670N a serious contender. And for even tighter control, the mid/sides mode not only offers separate treatment of mid and sides elements but also negates issues of the left/right balance becoming wonky due to the variations between different valves in the unit. When working with mid and sides, you should never end up with uneven left and right channels. Tackling a folk rock session, I use LAT/VERT mode to remove a couple of decibels from peaks on the master using a leisurely Time Constraint and the compression effortlessly smoothes out all the digital harshness of my otherwise in-the-box production. I squash sides slightly more than the middle, adding level consistency to background vocals and effects while leaving centre-panned lead vocals less compressed. I pump up the output gain of the sides a decibel louder than the mid component and the result is a gloriously wide sound that appears almost three-dimensional. A subtle bass thump is introduced too—in part due to the transformers in the circuit—and so a little EQ tweak is needed before going into the compressor when mastering. In other use cases, this might be just the thing to add weight to a kick, bass guitar or weedy lead vocal without boom or running out of headroom. Image: Press The big squeeze On individual tracks in the mix, I drive the 670N harder. It gently grabs at peaks, this time extending to about five decibels of gain reduction but never sounding squashy. This is especially effective on vocals, offering tighter control of peaks to preserve the level at the ends of phrases, while breaths are brought closer to the listener to tighten expression. Once again there’s a thicker low-end tone but also a seductive mid-band saturation. I’m surprised by how quickly it is to dial in a luscious result using my ears and a few knob clicks. Who said that adding analogue outboard to an in-the-box production slows things down? In dual-mono (IND) mode, it’s simple to process two of the main parts simultaneously. Even with just two parts running through the 670N, there’s a definite improvement to the quality of the mix – something that’s not easy to replicate with plugins. In my case, it’s dual lead vocals being compressed in a similar way, but it’d alternatively do a great job at adding a touch of class to a vocal while simultaneously driving the valves harder on the second channel for a gritty bass guitar line. Image: Press Should I buy the Herchild 670N? Clearly, any rackmount, dual-channel Vari-Mu compressor isn’t going to come cheap. The ubiquitous Manley Variable Mu costs $2,000 more than the 670N. Gainlab’s The Dictator and Tegeler’s Vari Tube both take up less rack space (2U and 3U, respectively) and can be picked up for fewer dollars than the 670N, but they lack the stereo linking flexibility and mid/sides smarts that make the Herchild more appealing for mastering and bus compression gigs. When you throw the Herchild’s roster of vintage valves and bold retro look into the equation, it emerges as the clear winner in its price bracket. If you’re searching for a slick-sounding and relatively affordable valve compressor for mixing and mastering, then you should seriously consider the Herchild 670N. It’s a perfect studio centrepiece that you’ll want to keep reaching for. I’m going to have to suffer the FOMO on this one – all my racks are 4U high. Key features Fairchild-style Vari-Mu compressor 4 NOS 6BA6 valves; 2 custom-designed input transformers Analogue VU meters Dual channels with switchable link modes Mid/sides operation Dedicated make-up gain (output) control Requires 5U of rack space External power supply The post Heritage Audio Herchild 670N compressor review: We’re going to need a bigger rack appeared first on MusicTech.