TEST: Sonic Farm Xcalibur JC

 How times have changed. For decades, sound engineers of all stripes went to great lengths to eliminate overloads and distortions of all kinds from recordings. In the early days of recording technology, tube-based analog equipment induced an almost latent saturation, which, especially in the summing stage, provided a considerable compression of the material and an accompanying first "mastering stage" long before this production step was planned as an integral part of a sound recording. Today, equipment resistant to overloading is no longer a special feature; rather, one sometimes tries to give the sound material the decisive "kick" with a dedicated half-wave cut at the right place. The Canadian company Sonic Farm carries the Sonic Farm Xcalibur JC, a saturation preamplifier in its portfolio, which offers far more unique selling points than just saturation.

The Concept of the Sonic Farm Xcalibur JC

It becomes apparent during the unpacking process that the Sonic Farm Xcalibur JC is not your typical 19-inch semiconductor equipment. Weighing nearly 8 kg and with an installation depth of 34 cm, one might initially mistake the 1U high rack unit for a power amplifier rather than a typical preamp. Nevertheless, this product is a 2-channel microphone preamplifier and saturator for processing microphone, line, and instrument signals, based on a Class-A tube circuit utilizing EF86 tubes. These pentode tubes, known for their low noise and high gain characteristics, contribute significantly to the unit's sonic signature.

The "JC" suffix stands for the signature version by engineer and producer Joe Chiccarelli, who celebrated his greatest successes with artists such as Alanis Morissette, Elton John, Bee Gees, Journey, and Frank Zappa. According to Wikipedia, his name is associated with over 50 million albums sold, though this seems a conservative estimate considering that the "Saturday Night Fever" soundtrack by the Bee Gees, which he mixed, alone sold over 40 million units. Chiccarelli's influence on the unit's design is evident in its versatility and attention to detail in the saturation stages.

One of the unique features of the Sonic Farm Xcalibur JC is the cascading capability of the two channels, which can be activated by a mini-switch in the center of the front panel. This feature allows users to create a serial signal path, effectively doubling the available gain and saturation options. In this configuration, one can also inflate the two saturation stages into a formidable distortion effect, reminiscent of classic tube overdrive pedals but with far greater clarity and control.

The fact that Sonic Farm has given considerable thought to overdriving is evident not only in the use of two pentodes per channel, providing up to +68 dB gain for microphone input and +48 dB for line and instrument signals, but also in the optional use of FET transistors for distortion. FET transistors are characterized by the fact that, when overdriven beyond 0 dB, they do not convey the harsh distortion of regular transistors, but rather produce a significantly softer distortion not unlike tube overdrive. This hybrid approach allows for a wide range of tonal possibilities, from subtle warming to full-on distortion.

The output levels of the channels are separately adjustable, with the preamp utilizing Cinemag output transformers. These high-quality transformers are known for their ability to add a subtle, musical coloration to the signal, further enhancing the unit's analog warmth.

The Front Panel of the Sonic Farm Xcalibur JC

Those expecting a pure 19-inch distortion unit will be surprised by the Xcalibur JC's comprehensive feature set. A considerable number of controls and switches on the front panel indicate that the Sonic Farm Xcalibur JC is equally concerned with high-quality preamp functionality as it is with saturation effects. The first three pushbuttons on the left side offer standard features: phantom power (48V), a 15 dB PAD switch, and an instrument selector switch that routes the input to the front panel jack.

The following three rotary controls "CLN" (Clean), "DRV" (Drive), and "BLD" (Blend) form the core of the unit's saturation capabilities. These controls, in conjunction with several toggle switches, allow for precise tailoring of the distortion character. The "CLN" control adjusts the input gain of the clean signal path, while "DRV" determines the amount of signal sent to the saturation circuit. The "BLD" knob allows for a perfect balance between the clean and saturated signals, enabling anything from subtle harmonic enhancement to full-on distortion.

A two-color LED (red/green) reflects the input level, providing visual feedback on the signal strength. It's worth noting that distortion in the red range is not necessarily desirable but merely indicates that the input level is too high for clean operation. This metering system allows for precise gain staging, crucial for achieving the desired level of saturation without unwanted clipping.

Following these controls is another selector switch for the output, allowing a choice between a low-distortion solid-state IC or a transformer. This feature provides two distinct flavors of output coloration, with the solid-state option offering a more transparent sound and the transformer adding a subtle, vintage-like character to the signal. A phase switch completes this section, allowing for easy correction of phase issues that may arise when using multiple microphones.

The upper row of the Sonic Farm Xcalibur JC is dominated by a total of 7 toggle switches, all of which have 3 switching states. This array of switches provides an unprecedented level of control over the unit's tonal shaping capabilities. Starting with a Fat Shelving Preset Boost and Gain Max switch on the left side, the switch in the left position (Fat) provides a low-frequency shelving boost from 300 to 1000 Hz, depending on the setting of the Gain switch two positions to the right. Lower gain settings correspond to a higher corner frequency and consequently a stronger bass boost. This filter does not use a separate stage but utilizes the clean tube amplification stage, ensuring that the bass enhancement remains musical and natural-sounding.

The boost level can be fine-tuned with the left of the two trim potentiometers, accessible from an upper flap located between the boost switches about a centimeter from the front panel. This level of detail in control allows users to dial in precisely the right amount of low-end enhancement for any source material. The maximum boost also depends on the Gain switch; the lower the Gain switch, the more bass boost is available, up to about 12 dB with a 6dB/octave slope.

The high-frequency shelving boost, labeled as "AIR," operates from 1 to 8 kHz and also depends on the Gain switch setting. Lower gain settings correspond to a lower corner frequency and consequently a stronger treble boost. In the left position, the corner frequency is about 1.5 octaves lower than in the right position. This filter also affects the clean tube amplification stage, ensuring that the high-frequency enhancement remains smooth and musical. As with the low-frequency boost, the exact onset of the AIR effect can be adjusted via a trim potentiometer inside the housing, allowing for precise tailoring of the high-end response.

After the aforementioned GAIN switch, we come to the microphone input impedance switch labeled "IMPED." The impedance selection is a crucial feature that can significantly affect the tonal characteristics of different microphones. The lower the impedance, the higher the load the preamplifier input exerts on the microphone. The standard values are 10 kΩ for the middle position (HI), 900 Ω for the left (LO), and 2400 Ω for the right (MED).

The "PAD" switch also affects the resulting microphone input impedance value, providing even more flexibility in matching the preamp to various microphone types. A change in input impedance tends to affect the sound of dynamic microphones more significantly, to some extent ribbon microphones, and to a lesser extent or not at all condenser microphones. Lower impedance values generally roll off the highs somewhat, which can be useful for taming overly bright sources or adding a vintage-like character to modern microphones.

A subsequent high-pass filter cuts at either 160 Hz (Pos. 1) or 80 Hz (Pos. 2) with 6dB/octave slope. Only the clean signal is processed by this high-pass filter, allowing users to remove unwanted low-frequency content before it reaches the saturation stage. This can be particularly useful for cleaning up boomy sources or reducing proximity effect on close-miked vocals.

The following ODf/ODf1 switch is a high-pass filter before the overdrive stage, which can be useful if too much bass or low mids hit the OD tube and cause excessive "mud" in the distorted signal. In this case, the unwanted bass or mids can be attenuated with this 6dB/octave filter with a gentle slope. The individual positions allow for full engagement (left), attenuation of bass and low mids (center), and attenuation of only bass (right). Depending on the instrument connected, interesting effects can be achieved here, especially in the Lo-Fi range.

In the JC signature version, an additional ODf2 control is employed. This is a post-drive low-pass filter with a pre-mix of 3 positions: 5.5 kHz, 12dB/octave (left); 18 kHz (center), and 1 kHz, 6dB/octave (right). The first position can be used to suppress buzzing distortions that may occur when processing some signals, particularly useful for taming harsh high-frequency content in heavily saturated signals. The middle position is practically a bypass, allowing the full frequency range of the distorted signal to pass through. The right position is useful when you want to mix in some saturation to make something sound bigger and fatter without the distortion becoming too obvious, effectively acting as a "thickening" effect.

The rear panel of the Sonic Farm Xcalibur JC is straightforward and functional, featuring 6x XLR connectors (4 in, 2 out), L/R microphone inputs, L/R line inputs, a ground lift switch, main fuse, mains selector switch, and an IEC power socket. This layout ensures easy integration into any studio setup, whether as a front-end for recording or as an insert processor for mixing and mastering applications.

As evident from this detailed breakdown of features, the Sonic Farm Xcalibur JC offers very comprehensive signal processing capabilities, allowing for extensive sound shaping at every stage of the signal path. The unit's design philosophy seems to be centered around providing maximum flexibility and control to the user, enabling everything from subtle analog warmth to extreme distortion effects. This level of control is particularly valuable in the context of modern production techniques, where the ability to precisely shape tone and add character to digital recordings is highly prized.

In Practice

Activating the Sonic Farm Xcalibur JC with what is probably the stiffest on/off switch I've ever operated, we're greeted by a strong red glow emanating from the unit. This visual feedback, reminiscent of classic tube gear, sets the stage for the sonic experience to come.

As a guitarist, the Sonic Farm Xcalibur JC immediately brings a broad smile to my face, thanks to the excellent quality of its distortion capabilities. The unit truly shines when processing instruments where the treble component is not too pronounced, such as Hammond organ or clavinet. In these cases, the Xcalibur JC produces outstanding sounds right out of the gate, easily reaching distortion levels comparable to a high-gain guitar amp, but with significantly less unwanted noise.

The saturation characteristics of the Xcalibur JC are notably smooth and musical, even at extreme settings. This is likely due to the careful implementation of both tube and solid-state circuitry in the signal path. The ability to blend between clean and saturated signals allows for a wide range of tonal possibilities, from subtle harmonic enhancement to full-on distortion.

One particularly impressive aspect of the Xcalibur JC is its ability to maintain clarity and definition even when heavily saturated. This is where the unit's hybrid design really comes into play, combining the warmth of tubes with the precision of solid-state components. The result is a distortion character that adds richness and complexity to the source material without becoming muddy or indistinct.

The extensive EQ and filtering options prove invaluable in shaping the distorted signal. The ability to tailor the low and high-frequency content both before and after the saturation stage allows for precise control over the final tonal character. This level of control is particularly useful when working with dense mixes or when trying to achieve specific vintage-style tones.

While the Xcalibur JC excels at more extreme distortion effects, it's equally capable of providing subtle coloration and harmonic enhancement. At lower drive settings, the unit imparts a gentle warming effect that can add depth and dimension to digital recordings. This versatility makes the Xcalibur JC a valuable tool not just for tracking, but also for mixing and mastering applications.

The question of whether to add a speaker (simulation) to the signal path is left to individual preference, but even without any additional sound processing, the Sonic Farm Xcalibur JC convinces across the board. Its raw output is remarkably usable and musical, a testament to the quality of its internal components and circuit design.

Of course, the product can also provide subtle fattening in the range of tape saturation, but it's the high gain reserves that truly offer a unique selling point in the preamp segment. The extensive filtering options ensure that there's something for everyone, and any remaining sonic possibilities can be addressed with a pre- or post-EQ.

One minor criticism could be leveled at the unit's noise floor, which becomes noticeable at extreme gain settings. However, this is a common characteristic of high-gain tube circuits and is generally not problematic in real-world recording scenarios. The noise is easily overshadowed by the signal in most applications, and the richness of tone more than compensates for any slight increase in noise.

Conclusion

With the Sonic Farm Xcalibur JC, the Canadian manufacturer has created an outstanding preamp with a focus on saturation, easily achieving the distortion levels of a high-quality dedicated distortion unit. The components used, along with the build quality and sonic possibilities, place this unit firmly in the top tier of studio equipment.

The Xcalibur JC enables the creation of characterful and defining sounds that can breathe life into thin or lifeless recordings. Its versatility makes it equally at home on individual tracks during recording and mixing, as well as on entire mixes during mastering.

While the price point of the Xcalibur JC places it in the professional and high-end project studio market, its performance justifies the investment for those seeking a truly versatile and high-quality saturation device. The unit's ability to impart everything from subtle analog warmth to extreme distortion effects, all while maintaining a high degree of clarity and musicality, sets it apart in a crowded market of analog-modeling devices.

In an era where digital perfection often leads to sterile and lifeless recordings, tools like the Sonic Farm Xcalibur JC provide a valuable means of reintroducing the character and imperfections that make recordings sound alive and engaging. Whether used subtly to add depth and dimension to digital tracks, or pushed to extremes for creative distortion effects, the Xcalibur JC proves to be a flexible and powerful tool in the modern recording studio.

A top-notch product that comes highly recommended for professionals and serious enthusiasts alike. The Sonic Farm Xcalibur JC represents a significant achievement in analog audio processing, successfully bridging the gap between vintage warmth and modern clarity.