Marcus had a staunch desire to design a preamp that allowed him to dial in his fabled tone quickly and consistency on stages and in the studio. In turn, he wanted to aid in developing a piece of gear that offers serious flexibility for nailing a wide variety of tones, while incorporating features he knew were important from years of A-level gigging and recording. The collaboration between SWR and Marcus was extensive and intimate, and the resulting gear is a neat glimpse into the master’s mind.
The Marcus Miller preamp packs a lot into its tworackspace chassis. It’s essentially a hybrid design, with two 12AX7 tubes handling input buffering and gain, compression, and DI duties, and numerous semiconductors tackling the amp’s other gain stages and filters. There are three instrument inputs: one on the rear panel to interface with rack gear (a wireless, perhaps) and two frontpanel jacks, switchable via a panel-mounted button. The front-panel jack overrides the rear jack, and since only one jack is operational at a time, the preamp makes it easy to use two basses (or a bass and a keyboard) on a gig. Interestingly, the rear-panel jack’s input impedance, 10kΩ, is significantly lower than the front panel’s more bass friendly 820kΩ spec—a sign that it’s designed to receive line-level signal from rackmounted gear, not a cable straight from the bass.
After the input, the signal reaches several forks in the electronic road, but notably, SWR included bypass switches galore to make the path of least resistance available. The extensive EQ—shelving BASS and TREBLE with three broadband semi-parametric filters—can be bypassed via a front-panel switch. Same goes for the BASS INTENSIFIER circuit, a cool filter that combines low-frequency boost (with continuously variable control over the filter’s cutoff) and compression to enhance low-end strength without undue muddiness. The robust tube-driven compressor, with controllable THRESHOLD, RATIO, ATTACK, and RELEASE parameters, is not only removable from the signal path, but also routable to either side of the EQ circuit with the COMP POSITION switch. Even the DI output offers an unusually flexible signal management scheme: the DIRECT (PRE) setting is a true all-tube transformer-coupled signal tapped off the back end of the first input stage; COMP OUTPUT offers either a pre- or post-EQ and BASS INTENSIFIER signal, depending on the front-panel’s COMP POSITION switch setting; and LINE (POST) includes every preamp stage except the MASTER VOLUME. If that weren’t enough, the DI offers a phase-reversal switch (useful when the DI signal is combined with a miked cabinet), LEVEL control, and XLR or q" TRS output. To top it off, most of the above is footswitchable.
Considering the preamp’s fairly complex feature- set, SWR’s interface design is laudable. The knob-heavy front panel was well organized and clearly labeled, and every essential routing option includes a bright status-indicating LED. The grey MUTE switch is a direct suggestion from Marcus, who was occasionally hitting the BASS INTENSIFIER by accident on gigs with a prototype that had a black MUTE switch—not good for tuning. Another strong Marcus influence is the AURAL ENHANCER filter, a complex tone-sculpting circuit that essentially cuts mids while boosting bass and treble. While it’s standard on every SWR head, the Marcus Miller preamp’s AURAL ENHANCER curve is different, with an alteration in the midrange cut frequency and a defeat option via the push-pull knob. The BOOST/COMP circuit is another cool idea that shows major Marcus influence. Its basic function is no big deal: a volume boost for solos or loud passages, with the degree of boost variable relative to the knob’s position. But its COMP BLEND knob reveals distinctive MM cleverness. It offers control of the compressor’s ratio, working in conjunction with the RATIO control: in the center position it’s the same as the setting on RATIO, but moving it increases or decreases the ratio, offering more or less compression when in BOOST mode. COMP BLEND is a cool idea that makes good sense in practice— a volume boost is nice for a solo, but we don’t want to go poking our fat noses in everyone’s ear. Adding compression control to the boost adds nuance to the tone, increasing volume but taming unruly dynamics.
The preamp’s construction felt rugged, with metal-barrel jacks and smooth-turning, solid-feeling knobs. Removing the top revealed clean interior construction, although it’s not eye-poppingly high end, with rarefied components and other audiophile cues. Rather, it’s solid and functional, although the pots are hard-wired to a circuit flush with the front panel—not the easiest thing to fix in a pinch.
POWER
Brilliant and shimmery, with substantial low-end heft and gently reticent upper mids, Marcus Miller’s sound is immediately identifiable, a definitive chapter in the instrument’s sonic encyclopedia. Yes, it’s in his hands, but it’s also in his gear. Thus, one of the immediate pleasures of the SWR is the ease with which I dialed in a reasonable approximation. I started with a Fender Jazz Bass of course, and then dialed in some gentle compression, a midrange scoop via the AURAL ENHANCER circuit, and bass boost and high-mid cut with the EQ. I detuned my bass’s E string to D, and went to work with my thumb, doing my best “Tutu.” Killing! The preamp sparkled and snapped just like I wanted: tight and controlled lows, quick and assertive pops, and dynamic sensitivity that wasn’t too adversely affected by the subtle compressor.
But Miller mimicry is not my forte, so I investigated the preamp’s other possibilities. Bypassing all the tone shaping, I tried to get a sense of the pre’s fundamental personality. It’s a dry and quick box, yet it’s not without its own richness and tube-y character. GAIN settings proved critical for initial coloration, with the higher range offering a hair more midrange color and texture. With everything bypassed, the pre was precise and fast, although perhaps a touch grainy in the upper range—great for hi-fi slap and fingerstyle, but perhaps not my first choice for sludgy R&B and soul. But then I started tweaking, and I discovered the SWR’s versatility. The BASS INTENSIFIER shored up the low end without being too nauseating or murky, and it has the psychoacoustic effect of seeming to slow down the response just a hair, making for a slightly more interactive playing sensation. The EQ was precise and capable, although as with all semi-parametric circuits (especially 3-band ones!), there’s treacherous tone-sabotaging potential there. I especially liked the compressor, and welcomed its four status-indicating LEDs. It felt particularly musical and legit, more like a high-end channel strip-style compressor than a tacked-on cheap-o circuit. Being able to place it before or after the EQ has a big impact on its behavior, as one would expect. If there’s a lot of boost coming from the BASS INTENSIFIER and EQ, it can be reined in for extra coherence when the compressor is routed after those stages. I tracked a couple of quick demos with the DI, and it was fantastic, especially in the DIRECT (PRE) position, offering full-spectrum solidity and compelling midrange color.
Given SWR and Marcus’ design intentions, the preamp is a complete success, offering all the necessary features for the stage and studio, plus a few genuinely clever ideas I never knew I wanted. I recommend you consider it, particularly for its versatility and crisp, contemporary tone.
SWR MARCUS MILLER PREAMP
List $1,299
Street $900
Pros Excellent versatility and thoughtful design; slick tone for Marcus hounds, but enough variety to satisfy most everyone
Cons None
Bottom Line Does a lot, and does it well.
TECH SPECS
Input impedance Front-panel, 820kΩ; rear-panel, 10kΩ
Tone controls BASS INTENSIFIER: adjustable (80–200Hz) lowfrequency boost and shelving compressor; BASS: ±15dB @ 70Hz (shelving); LOW: ±15dB @ 35Hz–180Hz (semi-parametric); MID: ±15dB @ 180Hz–1kHz; HIGH: ±15dB @ 1kHz–5kHz TREBLE: ±15dB @ 3kHz (shelving)
DI output Tube-driven, transformer-coupled balanced XLR with ground lift, phase, and DIRECT/COMP/LINE switches
Weight 13 lbs
Made in U.S.A. (some parts manufactured in Mexico)
Warranty Five years