To accomplish this task, the Pro 30M’s designer, Alex Cooper, recreated the vintage Marshall’s preamp circuitry as closely as possible—essentially substituting discrete transistors for the 12AX7 tubes. But here’s the real magic: Cooper also developed a really hip circuit that mimics the non-linearity of the Marshall’s phase splitter and output tubes, as well as the output transformer’s saturation characteristics and the 4x12 cabinet’s resonance and dynamic loading effects on the output stage. Residing on a 4" epoxy-encapsulated PC board, this ambitious solid-state, analog modeling circuit is the most essential component of Blue Tone’s proprietary Virtual Valve Technology.
While Blue Tone may be a new name to most North American readers, its unique design subtleties reflect more than 30 years of pro-audio experience. Besides developing the Pro 30M, Alex Cooper is also the Director of Engineering at Midas, Britain’s leading manufacturer of tour mixing consoles. Cooper’s years of high-end console design experience are evident in the 30M’s uncluttered front-panel layout, which flows logically from the input jacks (on the left) to the output controls (on the right). Turn the amp on its side, and the front panel reveals a striking resemblance to a console channel strip. The pro-audio influence is apparent on the inside, as well. The power supply is well shielded to prevent hum, and the PC board and its components are firmly secured to withstand the rigors of the road. Few guitar amps exhibit as much pro-audio influence in their design and construction.
The Pro 30M’s Bass, Mid, and Treble controls are voiced like a vintage Marshall’s, and they’re augmented by a pair of front-panel Contour buttons labeled Mid and Hot. Engaging the Mid button provides a moderate upward tilt of the mid and treble frequencies, while keeping the low-end trim and taut. This mimics the more aggressive frequency response and extra gain typical of some later Marshalls that used an additional .68uF cathode bypass capacitor on the second gain stage. It’s a cool feature that lets you chose between early plexi sweetness and more assertive textures. For more overdriven tones, the Hot button provides significantly more gain than the Mid boost, and it has the extra feature of being footswitchable. Engaging both Contour buttons simultaneously produces the amp’s thickest and strongest tones.
The Pro 30M’s Gain knob functions just like a Volume control on a vintage Marshall, and the Amp Level knob works like a master-volume control. There’s a row of five LEDs between the Treble and Amp Level controls. The two red LEDs on the left indicate the status of the Mid and Hot buttons, and a pair of blue LEDs monitor each half of the Virtual Valve Technology’s push/pull output stage simulator. These Blue LEDs begin to illuminate as the amp makes the transition into overdrive. The red Clip LED on the far right indicates when the output is being driven beyond its ability to track the signal’s full dynamic range. These pro-audio-inspired gain monitoring LEDs provide a rare peek into an amp’s dynamic nuances, and allow you to more skillfully control and manipulate tones and textures.
As an added bonus, the 30M is also equipped with auxiliary line-level and stereo headphone jacks. Located on the far right of the front panel, these q" outputs share a common Output Level control, and their frequency response has been shaped to emulate the sound of a miked speaker cabinet. There’s also a line-level q" Slave output on the rear panel.
Enough with the tech stuff—it’s time to talk about how this blue devil sounds and plays out in the real world. I compared the Blue Tone Pro 30M side-by-side with several vintage Marshall heads, and the results were impressive. I have never heard a solid-state amp that could so closely approximate the subtle midrange complexity, grind, and sweet kerrang of a vintage Marshall. In fact, I’ve tested some tube-powered Marshall replicas that failed to capture as much authentic texture as the 30M. Like a good tube amp, the 30M is very responsive to guitar volume changes. Plugged into the Dark input, my Strat’s neck pickup sounded big, crisp, and clean with the volume knob rolled down about half way, and transitioned very smoothly into overdrive as I gradually rolled the volume up.
Compared to a vintage half-stack, the Pro 30M is much more manageable on a gig, as it gets a similar mojo working, but at a much lower stage volume. Without any help from a P.A., it had just the right amount of power and headroom for a small-club R&B gig. And on a larger outdoor festival stage, its single Celestion Vintage 30 miked-up effortlessly, allowing the soundman to pump an authentic Marshall tone through the monitors with minimal EQ adjustment.
Perhaps what’s most impressive about the 30M is the way it captures the elusive “chaos factor” of a good tube amp’s dynamic response. It successfully conveys a musically responsive attack resiliency that few solid-state amps can approach, yet it also delivers a centered, focused, and assertive midrange thrust that some comparably powered tube amps can’t match. Occupying a unique niche in the world of guitar amplifiers, the Blue Tone Pro30M exhibits the best attributes of both tube and solid-state technologies, and it proves there’s always room for a fresh approach to amp design.