Ohio based Dr. Z has been on a roll of late with the introduction of the surgical steel pedal-steel amp (reviewed in the august issue), and now the EMS or “Essential Marshall Sounds,” which is designed to replicate the tones of three eras of classic Marshall 50-watt amplifiers: a mid-’60s JTM 50, a ’70s “small box” JMP, and an ’80s JCM800. To nail the essential ingredients for these brews, Dr. Z equipped the EMS with a pair of EL34 output tubes, which are fueled by selectable rectifiers: a 5U4G tube (for ‘60s-era response) and a solid-state type as per the ‘70s and ’80s models. Along with a set of Gain, Volume, Treble, Middle, Bass, and Presence controls, the EMS also features a Touch switch and a Hi/Lo switch that boosts the gain by adding another 12AX7 stage to the preamp.
The EMS is built on a rolled aluminum chassis and features hand-wired circuitry to all the components, including pots, jacks, switches, and tube sockets. It also carries a precise copy of the Drake 784-139 50-watt output transformer, which was a hallmark of vintage Marshalls with two EL34s.
The EMS on review here is the first one Dr. Z made with a “Bluesbreaker”-style cabinet housing two 12" Celestion G12 M speakers. The birch-ply cab is covered in black Tolex and is accented with gold piping and a woven grille. In this format the amp is big (32" wide by 23" tall), and it weighs a robust 62 lbs. Of course, as with all things Bluesbreaker, the open-back rig has a sound unto itself—one of the reasons why Brad Paisley went with the same-sized cabinet for his signature DB4 model (reviewed July 2016).
Tested with a Gibson Historic Les Paul, a PRS P90-equipped semi-hollow, and a G&L ASAT with a Duncan BG1400 bridge pickup, the EMS sounds as big as it looks. It has impressive girth even at low volumes, and while the Bass control doesn’t exactly pour on low-end when turned up, there was no shortage of beef with single-coils. This amp sounds very clear and warm at low Gain settings—great for fat jazz and blues tones—and the headroom is astonishing. Leave the gain switch in the Lo position and simply dial up the Volume to get a big, dimensional tone for rhythm playing or when you want a clean foundation for your drive, delay, or modulation pedals.
On the flip side, the EMS is really in its element churning out gritty crunch at medium to higher volumes. The response is a little tighter when using the solid-state rectifier, and the Touch switch (which adds a .047uF cap from the B+ center tap to ground in the high-voltage power supply) is designed to give a more tactile playing feel. Its effect is subtle, but, when combined with the tube rectifier, the amp treads into juicy, tweed-Fender-style territory with the Gain knob above two o’ clock and the gain switch either on Lo or Hi depending on how loud you’re playing and/or how much distortion you want. With minor adjusting of the tone controls (the Middle knob is particularly effective), the EMS conjured a good impression of my ’66 Marshall JTM-50, and had a similar sensitivity to guitar volume changes. Switching to the solid-state rectifier gives a little more punch, and—with the gain switch set to Lo and the Gain control turned up with the master Volume cranked—was reminiscent in sound and feel to my ’72 JMP Marshall non-master 50-watt (running though an open-back 2x12 with Celestion Vintage 30s.) The EMS is punishingly loud in this configuration, so fortunately there’s a Volume control to set overall levels without compromising the core tone. In Hi mode, the cascaded 12AX7 stages reflect Marshall’s ’80s-era solution for coaxing more overdrive from the JCM800. The EMS actually has quite a bit more overdrive and is more tonally consistent too, courtesy of some circuit modding by Dr. Z, and it’s all there with a sweep of the guitar’s volume knob: gutsy grind for rhythm playing, smooth transitions into sustaining solos, and the ease of going from humbuckers to single-coils with very little fiddling with the amp’s tone controls.
Put it all together and the EMS comes off as a mini library of old-school Marshall-flavored tones. The combo version may not be for everybody (plug-in casters are included, however), but it’s an impressive amp visually and sonically, and one that carries on the tradition of blues/rock righteousness as etched into history via the original Marshall model 1962 amplifier. The EMS enhances that platform for modern players (albeit with no effects loop), making it a standout model in the Dr. Z line and winner of an Editors’ Pick Award.
PRICE $2,499 street (2x12 combo); $1,899 (head only); $2,599 (EMS set with head and 2x12 cab)
CONTROLS Gain, Volume, Treble, Middle, Bass, Presence. Touch switch, Hi-Lo (gain) switch, Tube/Solid-State Rectifier switch.
POWER 50 watts
TUBES Three 12AX7 preamp tubes, two EL34 output tubes, 5U4G rectifier
EXTRAS Switchable tube and solid-state rectifiers. Extension speaker jack. Impedance selector (4Ω, 8Ω, 16Ω)
WEIGHT 62 lbs
SPEAKER Two Celestion G12 M “greenbacks”
KUDOS Broad range of British-style-sounds. Impeccable build quality.