Our goal with the latest Dr. Z amp, the EMS, was to produce the essential sounds of 3 generations of classic British amplifiers. Starting with the mid-60s JTM 50 variant, we combine a dual EL-34 power section with a tube rectified power supply, available by selecting “tube” via the rectifier switch on the back panel. Along with the tube rectifier, setting the EMS’ sensitivity switch to “low” and “Touch” response switch to the down position, this combination will produce the bloom and feel of the early American tweed amps but with the British charm of EL-34 output tubes.
Flashing forward to the 70s, the essence of the “small box” JMP amp is available in the EMS by selecting the “solid state” rectifier via the back panel, selecting “low” sensitivity, and using the “Touch” switch to match the amplifier with your choice of guitar. Using the same circuit topography of the JTM series, only with a more powerful solid state power supply, this sound is noted for its lightning quick response and cutting “kerrang” in the upper midrange.
Lastly, the EMS incorporates the cascaded gain stage design found in the 80s JCM series. By using the “high” sensitivity switch on the front panel, and selecting solid state rectification, hard rock and classic metal tones with tight bass response and singing gain will come screaming out of your guitar. We massaged the circuit to remove some of the annoying, persistent high-treble this era of amplifier has been maligned for and boosted the gain a bit further so that more “modern” drive tones are available higher on the gain knob.
The EMS, like all Dr. Z amplifiers, is 100% hand-wired in Maple Heights, OH using select components throughout its stages and built on a custom rolled aluminum chassis. It has a precise copy of the Drake 784-139 50-watt output transformer for authentic British crunch.
Power Output 50 Watts
Output Tubes 2 – EL34 (fixed bias)
Preamp Tubes 3 – 12AX7
Rectifier Switchable 5U4GB tube and solid state diodes
Controls Gain, Volume, Treble, Middle, Bass, Presence