The Rogers EHF-100 is more than just good sound and good value: It’s good news. Very highly recommended. –Art Dudley, Stereophile Magazine
Never before has music sounded so good coming out of your speakers. Clarity rules with the EHF-100 MK2. Trust us. Turn it on and youʼll be blown away by the concert hall quality. There may be other tube amps on the market, but nothing compares to the power and precision of this amp. The sound is stunning and so is the look. All you have to do is close your eyes and immerse yourself in the music.
- Made In The USA– Hand built to the most exacting specifications in our New York Facility. All amplifiers are fully evaluated and acceptance tested using the the best audio test equipment made by Audio Precision. We perform all of the tests in a typical Stereophile test evaluation and many more to characterize each amplifier. Each amplifier is shipped with a fully evaluated test data package so that the customer can see how his particular unit performed after acceptance.
- Transferable Lifetime Limited Warranty- Our Products are guaranteed FOR LIFE.
- Tube Complement: 2-EF86, 2-12AX7, 4-KT88
- Frequency Response: 65 Watts RMS Per Channel/0.1dB from 20Hz to 20kHz with Less Than 0.1% Total Harmonic Distortion
- Gain: 40dB
- Input: 4 Unbalanced, 100k Ohm
- Output: 2 ohm to 32 ohm
- Weight: 50 Lbs.
- Dimensions: 17″ width, 14″ depth, 10″ height
- Power Cable: Standard Cable Included, Rogers High Fidelity Quiet Cable Optional
- Fully Analog Remote Volume Control Function
I can imagine the gaiety and mirth that filled the halls of the electronics industry in the 1950s, as engineer after bespectacled engineer realized that the transistor would soon consign to the outposts of oblivion those ancient technologies that had preceded it. Before long—surely no more than a decade—the hated vacuum tube would vanish from the Earth, along with the tube socket, the tube tester, the tag board, the high-voltage rail, and that lowest rascal of them all, the output transformer. What a jubilant time!
I can’t imagine what went wrong.
The EHF-100 integrated amplifier ($6350) is one of two products made by Rogers High Fidelity, a new company in rural Warwick, New York. (When I first saw a Rogers amp, at Stereo Exchange in New York City, I assumed the brand name had something to do with the late, lamented Rogers loudspeaker company of Great Britain, but that turned out not to be the case.) Roger Gibboni, who studied engineering at Drexel University and who has over 20 years’ experience designing RF circuitry for the military and NASA, founded Rogers High Fidelity in 2009 with an eye to offering very high-quality, US-made tube amplifiers at less-than-extortionate prices.
In contrast with some recent integrated amplifiers, in which power amplifiers are paired with passive front ends, the Rogers EHF-100 has sufficiently high gain to be considered an integrated of the more traditional sort. Here, the majority of voltage gain is provided in the first stage: an EF86 miniature pentode tube. From there, the signal goes to a 12AX7 dual-triode tube, which is used in common-cathode mode to split signal phase for the push-pull output section that follows.
Power tubes in the Rogers amp are KT88s, operated in auto-bias mode: The cathode of each is held above ground by a chunky Dale resistor, ensuring that the KT88’s signal grid maintains a steady negative charge relative to the cathode. (I measured approximately 44V across each cathode resistor; consequently, although there was 514V between plate and ground, each KT88 sees a total B+ of only 470V.) The output section of the EHF-100 runs in Ultralinear mode, with plates and screen grids connected to the tapped primaries of very large Hammond output transformers. (I don’t know what percentage of primary windings are given over to the screen grid, but other Hammond Ultralinear transformers of my experience are set for 40%.) In addition to its Ultralinear operation, the Rogers EHF-100 also uses a small amount of global feedback. Gibboni says that the amp is fully class-A. Conclusions:
In my 28 years of writing professionally about domestic audio, I’ve reported on the products of literally scores of startup companies. None of them has approached, let alone matched, the level of professionalism evident in the Rogers High Fidelity EHF-100. From its design and construction through its packaging and documentation, this amp is among the most mature products I’ve had the pleasure of testing, from a company of any age.