Hi dhcod, thanks for the EL84 question. As a young man, I first came across the Music Reference electronics in a large, comprehensive publication from "The Tweak Shop" in the mid 1980's, a California retailer for Music Reference. Having experienced early McIntosh tube gear, I craved ownership of RM but had neither the budget nor confidence in the stability and longevity of tube amplification from that era. Through a compounded series of good fortune through good friends, I was able to purchase a RM-10 MKII a few years ago. It replaced my groundbreaking, purchased used NAD M2 Direct Digital Amplifier, a $6K all-in-one approach. My niche in our hobby is finding the best I can possibly afford, THEN going to work to improve the design. For example, the NAD M2's cheap case rings horribly, inexcusable for the price and a much-needed fix. (I'm pleased to note, NAD's new designs have addressed this.) After doing due diligence around the RM-10, I was NOT about to mess with Roger Modjeski's design. Interestingly, in switching amps, the humble 35W per side vs the 250W per NAD, the dynamics were greatly improved!! The perpetual mystery of audio. I first experimented with tube sets, which can be had for under $150. Next, I applied a full complement of Marigo Audio Lab VTS tuning dots, drawing out its deeper truth. A large "head's-up" to RM owners...do pay attention in cleaning the connector contacts found INSIDE the amplifier as well. There are O-Ring connectors on the inner wires. My two previous owner friends were unaware of this requirement and there is goodness to be had! I experimented with power cords to the amp, finding a sweet spot. Then!...despite my work under the hood, under both the amp and my Focusrite Clarett Pro DAC, I further isolate with one of these: IsoAcoustics zaZen Series Isolation Platform 17" W x 15" D: zaZen II (40 lbs Max) (amazon.com) Now, I don't know exactly where the improvement is being made, but the improvement is similar to a tangible cartridge upgrade. IsoAcoustics also makes a larger platform for heavier applications. So there you have it. In my experience, excellent affordable gear CAN be improved upon in cost effective and tangible ways. Do the homework and enquire from knowledgeable, reasonable people. Uber power, room speaker integration and carefully integrated affordable gear, can get very close to the crazy stuff, and be absolutely gratifying. The Music Reference RM-10 MKII found a permanent place in my approaching dotage system. Ever onwards! (bold print for old eyes) More Peace & even order harmonics! Pin |
Let me begin (oh no, here he goes again ;-) by recommending you head over to the AudioCircle site, where you will find a Music Reference section in the Forums. Roger was eventually kicked off it, but before that happened he posted for a number of years, providing his thoughts on a lot of technical issues, including those related to the design of all his amplifier models. Really fascination stuff. As I previously posted in a thread here on Audiogon, Roger told the story of Tim de Paravicini (one of the few hi-fi amplifier engineers/designers with whom he felt "aligned") telling Roger he could predict the bass response of a power amp by looking at it’s output transformers. It is well known that the more "iron" there is in a transformer, the better will be it’s reproduction of bass frequencies. Conversely, the worse will be the sound of the reproduction of high frequencies. Everything in hi-fi design is a matter of design choices, trade-offs that must be made. Every design choice comes at a cost. Roger Modjeski was not a "normal" hi-fi company owner. He freely admitted he didn’t enjoy running a business, or even building "product". What he liked was designing, finding solutions to engineering challenges. He stated every amp he offered was an answer to a design challenge, not just another amp. He didn’t design or build an amplifier to have a certain sound, but rather to be stable, linear, and distortion-free. To have no identifiable sound of it’s own. Of course, that is the oldest mantra in hi-fi, but imo he took it more seriously than do most amplifier designers. To hear Roger discussing amplifier design in the flesh, search for the YouTube videos of the talks he gave (three of them) at the annual Burning Amp Festival in San Francisco. In the RM-10, Roger set out to prove that 35 watts could be created by a pair of EL-84 tubes, twice what anyone else had ever been able to coax out of that tube. Damned if he didn’t do it! And without sacrificing tube life. You can learn how he did it by watching the Burning Amp videos and reading the Music Reference sections in the AudioCircle Forums. The RM-200 was Roger’s answer to the challenge of designing a tube amp that 1- was optimized for powering low-impedance loads, and 2- produced a hundred watts out of a pair of KT-88 (or 6550) tubes. Again, twice the normal power created by those tubes. I got myself an RM-200 specifically to drive the midrange/tweeter panels of my Magneplanar Tympani T-IVa, a notoriously inefficient planar-magnetic speaker. 100 watts is not nearly enough power for a T-IVa run full range, but the speaker is very easy to bi-amp, something Magnepan urged Tympani owners to consider. Used with a brute amp on the bass panels, the RM-200 is enough for the m/t panels when used in a moderately-sized room. I got myself an RM-10 for a specific application, one for which the amp is perfect: the Quad ESL. Roger used that loudspeaker and the 16 ohm LS3/5a as his speaker load in the design phase of creating the RM-10, the Quad a notoriously difficult speaker to drive. If an amp can remain stable, linear, and distortion-free when driving the Quad, powering just about any other speaker is a breeze. Not an inefficient, low-impedance speaker, of course (for that he offered the RM-200). As for the bass characteristics of the RM-10, that was immaterial to me. I have always used subs with my Quads, as did Roger. Removing the low frequencies from the bass panels of the Quad and the amplifier driving them results in a significant improvement in the sound of the combo, PROVIDING one has a sub/woofer of sufficient quality. I have the best: the Rythmik/GR Research OB/Dipole Sub, THE woofer for any and all dipole loudspeakers. The RM-10 and RM-200 came years after the RM-9, Roger’s first and most "conventional" amplifier. Roger started his hi-fi electronic career the same way Bill Johnson of ARC did: by repairing broken stuff. Johnson owned a repair shop, Roger worked in one while attending college. Roger made a point of investigating and analyzing the design of every amp he repaired, taking note of what caused them to fail. Building a dependable, trouble-free amplifier was a very high priority for Roger. In the RM-9, Roger’s goal was to create the most stable, linear, distortion-free push-pull/ultra-linear tube amp he could. One that provided long tube life, and of course superior sound. In his review of the RM-9 Mk.2, Dick Olsher asked the rhetorical question: "When we have the RM-9, who needs the McIntosh MC-275?" I haven’t owned a lot of amps, but I can tell you the RM-9 is a better amp than the ARC’s I owned in the 1970’s (of course that was a long time ago, and ARC designs have greatly evolved). In the 1980’s (I believe it was) Roger was hired by Harold Beveridge to design and build the tube amps included in the Beveridge ESL. Roger had previously discovered and become intrigued by the Futterman OTL amplifier, and he worked hard at solving the engineering problems that amp design presented. Roger’s final product was not just his own ESL loudspeaker, but one with no input transformers (the cause of a lot of non-linearity). Already an unheard of idea! But Roger went further, designing and building an OTL amp specifically to drive his hand-built, transformer-free ESL panels. Think about it: the output tubes of an OTL amp directly driving the ESL panels themselves. Talk about transparency! By the time the ESL/OTL had gone into production, Roger had moved from Santa Barbara up to the Bay Area. I was out in Palm Desert, and was unable to make it up to his new operation to hear his masterpiece before Roger’s illness made that impossible. The biggest regret of my hi-fi life. |
