Loudspeaker designer/manufacturer John DeVore shows reviewer Ken Micallef his system.


And quite a system in it is!

At one point John tells Ken that he searched for the best amplifier of each "type" he could find, to use in the development of his various model loudspeakers. John explains in great detail how his speakers interact with different types of amplifiers.

Amongst the rare, unique, rather expensive, and/or otherwise unusual amps he chose, two more common and affordable models stick out: The Parasound A21, and for medium-power push/pull tube amps the Music Reference RM-10. John didn’t call it out by model number, but as he described it as a push/pull design using EL84 tubes it can only be the RM-10 (the only amp matching that description that Roger Modjeski ever marketed).

Modjeski marketed three push/pull amps: the first was the general purpose RM-9 (four EL34’s for 125w/ch)---a favorite of former Stereophile reviewer Dick Olsher, the second the RM-200 (a single pair of KT88’s for 125w/ch), designed to work unusually well with low impedance loudspeakers---Michael Fremer’s reference "affordable" tube amp for many years, and lastly the cute little RM-10 (a pair of EL84’s for 35w/ch). Modjeski said the sound of the RM-10 was his favorite of the three.

 

https://youtu.be/i9WYbi7afGQ?si=qkf8AiUCF_9_z2cl

 

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Agree, appreciate the post. Anything DeVore would be considered end-game for me. He seems like a nice and approachable individual as well.

I’m sure his home system has changed since 2007, but nonetheless you can also find it here in Virtual Systems if you didn’t know.

 

@toro3: Hey, John has the same cassette deck as me, the Nakamichi BX300. Thanks for the link. It’s interesting; he has a lot more gear and LPs in the listening room at the DeVore factory that at his home. I’ll bet he spends more time at the former than the latter.

The turntable, arms, and phono cartridge collection at the factory are incredible! His wall of LP’s there looks like mine, but our musical tastes are miles apart. I’m sure John also has a wide variety of music in his collection, to also use in his loudspeaker design process.

 

 

That’s the common wisdom @jasonbourne71, but one of Modjeski’s goals in designing the RM-10 was to prove that it is not a fact but rather a fallacy. Modjeski and David Manley got into a heated debate in the pages of Stereophile on this very subject back in the 1980’s, I believe it was. Manley took the RCA tube manual literally, Roger unable to convince him that the manual was merely an application guide, not a tutorial on every tube's ultimate output potential.

If you read the technical reviews of the RM-10 by numerous publications, you will learn that the RM-10 does indeed produce 35 watts from a single pair of EL84’s per channel, and doing so with the amp operating in Class A for a portion of it’s output. That’s one reason DeVore chose it as his push/pull medium-power tube amp. Roger later made a special version of the RM-10 that was rated at 25 watts per channel pure Class A, again from a single pair of EL84s per channel.

By the way QUAD ESL owners, the RM-10 is a great amp for use with your loudspeakers. Unlike OTLs, the RM-10 has a low (for a tube amp) output impedance, so doesn’t interact with the insane impedance swings of the ESL the way OTLs do.

 

and the why is because RM was an excellent engineer and understood the very detailed RCA tube manual and SOA for that and many other tubes… MR products of which i’ve owned a few legendary for high performance with long tube life.

In this case doubt = wrong and very uninformed…. typical 

 

@jasonbourne71: While doubting a pair of EL84’s can produce 35 watts, you failed to question a pair of KT88’s producing 125 watts. And yet Modjeski did just that in his RM-200 amplifier. For proof, read the test bench results John Atkinson got in Michael Fremer’s Stereophile review of the amp, in both original (100 watt rating) and Mk.2 (125 watt) iterations.

Few hi-fi tube amp designers have/had the depth of knowledge about vacuum tubes that Roger Modjeski did. Luckily a lot of his wisdom on the subject survives in the pages of AudioCircle (in the dormant Music Reference Forum). He designed his first amplifier (a single-ended triode) as age 6! He started repairing hi-fi electronics at a retail store while still in high school, and studied tubes for the rest of his life, visiting many tube manufacturing plants in England, Europe, and Eastern Block countries..

He then went to work for Harold Beveridge, the ESL loudspeaker designer/manufacturer. When that endeavor ended he started RAM Labs, RAM Tube Works, and finally Music Reference. His final product was a direct-drive ESL loudspeaker (no input transformer), the ESL stators and diaghrams driven directly by an OTL amplifier. WOW!

 

and don’t forget RAM Tubes with fantastic computerized curve testing against many critical to in circuit test points…. flunking out some 90% of current production tubes… still in business and i recall operated by @clio

@jasonbourne71

Another comment just to post and stir the pot with no backup just opinion. I have heard all 3 of the RM amps listed as my close audio friends in my area have owned them and used as references in their systems in the past. They were all well built and a nice sound used with Devore 93 and 96 speaker systems at one location and the higher powered amps used with Quad 63 speakers used at another.

There were also a few (maybe 20?) RM9SE amplifiers manufactured.

I have one of them, purchased right after Roger died, and was told this was one of the remaining 3.

Jason Bourne 71 did you personally measure these specifications 

or even have these amps in your Audio system ? I see this a lot ,

if there is a topic about anything , this applies to Everyone from tweaks like Fuses to sound isolation, to speakers to amplifiers if you have not spent time comparing and listening to ,comparing 

then you speak out of totally ignorance. A opinion without Any basis is just babbling .maybe take up a 2nd hobby ,