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

@clio09 I would love to build the kit also. Please let us know.  Very exciting. 

Here is a video of Modjeski’s seminar at the 2015 Burning Amp get together in the Bay Area. It’s an hour and a half in length, and contains a lot of Roger’s thoughts on tube amplifier design. Some humour too.

https://youtu.be/io_yZENYlxY?si=fm15uYzIkfnWjVro&t=1

And here’s his shorter talk (just under an hour) at Burning Amp in 2018. This one is more about tubes themselves. Stereophile reviewer Herb Reichert---who himself has some experience at designing and building tube amps---is in the audience.

https://youtu.be/1pU3jNquDUo?si=oxppxXCRj8Hddysg&t=1

Thanks to the OP for this thread.  It's lead me to some very interesting reading.

@clio09 PLEASE do let us know when the kit version(s) are close!

Ok thanks!

@prof Unfortunately we do not have any 6FQ7s. 

When you are ready let us know. We don't ship worldwide any longer but we do ship to Canada. To help offset the tariffs we are thinking of providing an equivalent discount on goods for Canadian customers. 

@clio09 

thanks for the information about the tube stock.

I am in CANADA so I presume they would still be the

25% tariff slapped on by Canada.

Plus, financially, I’m not in a place to order the tubes at the moment.

But it’s good to know that You’ve got quite a few of them When that time comes.

I bought a whole bunch of different 5751 tubes And really nothing was as transparent as the ones from RAM.

out of curiosity, do you have A equivalent low noise 6FQ7 tube available!

@bdp24 I wish more people used 5751s. Roger originally stocked them for Conrad Johnson preamps. The GE gray plates we have don't seem to be of much interest to folks for some reason. Maybe I need to put them on sale for a bit so more people realize what a nice tube it is. Sadly, people prefer the ribbed plates, but Roger's research determined the solid plates were superior in electrical and reliability testing.

@clio09: Van Alstine used GE 5751 tubes (in place of the stock 12AX7's) in his modified Dynaco PAS pre-amp. Better than the ARC SP-3! 

And thank YOU @clio09, for both your post and keeping the Music Reference name and products alive.

Though reviews of tube amps in professional hi-fi mags commonly contain little exploration and explanation of amplifier circuit design, reading Modjeski’s writings on the subject (as well as other subjects ) is a free means of gaining a knowledge of what to look for in an amplifier. After Roger moved from Santa Barbara to the San Francisco Bay area, he offered a class in tube amp design at a local adult education facility. Students were not only taught electrical engineering, but also assigned the task of designing and building an amplifier of their own.

Positive reviews of tube amps that produce poor performance numbers raise a number of questions, questions to which Modjeski was willing and able to provide answers (in his AudioCircle Forum and at seminars he gave). Audiophiles tend to view the sound an amplifier produces---and the sound of the tubes in amps---being partially determined by factors other than good electrical engineering basics. Parts quality is one such factor.

While high end consumers look for boutique parts in their products, Modjeski was concerned first and foremost about parts ratings. He was an advocate of using a part with a voltage rating 10 times what that part would see in a circuit. I learned the wisdom of that approach when I turned on my factory-fresh ARC SP-3 the first time. I heart a "Pop!", then smelled smoke. I took it into my dealer, who found a resistor had blown when faced with the turn-on voltage rush. That resistor was of a voltage rating of only twice what the circuit called for. Roger didn’t make those kinds of mistakes.

Not to pick on ARC, but when the SP-3 was replaced with the SP-3a, Frank Van Alstine discovered that what was new and improved in the "a" version" were not the boutique parts claimed for it, but corrections in it’s circuit design, including the inaccurate RIAA response curve that Frank was already offering a correction for in his SP-3 modification. No "magic" parts required, just excellent electrical engineering.

That’s what Roger Modjeski was all about. It’s great to learn that @clio09 will soon be offering Music Reference products; for those who can’t wait, know that Roger "approved" of the tube electronics designed and built by Mike Sanders (Quicksilver) and Tim DeParavicini (EAR-Yoshino).

Thank you for posting the video.  I found the discussion of the EMT preamp particularly interesting.  I would bet it is a very nice sounding system given the DeVore speakers and a very nice complement of gear.  This past weekend I did get to hear the Devore/Komoro 300B amp that was shown as the amp that he is currently using in the video.  To me, it sounded decent--open, clear and nicely extended, but a touch lacking in "body" or "weight."  I heard them running some fairly high efficiency speakers.  This assessment was in comparison with a pushpull 6l6 amp designed as a clone of a Western Electric 124.  

@prof The Super Low Noise RAM 6922 are expensive but if you like the 5751 you will love the 6922. Also, no tariffs, we have hundreds in stock as Roger would buy thousands of tubes at a time. Contact us via our website and let's chat. I wish more people would appreciate the 5751s which are NOS GE solid plates. An exceptional tube.

Love Devore speakers!

Also, I  am using RAM’s “ Super low noise” 

5751 input tubes for my CJ premiere 12s And they are incredible.

Definitely the cleanest signal I have heard from the amplifiers.

I also really wanted to try the RAM Super low noise 6922 tubes

In my premier 16 LS2 Preamp, But they are incredibly expensive now (And even more, so since the tariffs, no doubt)

fantastic news !

Oh and speaking of the Manley-Modjeski Letters check this out:

https://www.ramtubes.com/manley-modjeski

@bdp24 thanks for posting. this. Not sure how I missed it but nice to know John DeVore liked the RM-10 with his speakers. There were two keys to enabling that amp to get 35 watts out of a pair of EL-84s. One was using a voltage doubler to put 700V on the plates. Roger always liked to write his own applications for tubes and not solely rely on the applications presented in the tube manuals. Also prior to his death Roger redesigned the RM-10 to more closely match the original circuit. As of today, the first RM-10 MkIII is built and being tested in my system. One new twist is that bias can now be safely set to 350mV, so just slightly more power than the original without stressing the tubes. We hope to have new production going soon. Roger also wanted this to be offered in kit form as well so we are working on those details as well.

Hoping to someday acquire the 96db Devore O/96. I’m using a 100db Volti Rival for its efficiency and neutrality to check out low watt tube amps, and comparing between the musical O/96 vs Rival seems like great sonic fun

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 , 

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.

@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.

@tomic601: Right you are, pal o' mine!

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: 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 RIP Sir. many who miss him.

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 

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.

I doubt the RM-10 can do 35wpc from a pair of 6BQ5’s. More like 15 wpc.

@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.

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.

Very cool!  Thanks for posting the link