[steverii]

Hey Roger, how about some info on the RM 300 mono blocks. What output and driver tubes do you use, how many output tubes,weight, etc.

Thanks,
Steve

[Roger A. Modjeski]

Steve,

The amp has 3-6BQ7 driver tubes, 6-KT-88 output tubes.  It can be supplied triode at 150 watts. There are two unusual features that I hope will delight the thinking audiophile.

Similar products from ARC, CJ, VTL etc. are real room heaters or as I like to call them Power Pigs. I though it a bit silly to be pulling 1.6 killowatts from the wall to listen to soft music at night when the family is asleep. My solution is simple. Turn off the power tubes you don't need at those levels. On the left side of the chassis there are 3 rocker switches that turn on/off their respective pair. You can rotate through the pairs (like tires) to wear them similarly. I think this is very clever. Saves tubes, saves electricity, saves air conditioning load.

One other feature this amp and the RM-200 MK II have in common is a switch to keep the capacitors formed to a bit higher than the operating voltage. When you hit the other switch to "play" mode the amp powers up and sounds like it has been on for hours, without paying for hours of electricity and tube life.  Music Reference amps draw about half as much power from the wall as other tube amps of comparable power. Tube life is extended and the amp runs cooler without sacrificing the detail and space these amps create.

Whether or not you are sensitive to the cost of electricity, this feature certainly helps the environment. Thanks to Richard Vandersteen for the suggestion and prodding to do this capacitor forming switch.

The RM-300 puts the value where it counts. Instead of some silly green display glaring at you on the front and sea of vacuum tubes on top, or the ability to hook up your computer to monitor the vital signs of your tubes; this amp is all about sound, all hand wired, all tube and reliable as all my products are.

I had to laugh when I visited the ARC suite at the 2006 Los Angeles Stereophile Show. There were two Reference 610 amps burning up electricity like there was no tomorrow (800 watts each at idle = 1.6 kW). Looking across the sea of 6550 tubes I saw two where the gettering on top was almost gone. As I left I tapped the tech on the shoulder and said.. "You might be interested to know that two tubes on the left amplifier are about to self destruct"

[shaynet]

How would you compare the sound of the RM-300 to that of the RM-200 or even of the RM-10?  Besides the ability to drive more difficult loads are there any sonic advantages?

[Roger A. Modjeski]

I strive for the qualities of neutrality, equal response through the musical range, midrange detail and good imaging. I tend to solve difficult problems in innovative ways to make the amplifiers reliable over many, many years. Each amplifier has it's work to perform and I don't advise people to get more amplifier than they need. I think a lot of people with 100 watt amps are using about 5 watts. That's why I made the RM-10. Jon Rutan of Audio Connection in NJ feels the RM-10 and the Vandersteen 1B speakers are a match made in heaven. The RM-10 is also perfect for the QUAD 57.

Sonically I think the best amps I make are the RM-9 SE, the RM-10 and the EM-7 series. All three are hand wired, have simple circuits, hefty power supplies and stability into all loads, even the small capacitance that makes some amplifiers go into oscillation. All three do something quite unusual with the chosen tubes. Everyone who hears an RM-10 can't believe that little amp can put out the volume and speaker control that it does. The EM-7 series has even nicer midrange and top, but it requires efficient speakers (we make those too). There is a lushness of sound from these EM-7 all triode, no feedback amplifiers. All my amps represent very good value for your $$. They require less maintenance than any other tube amp I know  of and lower long term cost because the tubes last 5-10 years. These are the cool running amps which helps your electric bill and the planet.

The 200 and 300 share the same output stage getting 100 watts per pair of KT-88s with stability, grace and longevity. The 300 is all hand wired for ultimate detail.

As you can see, I have more to say about how the amps work and how easy they are to own. Sonic qualities are so dependent on what's in the rest of the system, the source material and the room. I will say this. Every time I work out a new design I tend to hear things I have not heard before on recordings I know quite well.

[shaynet]

I haven't heard the RM-10, Mk II, but the original RM-10 was part of a system that I still remember as magic.  An RM-10, polyfusion front end, Mach 1 Acoustics m5 mini-monitors, and a small AMC powered sub.  Stunning.

How do the EM-7 amps compared to the 245.1? 

The RM-300 would probably be quite good with some of the lower sensitivity beasts in larger spaces. 

[Roger A. Modjeski]

I'm glad you have a pleasant memory of the RM-10. Even better than the memory is to get one and enjoy it. The differences in the MK II are largely cosmetic. From what I see out there the RM-10 is the only American made amplifier that is hand-wired, has great output power for those tubes (everyone else gets 17 watts a pair, I get 40 watts one ch driven, 35 both ch driven). The noise level is as low as one can get and in most systems the preamp noise becomes the liming factor. I will explain if anyone needs to know how that happens. I have tested several low cost amps from China and Japan and found them to be poorly constructed, noisy (usually hum), and have poor damping and high distortion. Some of them hurt my ears.

The EM-7 is as much like the 245.1 as I can make it. It is quite a value because the tube lends itself to simplicity with it's heater/cathode construction and ease of drive. The output triode has high peak current  and low output impedance. Plate resistance (which is all you have for damping) is several times lower than the 6DN7 used in the SEX amplifier kit. Maybe he used that tube because its the first one he found, but the 6EM7 is a much better choice for the application. The driver section of the EM7 is very similar to a 6SL7, it's a great combination in one bottle.

I make the 245.1 because it is an elegant amplifier and there are many 45 lovers out there. I love 45s too, but the tube itself and the extra stuff to run it raise the price.

The RM-200 is already very popular among Magnepan owners. I hope the 300 will be also and give low efficiency speakers they power they need.