[jman66]

Roger,

Can you elaborate on the differences between the RM-9, RM-9 MKII and the RM-9 Special Edition?
Thanks.

[Roger A. Modjeski]

The original RM-9 came out in 1985. I would go look up the price back then but we would all be shocked by how much you got for your money with that amp and those times. Common among all RM-9's are the ultralinear output stage, potted transformers, ability to use virtually all output tubes, very low noise and stable operation. I deliberately found a better way to handle the screen grids than my competitors had. Popular amps at that time often lost a screen resistor when a tube went. I though it absolutely ridiculous to ship a heavy amp two ways to replace a 25 cent resistor.

About 3 years into production it occurred to me that some further filtering in the main B+ supply would improve detail at mid and higher power levels. That was accomplished by adding two chokes and two filter caps making a separate pi filter for each channel. These chokes are rather special in that their winding resistance is only 5 ohms. At the same time I updated a few things that customers had requested. Speaker cables were getting bigger so bigger binding posts were provided. I had them custom made to my design in solid copper.

Although B+ fuses rarely blew it was inconvenient to take the bottom off to change one. Very few amplifiers had B+ fuses even then. B+ fuses are essential to save the tubes from destruction during a brief "lint short" or "white spark" as Jac at Emission labs calls them. No matter what the cause, if the current is not interrupted quickly the tube will be history.

Rather than just moving the B+ fuse to the top plate I decided to fuse each tube individually, that way you  could easily identify the faulty tube in the quartet. Now with 8 fuses on the top plate how would you know if one had gone? It's not always obvious and I didn't want to burden my customers with fuse worries. I worked out a nice LED system to show which fuse was blown. I always do whatever I can to make my designs easy to own and operate.

The last of the series is the RM-9 Special Edition. We make them in limited numbers and they have all the features mentioned so far but in addition some sonic and user friendly features. The difference from the MK II to the SE is a much bigger step than the MK I to MK II. The MK II is all hand-wired (previous models had PC board Driver circuits). PC boards save time in assembly and I feel they are OK for small tubes that run cool. I would never put output tubes on a PC board due to the heat and mechanical stress, yet a new $9,995 amplifier I just read about does just that. For that money you should get hand wiring. They claim this is an amplifier to hand down through the generations...Sure if it's not used much and you keep a fans on high. Yes, this wonderful amp has fans, the little DC kind just like the ones in your computer. The ones you always hear when you walk into the room.


Besides being very open and detailed, the SE is a very easy amplifier to deal with. I put the bias and balance controls on the top and they are rugged, custom made, bushing mounted pots (not little PC trimmers). There are 12 test points per channel for checking every tube without removing it. If something is sounding funny (or you just think it does) you can run through all the tubes in about 5 minutes, all from the top.

One last thing. The price is $8000. That's $2000 less than the similar powered, not so reliable amp which you will find in the August Stereophile. That amp has a handy "running time" clock so you can record the mean time between failures or between modifications, which ever comes first.

[jman66]

Roger,

I appreciate you taking the time to explain the RM-9 lineage. Guess my RM-9 that you just worked on is truly an oldie, #171.

[river251]

About 3 years into production it occurred to me that some further filtering in the main B+ supply would improve detail at mid and higher power levels. That was accomplished by adding two chokes and two filter caps making a separate pi filter for each channel. These chokes are rather special in that their winding resistance is only 5 ohms. At the same time I updated a few things that customers had requested. Speaker cables were getting bigger so bigger binding posts were provided. I had them custom made to my design in solid copper.

Can these chokes and caps be added to a Mk I?

Thanks.

[hoppy08520]

Yes. See these two threads:

http://www.audiocircle.com/index.php?topic=89099.msg878902#msg878902

http://www.audiocircle.com/index.php?topic=48121.msg435817#msg435817

You'd need to get in touch with Music Reference for the details.

[rbwalt]

here is a pic of the RM9SE's guts.

[river251]

Thank you, guys.

[Ralph]

In my not so humble opinion, the RM 9 should be brought back into production. I have never heard an amplifier that equals it for the sheer naturalness of the sound.

[rbwalt]

the rm9 is taken to a another level with the SE version. it is more open sounding, smoother,quieter, more dynamic but still retains the naturalness. i had a rm9mkII for 11 yrs and i do agree.

[escultor]

 Hello
    Im looking for RM-9, If somebody as one for sale.. or now of one, please let me now
 

[rbwalt]

will keep my ears and eyes open for a used RM9. you might want to see if roger has a used one.

rob.

[Roger A. Modjeski]

Hello
    Im looking for RM-9, If somebody as one for sale.. or now of one, please let me now
 

I have several used RM-9s available. They are factory reconditioned by me and come with a one year warranty. Prices range from $ 3,800 up depending on age, model and condition. Mods can be added. The price is based on what they typically go for plus the price of putting them in good shape and providing a warranty and customer care. Many of the amps bought on Audiogon end up here for significant repair. Just like used cars, the seller might not tell you about what is going on under the hood. Some amps out there have bad mods that need to be undone or have been overheated or abused.

Currently I have the following:

MK 1 upgraded to MK 2 status with solid copper binding posts, power supply mod and top mounted B+ fuse holder.  $3,800
MK 1 demo used only in one CES, pristine condition, no mods, LIKE NEW.  $4500.
MK II used in great condition  $5,500

All have rosewood frames. New Oak, Rosewood and Black Piano Laquer frames are available. Amps come without cages but I may have one used cage available for $350.

For those who want the ultimate RM-9 a few Brand New SE amps are available at $10,000. This the finest amp I have made and has replaced several amps costing twice as much in owners systems. It has 12 top mounted test points per channel that allow testing every tube in place and adjustable bias and output tube balance. The driver is self balancing. In the standard RM-9 the balance is for the driver, not the outputs, an often confused point.

Contact me at musref.roger@gmail.com if seriously interested.

[rbwalt]

roger is not kidding about the RM9SE . i had a MKII and now have a SE and it is a KILLER! Now this is not to put down or denigrate the MKII  in anyway. a great amp but the SE is a hole different animal. you simply can't lose with any of these fine amps period!

rob.