Home
AudioAsylum Trader
Tubes Asylum: REVIEW: Music Reference RM 10 Amplifier (Tube) by Marc Bratton

Questions about tubes and gear that glows. FAQ

For Sale Ads

FAQ / News / Events

 

REVIEW: Music Reference RM 10 Amplifier (Tube)

208.136.90.125


[ Follow Ups ] Thread:  [ Display   All   Email ] [ Tubes Asylum ]
[ Alert Moderator ]

Model: RM 10
Category: Amplifier (Tube)
Suggested Retail Price: $1475.00
Description: EL 84 35wpc push-pull tube amp
Manufacturer URL: Music Reference
Model Picture: View

Review by Marc Bratton on August 08, 2001 at 03:35:55
IP Address: 208.136.90.125
Add Your Review
for the RM 10


This is a wonderful little amplifier that the designer Roger Modjeski obviously put a lot of thought into. Some of the criteria that he very consciously designed into this amplifier are: 1.)Efficiency-both electrical, and in use of tubes and material. In this regard, he has succeeded admirably, as the amplifier only consumes 70 watts at idle, and not a whole lot more than that even at rated power. The tube complement consists of only 6 tubes-two 12AX7A's as inputs and drivers, and a single matched pair of EL 84's per side. He somehow manages to get an honest 35wpc per side out of those EL 84's, whereas most amplifiers only get 17.5 watts max. The amplifier is correspondingly small therefore, weighing in at only 16 lbs. The output transformers in particular are small-the smallest I've ever seen at this wattage. Everything is very high quality, however. Solid oak or cherry cab, all point-to-point wiring,solid brass speaker posts with multiple taps, and what appears to be a very straight forward design that kept in mind ease of service. 2.)Truly excellent sound, of course, in which I also feel he has succeeded...(3.)Long term reliability, both of the amp and the tubes. He expects 10,000 hrs use of the inputs, drivers AND the outputs, if kept biased to spec @ 30 milliamps.
As he states in his fairly well written owner's manual, he put over 5 years into this design, trying to get it to sound exactly like a smaller version of its bigger brother, the well known RM-9. I cannot say how well he has succeeded in this goal, as I've never heard the RM-9. But the little RM-10 succeeds on its own terms.
With 35 watts, of course, speaker selection does come into play, but not nearly so much as with SET amps. As this amp was "voiced" by Roger using the original Quads, this amp would probably be an excellent match for those speakers. For those who use high efficiency horns, this amp would be an excellent match as well, not only power rating wise, but also because of its phenomenal signal to noise ratio. I don't know how he does it, but this is THE quietest tube amp I've ever heard. Set your selector to a muted source, and turn the volume ALL THE WAY UP. Assuming you have either a deadly quiet preamp, like my Bryston was, or a passive, like my FT Audio, you'll hear nothing. Nothing at all. No hum, no tube rush, roar, or hiss, nada. Amazing. A whole lot of solid state amps are not this quiet.
K-horn users, this is your amp! This ultra low noise floor I believe is instrumental in its relaxed, unforced way it has with allowing little musical details to flow...more on that below.
As it comes from the factory, it is configured with 14 db of global negative feedback, which gives it a barely adequate damping factor of 12.5 into an 8 ohm load. This is where speaker selection comes in again. You're not going to get tight as a nut bass with a ported woofer with a damping factor this low. PRAT can suffer as well. When I mated this amp with a pair of Epos ES 11's, I got a rich, plummy, to die for midrange, sweet,clean, slightly rolled off treble, but bass that bordered on tubby. While this combination was luscious with string quartets, it left a bit to be desired with rock. With Vandersteen 2ce's, it wasn't bad at all, but again lacked authority in the nether regions, and could run out of steam when pushed.Surprisingly, a match seemingly made in heaven is with my Magnepan MMG's. Being such insensitive speakers, these have NO right to sound as fantastic as these do with this amp. I think it works because:(1.)The low damping factor is not such a big deal with the panel speakers as it is with cone speakers. (2.)The Maggies have a VERY benign modulus of impedance. Even though they are 4 ohms, they are a RULER flat 4 ohms. The RM-10 likes it, and the MMG's love the RM-10!
In my system, with these speakers, the little RM-10 handily beat out my beloved Conrad Johnson MV-50, which formerly had pride of place in my system. I'd say their overall "voicing" is very similar, so if you're familiar with the CJ tube amp sound, you'll get an idea of how the RM-10 sounds. Where the RM-10 handily beats my CJ is in quickness, dynamics, and detail. Even though it's rated to be less powerful than the MV-50, it just plain got out of the way of transients better. Dynamics, both macro and micro, were improved. Little spatial cues about the recording venue, and imaging was improved as well with the RM-10. Instruments and vocals were just more fleshed out, more "there". It definitely sounds a bit cleaner than the CJ as well in the all important midrange, losing nothing of the lushness of the MV-50. Quite a trick. I believe this is because it's a lot simpler and electrically quieter a circuit than the MV 50. Speaking of simpler and quieter...for those of you using passive preamps, as I am, this amp is made with you in mind. It has an input impedance of 100kohms, and only requires 0.8 volts, I believe, to be driven to rated output. Thus, it is a very easy amp to drive.
So, for those of you who are thinking of taking a plunge into tube amps, this one would be an excellent one to start with. Easy to bias (you'll need a voltimeter), stable, quiet, nice to look at, no nasty surprises,low cost tube replacement, reliable, and beautiful sound. Roger Modjeski's designs have stood the test of time, and his is no fly-by-night outfit. He'll be around. Speaking of which, I'm glad to see he's producing this amp again-it had been discontinued for a few years. If you get this amp, I predict it'll be around your place for a long time as well. Highly recommended.


Product Weakness: Forget about Stygian bass of the Gods. You have to mind what kind of speaker you match this amp with. While sensitivity is important, what seems to be more important is that the modulus of impedance be very benign. In this regard it IS more like a SET.
Product Strengths: Excellent build quality, reliable design. Al the usual reasons you buy a tube amp for are fully present in this amp. This is an amp for chamber music, vocals, jazz, folk, soft rock, classical. Headbangers probably would want more, but it does do rock surprisingly well with my MMGs.


Associated Equipment for this Review:
Amplifier: RM 10
Preamplifier (or None if Integrated): EAR 834P/FT Audio LW-1
Sources (CDP/Turntable): WTRP with ClearAudio Beta
Speakers: Magnepan MMG's
Cables/Interconnects: All DH Labs, except Kimber Select 1020 between preamp and amp.
Music Used (Genre/Selections): All kinds. Mostly symphonic, chamber music, rock.
Room Size (LxWxH): 26ft x 16ft x 8ft
Room Comments/Treatments: Typical living room, dealt with by careful speaker placement and RPG foam pads behind MMG's.
Time Period/Length of Audition: > 1year
Other (Power Conditioner etc.): Brickwall/Monster HTS 2000
Type of Audition/Review: Product Owner




This post is made possible by the generous support of people like you and our sponsors:
  Crux Audio  



Topic - REVIEW: Music Reference RM 10 Amplifier (Tube) - Marc Bratton 03:35:55 08/8/01 ( 17)