RMB Model 12/3 Loudspeaker

[RMB 12/3 in my listening room]


[Italian version here]

Product name: RMB 12/3
Manufacturer: RMB Loudspeakers - UK
Cost: 1200 (Currency conversion)

Reviewer: Mike Cox - TNT UK
Reviewed: May, 2017

If you are a regular reader of TNT-Audio you may remember my review of the 40/4 loudspeaker from RMB Loudspeakers. My colleague Andy Norman followed up with a review of the smaller 22/3 model. These are fine loudspeakers with a different slant on the styling, a little reminiscent of the old Naim SBLs for the smaller 22/3 model.

This time we have a new model in the RMB range and the smallest so far. Even so the the 12/3s are not small when compared to something like the classic LS3/5A. The 12/3s arrived very carefully packed and you will need to take great care when unpacking to avoid a finger in one of the diaphragms. The packaging is well designed and there are lots of markings to indicate which side to open the cartons and where to place your fingers to avoid a problem.
Once unpacked you need to bolt the stands to the base of the speakers. Compared, to the 22/3 model these speakers use a single column for the stand and to my eyes they are visually much nicer.

[RMB 12/3 Front View]

The finish of these speakers is superb, I love the black ink stain and high gloss lacquer. The recommended position is up close to a rear wall and at least 60cm from the side walls. I cannot place the speakers near a rear wall due to the room shape but they are more than 60cm from the side walls.

These speakers have an efficiency of 87dB for 1 watt at 1 metre and the recommended minimum power is 30 W/channel. In my enthusiasm to hear the speakers and to avoid too much fiddling I used my 2A3 integrated valve amplifier delivering a mighty 3.5W per channel, a mismatch you might think. The rest of the system is a Chord Hugo TT DAC fed from a PC running Audiophile Linux with all the music files stored on a network drive. For analogue duties I have a Pre-Audio turntable feeding Whest PS30R phono stage and a Benz Micro Wood cartridge.
Also on analogue duty is a Revox A77 that has been restored and playing some wonderful first generation tapes from Analogy Records (Review to follow).

The design is rear ported bass reflex and RMB recommend using a 4 ohm output for valve amplifiers with DNM single core speaker cable, the review samples came supplied with the required DNM cable. The bass mid drivers are 120mm with paper fibre cones, 25mm voice coils and vented pole piece. The tweeters are 26mm treated fabric dome units with a rear damping chamber, shallow horn profile and metal chassis.

The cabinets are constructed from 18mm high density birch plywood with multiple internal braces and felt lining in critical places. To my eyes the fit and finish is very good with the plywood structure used as a design feature. The speakers are bolted to the stands and the stands are supplied with spikes for use with carpet on wood floors. If the speakers are to be used on hard surfaces then felt pads are recommended in place of the spikes. To be fair to the speakers I swapped out the 2A3 valve amplifier and replaced it with MFA Classic transformer pre-amp feeding a self assembled class D amplifier built from modules that use the International Rectifier chipsets.

The amplifiers deliver about 200 watts per channel and are a very good class D solution in my experience. I also tried the speakers with other valve and solid state solutions that all worked well.

[RMB 12/3 Rear view]

How do they sound?

The first facet of the RMB 12/3 loudspeakers is the high level of detail and three dimensional sound stage, they make other speakers I have heard in my listening room sound rather vague and fuzzy.
Another feature is the lack of colouration, the 12/3 presentation is very neutral, they add very little of their own character, you hear the music as the recording engineer intended.
For me, in my room, I preferred the 12/3s being driven by the valve amplifiers in preference to the solid state amplifiers, the sound was sweeter with a richer tone.

As these speakers don't require masses of power, something like the DMID PP10 that I reviewed recently, may provide an elegant setup, it is a pity I did not have this amplifier around for this review.

Compared to my current reference speakers (open baffle using 15inch bass driver) the RMB 12/3 are never going to deliver the same weight of sound and impact. Even so, the results are very acceptable with good extension provided by the two 120mm drivers with the assistance of the rear port.

Playing my favourite Gregory Porter track "Liquid Spirit" from the album of that name the RMB 12/3s show respectable extension on the acoustic bass while getting on with the rhythm, the port at the rear does not obviously get in the way.

Another of my favourites is the Tallis Scholars singing Allegri's Misrere, the 12/3s ability to deliver details and three dimensionality really helps this performance, providing great focus and stability to the sound stage.

Other speakers deliver a slightly less precise sound stage that appears to waver slightly, like the optical affect you see with a heat haze causing the view ahead to waver on a really hot summers day, not that we have had too many of those recently!

To finish off the review, I replaced the class D amplifier with my 300B, like the 2A3 it was made in China and is also very well made. I have done some work on the 300B amplifier, replacing the coupling capacitors with some from Mundorf and also replaced the electrolytic power supply capacitors and added, in parallel, a Clarity polypropylene capacitor. The result is a much more robust power supply and delivering less wooly bass, cleaner mid-range and a more delicate treble. With the 300B powering the 12/3s the result was my favourite, a lovely delicate and airy treble on the percussion, the Mark Isham album "Blue Sun" was a delight.
This album has some deep electric bass which the bass drivers worked hard to deliver with little overhang and good articulation.

Finishing with my favourite female vocalist Mary Black, the high levels of detail and low coloration allowed the speakers to deliver a very atmospheric performance.

My particular favourite album from Mary is "Collected" from 1982. This album can sound a bit vague and soft through some systems, the 12/3s really stepped up to the challenge, particularly on the track "My youngest son came home today". This track starts very simply adding more instruments as the performance progresses, the Bodhran in particular can be hard to hear. The 12/3s let the music build in complexity with all the instruments clearly defined.

The "Mary Black Live" album has some fabulous tracks, in particular "Katie" and "The Crow on the Cradle", these live performances with the audience participation were spine tingling, especially the guitar solo to end Katie.


I know these speakers have a recommended power of 30W and I expect, in a larger room than mine (4m x 5m), this may be required, but for me it is not necessary.
What is more important is the quality of the power, I think it was Nelson Pass who advocated "The first watt is the most important", and it is really true with these speakers.
Sure if you like your bass deep and tight you might pick a solid state amplifier, but then you may not be looking at the 12/3s from RMB, the 40/3 might be a better choice.

If you are fan of the venerable LS3/5A then you may like the 12/3s, they look very different from the LS3/5A but have a wider window on the sound stage, more detail, and better bass extension.

As for the looks of the 12/3s, they follow the family tradition that may not be to everyone's taste. Put these prejudices aside and give these speakers a listen as you may be surprised and the visuals may grow on you as they did for me. The fit and finish is really very nice and if placed near the rear wall they take up little room space.

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© Copyright 2017 Mike Cox - mike@tnt-audio.com - www.tnt-audio.com