JMR Arpeggione Loudspeakers

Gothic Grilled Tuned Pipes

Product: JMR Arpeggione loudspeakers
Manufacturer: Jean Marie Reynaud - France; UK importer
Approx.cost: £700 (YMMV)
Dimensions: 845(h) x 200(w) x 290(d) mm inc grilles, spikes & sockets
Reviewer: Mark Wheeler - TNT UK
Reviewed: December, 2004

I was introduced to JMR loudspeakers by Paul Letteri, whose HighFidelityAudio company is the UK importer and direct retail supplier. Paul Letteri is an affable American who has settled in Britain and undertaken the tricky task of setting up an entirely new audio business over the past few months. Florida, just One US state, has over 600 hundred gun deaths a year which is more than the rest of the developed world combined; so its easy to understand why Americans move to Europe. Paul is a nice guy from Connecticut who has chosen to live in Europe so he obviously has taste & discernment & married a girl who lives in Cambridgeshire.

The UK audio scene tends to involve small gene-pools that adhere to distinct audio-philosophies. Although this has the advantage that importers carry a range of lines that they know will work very well together, the downside is that lucky accidents of synergy are less likely to be encountered. Paul seems to be trying to use his experience to spot combinations that will work well together, that may not seem obvious to the casual observer.

I was especially interested in the Jean Marie Reynaud range of loudspeakers that Paul imports. There are different quality levels and different sizes at each pricepoint. The pricepoints are not those typical of UK manufacturers, which might suggest that they're built to an idea rather than a market sector. This makes comparison difficult with rival brands on a similar-model value-for-money basis. So "I will not reason and compare" (William Blake).

The JMR Arpeggione loudspeakers are originals, despite a superficial resemblance to several of the many small-footprint floorstanding models that have appeared in the last 10 years to supplement the dominant stand-mounted mini-monitor genre.
These take up no more floor-space than a miniature on a decent stand, but have the advantage of larger internal volume for increased power-handling, bass extension and sensitivity (often called efficiency), or at least a better compromise when juggling these aspects or performance. Another major advantage is that the designer has more control over the floor-to-bass-driver distance and tweeter-ears relationship, knowing they will never be perched on a sideboard. Although most manufacturers now make similarly proportioned speakers, the only remotely similar product to the Arpeggione on the market is the 2-way, wood-veneered, transmission line loaded British PMC GB1, with fabric-dome tweeter above 140mm poly-cone bass-mid, that costs £995 per pair.
For £700 the JMR is a two-&-a-half way, wood veneered, transmission-line & port loaded speaker, with fabric-domed horn-loaded tweeter below 125mm doped-pulp-cone (165mm chassis) bass-mid.

The Arpeggione are veneered on all four sides and top surface and finished with a satin laquer or varnish coat. They look great with the grilles off and the tweeter waveguide may provide some superficial protection in this mode. The grilles are unusual, being shaped like an inverted gothic arch, hinting at the driver arrangement underneath.
The grilles comprise a carefully shaped black-painted mdf frame covered with stretched knitted black material that is sadly not only visually opaque but fairly opaque to high treble too.
I removed them for listening and replaced them for protection at other times as their rigid frame and good quality fixings made this much easy.

The Arpeggione are 845mm tall (33" for neanderthals) but take up only 0.054 m^2 (0.58sq.ft) of floor area, which is less than a typical stand. They need to be well away from walls but are slim enough not to intrude. They are drilled and tapped for 4 adjustable spikes and here is my first gripe with this loudspeaker.

Before I have even connected each Arpeggione to an amplifier they must be levelled. Four spikes can never be set up to have perfectly equal pressure. Even if they are embedded in a wooden floor they will soon no longer be equal due to the natural expansion and contraction of the floor through temperature and humidity changes.
On a more ideal masonry floor it is impossible to achieve perfect adjustment, whether or not through carpet. This means one spike will always be able to chatter with the vibration energy it is supposed to reference to ground. To make matters worse the spikes lack any hex-facets (or even two flats) and tightening the locknuts proved impossible without moving the position of the spike. I spent a long time investigating 4 vs 3 spikes back in the late 80s and 4 was usually inferior to 3, because with all other factors equal 3 spikes will always be less likely to wobble. A 3 spike arrangement would require a baseplate of larger footprint than the speaker to prevent toppling, but 3 spikes would still be easier to set-up and maintain and is likely to sound better most of the time. Do other enthusiasts readjust their spikes every time your speakers are moved for cleaning or do they just live in a filthy pit to avoid moving any equipment?
Even if they did they would never achieve the integrity of a 3 point arrangement. After considerable time consuming experiment I ended up establishing which 3 spikes were best placed to support the centre of gravity and placed an Isonode (flexible Polymer) on a spacer under the fourth corner. This sounded better than the four spikes and as good as just 3 and enabled a period of hassle-free positioning experiments without constant readjustment.

Arpeggione Aesthetics

The Arpeggione look very good, with a cherry stained "aniegre" veneer (I don't know aniegre) and bevelled corners to reduce diffraction. The corner bevels reveal a fillet of hardwood (looks like oak) stained cherry to match the veneer, not an exposed strip of stained mdf like so many other brands. This is an excellent touch at a pricepoint where plastic imitation veneer is still common (euphemistically called ash-vinyl finish), B&W DM 603 S3 £600 floorstander for example.
These strips of hardwood will also improve sound quality as they end by the spike inserts on the base and the speed of sound is higher in hardwood than mdf. This technique might mitigate against the often leaden acoustic qualities of mdf, which is usually chosen for its low cost rather than its audio performance whatever the adverts might lead you to believe. My own experiments (described in Speaker Builder 1999) indicated that hardwood bracing of mdf trasformed its performance as a cabinet material, regardless of how thin the strips of hardwood used.

Their styling draws mixed reactions. I like them. The inverted gothic-arched grilles were the main bone-of-contention for two female visitors who said they would prefer rectangular grilles. Most visitors male & female loved the look, although some used to seeing bigger boxes in my system refused to believe they would be adequate but were soon hearing tunes and forgetting the system.

Engineering & Design

I was intrigued by the description of the bass loading system as a triangular transmission line and I dug out my copy of Dr A R Bailey's May 1972 Wireless World article describing a triangular version of the "Non-resonant Loudspeaker Enclosure" he had described in the same journal in October 1965. That first paper had introduced the transmission-line concept to loudspeaker builders as a different approach to the tapered quarter-wave tube (TQWT) introduced by Paul Voigt in 1934, or Olney's similar vintage labyrinthine tuned quarter wave pipe (TQWP), but I am only aware of Radford previously describing a commercial speaker as a triangular transmission line.
I contacted Jean Marie, who after apologising for his english, proceeded to explain the philosophy behind the design decisions. "The loading principle used is similar to the Bailey system (TQWT) but the line expansion formula is more complex and the end of the line is with a tuned port". Very good English Jean Marie, you have no need to apologise.

Typically, the various tuned quarter-wave alignments match a pipe of length similar to a quarter of the wavelength of the free air resonance (known as fs in Thiele-Small parameters) to the rear of the driver. This loads the driver at resonance similarly to a reflex enclosure with the power handling benefits of much reduced cone-excursion at resonance, but it does not have the fast 24dB per-octave roll-off (equivalent to a fourth order hi-pass filter) of the reflex or vented alignments.
Reflex or ported alignments often have a sharp "knee" in the frequency response at the point where the roll-off begins, which can be an equivalent shape to a sealed-box Q=1.2 or greater. Both these reflex attributes have the disadvantage of poorer transient response making bass sound slower, woolly or poorly controlled compared with lower Q and lower roll-off rate alignments. Theoretically a first order, 6dB per-octave, roll-off with Q=0.5 would have the best bass transient performance, but this could only be realised by an open baffle of stupendous proportions.

Even more interesting is that Bailey's addition of damping material (the main innovation in the 1965 article) to the tuned-pipe recipe actually reduces the equivalent Q even further (easily spotted on impedance curves) and the roll-off rate to as low as 9dB per-octave, measured by Rick Schultz in Audio Express 8/03. This partly explains the very dry quality of transmission-line (TL) bass, and indeed why they often sound bass-shy. The myth that the pipe output significantly augments bass response around the free air resonance is completely unfounded as soon as damping material is added to the line. My own first attempt at a TL was intended to wring every last drop of bass from a small cheap driver and merely resulted in exposing what a small cheap driver it really was.

The JMR does not terminate the line with an equal-area vent, but with a tuned port. The port area is slightly less than half the driver effective radiating surface area which implies a fundamental difference from Dr Bailey's design. Bailey's designs gave line cross-sectional area and vent size above that of the driver radiating surface. I am guessing from the external dimensions of the cabinet that the line area is similar to the driver area and tuned to about 45Hz, which should fall below 40Hz with suitable stuffing.

The typical rising midband response of a small driver with a big magnet is addressed electrically in the Arpeggione. The woofer has dual voice-coils and is specially manufactured for JMR by Audax, whose top quality reputation should be familiar to most readers. One of the coils is fed from one set of the bi-wire terminals via a simple 6dB per octave first-order slope falling from 1200Hz. The upper terminal feeds the other coil and the tweeter (also made by Audax to Jean Marie's design) via a series configured 12dB per octave crossover at 4500Hz. The series crossover is less popular nowadays because it is harder to get right and does not allow a bi-wiring split, but it does have a number of advantages in component size and power handling, as described by Wilf Harms in HiFi News in the 60s.
Each biwire terminal on the Arpeggione offers 8ohm load and it would be interesting to bi-amplify them with identical amplifiers and cables. Because each biwire terminal feeds half the main driver motor assembly it is essential that similar construction same-length cables are used. I used 3x Sonic-Link AST300 to each bass section and 1x Sonic-Link AST300 (now rebranded Black Rhodium) to the full range section. It is reasonable value silver-plated multistrand copper found by Ben Duncan in HiFi news to have the most benign electrical characteristics in a group test, and it is flexible and easy to handle. Life is too short to waste time faffing with exotic cables.

The units are designed at factory and built on specification by Audax, they are exclusive. It's the same thing for the waveguide tweeter.

The Sound

The instructions note that these speakers take a lot of burn-in for the drivers to loosen up and everything to settle. I left them running for several days with talk radio (BBC Radio4) so that I did not make any premature judgements with music. During the day this was running at realistic human speech levels and during the night merely muttering quietly to themselves. When fired up with music they had the typical dry transmission-line bass and really fleet-of-foot timing and pace. I began to categorise them as real flat-earth speakers.

Over the next two weeks they continued to loosen up and the bass began to fill out a little more, gradually taking on almost BBC balance. I do not mean the excessive plumminess that makes cellos sound like they have flabby worn-out strings, but I do mean that extra weight that a full orchestra pizzicato passage has when heard a few rows back in the concert hall but which few modern domestic speakers achieve. So the balance is not typically flat-earth dry but the pace, rhythm and timing are flat-earth fast. The first speaker I heard pull off this trick successfully was the original Naim SBL.
The Naim was much bigger and relied on wall reinforcement to go louder and deeper than the JMR but I was immediately reminded of that experience despite aural memory's notorious unreliability. The JMR and the Naim SBL sound very different but they share that rare quality of being able to make good rhythm and full bass.

I enjoyed most kinds of music over those two weeks (except country & western which I couldn't enjoy under any circumstances) until I became sure the sound had stabilised. Now it was time to fill the lower chambers with sand and hear whether this improves bass damping as claimed. Unfortunately the two square plugs supplied were different; one being of a larger type than the other and had been crudely cut to try to make it fit.
A quick trial demonstrated that it would never fit in the hole so I contacted Paul who was unable to supply a replacement fast enough but gave me permission to perform whatever surgery would be necessary. This was the only quality complaint I can make about the fit and finish of any aspect of these speakers and it seems a shame that one part costing a few pennies should create such a bad impression.

Kiln dried sand is the only type to use for this job as the moisture content of other sand specs may damage the glues and panels. Try finding kiln dried sand in England in November. It is usually used for gap-filling in block paving so I thought small bags would be available at any DIY emporium. After trying all the big DIY sheds in two neighbouring cities I ended up having to buy 25kg of the stuff from a builders' merchant.
Curious to know how much mass could be added, I carefully weighed 3.3kg into the right speaker, squeezing extra in by the same vibro-poker technique used in concrete casting for sculpture. I inserted the square plastic plug and moved over to the other, into which I could only fit 3kg.
It is surprisingly difficult to fill the cavities with sand without causing marks and scratches to the speaker's finish and I would suggest the hole would be better placed on the bottom surface to accomplish this.

I was expecting the bass to tighten up even further and perhaps gain some slam, and JMR only claim better bass damping for this operation. However, the biggest immediate improvement was in the midrange. Vocals sounded clearer and more natural immediately but the bass sounded slowed. At first I wondered if this was a similar effect to sand filled pillar loudspeaker stands on old wooden floors that usually sound sluggish compared with light open frame stands on those floors. Wrong. Within one cd the speed had returned, presumably as the sand settled. The main difference with the sand is that vocals are clearer and bass goes much deeper. This applies on my cast concrete slab floor (approx 4m x5m x15cm thick) and may not be right on a springy old wooden floor.