JMR

CABINET

The proprietary acoustic load of our achievements has been rethought and optimized in terms of its profile but still remains
a triangular line tuned in ¼ wave leading to a front vent at the foot of the enclosure.

Thus this new version of our triangular line allows us to use almost no absorbent in the line itself, only the dividing wall is
covered by a little thin acoustic foam and a ring of cellular foam acts as an acoustic diode. on the back of the HP cones,
no absorbent slows down the flow of air in the load.
Thus the signal propagation speed in the line is much faster and the group delay of the system is greatly improved.
In order to better control the vibratory phenomena, we lined a large part of the internal surfaces of the cabinet with bitumen
and viscoelastic compound positioned experimentally at strategic locations.

The tweeter is housed in a part of turned solid wood partially debuffed, it is decoupled from the upper surface of the cabinet
using a bitumen gasket.
The entire cabinetry rests on a base which is itself decoupled by a viscoelastic compound joint and placed on adjustable points with a tailstock.

TWEETER

Tweeter AST (aérostriction)

It consists of a pleated diaphragm 25mm wide by 60mm high, the silicone support of which is covered with a very thin film
of extremely light avionics type aluminum, this diaphragm is traversed by an aluminum frame and the everything is surrounded
by two very powerful neodymium bars.
Its operating principle is that of the Heil or AMT transformer but it has the particularity of using a diaphragm perfectly devoid of
its own resonance.
Unlike AMTs using KAPTON for their diaphragm, this one is very smooth while being very informative and fast.
Unlike a conventional ribbon tweeter which pushes air in front of it, the aerostrictive tweeter squeezes air between its folds and
expels it with very high velocity,

It is not very fragile, offers very high power handling and a distortion rate very clearly lower than that of the ribbon, especially at
the end of the strip where its movements are the most important.
It therefore makes it possible to be used much lower in frequency than a ribbon while using a less steep filtering slope, moreover
its impedance curve
and perfectly straight and it has no marked resonance frequency.
Finally, its horizontal directivity is extremely low.
As it works in dipole, it is essential to associate it with a small load closed behind it which must be tuned experimentally and which
is damped by a specific extremely ventilated felt.

BOOMER / MEDIUM

These new 180mm HPs were developed in collaboration with a German company that only works on OEM products.
We had already collaborated on the CANTABILE JUBILÉ tweeter which, for me, is arguably the best textile dome tweeter I have heard.

It took almost a year and a half of work on several prototypes to finalize the study of this extremely powerful HP.

Its cone is made of 7 layers of carbon fibers and PEEK (Polyetheretherketone).
This structure is particularly long and complex to achieve because each layer must be produced with a very precise drying time
in order to allow the whole to be as homogeneous as possible.
This cone receives a plasma treatment on its external surface (granular) which prevents the formation of standing waves.
This cone combines great lightness with good rigidity but above all excellent internal damping.
The cone of a loudspeaker is a clever mix of rigidity and internal damping capacity to avoid the resonances specific to the material used.
On this particular point we have achieved particularly satisfactory results.

This cone is driven by a 37mm coil on two 16mm long layers on a ventilated fiberglass support, this support receives a surface
treatment in order to dampen its own resonance frequency as much as possible.
A ring of plasma-treated materials is placed on the field of the reel support, again to prevent the material of the reel support from
appearing acoustically.

The air gap has a pure copper ring in order to linearize the impedance of the loudspeaker at the end of the tape and to reduce its
distortion by improving the concentration of the magnetic flux around the coil.

Its speeder is ventilated and has a progressive profile to allow movement with a constant restoring force regardless of the amplitude
of its movement.

This woofer has a 100mm double ferrite magnet with double control ring and has a very strong magnetic field.

NBR rubber suspensions have an optimized profile at the level of their curvature in order to obtain a progressive fractionation and to
maximize the efficiency of the return according to the displacement distance of the moving crew.

Its salad bowl is made of aluminum and largely clears the rear face of the cone.

Its core is pierced but receives a damping treatment consisting of several discs of oriented microphonic felt.

A fabric dome impregnated with a specific treatment on its internal face covers the coil, it is glued to the cone using a latex-based glue.

These speakers are tensioned as usual, thanks to threaded stainless steel rods which push the cylinder head of the HP and are
tensioned on the wall rear wall of cabinetry.
This principle brings the mechanical reference of the loudspeaker back to the back of the loudspeakers and ensures a better
distributed mechanical force on the front face of the cabinet.
It improves the transient operation of the HP by stabilizing its mechanical reference.
This results in a medium cleansed of all distortions linked to the micro displacement of the HP motor and a much faster and better
damped impulse speed.
 

FILTERING

It has received a lot of attention and a very long optimization period.
During 6 months I compared and tried different filter configurations but also different types and brands of components in order
to retain only the best.
These components are extremely qualitative and therefore particularly expensive.
These tests were carried out to measure of course, but also and above all by listening in order to select those who, beyond what
the laboratory work could show, have shown themselves to be the most efficient in listening.

As usual, I wanted to reduce the number of these components as much as possible in order to obtain a speaker that is easy to power.
No resonant circuit or trap circuit.
Only the components necessary to achieve 6/12 / 12db / octave type filtering are used.

This is a 2.5-way configuration, the two bass midrange speakers working in tandem and in phase below 400hz where the bass speaker
is connected
in 6db / octave. The top speaker is dedicated to midrange / bass and connects to 3500hz with the tweeter and is not filtered in the bass.

This filter is made up of two distinct cells oriented and separated from each other in order to avoid intermodulation of the components
as much as possible.

We use silver armature capacitors with HP1132 cable termination (silver / copper).
The winding orientation is marked and they are specific to our use (manufactured under specifications by a French company SCR).

The chokes are made of large-dimension pure copper strips wound around a solid wood mandrel and trapped in wax in order to avoid
any unwanted radiation and intermodulation.
These chokes have the particularity of offering an extremely low distortion rate, a very low internal resistance and very high power
handling capacities.
This results in a very full bass, articulated with a lot of density, substance and great dynamics.
They are used both on the bass but also for the connection of the medium with the tweeter.

They are oriented with respect to each other in order to avoid any unwanted radiation.

The resistors for equalizing the level of the tweeter are of very high quality, they are wound and have the particularity of being surrounded
by a copper tube connected to the ground of the system (they therefore have three wires, input output and mass and must be oriented in the
direction of passage of the signal) the assembly is then trapped in an inert resin.
This copper tube plays the role of shielding (Faraday cage) and eliminates all the electromagnetic disturbances around the component which
are evacuated by the mass of the system, but also acts as an excellent heat sink.
Thus the rate of distortion of this resistor is particularly low.
During large differences in levels, conventional resistors tend to heat up enormously, which results in distortion.
With these resistances, the treble is very transparent (evacuation of micro discharges) and extremely dynamic with a sensation of
surprising naturalness, leaving room for all the micro information essential to a truly musical listening.
The harmonic gradient is much more logical and devoid of "slag", the treble is matier, fine, without persistence or undesirable grainy effect.

As usual, all filters are made by hand, without using a printed circuit, the components are soldered directly to each other using a ROHS
silver solder and are fixed with a flexible glue on the plates of forex which further isolate the components from vibrations.

The two cells are placed as far as possible from the magnetic radiation of the loudspeakers and are themselves acoustically shielded with
compound and foam.

All the internal cabling is done with our HP1132 cable, the section of which is doubled for the midrange and bass.

Each component is measured and sorted in pairs with a tolerance reduced to 1%.
Thus the components of the filter have perfectly identical values ​​on the pair of loudspeakers.

The loudspeakers are connected to high-quality pure copper Mundorf terminals, selected for their exemplary musicality.
They are fixed on a bituminized aluminum plate.
The cables are connected to the passive filter without soldering using pure copper eyelets, also from Mundorf.

DIRECTIONS FOR USE

Thanks to a very little directivity, it is not necessary to make the two speakers converge towards the ideal listening point, to pinch
them very lightly in order to make the most of the phase of the system.

The spacing will be determined experimentally.
It is ideal theory around 3m from axis to axis but this distance can be reduced.
In order to obtain a constructed and deep stereophonic image make sure to move the speakers away from the side and rear walls
by at least 80cm.

The best results in terms of spectral balance and musicality have been obtained by using our HP216B cable, the same used for
the internal connection of all system components.

IMPORTANT

This system was developed for domestic use, under no circumstances can it be used for public or private sound.

Any incident resulting from this type of use will in no case be covered by our warranty.