Martin Logan Monolith III Electrostatic Loudspeaker


The Monolith III stand alone. Powerful. Imposing.

Thrusting you into a world of harmony and purity discovered only by a chosen few.

It all began with this reference speaker project. Since its emergence in 1982, the Monolith has represented the culmination of reference level ML electrostatic technology and exhaustive crossover and dynamic driver research, providing dynamics, precision and bandwidth comparable at any price range. This system combines lush wood grain and black satin composite finishes into a strikingly beautiful cabinet, as elegant to behold as its sound reproduction is to experience. This pre owned Monolith III is a mid 1990s model and comes equipped with  the  external passive crossover.


Martin Logan Monolith III


The Martin Logan MONOLITH III represents the culmination of an intensive, dedicated group research program directed toward establishing a world class reference monitor utilising leading edge technology. This was without compromising durability, reliability, craftsmanship, or aesthetic design.

The original Monolith made its official debut in June of 1982 at the International Consumer Electronics Show.   it was selected for the prestigious Design and Engineering Exhibition as one of the most innovative consumer electronics products of that year. Since then, the Monolith has become the speaker of choice by the most demanding musicians, electronics manufacturers, and recording studios, as well as the most discerning critical listeners.

As a result of the continuous research and development program at Martin Logan, they decided that it was time to incorporate some of their latest technologies into the already outstanding Monolith. So, in January of 1990, the MONOLITH III was introduced to the marketplace.

With the MONOLITH III, Martin Logan have advanced the current state of the art in many areas of loudspeaker design. Bass response has better extension, superior impact and improved definition. High frequency response also has better extension and is much more natural in character. Much effort was spent on minimising all diffractive or reflective surfaces. This has improved over all transparency and image quality.

In addition, a great amount of energy was spent on the interface between the electrostatic element and the woofer, with astonishing results. The fruit of this labor was the passive IIIp INTERFACE and the superior electronic IIIx CROSSOVER. With either of these two devices, the transition from the electro-static element to the woofer becomes invisible and an unbelievable continuity of sound prevails. With the IIIx CROSSOVER another veil is lifted and you are brought even closer to the musical truth. Dynamic information suddenly becomes frightening. Power handling and system efficiency are enhanced as well.

Like the original Monoliths, all materials in the MONOLITH III speakers are  of the highest quality to provide years of enduring enjoyment and deepening respect. All trim pieces are constructed from selected hard woods. They are then grain and colour matched and finally hand finished. The cabinetry is constructed from a special high density hardwood powder board for structural integrity and is finished with a durable and attractive leatherette.

Through rigorous testing, the curvilinear electrostatic panel manufactured and used by Martin-Logan has proven itself to be one of the most durable and reliable transducers available today. Fabricated from a specially tooled, high-grade steel, the panel is then coated with a special high dielectric nylon delrin based polymer that is applied via a proprietary electrostatic deposition process. This panel assembly houses a membrane 0.0005 of an inch thick! Ruggedly constructed and insulated, as much as 200 watts of continuous power has driven the MONOLITH III’s energised diaphragm into massive excursions with no deleterious effects.


  • Frequency Response: 28–24,000 Hz ±3dB
  • Recommended Amplifier Power: 20‒500 watts per channel
  • Horizontal Dispersion: 30°
  • Vertical Dispersion: 48″ (121.92cm) line source
  • Sensitivity: 89 dB/2.83 volts/meter
  • Impedance: IIIp High pass – 4 Ohms, 1 at 20kHz, IIIp Low pass – 4 Ohms, IIIx (Exos) High pass – 47,000 Ohms, IIIx (Exos) Low pass – 100 Ohms . Compatible with 4, 6, or 8 Ohm rated amplifiers
  • Crossover Frequency: IIIp: 125 Hz. IIIx 125Hz 12dB/octave low-pass, 18db/octave high-pass
  • High Frequency Transducer: 48″ (121.92cm) CLS™ electrostatic transducer
  • Low Frequency Transducer: 12″ (30.5cm) high excursion, super light, high rigidity cone with extended throw driver assembly. Non-resonance chamber.
  • Components: Monolith III – Glass epoxy boards, Custom wound audio transformer, polypropylene capacitors, air core coils. IIIp Passive Crossover – Glass epoxy boards, polypropylene capacitors, 100% oxygen free copper coils, wire-wound resistors. IIIx (Exos) Active Crossover – Glass epoxy bards, metal film resistors, polypropylene capacitors, hand picked J-FETs, TIFFANY input/output connectors.
  • Inputs:  30-amp gold plated 5-away bi-wire binding posts
  • Weight: 54.5 kg
  • Dimensions: 187.3cm × 67.9cm × 29.8cm

Last but not Least

These magnificent speakers are in excellent condition. They are hooked up and an audition can be arranged easily .. don’t miss out. A true high end masterpiece that will double as a great conversation starter for any visitors to your listening den! These speakers are massive and we do not have the original packing. Whilst we are willing and helpful interstate transport will not be easy but we will consider. Local transport we will assist (as usual). The towers come with interface boxes and the short cables that connect interface box to panels.

For another pre owned High End Product head over to ARC D400

To view independent reviews on this amp go to Audio Review


Have a Question?

If you have any questions about this product, please don't hesitate to get in touch with us via:
  • Our address: 1/81 Guthrie St Osborne Park Western Australia 6017
  • Our phone: 08 9445 2783
  • Our email: pierre [@] OR jim [@]
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