WattMeister Model 2: The New Benchmark for Low-Wattage Amplification – 20Hz Performance at 99dB Sensitivity

Description

“I’ve spent years wanting to offer the low wattage/tube enthusiast a high efficiency loudspeaker that also contains the bottom octaves of deep bass in its correct proportions. With the Model 2, the compromise is officially over.” — Eric Alexander

A New Paradigm in High-Efficiency, Full-Range Loudspeaker Design (white paper)

Patents Pending | Author: Eric Alexander – President, Tekton Design, LLC

1. Introduction

For years, my design focus has been driven by the desire to transcend the performance limitations of traditional high-sensitivity loudspeakers—specifically those exceeding 98dB @ 1W/1m. This echelon of sensitivity is not merely a technical milestone; it is a fundamental requirement for the burgeoning world of audiophile-grade, low-wattage tube amplification (flea-powered amplifiers operating under 10 Watts).

Loudspeaker designers “skilled in the art” are intimately familiar with Hofmann’s Iron Law. This principle remains the primary roadblock in developing loudspeakers capable of true full-range performance when paired with low-output power stages. The “Law” dictates that a designer can only optimize two out of three core parameters:

• Low-frequency extension
• Compact enclosure size
• High efficiency

To achieve deep bass and high efficiency, the industry has historically accepted that the enclosure must be unrealistically massive and require less than ideal T&S parameters —essentially forcing the designer to sacrifice one pillar to save the others. Until now.

2. The Engineering Philosophy: Leveraging Systematic Inefficiency

In the realm of electroacoustics, the laws of physics are immutable; we do not “bend” them to our will. However, with a deep enough mastery of the underlying principles, we can identify and leverage inherent limitations within traditional design paradigms to achieve superior outcomes.

Hofmann’s Iron Law is often treated as an absolute finality, yet it is predicated on the behavior of standard, conventional acoustic architectures. By shifting the perspective from the driver as an isolated component to a proprietary, system-wide approach, we can reclaim lost energy and optimize performance in ways that standard designs simply overlook—this includes the finest examples in the world of extreme, “cost-no-object” audiophile-grade loudspeakers today. We aren’t breaking the laws of physics; we are utilizing a more sophisticated understanding of them to achieve performance-improved outcomes that were previously thought impossible.

3. New Product Innovation: The Actively Assisted High-Efficiency Loudspeaker

Through a proprietary new enclosure architecture and system approach (patents pending), we have challenged the fundamental trade-offs of the Iron Law.

The Technical Prototype

Consider a high-efficiency 15″ driver, such as the B&C 15100NA-8. The Thiele/Small (T&S) parameters for this driver are: Fs:47Hz, Qts:0.28, Vas: 88dm3 (3.1 ft3), Xmax: 10mm, Bl:26.3Tm, Sensitivity: 98dB, Nominal impedance 8 Ohms. The Thiele/Small parameters indicate that while this driver will produce phenomenal output—the specific type of efficiency required for a 2 or 3-watt amplifier—and high fidelity, it is physically incapable of producing deep bass on its own; period. For example, an extended bass reflex alignment (an enclosure modeled to produce the deepest bass possible without sacrificing sound quality) yields a -3dB point of 84Hz. The situation becomes even more restrictive in a sealed configuration: place the driver in a one-cubic-foot enclosure, and the -3dB point rises to 124Hz. Placing this driver in every commonly accepted enclosure type (sealed, vented, etc.) strictly adheres to Hofmann’s Law: we achieve efficiency and a compact footprint but sacrifice low-frequency extension. When driven by a low-wattage amplifier, the high-compliance air spring of the small enclosure physically prevents the cone from achieving the long-stroke excursions required to reproduce frequencies below 100Hz. 

The quandary is this: while these high-efficiency drivers are the absolute best—and only—choice for low-wattage amplifiers, physics effectively locks them out of the bottom octaves when used in a standard cabinet.

The Actively Assisted Isobaric Solution

To reclaim this “third leg of the stool,” we utilize an Actively Assisted Isobaric approach. Located directly behind our primary 15” woofer, and being directly driven by our low-wattage amplifier, we position a secondary high-excursion subwoofer of similar diameter. This internal driver creates an active isobaric chamber, maintaining equalized pressure regardless of the front woofer’s position or velocity.

This proprietary environment goes beyond merely simulating an infinite baffle; it creates a state of active mechanical coupling. By maintaining equalized pressure within the isobaric chamber regardless of cone position, the internal subwoofer effectively “decouples” the front driver from its inherent mechanical resistance to low frequencies and the high-compliance air spring of its enclosure.

More importantly, the superior motor force of the rear active subwoofer allows it to guide, steer, and couple the front high-efficiency driver with absolute precision. Rather than the front woofer struggling against internal compliance issues (the inability to produce deep bass) and the air spring of a compact cabinet, it is now actively assisted into the correct coordinates by the rear driver. This ensures the “gorgeous,” delicate personality of a low-wattage tube presentation remains perfectly intact, while the “muscle” of the internal driver—optimized for high moving mass and band-limited above 100Hz—supplies the missing bass (including infrasonic) energy with a level of control and low distortion previously thought impossible in a compact footprint.

Furthermore, the benefits extend into the realm of acoustic neutrality. It is a fundamental law of physics that sound cannot travel through a vacuum; I posit that an active isobaric chamber is the next best thing. Because the pressure within the chamber is always equalized, there is no internal pneumatic turbulence to color the sound or ring the cabinet walls. This effectively “silences” the enclosure, removing traditional cabinet colorations and allowing the primary driver to operate in an environment of unprecedented purity.

System Integration

The signal from the primary speaker is split and fed into a high-level reduction circuit (which does not affect or lower system impedance), an active low-pass filter (stripping frequencies above 100Hz), and a modern, high-wattage internal amplifier. This actively assists the front driver, facilitating the long, slow cone motions—musical octaves 0, 1, and 2—that are otherwise attenuated and/or impossible to reproduce.

Signal Integrity vs. Acoustic Compliance

It is critical to recognize that the full-range spectral content—specifically the low-frequency information contained within the resultant waveform (i.e., the music)—is presented in its entirety to the high-efficiency primary driver. However, Hofmann’s Iron Law dictates that deep bass will not be produced in this configuration; while the voice coil receives the full electrical energy of the signal, the driver’s compliance (as predicted by Hofmann’s Law) physically prohibits it from achieving the excursion and displacement necessary to reproduce deep bass at a balanced, linear level relative to the mid-bass and midrange. Consequently, the deep bass and infrasonic output is attenuated to a level that is virtually indiscernible, failing to meet the authoritative performance standards required by audiophiles, musicians, and recording engineers.

By integrating Active Assistance below 100Hz, the internal driver provides the necessary counter-force to overcome these system resistances. This effectively “frees up” the primary driver and exposes the deep bass and infrasonic content inherent in the resultant wave, facilitating the long-stroke excursions required for infrasonic reproduction. The result is a stunning transformation, allowing a compact footprint to deliver a world-class, full-range performance without compromising the high-velocity character of the primary driver.

4. Conclusion

The result of this architecture is a compact, high-efficiency loudspeaker capable of linear response down to 20Hz while maintaining a 99dB 1W/1m sensitivity rating. By integrating active assistance with traditional high-sensitivity drivers, we have effectively bypassed the historical constraints of Hofmann’s Iron Law, offering a world-class listening experience that bridges the gap between low-wattage purity and high-velocity physical realism.

5. Further Considerations

• Scalability: This architecture is inherently scalable, from high-performance headphones to large-format tower loudspeakers.

• Broad Market Applications: While inspired by the 2-watt “flea-power” community, this system is compatible with modern amplification.

• Magnetic Flux and Motor Linearity: Utilizing Klippel optimization, our research proves that typical playback levels do not push the primary driver into non-linear regions. The front driver is effectively “cradled” by the isobaric coupling, ensuring mechanical control and longevity.

• Power Requirements: This will be intuitive for many and surprising for a few audiophiles: yes, it requires being plugged into the wall. Because it is actively assisted, the loudspeaker requires you to plug it into the wall—110V standard and 220V optional.

6. The Listening Experience: What does it sound like?

The short answer is stunning. The experience is truly magical; imagine a 98dB–101dB sensitive loudspeaker delivering all of its hallmark detail and speed, while seamlessly producing the kind of deep, authoritative bass typically reserved for dedicated subwoofers. This technology allows you to experience the full frequency spectrum without the traditional compromises in sensitivity or footprint.

Respectfully submitted,

Eric Alexander

President, Tekton Design, LLC

Inventor & Audio Designer

Eric Alexander is the founder of Tekton Design and the recipient of over 20 industry awards for innovation in loudspeaker architecture.

 

WattMeister Model 2 – Technical Specifications

• Sensitivity: 99dB @ 1W/1m
• Frequency Response: 30Hz – 22kHz (Linear) | 20Hz In-room bass extension
• Nominal Impedance: 8 Ohms (Stable, amplifier-friendly load)
• System Architecture: Sealed enclosure, 3 -way hybrid with Active Isobaric Assistance (Patents Pending)
• Primary Woofer: 15″ Eminence (USA)
• Active Internal Assistant: Secondary 12″ Eminence Subwoofer (USA)
• Midrange/Treble: Patented 7-tweeter array: Experience “perfect midrange” with our patented, low-mass, polygon-oriented tweeter array. This unique design delivers the focused sound of a horn without the associated distortion, resulting in exceptional clarity and detail. Horn-loaded Eminence or B&C Italian-crafted midrange/treble compression driver unit optional
• Recommended External Power: 1 Watt – 300 Watts RMS
  • Optimized for: 2W–3W “flea-power” amplifiers; compatible with high-current solid-state (this includes class-D).
• Internal Amplification: 300W RMS dedicated low-frequency engine (below 80Hz)
  • Power Requirement: 120V Standard (220V Optional)
• Enclosure Dimensions: 39″ (99.06cm) H x 16″ (40.64cm) W x 13.75″ (34.93cm) D
• Weight: 78 lbs (35.38 kg)
• Finishes: All standard Tekton colors; custom colors and premium mirror gloss optional.