Overview
ZERO-Boxes are enclosed impedance-matching Autoformers designed to optimize the electrical interface between amplifier and loudspeaker. By increasing the effective speaker impedance, they allow amplifiers to operate under more linear, controlled conditions—reducing distortion, improving damping behavior, and stabilizing power delivery.
Each ZERO-Box contains our proven ZERO-Autoformer, mounted in a hand-finished hardwood enclosure with high-quality binding posts for long-term reliability and ease of use.
Hand-built in Lake Elmo, Minnesota.
Why ZERO-Boxes
- Impedance Matching
Multiplies speaker impedance by selectable ratios of 1.4×, 2×, 3×, or 4×. - Improved Amplifier Behavior
Reduces current strain, lowers distortion, and improves control over loudspeaker motion. - Broad Compatibility
Suitable for tube, solid-state, and OTL amplifiers. - Enclosed, Finished Design
Provides mechanical stability, protection, and straightforward system integration. - Built by Hand
Individually assembled and verified in the USA.
System Applications
ZERO-Boxes are particularly effective in systems where amplifier and loudspeaker impedances are poorly matched, including:
- Low-impedance speakers such as Magnepan, Quad ESL, SoundLab, Spendor
- Tube amplifiers using 8-ohm taps with 4-ohm speakers
- OTL amplifiers where available power is impedance-dependent
- Vintage and modern systems requiring improved electrical stability
Example power gains with OTL amplifiers:
- Atma-Sphere S-30 → approximately 50 W per channel
- Atma-Sphere M-60 → approximately 80 W per channel
Key Features
- Selectable impedance multiplication: 1.4×, 2×, 3×, 4×
- Example conversion: 4 Ω → 6 / 8 / 12 / 16 Ω
- Hardwood enclosure (Cherry or Birdseye Maple) with African Ebony accents
- Cardas solid-copper binding posts
- Jumper set included for box-to-speaker connection
- Hand-built in Lake Elmo, MN
- 60-day in-home trial
Design Notes
ZERO-Boxes are passive, linear devices placed directly between amplifier and loudspeaker.
- Signal path maintains correct polarity (Left-in → Left-out, Right-in → Right-out)
- No active components, no added gain, no tonal shaping
- Allows use of preferred speaker cables between amplifier and box
- Included jumpers connect the box to the speaker terminals
By reducing electrical stress, the amplifier operates more comfortably—and the system behaves more predictably.
Audible Result
Amplifiers sound less constrained.
Bass becomes more controlled and articulate.
Dynamics feel easier and more stable.
Spatial cues improve as distortion is reduced.
The system sounds calmer, stronger, and more coherent—because it is operating correctly.
Commentary
“An important new product category… greater flexibility at the amp-loudspeaker interface.”
— Dick Olsher, EnjoyTheMusic
“Greater sense of power and control, cleaner bass, and more precise spatial presentation.”
— Wayne Donnelly, EnjoyTheMusic
“They work — and their effectiveness can be explained by ordinary physics.”
— Richard George, TNT-Audio
Warranty & Support
Every pair of ZERO-Boxes is built for long-term use and includes:
- 60-Day Risk-Free Trial
- Lifetime Warranty covering materials and workmanship
- Responsive Support with fast repair or replacement if needed