Audiolab DC Block Direct Current Blocker at Vinyl Sound Buffalo, NY

The Audiolab DC Block is a compact single-component mains DC blocker and RFI/EMI filter from Audiolab (Cambridge, United Kingdom), available at Vinyl Sound in Buffalo, New York. Designed to be placed between a wall outlet and a single audio or AV component, the DC Block simultaneously cancels DC offset on the AC mains supply and filters differential-mode and common-mode RFI/EMI noise before they reach the connected component. Rated at a 600VA peak load and compatible with amplifiers up to 2x150W or 1x300W, it ships with both required cables — input and output — in a compact 113 x 59 x 140mm chassis weighing 0.7kg, available in Black or Silver finish.

DC on the Mains and Its Effect on Audio Equipment

The mains electricity supplied to domestic sockets should theoretically be a pure, symmetrical AC sine wave. In practice, the widespread use of asymmetrical electrical loads — dimmer switches, kitchen appliances, computer power supplies, phone chargers, and similar devices — causes the AC waveform to develop a DC offset component. The toroidal transformers found in high-quality audio amplifiers, preamplifiers, and source components are particularly vulnerable to this effect. Less than 500mV of DC on the supply — a level typical of the average household mains — is sufficient to partially saturate a toroidal transformer. A saturated transformer operates less efficiently, dissipates more heat, and vibrates mechanically in proportion to the degree of saturation. This vibration is the source of the familiar mechanical hum that can be heard from an amplifier chassis in an affected system. Beyond the physical vibration, a saturated transformer passes increased mains noise into the audio component's power supply rails, raising the noise floor and degrading the clarity and dynamic range of the reproduced signal. The DC Block addresses this at source by blocking and cancelling the DC voltage component before it reaches the component's transformer, restoring the symmetry of the mains waveform.

Dual-Action Filtering: DC Blocking and RFI/EMI Suppression

The DC Block's second operating function is a high-performance audio-class filter circuit that removes RFI and EMI from the mains supply alongside its DC blocking action. The filter operates against two distinct categories of mains-borne interference. Differential-mode noise — the dominant noise type introduced by switch-mode power supplies in televisions, computers, and other household appliances on the same circuit — is suppressed by the filter's differential-mode rejection stage. Common-mode noise — induced onto the mains conductors from airborne sources including Wi-Fi networks, mobile phones, and Bluetooth transmitters — is addressed by the filter's common-mode rejection stage. Both noise types elevate the noise floor of connected audio components and reduce the signal definition achievable from the component's internal circuitry. By combining DC offset correction with this two-mode filter in a single in-line device, the DC Block delivers a measurably cleaner power supply to the connected component with no active circuitry in the audio signal path.

Key Features

• DC Offset Blocking: Cancels DC voltage on the AC mains supply to prevent toroidal transformer saturation, mechanical vibration, and associated noise floor degradation in the connected audio component.
• Dual-Mode RFI/EMI Filter: High-performance audio-class filtering circuit targeting both differential-mode noise (from switch-mode power supplies) and common-mode noise (from Wi-Fi, phones, and Bluetooth).
• Single-Component In-Line Design: Placed between one wall outlet and one audio component — the most straightforward and cost-effective way to address DC and mains noise for a specific component.
• 600VA Peak Load Rating: Accommodates integrated and stereo power amplifiers up to 2x150W or 1x300W mono, as well as any source component, preamplifier, DAC, CD transport, or streamer.
• Both Cables Included: Ships with input and output cables — everything needed for immediate use with no additional cable purchase required.
• Universal Voltage Compatibility: Operates on 100-240V ~ 50/60Hz, making it suitable for use in the US at 120V and internationally.
• Compact Form Factor: 113 x 59 x 140mm and 0.7kg — fits easily behind or beside any component without occupying shelf space.
• Scalable System Use: Audiolab recommends starting with the amplifier as the primary candidate; additional DC Block units can be added to source components, preamplifiers, and DACs for incremental further improvement.
• Black or Silver Finish: Available in both finishes to integrate with any system.

Technical Specifications

What's in the Box

• Audiolab DC Block Direct Current Blocker
• Input Power Cord (wall to DC Block)
• Output IEC Cable (DC Block to component)
• User Manual

Frequently Asked Questions

What is the Audiolab DC Block?

The Audiolab DC Block is a compact in-line mains conditioning device that connects between a wall outlet and a single audio or AV component. It simultaneously blocks DC offset on the AC supply — preventing toroidal transformer saturation and mechanical hum — and filters differential-mode and common-mode RFI/EMI noise from the mains, lowering the noise floor of the connected component. It is rated at 600VA peak load with compatibility for amplifiers up to 2x150W stereo or 1x300W mono, and ships with both required cables in a 0.7kg chassis.

What is the difference between the Audiolab DC Block and the DC Block 6?

The DC Block and DC Block 6 use the same dual-action DC blocking and RFI/EMI filtering technology, but they differ in scale and application. The single DC Block is a compact in-line unit designed to condition the mains supply for one component at a time, connected between the wall and that component's IEC power inlet. It is the entry point to DC blocking and is best applied first to the amplifier, where DC-related transformer saturation has the most audible effect. The DC Block 6 is a full-width six-outlet conditioned power strip that applies DC blocking and RFI/EMI filtering to up to six components simultaneously from a single mains connection, housed in a 444mm chassis matching Audiolab's amplifiers and source components. The DC Block 6 also features a front-panel OLED voltmeter display. Multiple single DC Block units can be used to achieve whole-system coverage without the DC Block 6.

Which component should I use the Audiolab DC Block with first?

Audiolab recommends connecting the DC Block to the integrated amplifier or power amplifier as the first priority. Toroidal transformers — the type found in virtually all quality audio amplifiers — are the components most susceptible to DC offset-induced saturation. The effects of DC on the mains are most pronounced and most audible in amplifiers, where transformer saturation produces mechanical vibration, hum, and noise floor elevation that affects every signal passing through the amplification stage. Additional DC Block units can then be added to source components (CD transports, streamers, DACs) and preamplifiers for incremental further improvement across the whole system.

How does DC on the mains reach my audio equipment if it's not supposed to be there?

The AC mains supply becomes contaminated with DC offset through the operation of asymmetrical loads on the household circuit. Any device that draws current unevenly across the positive and negative half-cycles of the AC waveform — including dimmer switches, refrigerator compressors, washing machines, dishwashers, and the switch-mode power supplies in televisions and computers — skews the symmetry of the waveform as seen by other devices on the same circuit. The result is a DC component superimposed on the AC supply that, while typically below 500mV in amplitude, is sufficient to begin saturating sensitive toroidal transformers in connected audio equipment. Because these loads are permanently connected to the household mains, the DC offset is effectively a constant presence that worsens as more asymmetrical devices are added to the home.

Will the Audiolab DC Block work with my power amplifier's output power?

The DC Block is rated at a 600VA peak load with amplifier compatibility specified for less than 2x150W (stereo) or less than 1x300W (mono). This covers the vast majority of home hi-fi integrated and stereo power amplifiers, including the Audiolab 9000A (100W/ch), 9000P (100W/ch stereo, 300W mono), 7000A (70W/ch), and 6000A MkII (50W/ch), as well as comparable amplifiers from other manufacturers. Users with very high-powered amplifiers exceeding these ratings should consider the DC Block 6, which supports a total system load of 10A across all six outlets and is designed for whole-system application.

Can I use multiple Audiolab DC Block units for a whole-system application?

Yes. Each DC Block unit is designed for one component, so using multiple units across a complete system — amplifier, preamplifier, DAC, CD transport, and network streamer — provides cumulative DC blocking and RFI/EMI filtering at each component's mains input independently. Audiolab notes that each additional DC Block unit delivers further incremental improvement in overall system performance. For users who prefer a single-unit whole-system solution, the DC Block 6 provides six independently filtered and DC-blocked outlets from one chassis.

Where can I buy the Audiolab DC Block in Buffalo, NY or the United States?

The Audiolab DC Block is available at Vinyl Sound, an authorized Audiolab dealer in Buffalo, New York. The Vinyl Sound team can advise on whether the single DC Block or the six-outlet DC Block 6 is the better starting point for a given system configuration.