audiolab DC Block - Silver

Stop the Transformer Hum at the Wall Cord

The Audiolab DC Block is a compact mains filter and DC blocker that sits in line with one component. It ships in black or silver. It plugs between your wall outlet and your amplifier, and it needs no tools or rack space.

Mains power should be a symmetrical sine wave. Audiolab says dimmer switches, kitchen appliances and computer power supplies use that wave unevenly, which leaves DC voltage on the line. Less than 500mV of DC, typical in an average home, can saturate a toroidal transformer and cause audible mechanical vibration.

Two Jobs in One Small Box

The DC Block blocks DC of up to 1.2V (1200mV) and rebalances the mains sine wave. A high-frequency filter also suppresses noise on the line, including differential-mode noise from cheap switch-mode supplies and common-mode noise from phones, Wi-Fi and Bluetooth.

Audiolab says the noise floor drops and the sound gains greater focus, with reduced grain, improved clarity, better-defined bass and airier treble. Those are Audiolab’s claims for the design. Overload protection is built in as well.

It is rated for 8 amps, which is about 960 watts at 120V. The unit weighs 0.7kg (1.5 pounds) and works on 100V to 240V mains at 50 or 60Hz. One IEC cable and one power cord come in the box.

Who Is This DC Blocker Best For?

• Your amplifier buzzes from inside the chassis. — The DC Block removes the DC offset behind that transformer vibration, so the amp can run quietly again
• You own one large amplifier with a toroidal transformer. — It guards the one component most prone to DC, without touching the rest of your rack
• You want a fix you can finish in minutes. — It plugs in line with the cord you already have, with no tools, wiring or shelf space needed
• You live with dimmers and shared circuits. — Those loads leave DC on the line, and this puts a filter between them and your amp
• You want to treat the whole rack. — The DC Block feeds one component at up to 8 amps. The Audiolab DC Block 6 covers six components at once

How Does It Connect to Your System?

Unplug your amplifier from the wall. Plug the DC Block’s power cord into the wall. Then link the DC Block to your amplifier with the IEC cable from the box.

There are no settings and nothing to configure. Power up and listen. If the chassis hum was DC-related, it should be gone.

Pairs Well With

Building your system? Here are some great companions for the Audiolab DC Block:

• Power cables to carry clean power the rest of the way to your gear
• Power conditioners for surge protection alongside DC blocking
• Integrated amplifiers with toroidal transformers that can hum on a dirty line
• Stereo amplifiers for DC-sensitive power supplies

Frequently Asked Questions

How do I know if I have DC on my mains?

Listen for a buzz from the amplifier chassis itself, even with the music off. Audiolab says DC offset can make a toroidal transformer vibrate audibly. A buzz from the speakers usually has another cause, such as a ground loop.

How do I install it?

Plug the power cord into the wall and the DC Block. Use the supplied IEC cable to connect the DC Block to your component. It takes a few minutes and needs no tools.

How much power can it handle?

It is rated for 8 amps, about 960 watts at 120V. That suits an integrated amp or a single stereo amplifier. Check your component’s power draw against that rating first.

What is the warranty?

Audiolab’s warranty is three years if you register within 90 days of purchase, otherwise one year or your country’s longer statutory period. It is for the original owner, bought new from an authorized Audiolab dealer, and is not transferable or valid outside the country of purchase.

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Learn More

Want to learn more about DC offset, toroidal transformer hum, or cleaning up your AC power? Visit our Learning Center for guides, tips, and expert advice.