audiolab DC Block - Silver

Audiolab DC Block

What You Need to Know

Why Your Amplifier Hums — and What DC on the Mains Has to Do With It

The AC coming out of your wall is supposed to be a symmetrical sine wave. In practice it rarely is. Dimmer switches, hair dryers, LED drivers, and inexpensive switch-mode power supplies all draw harder on one half of the cycle than the other, leaving a small DC offset riding on the line — usually under 500 millivolts, but enough to cause real trouble.

Your amplifier almost certainly uses a toroidal transformer, prized in audio for low stray magnetic fields and quiet operation — and notoriously sensitive to DC. A few hundred millivolts is enough to push the core toward saturation, and a saturated toroidal vibrates mechanically. You hear it as a buzz from the chassis itself, separate from your speakers. Efficiency drops, heat rises, and the sound softens: less dynamic punch, a haze over the midrange, looser imaging. If you've ever noticed an amp humming worse in one house than another, or worse at certain times of day, this is why.

A Targeted Fix, Installed in Five Minutes

The DC Block sits inline between your wall outlet and your amplifier's power cable, rebalancing the waveform so both halves are symmetrical again. With the DC gone, the transformer stops saturating, the mechanical hum drops away, and the power supply returns to running efficiently.

It also includes an audio-class filter that attenuates RFI/EMI on the line — both common-mode interference from Wi-Fi and Bluetooth devices, and differential-mode noise fed back by switch-mode supplies and LED drivers. Installation is genuinely a five-minute job: plug the DC Block's cable into the wall, plug your amp's cable into the DC Block. No tools, no rack space, no rewiring.

Sized for One Amplifier, Finished to Match It

The DC Block is rated for a 600VA peak load — roughly one amplifier up to 300W, or a stereo amp up to 2×150W. That covers most integrated amps, mid-sized stereo amps, and powered subwoofer chassis. For a monoblock pair or your whole rack at once, step up to the DC Block 6. Both black and silver finishes are offered, color-matched to the rest of the Audiolab line.

What the DC Block Is Not

This is not a surge protector. There are no MOVs, no joule rating, no transient suppression — it will not protect your gear from a lightning strike or a major line surge. If you need that, look at a full power conditioner such as an AudioQuest Niagara or Furman Elite, or run the DC Block downstream of a dedicated surge protector for both benefits.

What it does, it does exceptionally well in its lane. For the specific job of taking DC offset off the line feeding one amplifier, this is the most efficient tool you can buy.

Connections & Specifications

Connections

• 1 × IEC C14 input — connects to the wall via an IEC power cord
• 1 × IEC C13 output — accepts your amplifier's existing IEC power cord
• Inline device: fits between the wall outlet and a single component

Specifications

• Function: Mains filter and DC blocker
• DC removal: Yes
• RFI/EMI filtering: Common-mode and differential-mode
• Power requirement: 100–240V, 50–60Hz (universal)
• Peak load: 600VA
• Amplifier compatibility: Up to 2×150W or 1×300W
• Dimensions (W × H × D): 4.4" × 2.3" × 5.5" (113 × 59 × 140 mm)
• Weight: 1.5 lbs (0.7 kg)
• Finish: Black or silver
• Warranty: 3 years parts and labor with registration; 1 year limited without

Frequently Asked Questions

Will the DC Block help my system?
The clearest sign you have DC on the mains is a mechanical hum from the amplifier's chassis — audible in a quiet room even with the volume down or the amp in standby. If your amp hums, the DC Block can make it disappear entirely. If it doesn't, the improvement will be subtler: a small lift in clarity and dynamics from the RFI/EMI filtering alone.

Which model should I buy?
One amplifier that hums, with a modest rack otherwise: the single DC Block is the surgical, affordable answer. Treating your entire system — amp, preamp, streamer, DAC, phono stage — or planning to expand: the DC Block 6 feeds up to six components with DC removal and filtering on every outlet.

Isn't this just an expensive ferrite choke?
No. A ferrite bead filters high-frequency common-mode noise and does nothing about DC offset. The DC Block uses a dedicated DC-blocking circuit that passes AC through unchanged while preventing any DC component from reaching your amplifier. If your amp is humming because of DC on the line, no amount of ferrite will fix it.

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