Audio T Verdict
The Audiolab DC Block is a compact and affordable solution for audio equipment affected by DC contamination and high-frequency noise on the mains supply.
Its DC-blocking circuit can reduce transformer saturation and the mechanical hum or vibration this can cause, while additional RFI and EMI filtering tackles common-mode and differential-mode mains noise.
It is particularly useful for a single amplifier or source component with a removable IEC mains connection, provided the equipment remains within Audiolab’s published 600VA peak-load and amplifier-compatibility limits.
Audiolab DC Block Mains Conditioner
The Audiolab DC Block is a compact single-component mains conditioner designed to improve the quality of the AC supply reaching compatible Hi-Fi and home cinema equipment.
It combines two complementary functions within one unit: blocking unwanted DC voltage present on the AC mains waveform and filtering radio-frequency and electromagnetic interference.
The DC Block connects between the wall socket and one compatible audio component using the supplied mains lead and IEC jumper cable.
What Is DC on the Mains?
The electricity supplied by a domestic wall socket should ideally consist of a symmetrical alternating-current waveform.
Many everyday electrical products draw current unevenly across the positive and negative sections of this waveform. Potential sources include:
- Dimmer switches
- LED lighting and drivers
- Computer power supplies
- Phone and laptop chargers
- Kitchen appliances
- Televisions and games consoles
- Solar-power inverters
- Electric-vehicle charging equipment
This uneven loading can offset the AC waveform, creating a small DC component within the mains supply.
Transformer Saturation and Mechanical Hum
Toroidal transformers are widely used in amplifiers and other audio equipment because they can provide an efficient and low-noise power supply.
They can, however, be sensitive to DC offset. Audiolab states that less than 500mV of DC can be sufficient to cause a toroidal transformer to enter saturation.
Possible symptoms include:
- Mechanical humming or buzzing from inside the equipment
- Transformer vibration through the casework
- Reduced transformer efficiency
- Increased operating noise
- Performance that varies at different times of day
The DC Block removes or cancels this DC component before the mains supply reaches the connected equipment.
Listen Carefully to Where the Hum Comes From
The DC Block is most relevant where the sound comes mechanically from the equipment’s casework or transformer.
Hum heard through the loudspeakers may instead be caused by a ground loop, turntable earthing, an interconnect, a source component or another system fault.
Rebalancing the AC Waveform
By blocking unwanted DC voltage, the DC Block helps restore a more symmetrical AC waveform before it enters the connected component.
This can reduce transformer saturation and allow the equipment’s internal power supply to operate under more suitable conditions.
Results will depend on the mains supply, connected product and cause of the original problem. A system without meaningful DC contamination may show a smaller change than equipment with an audibly vibrating transformer.
RFI and EMI Filtering
The DC Block also contains a high-frequency filtering circuit for reducing radio-frequency and electromagnetic interference on the mains supply.
It is designed to address two principal forms of contamination:
- Differential-mode noise: Noise appearing between the live and neutral conductors
- Common-mode noise: Noise appearing in the same direction across conductors relative to earth
Potential sources include switch-mode power supplies, computers, chargers, wireless equipment and other electrical products operating within or close to the home.
Potential System Benefits
Audiolab states that reducing DC offset and high-frequency contamination can lower the perceived noise floor and allow the connected audio component to operate more effectively.
Depending on the system and mains conditions, listeners may experience:
- Reduced mechanical transformer hum
- Less casework vibration
- A quieter background
- Improved clarity and focus
- More clearly defined bass
- Reduced grain or hardness
- Better separation between musical details
Mains conditions vary considerably between properties, so the degree of improvement cannot be guaranteed to be identical in every system.
Designed for One Audio Component
The Audiolab DC Block provides one conditioned output and is intended to supply one compatible audio component.
Suitable products may include:
- Integrated amplifiers
- Stereo power amplifiers
- Preamplifiers
- CD players and transports
- Network music players
- DACs
- Phono stages
- Other compatible audio equipment with an IEC mains inlet
The connected product must remain within the DC Block’s published electrical limits.
Treating Several Components
Do not use the single-output DC Block to supply an entire multi-way mains distribution block.
For several pieces of equipment, consider the Audiolab DC Block 6 Way Mains Controller or another properly rated mains-conditioning solution.
600VA Peak-Load Capacity
The maximum published peak load is 600VA.
This is intended for audio equipment whose power requirements vary with use. It should not be interpreted as permission to connect a permanent 600-watt load.
Audiolab specifically states that the DC Block must not supply permanent high-power appliances such as heaters or similar products.
Power-Amplifier Compatibility
Audiolab publishes the following amplifier-compatibility guidance:
- Stereo power amplifiers rated below 2 × 150 watts
- Single-channel or bridged amplifiers rated below 300 watts
These are strict less-than limits rather than inclusive maximums.
Amplifier design, efficiency and peak current demand vary, so speak to Audio T before connecting an unusually powerful amplifier, active subwoofer or other demanding product.
IEC Mains Connections
The rear panel provides an IEC mains input and one conditioned IEC output.
The package includes:
- One regional IEC mains lead for connecting the DC Block to the wall socket
- One IEC C14-to-C13 jumper lead for connecting the DC Block to the audio component
The connected audio product must have a compatible removable IEC mains inlet.
How to Connect the DC Block
Switch the audio component off before making or changing any mains connections.
- Connect the supplied IEC jumper lead between the DC Block output and the audio component’s mains inlet.
- Connect the supplied regional mains lead between the DC Block input and the wall socket.
- Check that every connector is fully inserted and secure.
- Switch the connected audio component on normally.
Do not force an incompatible connector or use a damaged mains cable.
Electrical Safety
Do not open or modify the DC Block. There are no user-serviceable parts inside.
Disconnect it from the mains before moving equipment or changing power connections. Consult a qualified electrician where there are concerns about the condition, earthing or safety of the household electrical supply.
Not a Voltage Regenerator
The DC Block does not create a completely new AC waveform in the way that a mains regenerator does.
It blocks DC offset and filters high-frequency contamination while allowing the AC supply to pass to the connected equipment.
It should not be described as a voltage stabiliser or automatic voltage regulator.
Not a Substitute for Surge Protection
Audiolab does not publish a surge-protection or lightning-protection rating for the DC Block.
Its purpose is DC blocking and mains-noise filtering rather than protection from severe overvoltage events.
Where surge protection is required, use an appropriately rated product and seek professional electrical advice.
Troubleshooting Persistent Hum
If the noise remains after installing the DC Block, check:
- Whether the sound comes from the equipment or loudspeakers
- Turntable ground connections
- RCA, XLR and phono interconnects
- Loose or damaged mains cables
- Speaker-cable strands touching adjacent terminals
- Aerial, television and network connections
- Products connected to different wall sockets
- Whether the equipment itself requires servicing
A DC blocker cannot correct every form of hum, buzz or electrical fault.
Compact Installation
The DC Block measures just 113mm wide, 59mm high and 140mm deep.
Its compact size allows it to sit behind or beside an equipment rack, provided the cables are not sharply bent or placed under strain.
Keep the unit dry, allow reasonable ventilation and do not cover it with fabric or place it close to a strong source of heat.
Finish Options
The Audiolab DC Block is available in:
Key Features
- Single-component DC blocker and mains conditioner
- Blocks unwanted DC voltage from the AC mains supply
- Helps rebalance an asymmetrical mains waveform
- Can reduce transformer saturation
- Can reduce mechanical transformer hum and vibration
- High-frequency mains filtering
- RFI and EMI noise reduction
- Common-mode and differential-mode filtering
- Compatible with suitable audio products using an IEC mains inlet
- 100–240V AC, 50–60Hz operation
- 600VA maximum peak load
- Published amplifier compatibility below 2 × 150W or below 1 × 300W
- One conditioned IEC output
- Regional IEC mains lead included
- IEC C14-to-C13 jumper cable included
- Compact 113mm-wide enclosure
- 0.7kg net weight
- Black or Silver finish
- Three-year extended warranty when registered within 90 days
Frequently Asked Questions
Is this page for the Audiolab 6000A amplifier?
No. Although the existing page address mentions the 6000A, the product listed is the Audiolab DC Block mains conditioner.
What does the Audiolab DC Block do?
It blocks unwanted DC voltage on the AC mains supply and filters high-frequency RFI and EMI contamination before power reaches the connected audio component.
Can it reduce transformer hum?
Yes, where the mechanical hum is caused by DC offset saturating the component’s transformer.
Will it remove hum from my speakers?
Not necessarily. Loudspeaker hum can be caused by ground loops, turntable earthing, faulty cables or other signal-path problems.
Does it improve sound quality?
It can allow equipment affected by DC offset or mains noise to operate more effectively. The scale of any audible change depends on the system and local mains conditions.
Can it power an amplifier?
Yes, provided the amplifier remains within Audiolab’s published compatibility and peak-load limits.
What is the amplifier limit?
Audiolab specifies stereo amplifiers rated below 2 × 150W or a single-channel amplifier rated below 300W.
Can it be used with the Audiolab 9000A?
The 9000A’s 2 × 100W rating is within the published amplifier guidance, although complete system compatibility should still be checked.
Can it be used with a source component?
Yes. It can supply compatible CD players, transports, streamers, DACs, preamplifiers and other audio products with a suitable IEC mains inlet.
Can I connect a multi-way mains block to it?
The single-output DC Block is intended for one component. Use the Audiolab DC Block 6 or another suitably rated solution for several products.
What is its maximum peak load?
The published maximum peak load is 600VA.
Can it power a permanent 600-watt load?
No. Audiolab states that it is intended for audio equipment with variable power demand and must not feed permanent high-power loads such as heaters.
Can it be used with an active subwoofer?
Only where the subwoofer’s power demand is demonstrably within the published limits. Seek advice before connecting a high-powered subwoofer.
Does it regulate the mains voltage?
No. It blocks DC offset and filters mains noise rather than acting as a voltage regulator.
Is it a mains regenerator?
No. It does not generate a completely new AC waveform.
Does it provide surge protection?
Audiolab does not publish a surge-protection rating for the DC Block, so it should not be presented as a dedicated surge protector.
Which mains connections does it use?
It uses an IEC mains input and a single conditioned IEC output.
Are the required power cables included?
Yes. It includes a regional IEC mains lead and an IEC C14-to-C13 jumper lead for the connected component.
Can it connect to equipment with a captive mains cable?
It is designed for equipment with a compatible removable IEC mains connection.
Does it need to be switched on separately?
There is no separate operating procedure beyond connecting it correctly and switching the connected audio component on normally.
Can it remove every type of electrical noise?
No. It targets DC offset and high-frequency mains contamination but cannot correct every ground, signal, component or household-wiring fault.
What are its dimensions?
It measures 113mm wide, 59mm high and 140mm deep.
How much does it weigh?
The net weight is 0.7kg.
Which finishes are available?
The Audiolab DC Block is available in Black and Silver.
What warranty is included?
Audiolab offers an extended three-year warranty when the product is registered online within 90 days. Without registration, cover is one year or the applicable statutory period, whichever is longer.
Related Audiolab Products and Audio T Guides
Why Buy From Audio T?
- Help identifying mechanical transformer hum
- Advice separating mains noise from ground-loop problems
- Amplifier and peak-load compatibility checks
- Single-component and multi-way mains-conditioning guidance
- IEC mains-cable and connection advice
- Home demonstrations where available
- System troubleshooting and setup support
- Warranty-registration assistance
- Ongoing after-sales support
Contact your local Audio T store to discuss whether the Audiolab DC Block is suitable for your equipment and mains-noise problem.