# AAL – Audio DC-Blocker

Reduces transformer hum, buzz and mechanical vibration caused by DC offset on the AC mains.

- **Seller:** [Analog Audio Lab's store](https://lectronz.com/stores/aalab), LES MONTS D AUNAY, Calvados, France
- **Price:** €105.00 (EUR, before shipping and taxes)
- **Availability:** In stock
- **Categories:** Audio, Amplifier
- **Country of origin:** France
- **Product page:** https://lectronz.com/products/aal-audio-dc-blocker

## Options

**Output electrical outlet**

- Schuko Furutech [Add €20.00] (1 left)
- IEC C13 (1 left)

## Images

![AAL – Audio DC-Blocker](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6NzEwMTMsInB1ciI6ImJsb2JfaWQifX0=--cc8e702c52ff8e7488011a9c16955e4cdac5527f/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGciLCJyZXNpemVfdG9fbGltaXQiOls5NjAsNjQwXSwic2F2ZXIiOnsic3RyaXAiOnRydWV9fSwicHVyIjoidmFyaWF0aW9uIn19--970c165836a83091725a1a0fd4f37ce9408da1bf/IMG_20260522_160837.jpg)
![AAL – Audio DC-Blocker](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6NzEwMDksInB1ciI6ImJsb2JfaWQifX0=--2398a8d70312be570a90b3c96030b8b1d03f7731/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGciLCJyZXNpemVfdG9fbGltaXQiOls5NjAsNjQwXSwic2F2ZXIiOnsic3RyaXAiOnRydWV9fSwicHVyIjoidmFyaWF0aW9uIn19--970c165836a83091725a1a0fd4f37ce9408da1bf/IMG_20260522_160853.jpg)
![AAL – Audio DC-Blocker](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6NzEwMjEsInB1ciI6ImJsb2JfaWQifX0=--f6306d2c8594dcad7d7d833f9a00b91432ace89a/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGciLCJyZXNpemVfdG9fbGltaXQiOls5NjAsNjQwXSwic2F2ZXIiOnsic3RyaXAiOnRydWV9fSwicHVyIjoidmFyaWF0aW9uIn19--970c165836a83091725a1a0fd4f37ce9408da1bf/IMG_20260522_160909.jpg)
![AAL – Audio DC-Blocker](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6NzA5ODksInB1ciI6ImJsb2JfaWQifX0=--95169f36f4b5f069c833850438b324a1c8242dfb/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGciLCJyZXNpemVfdG9fbGltaXQiOls5NjAsNjQwXSwic2F2ZXIiOnsic3RyaXAiOnRydWV9fSwicHVyIjoidmFyaWF0aW9uIn19--970c165836a83091725a1a0fd4f37ce9408da1bf/IMG_20260522_125925.jpg)
![AAL – Audio DC-Blocker](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6NzA5OTMsInB1ciI6ImJsb2JfaWQifX0=--28cb5597e00e99d29c1fb2c64b4e850562d89b28/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGciLCJyZXNpemVfdG9fbGltaXQiOls5NjAsNjQwXSwic2F2ZXIiOnsic3RyaXAiOnRydWV9fSwicHVyIjoidmFyaWF0aW9uIn19--970c165836a83091725a1a0fd4f37ce9408da1bf/IMG_20260522_125946.jpg)
![AAL – Audio DC-Blocker](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6NzA5OTcsInB1ciI6ImJsb2JfaWQifX0=--eff286798a35e1a3b3126b0a79b7213b28cf1d1c/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGciLCJyZXNpemVfdG9fbGltaXQiOls5NjAsNjQwXSwic2F2ZXIiOnsic3RyaXAiOnRydWV9fSwicHVyIjoidmFyaWF0aW9uIn19--970c165836a83091725a1a0fd4f37ce9408da1bf/IMG_20260522_130005.jpg)
![AAL – Audio DC-Blocker](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6NzEwMDEsInB1ciI6ImJsb2JfaWQifX0=--68553a0c2cb8eb5bb3e56a56294ca8ddd035f9bf/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGciLCJyZXNpemVfdG9fbGltaXQiOls5NjAsNjQwXSwic2F2ZXIiOnsic3RyaXAiOnRydWV9fSwicHVyIjoidmFyaWF0aW9uIn19--970c165836a83091725a1a0fd4f37ce9408da1bf/IMG_20260522_130528.jpg)
![AAL – Audio DC-Blocker](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6NzEwMjUsInB1ciI6ImJsb2JfaWQifX0=--db11b501732cad6b12a7cf5463a9575aad4d0d10/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGciLCJyZXNpemVfdG9fbGltaXQiOls5NjAsNjQwXSwic2F2ZXIiOnsic3RyaXAiOnRydWV9fSwicHVyIjoidmFyaWF0aW9uIn19--970c165836a83091725a1a0fd4f37ce9408da1bf/IMG_20260522_125618.jpg)
![AAL – Audio DC-Blocker](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6NzEwMDUsInB1ciI6ImJsb2JfaWQifX0=--9a400c78436caf4afce736c19b3fcb55fad8c61d/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGciLCJyZXNpemVfdG9fbGltaXQiOls5NjAsNjQwXSwic2F2ZXIiOnsic3RyaXAiOnRydWV9fSwicHVyIjoidmFyaWF0aW9uIn19--970c165836a83091725a1a0fd4f37ce9408da1bf/IMG_20260522_130102.jpg)

## Description

##What is it?

The **AAL – Audio DC-Blocker** is a passive mains DC filter designed to **reduce transformer hum, mechanical vibration and buzzing** caused by **DC offset on the AC mains**.

Especially effective with toroidal transformers commonly found in audio amplifiers, DAC power supplies and Hi-Fi equipment.

Designed with carefully selected and optimized components, the circuit operates transparently without affecting dynamics, transient response or audio quality.

**Typical symptoms solved**

- Transformer buzzing or humming noise
- Mechanical vibration from toroidal transformers
- Transformer hum or buzz appearing mostly in the evening or at certain times of day
- Equipment becoming quieter when connected to a different outlet or circuit

##Why did you make it?

Many modern electrical appliances inject asymmetrical loads into the mains, creating a small DC component that can saturate transformer cores and cause audible buzzing or vibration.

The **AAL – Audio DC-Blocker** was designed to help restore quieter operation and improve listening comfort while preserving musicality and amplifier dynamics.

**Typical Applications**

- Power amplifiers with toroidal transformers
- Integrated amplifiers
- DAC power supplies
- Tube equipment
- Hi-Fi systems
- Studio equipment with noisy transformers

**Particularly useful when:**

- Transformer hum increases in the evening
- Equipment becomes quieter on another outlet or electrical circuit
- Toroidal transformers mechanically vibrate or buzz

##What makes it special?

**Optimized for your equipment**

Fuse value and optional inrush-current limiting (**NTC**) are individually selected according to the connected equipment.

This helps ensure optimal protection and proper startup behavior..

**Example:**

230V / 2.3A device → fuse and NTC selected accordingly.

If unsure, simply provide your equipment power rating or rear-panel specifications.

**Carefully selected components**

- Audio-conscious component selection
- High-quality safety capacitors and power components
- Robust thermal and electrical margins
- Designed for reliable operation without compromising audio performance

**Electrical specifications**

- 230V / 50Hz operation
- Nominal current: 4.35A
- Suitable for equipment up to approximately 1000 VA (depending on transformer type and startup behavior)

##Why this price?

Built using carefully selected high-quality components (Cornell Dubilier, WIMA, Wishay, TDK.) chosen for performance, reliability and long-term durability.

All parts are sourced from reputable suppliers to ensure quality and traceability.

##Who did it?

Designed, hand-assembled and individually tested in France by **AAL — Analog Audio Lab**.

*Practical electronics designed to solve real-world problems.*

[analog.audio.lab@gmail.com](mailto:analog.audio.lab@gmail.com)

**Early customer feedback**

- “The transformer noise completely disappeared.”
- “Everything works perfectly — I’m delighted.”
- “A real improvement in listening comfort.”
- “Even the transformer mechanical hum is gone.”
- "..."