AU-100 Dual Channel Audio Isolator, Ground Loop Hum Eliminator, XLR / 6.35 mm TRS / RCA / 3.5 mm AUX, 20 Hz-20 kHz
AU-100 is a two-channel audio isolator in a desktop housing. Each channel passes through its own 600:600 permalloy transformer in a sealed shielding can, so the audio crosses while the ground connection between the two pieces of equipment does not. Five interface types are brought out on each side, balanced and unbalanced signals convert in both directions, and a LIFT/GND switch on the input panel deals with a loop that will not otherwise let go.
- Two independent channels, each on its own 600:600 permalloy isolation transformer
- Five interfaces: balanced XLR, 6.35 mm TRS, gold-plated RCA, 3.5 mm AUX
- Full balanced and unbalanced conversion, in both directions
- One-touch LIFT/GND switch, and blocking of 50/60 Hz AC power noise
- Frequency response 20 Hz to 20 kHz within ±0.2 dB
- THD below 0.001 % at 1 kHz; CMRR above 90 dB at 60 Hz
- Extruded aluminium alloy enclosure, double-layer shielded PCB
1. Product Name
AU-100, a two-channel audio isolator in a desktop housing. It sits in the signal path between two pieces of equipment that share a mains earth and removes the hum and buzz that the resulting ground loop puts on the line. Each channel has its own transformer, so the two are isolated from each other as well as from the equipment on the far side.
Why a transformer and not a filter. A ground loop is a circuit, not a noise source, so filtering the audio treats the symptom. Breaking the ground path removes the loop itself: the signal still crosses, through the transformer, but the current that was circulating through the cable screen has nowhere to go. That is why the unit is specified against 50/60 Hz AC power noise, the frequency the loop carries.
2. Construction & Materials
Two transformers, one per channel. Each channel runs through a 600:600 permalloy transformer sealed in a shielding can, marked 600:600 and 1+1:1+1 on the can. The cans are the reason the part is quiet as well as isolated: a transformer without a can is an aerial as much as a component. One point to confirm on the order: the renders supplied with this listing show two different can markings, ZXY2207 on one unit and PC-1 PRO+ on another, both 600:600. Ask which transformer is fitted to the build you are buying.
The housing and the board. A heavy-duty extruded aluminium alloy enclosure in black brushed finish, carrying the Isolator name plate and the AU-100 marking. Inside, a double-layer shielded PCB carries the two transformer cans, the connector blocks and the function switch, whose contacts are silver-plated.
3. Feature
Two independent channels, A and B. Each channel has its own transformer, so the two paths are isolated from each other as well as from the equipment on the far side.
Two 600:600 permalloy transformers in sealed cans. One per channel. The can shields the winding as well as holding it, which matters in a rack full of switching supplies.
Five interface types per side. Balanced XLR, 6.35 mm TRS/TS, gold-plated RCA and 3.5 mm AUX, so the adapter chain that usually sits between a console and a computer is not needed.
Balanced and unbalanced conversion, both ways. A balanced output can drive an unbalanced input, and an unbalanced source can drive a balanced line.
One-touch LIFT/GND switch. On the input panel, for the loop that survives the transformers because a second ground path exists.
Blocks 50/60 Hz AC power noise. The frequency a mains ground loop carries, which is the hum the unit is specified against.
100 % galvanic isolation. No conductive path between input and output; the signal crosses magnetically.
Flat response, 20 Hz to 20 kHz within ±0.2 dB. The whole audio band, stated as a tolerance rather than as a claim of transparency.
THD below 0.001 % at 1 kHz, CMRR above 90 dB at 60 Hz. Distortion and common mode rejection stated as figures, so the unit can be compared with another on paper.
Extruded aluminium housing, double-layer shielded PCB. A rigid box that also acts as the shield, with the board screened on both faces.
4. Advantage
The loop is broken, not filtered. A ground loop is a circuit; opening it removes the hum at the source instead of notching it out of the programme material.
One box replaces the adapter chain. XLR, 6.35 mm, RCA and 3.5 mm on both sides, so whatever the venue has is plugged in directly.
Mixed equipment stops being a problem. Balanced console gear and unbalanced consumer gear convert in both directions through the same unit.
Quiet in a hostile rack. Sealed permalloy cans and a double-layer shielded board keep external fields out of the windings.
A switch for the stubborn case. When the transformers alone cannot break the loop, the LIFT position on the input panel opens the ground.
Nothing to power. The unit is passive, so there is no supply to fail and no active stage adding its own noise.
5. Application
Studio recording. Between console, audio interface and outboard gear, where a shared earth is normal and hum is not.
Live sound systems. Between stage boxes, consoles and amplifiers, where the earth paths run through long cable screens.
Broadcast and installation. Conference rooms, lecture halls and fixed AV racks, where the cabling is installed once and has to stay quiet.
Video conferencing and interpretation. Computer audio fed into a house system, the case the application render shows: laptop to isolator to projector.
6. Specifications
The tables below reproduce what the supplied material states for AU-100. Where no figure is given, the cell says so rather than carrying a number in from another model. The acoustic figures come from the supplier's specification panel for this model; the measurement set-up behind them is not stated.
6.1 Summary
| Item | Specification | Note |
|---|---|---|
| Model | AU-100 | Dual channel audio isolator |
| Channels | Two, A and B | One transformer per channel |
| Transformers | 600:600 permalloy, sealed cans | Can marking differs between renders |
| Interfaces | XLR, 6.35 mm TRS, RCA, 3.5 mm AUX | Five types, both panels |
| Conversion | Balanced and unbalanced | Both directions |
| Ground switch | LIFT / GND, one touch | On the input panel |
| Frequency response | 20 Hz to 20 kHz, ±0.2 dB | As stated for the model |
| Distortion | THD below 0.001 % | At 1 kHz |
| Common mode rejection | Above 90 dB | At 60 Hz |
| Isolation | 100 % galvanic | Between input and output |
| Enclosure | Extruded aluminium alloy | Black brushed finish |
| Circuit board | Double-layer shielded | Two transformer cans fitted |
| Dimensions and weight | Not supplied | Request the drawing |
6.2 Acoustic performance
| Parameter | Value | Condition |
|---|---|---|
| Frequency response | 20 Hz to 20 kHz, ±0.2 dB | Stated as flat response |
| Total harmonic distortion | Below 0.001 % | At 1 kHz |
| Common mode rejection | Above 90 dB | At 60 Hz |
| Phase and isolation | 100 % of units tested | Signal phase and isolation |
| Measurement conditions | Not stated | Level, impedance and analyser not given |
6.3 Interfaces and panels
| Item | Detail | Note |
|---|---|---|
| Input panel | XLR balanced A/B, 6.35 mm, RCA, AUX, LIFT/GND | Switch sits between AUX and channel B XLR |
| Output panel | XLR balanced A/B, 6.35 mm, RCA, AUX | No switch on the output side |
| Balanced connector | XLR, male and female | Swiss-type pattern |
| Unbalanced connectors | 6.35 mm TRS/TS, RCA, 3.5 mm AUX | RCA sockets gold-plated |
| Conversion | Balanced to unbalanced and back | Full conversion, both directions |
6.4 Construction
| Item | Specification | Note |
|---|---|---|
| Enclosure | Extruded aluminium alloy | Heavy-duty, black brushed finish |
| Shielding | Sealed permalloy cans, double-layer PCB | Cans fitted over both transformers |
| Transformer marking | ZXY2207 or PC-1 PRO+ | Both 600:600; confirm the fitted part |
| Function switch | Silver-plated contacts | LIFT/GND, on the input panel |
| Connector plating | Gold-plated RCA, XLR bodies | As marked on the build render |
| Power | None required | Passive unit, no supply input |
The LIFT/GND switch. One touch, on the input panel, between the AUX socket and the channel B XLR. The position marked LIFT opens the ground connection; the position marked GND leaves it connected. It is there for the case where the transformers alone are not enough, which happens when a second ground path exists through a rack rail or a mains distribution board.
6.5 Quality and testing
| Item | Requirement | Condition |
|---|---|---|
| Signal phase and isolation | 100 % of units tested | Stated for every unit |
| Frequency response | 20 Hz to 20 kHz, ±0.2 dB | Model figure, set-up not stated |
| Distortion | THD below 0.001 % | At 1 kHz |
| Common mode rejection | Above 90 dB | At 60 Hz |
| Certificate number | Not supplied | No test report with the material |
7. Ordering
The unit is ordered as AU-100, marked ZXY AUDIO on the housing. It is a two-channel isolator with the five interface types on both panels and the LIFT/GND switch on the input side. Before ordering, confirm the transformer fitted to the build (the renders show both ZXY2207 and PC-1 PRO+ cans, both 600:600) and confirm packing, since neither the packing nor the lead time is stated in the supplied material.
Certification: no certificate or test report was supplied with this listing, so no compliance claim is made on this page and the render that carries a row of certification badges was not used. If the listing needs a certificate, quote the number from the certificate itself.
Brand / manufacturer: ZXY AUDIO, Shenzhen Zhixiangyuan Electronics Co., Ltd. http://www.zxycoil.com