Audes ST-900DC power conditioner

Audes ST-900DC power conditioner – Versatile Mains Filtering for the Complete System

The Audes ST-900DC power conditioner is a versatile mains filter with integrated DC blocker, developed by Estonian manufacturer Audes for use with high-end audio and AV equipment. At the heart of the Audes ST-900DC power conditioner is a 900 VA balanced toroidal transformer — designed entirely in-house — that galvanically isolates connected equipment from the mains. With five CEE 7/3 sockets, the ST-900DC provides enough connections for a complete medium-sized system.

Low Output Impedance for Dynamic Current Demands

During highly dynamic musical passages, a power amplifier draws current peaks of 50 to 100 amperes from the mains. The ST-900DC has a very low DC output resistance and delivers these peaks without voltage drop — thanks to its large transformer core and high number of turns in the primary winding. The amplifier's response to the audio signal improves measurably, particularly in the lower frequency range.

Low-Pass Filtering at 800 Hz Against Mains Pollution

The transformer is designed to act as a low-pass filter with a cut-off frequency of 800 Hz. Interference from dimmers, switch-mode power supplies and solar panels is almost entirely removed. The symmetrical winding construction works on the principle of mutual cancellation. All five CEE 7/3 sockets are galvanically isolated from the external mains network.

DC Blocker and Protection Circuits

The integrated DC blocker eliminates direct current components from the mains supply, preventing mechanical hum in transformers of connected components. The ST-900DC also features overload protection and thermal protection that shuts down at 90 °C and reconnects automatically at 75 °C.

Key Specifications

• Type: Power conditioner with integrated DC blocker
• Power rating: 900 VA
• Inlet: 10 A, IEC C14
• Outlets: 5 × CEE 7/3 (16 A / 250 VAC)
• Transformer: Balanced toroidal, 230 VAC / 115 + 115 VAC
• Filter: Low-pass, cut-off frequency 800 Hz
• Thermal protection: Shutdown at 90 °C, auto-reconnect at 75 °C
• Dimensions: 477 × 121 × 347 mm
• Weight: 17 kg
• Origin: Estonia

Frequently Asked Questions

Which systems is the Audes ST-900DC power conditioner suited to?

The ST-900DC suits medium-sized systems combining source components and power amplifiers. With 900 VA and five outlets it offers more capacity than the ST-500DC, whilst remaining more compact than the ST-1500DC for larger or more demanding amplifiers.

What is the difference between the ST-900DC and the ST-900 without DC blocker?

The ST-900DC has an integrated DC blocker that filters out direct current components from the mains supply. This prevents mechanical hum in transformers of connected components. The ST-900 without the DC suffix does not have this function built in as standard.

Does the ST-900DC work without an earth connection?

Yes. The symmetrical transformer construction ensures the power conditioner operates correctly without an earth connection. Mains plug polarity makes no difference either.