D/A Converter Ypsilon Electronics DAC 1000 SE Silver

Non-oversampling R2R converter with discrete logic and a valve analogue stage

The DAC 1000 SE is a non-oversampling D/A converter with no digital filters and no complex signal processing ahead of the conversion stage. It offers six digital inputs — Coax, BNC, AES and optical with PCM 24/192 support, while USB and I2S over an HDMI connector run up to PCM 24/384. The USB input also accepts DSD files from a computer or server up to DSD256 and converts them natively, without conversion to PCM.

At the heart of PCM conversion is an R2R ladder built in-house by the manufacturer, made up of discrete high-speed logic and precision resistors. While the standard DAC 1000 uses Vishay metal-film resistors with tight tolerance and low drift, the SE version is built around custom-made naked foil resistors. The output noise of this architecture is low, so only mild supplementary filtering in the analogue section is required. Native DSD conversion is handled by a separate path with a dedicated transformer and chokes combined with an AKM chip, of which only the output stage is used; the converter detects the presence of a DSD signal automatically.

The USB input is galvanically isolated and powered by internal supplies, with reclocking handled by local ultra-low phase noise clocks. The I2S input offers the shortest signal path with no processing whatsoever — LVDS transmission over an HDMI connector carries the digital signal without added jitter, is isolated against ground loops, and the signal is re-aligned to the incoming master clock. The result is a stable time base, legible microdynamics and precise localisation of instruments within the stereo image.

The analogue section is single-ended, with a Siemens valve in triode configuration (one per channel). Coupling between the converters and the valve uses a proprietary “wire capacitor”, keeping the signal path as direct as possible. The valve is transformer-coupled to the output, resulting in a very low output impedance of 30 ohms and trouble-free operation with longer interconnects or a lower amplifier input impedance. The power supply is built around a valve rectifier and a choke, delivering calm, low-noise high voltage. Operating status is shown on an LCD display, and the unit can also be controlled by remote.

Key features

• Conversion: Non-oversampling discrete R2R ladder with no digital filters
• Resistors: Custom naked foil resistors in the SE version
• Formats: PCM 24/384 over USB and I2S, native DSD256
• Analogue stage: Siemens triode valve with transformer output
• Power supply: Valve rectifier and choke for low noise