The Hifimediy Sabre U2 Asynchronous DAC was developed by DIY (do it yourself} enthusiasts in the purpose of making a really good but cheap dac that could compete against regular commercial DAC's costing many times as much. It utilises a DAC chip from ESS Technology, whose DAC chips is highly regarded. The ES9023 chip is their simplest DAC chip which keeps many of the features of their bigger brothers at a minimal cost.
The Hifimediy U2 Dac works in USB Asynchronous mode using the standard USB Audio protocol. No drivers are needed in Windows, Mac OSX and Linux for up to 96kHz/24Bit Asynchronous transfers.
Asynchronous transfer means that the timing of the data flow is controlled from the device (DAC) instead of from the computer. Computers are not the best to keep a steady clock so it is much preferred to use an external master clock. The Hifimediy Sabre U2 is clocked by a 27Mhz oscillator which is buffered by a low jitter PLL1705 as the master clock source.
USB Audio uses Isochronous data transfer in either synchronous, adaptive or asynchronous mode.
* In synchronous mode, the length of a second is defined by the host device. That is, the host will send data at a rate, and the device has to exactly match that rate.
* In asynchronous mode it is the other way around, the device sets the definition of a second, and the host has to match the device.
* In adaptive mode the data flow determines the clock.
The U2 uses the SA9023 USB receiver chip from SAVITECH (not to be confused with the DAC chip ES9023). It accepts 32kHz, 44.1kHz, 48kHz, 88.2kHz and 96kHz inputs at 16 and 24bit. The SA9023 USB receiver is set to work in slave mode with the 27Mhz oscillator is the master clock source, buffered by the PLL1705 chip.
The U2 dac can be used together with the USB Isolator
. it will isolate the power from the PC and give a cleaner 5VDC power to the DAC. We have experienced improved clarity in soundstage and separation using this isolator together with the Hifimediy U2 and UAE23 dac's.
- Asynchronous USB transfer
- Output on 3.5mm headphone jack.
- Volume Level is controlled by the normal volume control keys on your computer. (no need to use the volume control inside iTunes etc.)
- No drivers required for Mac, Windows and Linux!
- Normal line level output (2Vrms) when connected to amplifiers/preamps. For headphones the level decreases down to 1Vrms for 32ohm headphones
- The U2 can also work as Asynchronous USB to optical converter when not using the analog output.
Highlights about Sabre ES9023 dac chip:
- The sound go straight out of the DAC chip and into your headphones or amplifier. It is not needed that the sound signal go through a capacitor to remove a DC voltage, there is no DC voltage to remove! This omits the need of a coloring cap which adds costs and reduces sound quality.
- Jitter Eliminator! The ES9023 utilISed patented HyperstreamTM architecture and Time Domain Jitter Eliminator.
- 112db DNR
Savitech has released an ASIO driver for the SA9023 usb chip. ASIO drivers can provide lower latency, and is to optional to use.
Asio drivers is only recommended for advanced users, and is not required for normal audio playback.
It can be downloaded here.
Note: Normally amplifier inputs are from 10K to 100K ohm. Normal headphones are from 32 ohm to 250ohm.