UDA18 USB DAC with Isolated USB signal
The UDA18 is an update to our 9018D series and we’ve added several features. The biggest change is the USB i2s isolation. We have earlier made a standalone i2s/DSD isolator board, and we’ve now included this ISO7240 isolator chip into this DAC. The benefits are lower interference and noise from USB, which makes the sound clearer with a darker background.
DAC with digitally adjusted lossless volume control
The DAC chip is the ES9018K2M that we also use in the 9018D and the other 9018 series DACs. It is great chip with a very transparent sound and also has the ability to control the volume digitally. We use a potmeter to set the output volume level from the DAC chip. The sound doesn’t have to go through this potmeter as normally with an analog volume control. In the UDA18 the DAC chip reads the setting of this volume control potmeter and sets the output volume accordingly.
Optional DC power input
The DAC can conveniently power from USB, but you can also connect a high quality DC power to further improve the sound quality. It will automatically detect and power from external DC when connected. When you use an optical signal then you have to connect power either from USB or DC supply.
No drivers needed
The UDA18 uses the Savitech SA9227 USB receiver in asynchronous USB mode. It doesn’t need any drivers in Mac and Linux, and you can set the H/F switch to “F” (audio class 1.0) for plug and play without needing drivers in older Windows versions. In Windows 10 you no longer need drivers for higher sample rates. There are drivers available for older Windows versions enabling >96kHz and DSD (audio class 2.0 mode, set the switch to “H”).
iPhone compatibility: It works with original apple lightning to USB adaptor camera connection kit (external DC power required). It does not work with the $4.99 cable that we sell, nor the lightning cable we sell as that one is for microUSB connectors.
Android compatibility: So far we have tested with Xiaomi phone only. It works natively also without external power connected.
The output stage chip is TPA6120A. It has enough power for most headphones and can also drive line level loads such a preamps, amplifiers. The differential signal from the ES9018K2M DAC chip is fed to an OPA2134 before the TPA6120A.
- Chips: SA9227, ES9018K2M, TPA6120A
- Digital lossless volume control
- Isolated I2s/DSD signal with isolator chip
- Two inputs: Optical and USB selectable by switch
- Optional DC input. Can run on USB power when DC power is not connected
- USB input supports all frequency rates up to 384kHz 16/24/32 bit and DSD128
- Optical inputs supports up to 192kHz
- High speed/Full speed switch. Chose Full speed for no drives use in Windows up to 96kHz/24bit
- Asynchronous USB transfer. DAC is clocked by 100MHz oscillator
- Inputs: USB (type-B), Optical SPDIF selectable by switch
- Output: 3.5mm connector
- SNR: 120dB
- THD: -117dB
- Output power: 200mW @30ohm, 40mW @250ohm, 17mW @600ohm.
- DC input: 5-6VDC min 400mA (not included)
- DC input plug: 5.5/2.1, inside pin is positive.
- Size: 10 x 8 x 3 cm