Ships in 2-4 days.
Slimline USB DAC and
The UHA-4 is a slimline USB DAC and amplifier combo featuring digital volume control, crossfeed, and low-noise performance. At less than 1/2 inch thick, the UHA-4 is highly portable and fits easily into a pocket. The all-aluminum construction is sturdy yet lightweight.
The digital volume control in the UHA-4 provides very tight level matching from channel to channel. Using the Alps up/down actuator, the volume can be adjusted in 2 dB steps. The previous volume setting is automatically restored at power-up.
The UHA-4 crossfeed circuit is based on the popular Linkwitz design. It works by feeding a delayed and low-pass-filtered version of the sound to the opposite ear, mimicking the way our ears work in typical acoustic environments. This reduces the unnatural sound which headphones can produce, especially on recordings with heavy left-right panning.
The op-amp in the output driver section is the popular AD8610 from Analog Devices, the same op-amp used in the UHA-6S and UHA-6 amplifiers. The UHA-4 can drive a wide range of loads, from high-sensitivity earphones to high-impedance headphones at 16 ohms up to 300 ohms.
Digital volume control. The digital volume circuit, actuated by an Alps up/down pushbutton control, provides extremely tight channel matching for a stable stereo image at all volume levels. The previous volume setting is restored automatically at power-up.
Crossfeed with bypass. The crossfeed circuit sends a delayed and filtered version of the sound to the opposite ear, mimicking the way we hear in a real acoustic environment. This reduces the unnatural sound of hard panning which can occur while listening to some music with headphones.
True ground audio reference. With bipolar voltage rails at +/-6 VDC, there is no need for an output ground buffer which can cause additional output distortion and other audio artifacts. This also allows the UHA-4 to be used as a low-noise DAC/preamp into a line input such as an A/V receiver.
Two-position gain control. Optimize performance for your headphones or earphones by choosing from two gain settings.
Automatic input selection. The input source is automatically selected based on the following priority: analog –> USB.
Advanced battery management. Use any high-power USB port or USB charger accessory to charge the UHA-4. The power indicator turns red when the battery is low, and an internal circuit disconnects the battery before discharging completely, maximizing the lifetime of the battery. The UHA-4 uses a commonly available iPod battery.
Plug-and-Play USB operation. The UHA-4 uses the standard USB audio drivers which are included in Windows and Mac operating systems.
- Max output power:
- 20 mW into 16 ohms
- 40 mW into 32 ohms
- 50 mW into 100 ohms
- 15 mW into 300 ohms
- THD+N, A-weighted:
- <0.025%, 1 mW into 32 ohms
- <0.025%, 1 mW into 100 ohms
- Dynamic range, A-weighted:
- 93 dB, USB input
- 102 dB, analog input, 32 ohm load
- 108 dB, analog input, 100 ohm load
- +10 dBV max into high-impedance load (>600 ohms)
- Frequency response: 13 Hz to 22.5 kHz, +0/-1 dB
- Output impedance: 0.4 ohm
- Op-amp supply rails: +/-5 VDC
- Battery life: 24 hours typical
- Enclosure: aluminum
- Dimensions: 3.3″ x 2.75″ x 0.47″
- Digital volume control
- Crossfeed (with bypass)
- Two-position gain select
- Automatic input selection
- Rechargeable battery, charged through USB
- 16-bit/48kHz USB digital audio
- DAC: Texas Instruments PCM2706
- Output driver op-amps: AD8610
- 1/8″ analog input
- Uses standard USB audio drivers, no software needed
- Compatible with Mac OS X and Microsoft Windows
- Power/low-battery and charge indicator lights
- Available in silver or black
- Includes Micro-USB cable and self-adhesive rubber feet.
UHA-4 User Guide (pdf, 283 kB)