UHA-4

Slimline USB DAC and Headphone Amplifier with Crossfeed and Digital Volume Control



$199

In stock

Available to ship: 1-3 business days

Choosing output op-amps

The UHA-4 is a USB DAC and amplifier combo featuring digital volume control, crossfeed, and a slimline case. At less than 1/2 inch thick, the UHA-4 is highly portable and fits easily into a pocket. 

The digital volume control provides excellent channel balance across the entire adjustment range. The Alps control allows adjustments in 2-dB steps.

The UHA-4 crossfeed circuit works by feeding a delayed and filtered version of the sound in each channel to the opposite ear, mimicking the way we hear sounds in a natural acoustic environment. This helps to reduce the fatigue and unnaturalness produced by some headphones, especially on recordings with wide stereo separation.

The UHA-4 can drive a wide range of loads, from high-sensitivity earphones to high-impedance headphones.

Features

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.

Specifications

  • 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 dBu 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″

Summary

  • 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.

User Guide

UHA-4 User Guide