The PHDA02 - a reference class headphone amplifier with Stereo, Mono, and Dual Mono operation modes.
In Stereo mode, the L/R input signal is fed to the left and right earphones while the volume level is set by the Stereo/Left control. The front panel inputs provide simultaneous connection of two headphones in parallel. In Mono mode, the left and right channels are summed, and the resulting mono signal is fed to both the left and right earphones. Again, volume is governed by the Stereo/Left control. In Dual Mono mode, the left and right channels can be used independently with individual level controls for the left and right earphones.
The PHDA02 operates with all headphones with an impedance of 8 up to 200 Ohms. Impedance matching is achieved by a specially designed switchable transformer. Uncommon and costly, this solution provides superior performance, dynamic range, and signal- to-noise ratio at all loads.
Combo input sockets allow for balanced XLR and unbalanced TS headphone connection while parallel XLR outputs facilitate daisy chaining multiple units. The integrated power supply operates with mains from 100 VAC to 240 VAC.
The PHDA02 is equipped with low-noise op amps, and the output amplifiers' discrete power transistors are mounted on heatsinks. Dimensions are 1 U 9.5."
LDHPA6 6-Channel Rackmount Headphone Amplifier
The LD Systems HPA 6 is a highly flexible 1U 19“ rack format headphone amplifier with 6 fully independent channels and comprehensive features for a wide range of professional audio monitoring applications.
Each channel provides a 6.3 mm TRS headphone output on the front panel with level control, mono/stereo switching, discrete left/right muting and a 6.3 mm TRS Aux input with Main/Aux balance control for mixing in further signal sources. Four-segment LED meters permit visual output level monitoring, and two 6.3 mm TRS outputs per channel on the rear allow for connecting a total of 18 headphones.
The HPA 6's main section features a master level control with eight-segment LED metering and 6.3 mm TRS input to mix in an additional source with all channels. The rear panel provides the main stereo inputs on balanced XLR and 6.3 mm TRS connectors and stereo outputs for daisy chaining multiple units.
LD Sytems HPA 4 - a compact and powerful headphone amplifier
The LDHPA4 has small dimensions, can handle up to 4 headphones and has an output power with no equal in its class. That means high volume with no distortion. With these features the LDHPA4 is an essential tool for every project- and home studio.
The LD Systems HPA 1 is a versatile headphone amplifier with high power output for stage, studio and home recording and is the perfect solution for wired in-ear-monitoring.. The compact device in a rugged, ergonomically shaped plastic housing with soft-touch surface and practical belt clip is very extensively equipped.
In addition to locking XLR connectors for the stereo signal L/R input, the HPA 1 has a balanced 3.5 mm stereo jack as AUX input, which can be used in parallel for clicks or playback. It is protected for safe operation against excessive input levels; a hollow pin socket with negative internal contact enables the connection of a network adapter for fixed operation.
A 3.5 mm stereo jack is provided as earphone and headphone output. Volume level and balance can be set with easy-grip knobs, a push-button switches between the summed mono and stereo signals. A full-fledged limiter is integrated for distortion-free playback and as protection against feedback.
The LD Systems HPA 1 has bi-colour LEDs to facilitate the features overview, which displays the response of the limiter during peaks and the battery status. At 165 grams, the headphone amplifier is distinctly light-weight and can be operated for up to 12 hours thanks to a high quality 9 V block battery.