Heed Audio Obelisk PRE
The Obelisk PRE is the "command center" of the Obelisk range, a thoroughbred analogue preamplifier with the option of using one or two of its inputs for digital-to-analogue conversion by add-on DAC modules. It is a keenly priced design that we're convinced more than holds its own against many class-leading but prohibitively expensive high-end competitors.
Although rather traditional in its basic topology, the circuit design of the Obelisk PRE represents the convergence of cutting edge ideas with highest-grade components. As opposed to many preamplifiers that have "dumbed-down" internal power supplies in order to present more dramatic sonic benefits with optional auxiliary power supply upgrades, the PRE has a sophisticated and generously sized on-board power supply that is based on a top-quality Noratel transformer and two 10.000µF Mundorf capacitors, custom made to our own specifications. Nevertheless, the last ounce of the PRE's performance can be elicited by adding the Obelisk PX power supply.
The PRE accommodates 6 inputs of which one is exclusively dedicated to the digital domain and can be used with our optional Dactil 1.2 DAC module via 75 Ohm S/PDIF or TOSLINK connections, while a second one will accept either a further DAC module (only via S/PDIF in this case), or our optional MM phono module for vinyl replay (sans module, this input works as standard line-level connection).
Since DAC circuits are highly prone to interferences caused by analogue circuits integrated nearby on the PCB, we provided the on-board supply environment of the DAC module with two independent supply rails using a smart „unit within the unit" solution. Furthermore, all analogue amplifying stages (including the MM phono module) are built in dual-mono configuration and fed through no less than seven fully regulated voltage supply rails.
Modules can be easily inserted into slots on the main PCB and dedicated by jumper settings. Using modules internally instead of stand-alone auxiliary units provides many advantages: absolute synergy, no external cables and plugs, shortest possible signal paths, saving unnecessary costs for external case and power supply, etc.
The two pre-out connections of the Obelisk PRE make various configurations possible. Beside traditional single power amplification, it is also possible to use two power amplifiers for bi-amping or active mode. A tape-out connection is also available for use with a recorder or a headphone amplifier, ideally our Heed Audio CanAmp.
Frequency response (+0, -1dB, unity gain): 1Hz – 105kHz
Frequency response (+0, -3dB, unity gain): 1Hz – 220kHz
Input impedance: 10kΩ
Input sensitivity (at 775mVRMS out): 220mVRMS
Output impedance: < 35Ω
Maximum output level (at THD = 1%): 7.5VRMS
Total harmonic distortion (full range): < 0,005%
Signal to noise ratio (at 775 mVRMS out, unweighted): > 100dB
Max. power consumption: 10W