The word "discrete" conjures up the high end and high end prices, but at £200 + VAT it's affordable by most, but the sound of this solid state transistor amp equates to tube headphone amps costing nearly 10 times that!
Whether you believe in global warming or not energy costs are rising at a terrifying rate, but as every audio enthusiast knows - leaving equipment on keeps it "burned in" and ready for action.
Graham Slee ingenuity has resulted in success again making the Novo headphone amp perform to perfection with a truly green energy saving switched mode plug-top power supply. It fully complies with world-wide energy and environmental legislation.
Everything about this headphone amplifier is incredible but true! The Graham Slee Entheos (enthusiast's) Series Novo stereo headphone amplifier is a discrete solid state transistor configuration, using an IC voltage regulator. There are six transistors per channel. The "fast" voltage amplifier stage uses a current feedback input and a current source to drive a small signal transistor class AB push-pull output stage. The output is capacitively and resistively coupled to prevent headphone damage/short circuit damage and an output impedance reduction network minimises any signal distortion these components could add. The Novo uses multi-path negative feedback to reduce distortion without degrading the musicality of the signal.
The Novo is supplied with an Energy Efficient plug style AC/DC mains adapter power supply for universal mains use: 90-250V ac; supplied with a selection of plug heads to suit the customer's mains outlet. The power supply is of the switched mode type and sensitive users may detect a slight tingling sensation from the Novo case: this is normal and within world safety standards, but can be eliminated completely by connecting a wire to the Novo "aux ground" post; the other end to earth (either mains earth or an earth spike - seek qualified assistance if unsure). When connected to an earthed source this wire will not normally be required. The switched mode power supply emits an ultra-sonic whistle which cannot normally be heard, but in the presence of other persistent noise (such as air-con, refrigerators etc) a beat frequency (chirping) may be heard. Careful positioning will minimise this effect.
A Chained set of phono/RCA jacks enables the stereo input to be routed to other equipment such as a power amplifier. The input impedance is greater than 39 kilo Ohms so as to be virtually transparent to the source.
The output jack is designed for standard 1/4 inch/6.35mm headphone plugs (B-gauge) and can also be used with tapered A-gauge plugs. Headphones of impedance 8 - 2,000 Ohms may be used but best results will be obtained with impedances of 16 - 600 Ohms. An impedance reduction network reduces the driving impedance "seen" by the headphones and compensates for the headphone's cable capacitance, leading to a more focused musical image than purely resistive or power-amp configuration headphone amplifier outputs. It also reduces the apparent differences between dissimilar headphones.
The volume control can be set at any position to give comfortable listening. Unlike Hi-Fi amplifier volume controls, it can be set at any position and still give excellent performance. This is preferable to the contact resistance and wear of a gain switch, which would otherwise be required.
Specifications:
* Dimensions: L. 10.5 W. 10.5 H. 5 (cm) approx. excluding controls and connectors
* Output: 150mW rms into 32 Ohms, 40mW rms into 600 Ohms (both channels fully driven - 0.05% THD)
* Input Impedance: greater than 39 kilo Ohms
* Recommended input range: 200mV - 1V rms (2.8V p-p)
* Frequency Response (worst case): Flat: 43Hz to 16kHz (-1dB), 22Hz to 30kHz (-3dB) (volume control at 3 o'clock position)
* Channel Balance: 0.5dB typical
* Hum & Noise: -80dB CCIR Q-pk 20Hz-20kHz (into 30 Ohms)
* Stereo Crosstalk: -64dB typical
* Distortion (THD+Noise): 0.02% at 1 kHz into 30 Ohms, and 12 o'clock volume control position