The Raptor
EMMELINE By Ray Samuels Audio

Emmeline II "The Raptor" Headphone Amp

The Raptor was designed with two goals in mind, first an amp with a small foot prints, secondly an amp capable of driving any headphones available in the high end whether being high or low impedance. The Raptor is an output transformer less amp “OTL”; it is designed using a single 12AU7, a triode, as input/gain for both channels & two powerful driver tubes “5687” one for each channel, in a SRPP configuration to drive the load. The parts used in the construction of the amp section are audiophile quality components, hand selected and matched to provide a perfect balance between the two channels. All resistors are Holco, 1 watt film resistors with .5% accuracy, the caps are “Musicap” pure polypropylene by Hovland. All power resistors are military grade with 1% tolerance by Vishay. The tube sockets are ceramics with Gold contacts soldered to a military spec 2 oz FR4 printed circuit board with a military specs solder. All signal lanes & power lanes have been routed & isolated from each others with ground lanes & ground patches to lower the floor noise to a complete black silence. The amp chassis is shielded with DC ground to stop any RF signals from disturbing the components. Two sets of RCA inputs, for two sources, are provided on the back panel of the Raptor, switching between the two sources is accomplished via toggle switch, located on the back panel also. 1/4 inch headphone jack is located on the left side of the front panel, on the right of that red LEDs circle is illuminating the Volume control knob. The Amp chassis is connected to the external power supply chassis through 3 conductors, 16AWG, 600V shielded cable. The DC cable is terminated by using an AMP connector with locking ring. The power chassis houses a super power supply, with a custom built, PLITRON, toroidal transformer designed to meet our specs in regard to size, voltage and current requirement. The power supply is dead quite. Two stages of rectifications follow the full wave bridge rectifier, each stage with current limiting 1% Vishay power resistors, these two stages slow down the current hungry caps, allowing the filament voltage to get to the tube first before the plate voltage rises to the required voltage. A high voltage regulator is implemented in the power supply to keep the voltage steady no matter how the AC voltage fluctuates. As to the filament voltage, a very powerful, compact universal switching power supply is used with 12VDC, 3.4 amp of current. It makes the amp flexible to work in any country no matter what the voltage might be. The power supply uses high grade Panasonic power capacitors rated at 105C. The printed circuit board is designed to circulate the air internally to keep the power supply cool. Again Military grade FR4 2oz printed circuit board is used with military specs, 1% tolerance, power resistors, both the amp and the power supply are hand crafted, with hand selected components, perfectly matched between the left and the right channel for an accurate sound balance production. The power supply is shielded with AC ground, red LED in the front panel indicated that the amp is turned on. The on/off switch is installed on the back panel of the power supply. Few warning are silk screened on the top of the power supply indicating the risk of opening the top cover. Also instructions not to block the top and the bottom vents of the power supply, the last warning is not to place the amp section on top of the power supply. The Raptor has three years, full warranty parts and labor, tubes 90 days, that is transferable to second or third owner no question asked. h2. Specifications * Input impedance 50K * Frequency response 10-300k * Total harmonic distortion around .09% * Output impedance 32-2000 ohms * Gain around 14 * Tube compliment, one12AU7 for input * Driver tubes two 5687 as buffers. h2. Dimensions (Amp Section) * Front, left to right, 5.75” * Depth, front to back, 4.25” * Height, no tubes, 2.00” * Height with tubes, 4.00” h2. Dimensions (Power supply) * Front, left to right, 8.00” * Depth, front to back, 5.75” * Height, 3.00” * Weight around 8 pounds.