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portable V4
QUALITY COMPONENTS:
Highest performance  Panasonic ERA  , 0.1% precision film resistors. (These resistors are of the highest quality: Accurate, Stable and Low-noise)
ADA4627 opamp or see buying options for other OpAmps
High quality Nichicon audio-grade electrolytic smoothing capacitors
Wima DeCoupling capacitors
Alps volume pot
2x TLE2426 precision rail splitter ICs

 
DUAL AMPLIFIER DESIGN: Amplifier has been built to very high standards around two ADA4627 OpAmps(or AD8610, opa627). Each opamp works 100% independently from each other for powering the left and the right channels for excellent channel separation and better drive capability. ADA4627s are ultra low noise, ultra low distortion amplifiers.

DUAL TLE2426 VOLTAGE REF IC:Each OpAmp has its own local voltage reference IC. This method delivers better current to OpAmps for maximum output.
(
Higher current voltage-ref option is available during check-out)

•MULTI STAGE DeCOUPLING CAPACITORS ARRANGEMENT Various values of  high quality film and electrolytic  capacitors filter all ripple noise, eliminates copper track inductance/resistance for ultimate stability. Each OpAmp has its own local DeCoupling circuit.

•AUDIO CIRCUIT LAYOUT Circuit layout is designed very carefully for maximum audio performance + lower noise.

•2x li-ion RECHARGEABLE POWER SOURCE: Power source of this amplifier are 2x 18650 type li-ion batteries. Battery voltages are stepped-up to 20volts by conversion circuits. One full charge can last up-to 36 hrs of use.
(times depend on the volume level but are realistic)

•CHARGING: Charging circuit is inside the amplifier itself. Powered with any standard 500mA(min), 5v USB output.
(note: Depending on the battery levels charging current varies between 200mA - 700mA. It is recommended to use the supplied USB PSU for charging)
Charging times: 9 - 12 hours overnight charge. Charging current stops auto when batteries are full.
Above times are for near empty batteries. Depending on use usually 4 - 6 hours top-up charge is enough.   

•DUAL GAIN  Gain of the amp can be altered to suit your headphones better. There are two gain settings.  Gain-1 is set to 2x and gain-2 is set to 5.5x. Gain changing between 1 and 2 is simply done with the switch on the PCB. The switch is located within millimetres of opamps for less distortion.

•BASS ENHANCE MODE: V4 has very carefully arranged bass-enhance filter.  Filter components have been placed very-closely and within exact matching distance from each amplifying opamp. When activated it enhances the low end sound spectrum approximately by 20% which can help over-bright headphones.  When de-activated its effect is completely removed from the output.
(Bass enhance mode is not over-powering! It adds enough depth without loosing the performance in rest of the sound spectrum)

•BUILD PROCESS:
All soldering are done by hand to perfection with 2% silver solder.
Components are installed very closely to OpAmp ICs for minimum noise and better sound.
Circuit layout is designed very carefully for maximum audio performance.

•EXTERIOR:
Very high quality aluminium enclosure. Dimensions: 27mm x 78mm x 120mm (H-W-D).
Solid Aluminium volume knob
Push button on/off switch.
Red power-on led, Red charger-on led.

•CONNECTIONS:
INPUT: 3.5mm Jack socket (can be connected with suitable cable to: DVD/CD, Ipod, MP3 player, computer sound cards, etc)
OUTPUT: 6.35mm Jack socket (choice of 3.5mm jack socket is available)

•SUPPLIED WITH:
-UK type 5v USB power-supply-unit
(Adaptors are given for EURO, USA and AUSTRALIA type mains sockets)
-Rubber feet

IN DEPTH

V4 uses 2x ada4627 OpAmps configured as dual-mono amplifier. These OpAmps deliver richness with great transparency without much treble glare; offering wide, deep, and fuller soundstage.
Other OpAmp  choices are available during check-out.

Below shows a basic diagram of a dual-mono amplifier. In a dual-mono design left and right channels share no internal components. Each have their own dedicated DC power source. This eliminates mutual interference + current sharing between channels hence creates better channel separation. Overall results are better stereo image, improved sonics, lower distortion and noise.

 

 

DESIGN/BUILD: