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发表于 2010-10-3 10:14:01
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The "Caffeine" Headphone Amplifier
The "Caffeine Ultra" Amp is truely a high fidelity amp at the lowest price possible. It uses the amazing AD8397 opamp and two TLE2426 railsplitter to create the virtual ground. Furthermore, it includes two slide switches for gain and bass boost (8dB). Advanced customers agree: If this amp would be housed in a "commercial" enclosure the price could be raised up to $200!
Superior Sound Quality
The amp is equipped with the newest generation of high performance audio amplifiers--the AD8397 opamp. Standard "CMOY" based amplifiers use the OPA2134 or OP2277 opamps which are capable of providing 25mA output current only (without buffers). The AD8397 is capable to provide 310mA output current with excellent linearity. Could you imaging how much better this opamp sounds? If you had compared this amp to the standard CMOY amp you would never want to hear a CMOY amp again!
Superior Build Design
The design of this amp is superior to others as it uses a professional circuit with two Keystone battery connectors. There are no loose cables to clutter the inside of the amp, and the Keystone connector holds the battery securely. Even when the amp is moved or flipped over the battery stays in place.
Powering the Amp
The amp needs one 9V battery for powering. You can expect 40-60 hours of battery life using alkaline batteries. Rechargeable batteries will last about 20 hours (depends on the battery type, music and headphones). Optionally a 9-18V DC external wall adaptor can be used to power the amp.
Battery Charging
The amp charges all 7.4 or 8.4V rechargebale batteries with a so-called trickle charging that forces a constant current (35mA) into the battery. A completely flat 250mA rechargeable NiMH battery will be charged in 8-12 hours and will last more than 15 hours using Sennheiser's HD650 at very load play back.
Attaching the Amp
The amp comes with four pair velcro dots. Four "Loop" dots are already sticked at the bottom. They look very nicely on the amp, safe the buttom from getting scratched and they can be used to attach the amp to any surface (player, laptor, desk etc.).
Key Features and Components
- AD8397 high performance opamp
- LM6171 ground driver
- adjustable gain of 2.5x (8dB) and 9.3x (19.4dB)
- 22 ohm output resistors (to reduce sibilance when using lean headphones)
- detachable bass boost of 7.3dB in low gain and 9.4dB in high gain
- trickle charging using LM317 constant current of 35mA (10 hours charging time)
- black circuit board with chemical nickel-gold letters (no silk print!)
- toggle switch by NKK Nikkai
- 1/8'' (3.5mm) audio jacks
- blue low current LED in a silver housing
- 9mm volume potentiometer (low noise)
- aluminium volume knob with durable rubber rings
- 1% SMT resitors thin film type
- low-ESR 820μF power cap (FM Panasonic series)
- 9V battery connectors by Keystone
- size with knob: 2.44" wide X 4.45" long X .95" thick (6.2 x 11.3 x 2.4 cm)
[ 本帖最后由 岳安 于 2010-10-3 10:15 编辑 ] |
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发表于 2010-10-3 10:07:58
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