QubesAUDIO 0 Report post Posted February 18, 2015 A28 fully balanced class A headphone amplifier S$799 Only Silver color left Last 3 sets Now CNY offer $688 A28 is a fully balanced class A headphone amplifier constructed by 4 amplification channels. Its complete connections are convenient to connect source and headphones with different terminals. Outputs: Unbalanced 6.35mm, 2 sets Balanced 3 pin XLR Balanced 4 pin XLR Inputs: Unbalanced RCA Balanced XLR The circuit, construction and components are fine tuned and selected over years of design and listen experience, aimed for best sound quality within a certain cost, and not just use hifi grade parts in blind. The amplification is OPAMP driven complementary transistor buffer (also known as “Diamond Buffer”). After trying dozens of OPAMPS – from pristine NE5534 to the latest offers from major manufacturers, OPA 2604 was chosen because we feel it sounds most balanced in this particular design. The output is MJE243/253 middle powered transistor. Other details include: Plitron power transformer from Canada, Neutrik XLR connectors, and Alpha 4-gang potentiometer made in Tai Wan. Unbalanced inputs are converted to balanced signal by an OPA1632, and the balanced/unbalanced input selection is done by a group of relays to optimize signal path. Use note: use balance input can get better performance , Input signals from the rear panel switch selection. Two headphone jacks of the front panel is double jack, can connect double 3 pin balance headphones, also can connect 6.35 headphones. 4 pin balanced output can only be connected 4 pin headphones, not through the connector to connect unbalanced headphones, otherwise it will damage it Please be noted, if you use a same source to feed A28, do not connect the RCA and XLR interconnects altogether. This will cause common ground interference and degrades the performance of the RCA input signals. (This applies not only to A28 but other similar products in our tests). Practical Performance: ●SNR:>120dB ●THD+N: 0.0005% ●Crosstalk >100dB ●Frequency response:20-20KHz-0.3dB ●Balance output power :600ohm:400mW 300 ohm:700mW 150 ohm:1.3W 32 ohm:2.5W ●unbalance output power: 600ohm:120mW 300 ohm:200mW 150 ohm:350mW 32 ohm:800mW ●Power Consumption: <30W. ●Dimensions: 250*200*55mm. ● Weight: 3Kg. P18 Power Processing Center S$339 Now $288 with IeGO Gold plated IEC Common power filters are usually designed for home appliances and come with tiny ferrite core. Using this kind of design on audio systems will compress the dynamic and loss the details. YULONG’s engineers have many years of experiences in power source design for telecommunication base station and audio equipment design. By utilizing their skills and experiences, they designed P18 power filter. P18 uses an enormous ferrite core, winded with 11 AWG Pirelli wire. Vishay 8uf X2 MKP as common-mode filter Vishay Sprague Y2 as differential-mode filter Vishay transient voltage suppressor is used for avoid sudden impulsive noise signal LITTLEFUSE varistor (VDR) is used for absorbing voltage surge Double layer parallel wide traces on PCB with 20 ounce copper. 11 AWG Pirelli wire is used for internal wiring. Schurter IEC inlet socket Cooper IG8300 receptacles Specially designed aluminum enclosure provides great Electromagnetic shielding Two groups of output, separates digital and analog equipments Phase and grounding error LED indicators P18 provides great contact performance and capable of handling 6000W power dispatching. With high standard filtering, P18 provides continuous pure powers to audio equipment. As a result, P18 gives a fantastic listening experience with detailed, full and rich sound in a dark background. Buy with peace of mind with local 1 year warranty. Drop by to hear it for yourself. KC.Tan Qubes AUDIO 756 Upper serangoon road, Upper serangoon shopping centre #04-35 (S)534626 Tel: 90693001 whatsapp/sms for demo appt Open Sat 1.30~6pm Share this post Link to post Share on other sites