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HOME  >>  PRODUCTS  >>  Assembled B22 mono headphone amplifier board base on β22 (beta 22)
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Assembled B22 mono headphone amplifier board base on β22 (beta 22)
Item ID:16041928
List Price:US$37.00
Price:US$33.50
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Note: The default price is for one mono B22 headphone amp board, to built a stereo headphone amp, you need buy 2 of this board.

This is a assembled & tested board.

Overview

β22 ("beta 22") is a high-end, reference-quality DIY stereo amplifier for dynamic headphones. It could also be built as a power amplifier for speakers (18Wrms into 8Ω unbalanced, or 50Wrms into 8Ω fully-balanced), or as a preamplifier.

The all-discrete (no integrated circuits), fully complementary and cascoded topology, high-current MOSFET output stage, full class A operation and carefully tuned operating points provide vanishingly low distortion, high speed, wide bandwidth, low output impedance, and high output power. All elements of the design were critically examined to create an amplifier that performs as well on the test bench as it does with music.

The β22 is the result of a community service project for the audiophile hobbyist. The schematic diagram is open source. The circuit design, as well as the printed circuit board layout are the work of AMB with participation from the DIY community. It is designed to be relatively easy to build, but it is not recommended as a first-time project for the beginner.



The β22 project is primarily centered around the main amplifier board. Each board supports one channel. This acution is inlcude 2 channle kit.


To build a working amplifier, you will also need a regulated DC power supply to provide power to the board(s), as well as select and/or build an enclosure chassis to house the amplifier boards (and optionally, the power supply). For further information see the following:

Power supply

The β22 amplifier board does not include a power supply (PSU). It needs a separate dual-rail DC supply to provide power to the circuit.

The recommended PSU to use is our HP-X regulated PSU. Designed specifically to be β22's companion PSU,
HP-X elegantly mirrors the all-discrete, fully-complementary, MOSFET-driven theme of the β22 amplifier, while offering low noise, high PSRR, wide bandwidth, well-behaved transient response, low output impedance, excellent line/load regulation and high output current capability. One HP-X PSU board is capable of driving up to four β22 boards when serving as a headphone amplifier. For speaker amp duty, one HP-X board should be used per β22 board.

Other PSUs can be used, as long as it provides the required output voltage and current, and has enough performance not to compromise the quality of the β22 amplifier.

The current draw from the β22 board is approximately 200mA per board as a headphone amplifier, depending on its quiescent current (bias) adjustment settings. As a speaker amplifier, the current draw could have peaks of over 5A per β22 board, while it idles at the same 200mA. It is a good idea to use a power supply with some headroom above the maximum draw.

β22 is designed to operate between ±24V to ±30V DC rail voltages. Highest output voltage swing and output power is attained at ±30V, while ±24V will make the amplifier run cooler. The amplifier should not be operated outside the recommended supply voltage range.

Do not use an unregulated power supply when β22 is configured as a headphone amplifier. The high ripple in an unregulated supply will compromise the performance. If β22 is being built as a speaker amplifier only, you may consider an unregulated supply if you're on a budget. The β22's high PSRR design helps minimize the performance loss, and any incremental noise due to rail ripple would be less audible because speakers are less efficient, and also due to the listening environment and distance. If an unregulated supply is used, do not allow the rail voltages to exceed ±30V give or take a couple of volts, or there is a risk of overvoltage damage.

Always measure the actual output voltage of the power supply before connecting it to the amplifier for the first time, to make sure its output voltage is as expected.

The recommended configuration for the β22 is to use an outboard power supply. This allows the power transformer and other AC components to be located far away from the sensitive amplification circuitry for minimum induced hum and noise. You may instead use a large chassis and put all β22 amplifier boards and the power supply in it, but be sure to position the power transformer and other AC components as far from the amplifier boards as possible. A toroidal power transformer is recommended in this setup for its lower magnetic field leakage.






Measured results (σ22 PSU ±30V)
Input impedance with 50KΩ input volume potentiometer set to maximum
47.6KΩ
Output impedance less than 0.01Ω, 20Hz - 20KHz
Maximum output voltage
at 1KHz, prior to onset of clipping
43Vp-p (15.2Vrms) unloaded
38Vp-p (13.4Vrms) into 32Ω
Power output 0.75Wrms into 300Ω
5.6Wrms into 32Ω
18Wrms into 8Ω
Frequency response at 0dBV output
0Hz - 2.5MHz, +0dB -3dB
Rise time 100KHz square wave, at 43Vp-p output, 10% to 90%
175nS
Slew rate 100KHz square wave, at 43Vp-p output
198V/µS
Noise level
Dynamic range
Total harmonic distortion
Intermodulation distortion
Stereo crosstalk


PCB size:155mm*50mm



this is the kit link http://www.diyerzone.com/headphone-amp/amp-kit/diy-hi-end-b22-mono-headphone-amplifier-kit-base-on-22-beta-22.html






http://www.diyerzone.com/u_file/product/16_04_19/ecf50138bd.jpg


http://www.diyerzone.com/u_file/product/16_04_19/f7a58a6b08.jpg


http://www.diyerzone.com/u_file/product/16_04_19/314c2cd698.jpg

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