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β22放大器制作全攻略 要的就是完成度和原汁原味 与各位DIY分享
DIY也好几年了,其中辛酸不少.做为一个普通的DIY爱好者,总是期望用自己的双手制作出一台让自己倾心和满意的作品.可是做为电子制作,不像艺术创作,可以停留在形和神的层面,而制作出一台优秀的放大器,必须遵循着严谨和科学的设计,正确的选材.完善的工艺制作,其中重复着不断的调试和反复制作的过程.可是并非所有人都能完成这一过程,特别是非电子行业的人,对于线路的设计和调试是无法完成的,而接触模拟电路不久的新人也无法完成较为复杂的设计和制作,作品往往完成度很低,个体制作对于合适元器件和配套机壳的制作也是非常困难,也无法投入那么大的精力和金钱.虽然网上有很多电路图纸,其中不乏优秀的设计制作,可是无论是图纸的正确性,还是可实际制作的可能都非常低.我走过很多这样的冤枉之路.所以DIY出一台公认优秀的电路,而且对元件又不苛求好声而且完成度可以和厂机媲美乃至超越的作品是非常不容易的,
优秀的电路而且对元件的依赖性要很小,就必须通过电路的科学设计来规避元件自身的缺点,胆机要全直耦,而且不依赖胆自身和输出牛是不大可能实现,所以只有选用晶体管,晶体管较为容易做出较高的通频带和频率平坦性,较低的线性和非线性失真,而实现这一切运用负反馈是必须的,所以要有较高的转换速率来克服负反馈带来的瞬态互调失真, 拥有足够的功率储备和负载能力也是必需的.β22的出现仿佛解决了上面的绝大部分问题,全直耦,频宽轻松上十几M,转换速率高达300V/us,可以完美地再现100K方波,极低的谐波和互调失真和强大的负载能力, 驱动8欧姆的箱子可以输出甲类18W, 伺候耳机是绰绰有余,伺候灵敏度高的箱子也非常不错,先详细了解下β22吧:
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β22
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. Please see the Tech highlights section for a detailed description.
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 History & acknowledgements section gives a summary of how β22 came to be, and gives credit to those whose work inspired its archtecture.
To obtain the blank printed circuit board and some related parts, visit the AMB audio shop. Other parts are available from online vendors. See the Parts list section.
Please be sure to read every section of this site carefully before attempting to build the β22 amplifier. There are many options to consider, some of which would affect your choice of chassis, heatsinks, various parts and wiring scheme. If you don't thoroughly understand everything, please consider having someone more experienced to build the amplifier for you, or build a simpler project.
β22是一部hi-end参考级的针对动圈耳机的DIY放大器。而且它不仅仅可以作为耳放来使用,同样也是一部性能优异的前级,或是一部小功率的后级(作为后级使用时,配置成单端模式,驱动8ohm的喇叭能输出18w额定功率,配置成平衡模式使用,能够输出50w额定功率)。β22由全分立元件组成,全互补对称和沃尔曼折叠架构,大电流输出的mosfet管输出级,全电路甲类工作状态,以及细致选择和调整的工作点,保证了整部放大器性能优异,具有极低的失真,高速度,高带宽,极低的输出阻抗和很高的输出功率。β22从输入到输出全部都是互补对称的结构,能够很好地消除奇次谐波失真(偶次谐波失真也很低),具有很好的实际听感。全机具有对称的开机和关机行为:由sigma22电源板供电的时候,开关机不会有“碰”的一声。电路中的每一级都工作在纯甲类状态,因此不存在交越失真,也使得谐波失真和互调失真降至最低。
来张官方的测试图 100K的 方波和 相移
The square wave graphs show that there is minimum slewing and ringing at the leading and falling edges. The 100KHz sine, triangle, and Lissajous graphs also show very small amount of phase shift between the input and output. Within the 20Hz to 20KHz audio band, there is no measurable phase shift.
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