高保真音响设计制作论文开题报告
有源音箱设计报告
有源音箱设计学院：移动通信与软件学院 班级：电信产品班学生：任杰（原理图）彭婷婷（PCB制作） 郑波（软件仿真）1有源音箱设计（论文）开题报告设计（论文）题目 有源音箱的设计一、选题的背景和意义：音乐是生活的一部分，音箱又是提高音乐享受的必要工具音箱的成本低，价格极易被接受，独立的外置功放的机壳应该具备足够的机械强度并有良好的屏蔽性，有源音箱的功放设置在音箱内部，比功放要少一套机壳，成本得以大幅降低。
而且有源音箱连接简单，使用方便。
人对音速浓厚的兴趣，故而希望将此因素运用到毕业设计中，带给更多的人美的享受。
二、课题研究的主要内容：1. 有源音箱组成；2. 集成功率放大器的原理；3. 集成前置放大器的原理；4、集成稳压电源的原理；5. 电路的装配和调试。
三、主要研究（设计）方法论述：1. 采用集成电路的设计；2. 采用集成电路设计集成前置放大器电路；3. 采用集成电路设计集成功率放大器电路；4. 集成稳压电源的设计。
二、主要技术指标：1.电源电压：AC220V50Hz；2.频响范围：90Hz—20KHz；3.负载阻抗：8Ω；4.最大不失真输出总功率：15W。
摘 要有源音箱主要由功放组件和电源变压器组成。
功放组件主要是前置放大器和功率放大器组成，前置放大器主要负责信号的电压放大、音量控制、多路音源的切换、音调调整以及阻抗匹配等功能，而功率放大器在整个音响系统中起到了“组织、协调”的枢纽作用，在某种程度上主宰着整个系统能否提供良好的音质输出，电源变压器则为功放组件提供电能。
通过对集成前置放大器，集成功率放大器的设计和集成稳压电源的设计完成有源音箱的设计。
关键词：前置放大器；功率放大器；电源第1章 前言1.1 本设计的意义有源音箱实际上就是功放机与音箱的结合体。
咱们过去在市场上见到的家庭影院组合，是把功放机与音箱分开的，而有源音箱就是把功放机放在了音箱里。
在多媒体应用丰富的今天，一套多媒体音箱基本上是每一套系统中的标准配置。
音响放大器课开题报告
攀枝花学院专业基础综合实验报告音响放大器设计与制作学生姓名：李义学生学号： 201010501035 院（系）：电气信息工程学院年级专业： 2010级电子信息工程一班指导教师：李会容二〇一三年四月开题报告摘要本实验介绍了音响的构成、功能、及工作原理，它由TDA2030芯片所组成的功放电路，LM324四运放大器为前置放大和音调放大构成，本身具有电源电压范围宽，静态功耗小，可单电源使用，价格低廉等优点。
而TDA2030一款输出功率大，最大功率到达35W左右，静态电流小，负载能力强，动态电流大既可带动4-16Ω的扬声器，电路简洁，制作方便、性能可靠的高保真功放，并具有内部保护电路。
本设计的功能是将输入音频信号进行放大，是一种可普遍用于家庭音响系统、立体声唱机等电子系统中，便于携带，适用性强。
关键词：TDA2030 OTL 输出功率LM324AbstractThis article describes the sound of the composition, function, and principle, it is formed by the TDA2030 chip power amplifier circuit, LM324 quad op amp as the preamp and tone to enlarge constitute itself with supply voltage range, the static power consumption can be a single power use and low cost advantages. The TDA2030 a high output power, maximum power reaches 35W or so, the static current, load capacity, dynamic current can drive large 4-16Ω speaker, circuit simplicity, making convenient and reliable high-fidelity power amplifier, and an internal protection circuit. This design feature is the input audio signal amplification,Is generally available for home audio systems, stereo player and other electronic system, portable applicability.Key words :TDA2030 OTL Output power LM324一．选题意义细心观察我的身边，现在音响可以说是无处不在，做为一个现代人，我们已经离不开音响。
高品质功率放大器的设计的开题报告
高品质功率放大器的设计的开题报告开题报告一、题目高品质功率放大器二、设计目的和意义1.设计目的：（1）了解音响放大器的构成，并组成一个简单的音响放大器。
（2）理解音调控制器，集成功率放大器的工作原理和应用方法。
（3）理解和掌握音响放大器的主要技术指标和测试方法。
（4）根据给出的技术条件和指标，设计音响放大器。
（5）能够独立接电路、掌握调试技术。
2.设计意义：近年来，现代电子技术的飞速发展和家庭影院需求档次的不断提高, 人们已基本上不满足于普通的家用音响所能够提供的音质音效了, 需要音质更纯正、立体声音效更佳、高低音的频率响应丰满、功能更佳智能化的影音系统，甚至需要有音乐厅演绎效果的音频还原设备等。
原来设计比较粗糙的普通家用功放已经满足不了多数用户对音乐完美还原追求的需要。
该课题主要对音频功率放大器的元件参数及性能指标进行了分析研究,对常见大功率音频放大电路元件参数性能在理论上进行较深入的分析。
整个过程对设计制造各种高性能音响放大设备具有很强的参考作用。
三、高品质功率放大器的现状和发展趋势1.现状：随着时代的进步，科技的发展，音频功率放大器已经广泛运用到人们的生活学习中.它在人们正常生活和生产中起着越来越重要的作用.2.发展趋势：（1）早期的晶体管功放（2）晶体管功放的发展和互调失真（3）功放输入级——差动与共射-共基（4）放大器的电源与甲类放大器（5）其他类型的放大器四、设计内容、途径、技术指标1.研究内容及基本要求：（1）研究内容：设计并制作具有弱信号放大能力的低频功率放大器。
（2）基本要求：研究工作要求通过文献查阅，收集相关材料等方法，在此基础上进行分析研究，探讨满足指标参数的电路。
2.研究途径：这类放大器在广播电台、电视台、电影制片厂、录音公司、音乐厅、重要社会活动场所、体育运动场馆、文艺演出场所、会堂、会议厅等等场合作为监听和扩声之用，这些都是需要大量专业级音频设备的地方.3.技术指标：输出功率、效率、功率增益、带宽和谐波抑制度（或信号失真度）等。
音箱设计报告范文模板
音箱设计报告范文模板1. 引言音箱是一种借助电源供电的装置，用于放大并播放声音。
随着人们对音质需求的提高，对音箱的设计和质量要求也越来越高。
本文将介绍一款全新的音箱设计方案，旨在提供优质的音质和出色的外观设计。
2. 设计目标本音箱设计项目的主要目标包括以下几点：- 提供高保真音质，还原最原始的音频信号；- 支持多种音频输入方式，如蓝牙、AUX、USB等；- 具备良好的低音扩展能力，提供更浑厚的低音效果；- 具备简约而时尚的外观设计，适应不同的室内环境。
3. 技术方案3.1 音质优化技术为了提供高保真的音质，我们采用了以下技术方案：- 采用高品质数字音频解码芯片，支持多种音频格式的解码；- 应用数字信号处理技术，通过调整音频参数来实现音质优化；- 选用高品质的音频功放芯片，提供更清晰、更透彻的音频输出。
3.2 多种音频输入方式为了满足用户的不同需求，我们将音箱设计为支持多种音频输入方式：- 蓝牙无线连接：用户可以通过蓝牙连接手机、平板等设备来播放音乐；- AUX输入：用户可以通过连接音源设备的3.5mm音频线来播放音乐；- USB接口：用户可以通过连接U盘等存储设备来播放音乐。
3.3 低音扩展技术为了提供更浑厚的低音效果，我们采用了低音扩展技术：- 采用专业的低音扩展算法，通过电子调音来增强低音的表现力；- 使用高品质的低音扩展器件，提供更低的低音延伸，并减少音频失真。
3.4 外观设计本音箱采用简约而时尚的外观设计，具备以下特点：- 采用高质量的木质材料，提供更好的音质表现；- 采用经典的方形设计，适应不同的室内环境；- 选用时尚的亮面处理工艺，提升整体美感。
4. 技术参数本音箱设计方案的主要技术参数如下：- 频率响应范围：20Hz - 20kHz；- 信噪比：≥90dB；- 蓝牙版本：5.0；- 最大输出功率：50W；- 电源电压：AC 100-240V。
5. 结论通过对音质优化技术、多种音频输入方式、低音扩展技术以及外观设计的应用，我们成功地设计出一款具备优质音质和出色外观的音箱。
高保真音响设计制作方案
高保真音响设计制作方案目录引言 (3)1 高保真音响系统 (4)1.1 高保真音响系统定义 (4)1.2 高保真音响系统组成 (5)2 高保真功率放大器 (6)2.1 功率放大器种类 (6)2.2 高保真功率放大器主要技术指标 (7)3 功放电源 (11)3.1 功放电源概述 (11)3.2 功放电源组成 (11)3.3 整流滤波电路 (13)3.4 稳压电路 (16)4 方案论证及阐述 (17)4.1 设计要求 (17)4.2 方案论证 (17)4.2.1后级放大器方案选定 (17)4.2.2前置放大器方案选定 (17)4.2.3音调芯片方案选定 (18)4.2.4电源方案选定 (18)4.3 具体方案阐述 (18)4.3.1前级放大器方案阐述 (19)4.3.2后级放大器方案阐述 (22)4.3.3功放电源方案阐述 (25)5 高保真功放制板 (26)5.1 制板注意事项 (26)5.2 制板经验总结 (27)5.2.1制板步骤 (27)5.2.2Protel99se的使用经验总结 (28)5.2.3制板遇到的问题 (29)6 功放调试 (30)6.1 调试步骤 (30)6.2 模块调试 (30)6.2.1电源调试 (30)6.2.2音调模块调试 (30)6.2.3前置放大模块调试 (31)6.2.4后级功放模块调试 (31)6.3 整体调试 (32)7 高保真功放性能指标测试 (32)7.1 性能指标测试的必要性 (32)7.2 主要性能指标测试 (32)7.3 测试所用仪器 (35)7.4 测试结论 (35)8 总结 (36)8.1 完成程度 (36)8.2 技术优点 (36)8.3 技术缺陷 (36)8.4 毕设感受 (36)参考文献 (38)附录 (39)附录1电路原理图 (39)附录2 PCB 图 (43)摘要随着国家经济蒸蒸日上，现代科技不断发展，这些使人们在物质享受之余，也有了更多的精神享受的需要。
有源音箱论文设计
1 前言
1.1 本设计的意义
音乐是让生活多姿多彩，音箱又是提高音乐享受的必要工具。随着电视技术，音响技术，数字技术的不断发展，以及人们的生活水平的不断提高，市场中音响器材也是琳琅满目，给音乐爱好者带来更多的选择。而有源音箱将功放设置在音箱内部，比功放要少一个机壳，成本得以大幅度的降低，再加上其音箱连接简单，使用方便，得到众多消费者的青睐。应用自己学过的专业知识，亲手设计制作一个有源音箱使用起来更是具有实际意义。高音清爽，低音震撼给人带来更多美的享受。
进入截止，而原先截止的三极管进入导通、放大状态，两只三极管在不断地交替导通放大和截止变化。
2．按输出极与扬声器的链接方式
功率放大器电路的另一种划分主要是由功放级输出电路形式来决定，常见的的音频功率放大器主要有下列几种：
（1）变压器耦合甲类放大器电路主要用于电子放大器中；
（2）变压器耦合推挽功放电路主要用于一些输出功率较大的电子Βιβλιοθήκη 放大器中；福建信息职业技术学院
毕业论文（设计）
论文题目：有源音箱的设计与制作
系别：电子工程系
专业：通信技术
班级：通信0811班
学号：**********
******
指导老师：谭巧老师
有源音箱
摘要：本文介绍了有源音箱的设计及制作过程。有源音箱主要由功放组件和电源变压器组成。功率放大器是电子电路中一个十分重要的部分，它在整个音箱系统中起到了“组织、协调”的枢纽作用，将音频信号放大足以推动扬声器工作。目前集成功放则凭其制作简单，成本低廉，重放音质尚可等特点替代分立元件成为主流。此次我就是采用双声道集成芯片TEA2025来设计高保真音频功率放大器，TEA2025双声道功率放大集成电路具有声道分离度高、电源接通时冲击噪声小、外接元件少，最大电压增益可由外接电阻调节等特点。该功放设计避免了分立元件组合电路布线复杂、输出信号失真大的缺点。
高效率音频功率放大器开题报告
【6】Shannon,C.E. 1948: A mathematical theory of communication, Bell System Technical Journal, 27(1948),379-429 and 623-656
D类音频功率放大器不同于模拟音频功率放大器，它具有全新的结构方式，是PWM开关脉冲功率放大器。为了提高音频功率放大器的效率，必须进行大量的研究试验工作。
实验设计：
1、选用一个220V～15W，12V×2的变压器供电，一块音频功率放大集成块TDA2030，一块双通道音频功率放大电路集成块CD2025CP作功率放大器。一块内部包括有两个独立的、高增益、内部频率补偿的双运算放大器F4558，作为放大电路，通过喇叭输出音频信号。
6、设计并制作音频功率放大器外壳。
考虑到性价比，主要元器件拟定采用：CD2025CP、F4558A、TDA2030A。
论文（设计）拟定提纲
第一部分为绪论部分，综述本文的研究背景，阐明课题的意义。
第二部分主要介绍高效率音频功率放大器的各个功能模块的具体设计。
第三部分为论文的总结、参考文献和附录部分。
主要参考文献
本科生毕业论文（设计）开题报告
论文（设计）题目
高效率音频功率放大器
学生姓名
系、专业
指导教师
选题目的、价值和意义：
论证D类音频功率放大器研究的必要性和重要性，解决D类音频功率放大器的技术关键，用商业化通用器件，完成D类音频功率放大器设计及样机制作，为D类音频功率放大器的开发提供技术条件。
多媒体音箱家电化是一种潜伏的趋势，在2.1+1产品上这种脉络表现的更加明晰，独立功放的平台整合性也给打通多媒体音箱与传统音响的界限打下了坚实的基础，在这个平台上，可以实现2.1+1，5.1+1，真正达到影音娱乐的目的。
高保真音响设计制作探讨(论文)
题 目： 高保真音响设计制作院 （系）： 计算机系专 业： 自动化学生姓名：学 号：指导教师：职 称：理论研究实验研究工程设计 软件开发目 录引言 (4)1 高保真音响系统 (5)1.1 高保真音响系统定义 (5)1.2 高保真音响系统组成 (5)2 高保真功率放大器 (7)2.1 功率放大器种类 (7)2.2 高保真功率放大器主要技术指标 (8)3 功放电源 (11)3.1 功放电源概述 (11)3.2 功放电源组成 (12)3.3 整流滤波电路 (14)3.4 稳压电路 ............................................................. 17 4 方案论证及阐述 (17)4.1 设计要求 (17)4.2 方案论证 (18)4.2.1后级放大器方案选定 (18)4.2.2前置放大器方案选定 (18)4.2.3音调芯片方案选定 (19)4.2.4电源方案选定 (19)4.3 具体方案阐述 (19)4.3.1前级放大器方案阐述 (19)4.3.2后级放大器方案阐述 (23)4.3.3功放电源方案阐述 (26)5 高保真功放制板 (27)5.1 制板注意事项 (27)5.2 制板经验总结 (28)5.2.1制板步骤 (28)5.2.2Protel99se的使用经验总结 (29)5.2.3制板遇到的问题 (30)6 功放调试 (30)6.1 调试步骤 (31)6.2 模块调试 (31)6.2.1电源调试 (31)6.2.2音调模块调试 (31)6.2.3前置放大模块调试 (32)6.2.4后级功放模块调试 (32)6.3 整体调试 (32)7 高保真功放性能指标测试 (33)7.1 性能指标测试的必要性 (33)7.2 主要性能指标测试 (33)7.3 测试所用仪器 (36)7.4 测试结论 (36)8 总结 (37)8.1 完成程度 (37)8.2 技术优点 (37)8.3 技术缺陷 (37)8.4 毕设感受 (37)参考文献 (37)附录 (38)附录1电路原理图 (38)附录2 PCB 图 (41)摘要随着国家经济蒸蒸日上，现代科技不断发展，这些使人们在物质享受之余，也有了更多的精神享受的需要。
智能音响开题报告
附页智能音响系统开发设计一、研究目的和意义音响系统在家庭影院、会议室中的应用越来越广泛，与我们日常生活有着密切关系。
随着生活水平的提高，人们越来越注重视觉，音质的享受。
在大多数情况下，增强系统性能，如更好的声音效果，是促使消费者购买产品的一个重要因素。
音响系统主要由功率放大部分和音箱组成。
功率放大部分主要是放大信号、调节声音音调。
音箱用来还原声音。
本次设计音响系统采用集成电路以及显示电路完成，攻放部分有三部分组成前级放大、音调调节和功率放大级。
前级放大主要任务是完成小信号电压放大任务，同时要求低噪声、低温漂。
音调调节主要完成高低音、音量调节。
功率放大级主要任务是在允许的失真限度内,尽可能高效率地向负载提供足够大的功率，要求是输出功率要大、效率要高。
通过详尽的资料查询和严密的方案论证后，我们选择通过集成运放NE5532、TDA7294的配套使用来使本电路系统设计简洁、实用并且达到高增益、高保真、高效率、低噪声、宽频带、快响应的指标。
二、主要研究内容2.1智能音响系统的基本设计思想整个电路主要由稳压电源、前级放大器、音调调节、左右声道放大器、重低音放大器、智能化部分共六部分构成。
稳压电源选用大功率的环形变压器作为动力提供。
主要是为功率放大的输出级电路提供稳定的直流电源。
另外还需要小功率的变压器做一些别的电路提供直流电源。
前级放大器主要是电压的放大。
左右声道放大器、重低音放大器实现电流、电压的放大。
系统中还将运行的总功率以及音频的频率在液晶上显示。
设计的电路结构简洁、实用，充分利用到了集成功放的优良性能。
实验结果表明该功率放大器在带宽、失真度、效率等方面具有较好的指标、较高的实用性,为功率放大器的设计提供了广阔的思路。
2.2单元模块电路a）本系统电源设计采用环形变压器，整流管用3A的1N5408作整流，10000uF的电解电容作滤波，金属草帽封装的稳压器作稳压。
开题报告范文汽车音响
学生姓名学号系别专业指导教师年月日网络环境下地数字化汽车音响设计论题论题地依据: .说明本论题研究地理论意义和现实意义.综述国内外有关本论题地研究动态和自己地见解.本论题研究地理论意义和现实意义年，美国出现了第一台汽车收音机，拉开了汽车音响发展史地序幕，随着电子技术地发展，美国、欧洲、日本等国家开始研发各种基于电子技术地汽车音响设备.由于汽车销售在中国并未普及，因此在八十年代后，中国地汽车音响产业才开始进入了稳步发展时期.时至今日，中国汽车音响已经成为一个集卫星导航定位、路线规划以及、电视等功能地数字化音频系统[].研究网络环境下地数字化汽车音响，对于我们了解汽车音响地结构、加深对数字化汽车音响地认识、充实数字化音响技术地理论研究，都有非常重要地意义.与此同时，在经济全球化地大环境下，对数字化汽车音响进行研究，开发出基于时代背景地新型音响设备，也具有深远地现实意义.这样不仅能降低国内汽车音响生产成本，让中国爱车一族受惠，还能开拓国外市场，让中国汽车音响产业走向世界，提升我国地经济实力和综合国力..国内外有关本论题地研究动态和自己地见解目前，对于数字化汽车音响地研究，主要集中在两点上：一是对基于数字化技术地汽车音响设计研究，主要研究成果包括：赵嘉祥先生地《基于蓝牙通信地汽车音响软件设计与实现》[]，廖媛地《汽车音响娱乐系统功能应用设计》[]，等学者研究地《》[]，等学者研究地《》[]等.二是关于数字化汽车音响设备地改装研究，如; 先生地《品音乐,享生活——宝马汽车音响改装案例》[]等.除此以外，从理论、人文、教育、发展趋势等角度对数字化汽车音响进行研究地文献也开始增多.由此可见，“数字化汽车音响”在国内外是有一定地研究基础地，但是，针对于网络环境下地数字化汽车音响地研究却比较少，特别是在网络技术、电子技术发展迅速地今天，知识老化加快，新地音响产品层出不穷，如果我们不贴近于现实，对网络环境下地数字化汽车音响进行更深入地研究，即使以后投身于专业相关地工作，在工作中也会缺乏创新性，无法灵活运用所学地专业知识应用于实践.另外，新时代地汽车音响设备，非常注重满足客户地个性化需求，而在网络环境下，数字化汽车音响可以有很大地灵活性，如何在应用数字化技术地基础上，满足不同客户地个性化地需求，也成为了数字化汽车音响设计地难点和重点，需要在数字化汽车音响地硬件设计和软件设计中进行研究.论题研究地主要内容：一、汽车音响发展现状二、音响系统地总体设计及原理三、网络环境下地数字化汽车音响设计（一）网络与数字化汽车音响（二）数字化汽车音响硬件设计（三）数字化汽车音响软件设计（四）数字化汽车音响设计实例四、对数字化汽车音响设计问题地反思五、结语论题研究地基本方法：、文献检索法：全面收集、整理和分析汽车音响相关地声像和文字资料，在此基础上提出论点.、引证法：通过引用业内权威人士对本论题中论点相关方面地观点言论，作为主要论点地支撑.、调查法：对汽车音响行业进行实地调查，了解行业资讯，紧贴行业动态进行研究.、例证法：通过引用和本论题地论点相关地研究成果，作为论据地佐证材料.论题写作地进度安排：年月日前，完成调研、收集资料，阅读资料.年月日前，拟写出写作提纲.年月日前，完成初稿起草.年月日前，完成论文修改.年月日前，完成定稿打印.主要参考资料：[]李昆鹏,马俊,田磊. 汽车音响现状及发展趋势[]. 河南省汽车工程学会.第九届河南省汽车工程技术研讨会论文集[].河南省汽车工程学会.[]赵嘉祥. 基于蓝牙通信地汽车音响软件设计与实现[].大连理工大学.[]廖媛. 汽车音响娱乐系统功能应用设计[]. 汽车工程师.[] . []. :.[]. . . . .[]. :.[]. 品音乐,享生活——宝马汽车音响改装案例[]. 音响改装技术.指导教师意见（研究地理论意义或应用价值、创新之处、研究方法可行性等）： 开题报告会议记录摘要（学生阐述地内容、指导小组所提问题及学生地回答等）： 年 月 日 地点：开题报告会与会人员姓 名 职务（职称）指导小组意见：负责人签名：年月日系意见：系主任签名：年月日。
作用于高保真音响设备的音频放大器论文
毕业论文作者学号系部电子信息工程专业电子信息工程题目作用于高保真音响设备的音频放大器指导教师丁文秋评阅教师完成时间：年月日毕业设计(论文)中文摘要毕业设计(论文)外文摘要目录绪论 (6)二．放大器的程序设计 (7)〔一〕电路选型 (7)〔二〕参数计算 (8)〔三〕元器件选择 (8)〔四〕验证定型 (9)三．晶体管前置放大器 (10)〔一〕根本单元电路 (10)〔二〕负反应放大器 (10)〔三〕直流放大器 (12)四、功率放大器 (14)〔一〕功率放大器设计要点 (14)〔二〕功率放大器的类型 (16)〔三〕音频放大器的设计 (17)五、LM1875的简介 (25)〔一〕LM1875的参数简介 (25)〔三〕LM1875的电路特点 (26)六、电路设计 (27)〔一〕典型应用电路 (27)〔三〕双电源音频功率放大器PCB图 (28)七、电路制作与调试 (30)〔一〕利用PCB制作电路板 (30)〔二〕装配与调试： (30)八、电路图的绘制与制板中应注意的问题 (32)〔一〕S CH原理图应注意常见问题 (32)〔二〕PCB设计中应注意的问题 (33)〔三〕焊盘应注意的常见问题 (34)九、总结 (35)致谢 (36)参考文献 (39)绪论音频放大器已经有快要一个世纪的历史了，最早的电子管放大器的第一个应用就是音频放大器。
然而直到现在为止，它还在不断地更新、开展、前进。
主要因为人类的听觉是各种感觉中的相当重要的一种，也是最根本的一种。
为了满足它的需要，有关的音频放大器就要不断地加以改良。
进入21世纪以后，各种便携式的电子设备成为了电子设备的一种重要的开展趋势。
从作为通信工具的，到作为娱乐设备的MP3播放器，已经成为差不多人人具备的便携式电子设备。
陆续将要普及的还有便携式电视机，便携式DVD等等。
所有这些便携式的电子设备的一个共同点，就是都有音频输出，也就是都需要有一个音频放大器；另一个特点就是它们都是电池供电的。
多媒体音箱设计【开题报告】
毕业设计开题报告工业设计多媒体音箱设计1、绪论信息时代的成熟，一系列信息配套产品也逐渐完善，多媒体音箱作为这个时代电脑与外界最主要的声音传播媒介，有着不可忽视的作用，更有着非常宽广的市场前景。
多媒体音箱正期待着最有才华的设计者为它的市场带来新一轮的购物潮。
随着电脑的普及，网络技术的盛行，数码用品和多媒体产品的发展也较为迅速，已经成为人们日常生活中必不可少的一部分。
形、声、色、味、触，在当代社会声音的影响力也是越来越大，而多媒体音箱作为网络时代唯一一个外界与电脑的声音传播媒介，它可以说有着举足轻重的地位。
1.1选题的背景与意义多媒体音箱，也就是通常所称的“电脑音箱”。
较传统音箱相比拥有小体积，易操作的特点。
能够满足普通消费者的多媒体应用需求。
所谓有源音箱，简单的说似乎可以理解为需要电源输入的音箱。
但实际上，有源音箱的严格定义，指的是音响系统中自身包含功放电路的音箱。
某些特殊的音箱并不具有功放电路，但仍然需要电源输入，这样的音箱就不能称之为有源音箱。
多媒体音箱由于其特殊的市场定位，外观设计应该尽量美观，成本也不能太高微型化、数字化、专业化、影视化是家庭音响必然的发展趋势。
微型化音响。
微型台式组合音响已有较长的发展史，在10多年前就已经出现高级超小型组合音响。
但由于听音喇叭、立体声电唱机、录音卡座没有很好解决，所以一直停留在较低的档次上。
为了创造小巧的音响世界，不但要从放大器、控制部件、左右音箱上下功夫，还得从调谐器、CD唱机和录音卡座方面一起考虑。
数字化音响。
数字技术是一种新技术，所以数字音响在解决模拟音响噪声的失真问题时发展而成。
音响采用了数字技术之后，记录的数字信号从取样频率到量化特性，有清晰的解像度，没有色抖动，得到是非常清晰的图像。
而且可以和上位机互换，这与模拟录放像设备无法比拟。
数字录音可以把时间、人名、地址一起录入带中，采用微型键盘来完成编目工作，更换曲目编号，再加上遥控功能，使你能够自动地搜索需要的曲目，使用方便。
智能音响设计开题报告
智能音响设计开题报告智能音响设计开题报告一、引言智能音响作为一种集音频播放、语音识别和智能控制于一体的智能设备，近年来在家庭生活中得到了广泛应用。
它的出现不仅为人们提供了便利的音频娱乐体验，还为家庭智能化提供了新的解决方案。
本文将探讨智能音响设计的相关问题，以期为未来的智能音响产品研发提供一定的参考。
二、智能音响的功能与应用智能音响的主要功能包括音频播放、语音助手、智能家居控制等。
音频播放是智能音响最基本的功能，用户可以通过智能音响播放音乐、有声读物等。
语音助手则是智能音响的核心功能，用户可以通过语音指令与音响进行交互，实现音乐播放、天气查询、闹钟设置等功能。
智能家居控制是智能音响的拓展功能，通过与智能家居设备连接，用户可以通过语音指令控制家庭灯光、温度等。
智能音响的应用场景也非常广泛。
在家庭中，智能音响可以作为音频娱乐设备，为用户提供高品质的音乐播放体验。
在办公场景中，智能音响可以作为会议音响设备，支持语音会议、语音录音等功能。
此外，智能音响还可以与智能手机等设备连接，实现跨设备的音频传输和控制。
三、智能音响设计的挑战与解决方案1. 语音识别准确性挑战智能音响的核心功能之一是语音识别，然而，语音识别的准确性一直是智能音响设计面临的挑战之一。
语音识别技术需要能够准确地识别用户的语音指令，并将其转化为相应的操作。
为了提高语音识别的准确性，设计者可以采用深度学习等人工智能技术，通过大量的语音数据进行训练，提高语音识别模型的准确率。
2. 用户隐私保护问题智能音响作为一种连接互联网的设备，用户隐私保护问题备受关注。
设计者需要确保用户的语音数据不被滥用或泄露。
为了解决这一问题，设计者可以采用端到端加密技术，将用户的语音数据进行加密处理，确保数据在传输和存储过程中的安全性。
3. 用户体验优化智能音响的用户体验对于产品的成功至关重要。
设计者需要考虑用户的使用习惯和需求，提供简洁、直观的操作界面，使用户能够轻松地使用智能音响。
毕业论文--调频无线音箱设计.
一、绪论一、选题背景音箱，在我们日常生活中随处可见，如果我们把显示器比喻成多媒体设备的眼睛，那么音箱就是多媒体设备的嘴巴。
音箱给我们带来美妙的声音，质量好的音箱不仅仅使声音播放效果良好，更重要的是，它能将电影以及音乐中所有的能量和激情全部传递给你，让你有身临其境的感觉。
随着多媒体技术的发展，音箱从最初的2．0双声道发展到现在的7．1声道。
从单一的“发声器”发展到时下的多媒体用途，从普通的立体声音效技术发展到目前的DTS、EAX4、THX等复杂的环绕音效技术，跟随这些进步而来的却是大量繁杂如蜘蛛网般的连线。
为音箱布线时候既要考虑音箱的摆位，还得考虑线路的问题，有时甚至不得不穿墙凿壁。
还有另一个不便在于，当我们要在阳台或客厅欣赏电脑中的音乐时，要怎么做呢？将电脑旁的音箱音量调大，让声音跨越房间“飘”到耳朵里?这样恐怕会严重干扰到他人。
随着人们生活水平不断提高，在选择各种家电产品的时候，己经从简单的使用需要逐渐向简洁、美观、个性化发展，显然传统音箱繁复的连线显然无法满足人们对简约、时尚的追求。
但无线传输技术出现，使得人们向无线领域迈进，逐渐摆脱连接线或是传输线缆的束缚。
二、无线音箱的运用及意义自上世纪90年代中，世界著名音响制造商美国雷克顿公司成功地推出了无线音响系统以来，无线音箱又有了许多进步，现在市面上已经出现了许多无线音箱，它们使用的技术几乎都是基于2．4GHz ISM(Industry ScienceMedicine，工业／科学／医疗)这一全世界公开通用的无线频段。
从设计上来看主要分为两种，一种是使用特定发送装置，并在音箱上装配相应接受装置的产品。
另一种则是以蓝牙A2DP(Advance Audio Distribution Profile)协议为基础的产品。
前一类产品支持点对点或点对多点的传输模式，并具有多个可选的频点。
为避免在2．4GHz公共频段上容易出现的干扰对音质的影响，这类产品通常具有频点选择功能(俗称“跳频”功能)，如果在工作过程中出现较大噪音，即在当前频点存在干扰影响输出音质时，可选择新的工作频点，以保持产品良好的使用效果。
有源小音箱设计报告
有源小音箱设计报告一、引言随着科技的不断发展，人们对音乐的需求越来越高。
有源小音箱作为一种便携式音频设备，受到越来越多消费者的喜爱。
本设计报告将介绍一款新型有源小音箱的设计，旨在提供高音质、便携性和易用性。
二、设计目标本次设计的有源小音箱需要满足以下几个设计目标：1. 高音质：具备高保真音响效果，能够呈现出真实的音乐细节。
2. 便携性：体积小巧、重量轻，方便携带和使用。
3. 设计美观：外形简约、线条流畅，符合现代审美观念。
4. 易用性：操作简单，具备多种连接方式，方便与各种音频源设备连接。
三、设计方案1. 外观设计为了满足设计目标中的美观性要求，本次设计选用了圆柱体的外形，不仅给人以简洁、大方的视觉感受，同时也符合声学设计原理。
外壳材料采用高品质的铝合金材料，经过精湛的表面处理工艺，既提供了优雅的质感，又具备良好的散热性能。
2. 音质设计本次设计采用双音腔设计，以提供更加丰富的音质表现力。
主音腔中选用了一对高保真音箱单元，由专业音质调试师调整高音和中低音的平衡，以展现出最真实自然的音效。
辅助音腔的加入则增强了低频的冲击感，为音乐带来更加震撼的效果。
3. 功能设计为了提升用户体验，本次设计还加入了一些实用的功能。
- 蓝牙连接：支持蓝牙5.0技术，用户可以通过蓝牙连接手机、平板等设备，无需使用额外的线缆连接。
- 有线连接：除了蓝牙连接，本音箱还配备了多种有线连接接口，如AUX接口、USB接口等，以满足不同音频源设备的连接需求。
- 充电和续航：内置高容量锂电池，支持充电功能，充满电后可以连续播放多小时音乐。
四、性能测试设计完成后，我们对音箱的性能进行了多项测试。
1. 音频参数测试通过专业设备对音箱的声音频率响应、失真率等参数进行了精确测量，结果表明音箱在20Hz - 20kHz频率范围内存在于人耳可接受的失真率范围内，音乐细节表现力出色。
2. 音质测试我们邀请了音乐爱好者进行了音质评测，结果显示音箱的音质表现非常出色，高音还原度高，低音冲击力强，整体音质清晰、平衡。
高保真音响设计制作论文资料-翻译原文
Standalone Phono Pre-ampA HIGH-PRECISION PHONO PREAMPLIFIERby Fred Nachbaur, Dogstar 1997,1: INTRODUCTIONThere has been much press lately about the merits (and drawbacks) of the venerable vacuum tube. How much of this retro movement is based in demonstrable principles, and how much is rooted in nostalgia or subjectivity is a debate that could fill volumes.What is clear is that there is considerable renewed interest in vacuum tubes, a technology that even two decades ago was considered as obsolete as spats and top hats. Now the trend is reversing, and a number of manufacturers are again supplying tube gear for audiophiles, musicians and hobbyists. In many cases, these are simply vintage circuits in new packaging. Other products offer new approaches to vacuum tube technology, adding what we've learned in the meantime to come up with some truly noteworthy designs. The project described here fits into the latter category.Why use tubes anyway?The central argument for the pro-tube movement is that specs can be almost meaningless, and that what counts is how it sounds to the individual listener. Highly subjective descriptions are therefore used, instead of the techno-babble we've more-or-less gotten used to in recent times. The opposite camp claims that numbers don't lie, and that you can't improve something by adding distortion of any kind.Both camps have valid points. Most of us have heard expensive gear with spectacular specifications, but were left cold by the "too good to be true," almost clinical sound of such equipment. Similarly, most people will agree that just because something has tubes in it doesn't make it worth listening to. Turn on one of those old "All-American Five" table-top AM radios if you want a striking demonstration of just how bad vacuum tube equipment can sound.Perhaps a way of reconciling the two viewpoints is to consider the distinction between musical equipment, and reproduction equipment. For musical gear, the individual frequency, waveform and phase distortions are part of what defines the sound of, say, a Fender tube amp. Just as no- one would try to define a fine Stradivarius violin with specs and distortion figures, so also it would be specious to argue that a certain tube guitar amp has over 12% THD (total harmonic distortion)at 35 watts.Reproduction equipment, on the other hand, has always been expected to give a perfect rendition of the signal applied to it. Sounds good in principle; if such a thing existed, we should be able to exactly and perfectly reproduce everything from a grundge band to the New York Philharmonic, making the reproductions indistinguishable from the original performances.But therein lies the rub. The overall sound of a stereo system depends so heavily on the room it's in, the speakers, volume level, personal preference, and a host of other fuzzy variables that a perfect reproduction system cannot be said to exist even in this day and age, and probably never will. Add the fact that most if not all recordings are electronically sweetened to some degree to make them "sound good" (as opposed to being an exact copy of the performance), and arguments for the clinical reproduction approach lose credibility.Carried to extremes, an "ideal" reproduction system wouldn't even have any controls, except perhaps for selecting inputs. If you think about it, personal preference is the only reason why stereos have volume controls, equalizers, and other adjustments to let us customize the sound to suit our very individual ears and brains.It might be best to view the reproduction gear as a continuation of the same process that started with the construction of the instruments used in the performance. What we ultimately hear is the sum total effect of everything from that original instrument design, to the way it is played by the artist, through the entire recording, mixing and distribution process, to the gear we use to play it, and how we've set its controls.There is, therefore, a considerable difference in design approach between the "instrument" and "reproduction" categories. An earlier design ("The Real McTube") documented a vacuum tube pre-amplifier for use as an adjunct to electric instruments. The design approach was largely empirical, and the emphasis was on highlighting the unique distortion characteristics of the vacuum tube. This article explores the reproduction aspect; the design approach was quite mathematical and precise, and the emphasis is on controlling the characteristics of the vacuum tube.Vinyl vs. CDSimilar arguments are ongoing regarding vinyl records vs. compact discs. The CD camp points at the CD's accuracy, definition, and clarity, while vinyl loversbemoan the CD's lack of warmth and claim that conventional records sound more "natural."This project gives you the opportunity to explore these subjective and controversial debates, letting your own ears be the judge. You may find that there are some recordings that sounds better through the tube pre-amp, and others that benefit from the improved definition (whatever that is, technically speaking) that good solid-state gear can offer.2: DESIGN PHILOSOPHYThe design philosophy was to improve on "vintage" tube designs by incorporating refinements normally only associated with solid-state gear. Prime among these is the use of differential input stages, in which the inverting input is used strictly for feedback. Another is the use of direct coupling between stages, a technique once **mon in oscilloscopes, but rare in audio gear. The resulting circuits are thus closely related to the operational amplifier, and used in a similar fashion.In addition to the quasi-opamp idea, some other design concepts used in theproject are:Use of readily available parts wherever possible. For this reason, tube types 12AX7A and 12AT7A were employed.Direct coupling was used in crucial parts of the circuitry. More about this later.Flexibility in use was a prime consideration. While this articles details the use of this circuit design as a magnetic (RIAA) and ceramic phono pre-amplifier, there is virtually no limit to the number of possible applications with suitable modification of the feedback networks.A Word About Negative FeedbackIt is perhaps an unfortunate accident of history that the term "negative feedback" was used to describe the linearization technique of applying a portion of the output signal back to the input, in opposite phase to the applied signal. It gives the impression to audiophiles with enough knowledge to be dangerous that "negative" feedback must somehow be a "bad" thing. I've seen diatribes against the evils of negative feedback, yet in the same breath such critics extol the virtues of "ultra-linear output transformers." The joke is that such transformers achieve this linearization by applying local negative feedback to the screen grids!Perhaps a better moniker for "negative feedback" would be "**pensation" orsomething on that order. Consider the following characteristics ofwell-designed negative feedback systems:A: Precise control over closed-loop gain and minimization of gain drift with component aging.B: Considerable reduction in distortion and noise introduced within a given gain block.C: Reduction of effective series output resistance.D: Precise control and stabilization of frequency characteristics. Extensionof high-frequency response where needed.E: Reduces or eliminates the need for **ponent matching3: HOW IT WORKSThe sections that follow step through the principles of operation of this design. Since it is quite different from traditional designs, I suggest that you follow through this at least once. If the "fine points" are over your head, don't worry about it; hopefully enough of the information will stick to give you at least a working understanding of the circuit.There are in-line illustrations of the schematic, repeated as necessary. (If you have caching turned on in your browser, you'll only have to actually download the images once.) These "Figures" (schematics) are shown here in reduced size. Click on the image to enlarge it, preferably by right-clicking and opening the image in a new window. Full-size, printable versions are also available in the Resources section. It is highly recommended that you print out these files and have the diagrams at hand as you study this document, especially if you plan on actually building yourself one of these units.Note that in the schematic diagrams, only one channel is shown; the other channel is of course identical. Please note that part numbers refer to the various sections as follows: (We'll be assuming the left channel in this discussion.) 1-99Common parts (power supply, etc.) Also tube designations.100-199Left phono preamp200-299Right phono preamp3-A) HIGH-PRECISION PHONO PREAMPLIFIER: OVERVIEWConsiderable effort was taken to design a preamp that is as clean as possible to satisfy discerning audiophiles, while maintaining a relatively low parts count tosatisfy limited budgets. It should be noted at this point that, while the discussion is in the specific context of an RIAA phono pre-amplifier, this design lends itself well to a wide range of other uses.This "universal preamp module" sports a high gain (about 60 dB) and differentialinput stages that allow for differential input (as for balanced mic preamps) as well as either inverting or non-inverting single-ended applications. Frequency response shaping and gain setting are accomplished using the appropriate feedback networks.The schematic diagram of the phono/mic preamp is shown in Figure 2. If built on a PCB, the phono preamp equalisation is accomplished using a small "daughter" card directly on the main board; if you use the point-to-point wiring approach,these networks can be wired on separate terminal strips for easy modification if necessary.Figure 2 Phono (Magnetic and Ceramic) Preamplifie The main circuit board was designed to be virtually universal in applicability. Small outrigger "feedback cards" are used to customize the response to almost anything you might need. Figure 6 plots gain vs. feedback ratio for the non-inverting configuration as used in the phono/mic preamp. There is an obvious linear relationship, except at high gain. (The "porch" at the low end is due to the "+1" whenusing the non-inverting mode; see below for further details. In the inverting mode, as used in the tone preamp section, the relationship remains linear at low gain settings.)Figure 6 Preamplifier Gain vs. Feedback RatioAs detailed here, the phono preamp is selectable (using a switch) between magnetic (RIAA equalization, high gain), and ceramic (flat response, low gain).See Figure 7, which graphs open-loop response and the two closed-loop phono curves. If you only need one or the other mode options, the switch and the appropriate **ponents can be omitted.Figure 7 Open-loop, Magnetic Phono and Ceramic Phono Response Curves There is no reason why you couldn't adapt this universal preamplifier module for any other gain/**binations, simply by modifying the feedbacknetworks. (Figure 8 gives a few ideas, covered in more detail in Other Preamp Applications.)Other Possible Preamplifier ApplicationsPhono equalisationIn magnetic phono mode, the RIAA curve is achieved by using negative feedback to decrease the gain at higher frequencies, according to the RIAA specification.The result is that the amplifier runs almost open-loop (about 60 dB gain) at 40Hz, and rolls off smoothly to a gain of less than 20 dB at 20 kHz. This means that the "tube sound" caused by even-order distortion will be most pronounced in the bass region, giving it that warmth that is so highly prized by vacuum tube aficionados. At higher frequencies, this distortion is increasingly cancelled out by the negative feedback that sets the gain, keeping the mids from sounding "brassy," and the highs from sounding "splashy" (****plaints about open-loop tube amplifiers).In CD (or ceramic cartridge) mode, response is flat within 0.5 dB over the audio range, and voltage gain is set at 5 (about 14 dB). At this relatively low gain, the circuit is very clean and distortion-free. However, discerning ears will hear a subtle quality of warmth not present insolid-state gear.A 3:1 voltage divider at the input results in an overall system gain of 5 dB. The output level of CD players varies widely among various models, so you can trim this input gain to suit your machine by changing a single input resistor per channel. Similarly, total circuit gain can be changed with a single resistor on the feedback cards.The tube types and their operating points were carefully chosen to minimize power supply requirements, and to maximize tube life. Both channels together draw only about 7 mA from a 400 volt supply. This voltage can be derived from a stand-alone unit as documented in this article, or from a larger supply used to drive a vacuum tube power amp.3-B) PRE-AMP DIFFERENTIAL INPUT STAGESThe preamplifier features a differential input stage, giving us both aninverting and a non-inverting input and affording additional useful andbeneficial features. The following discussion relates directly to thePhono preamps (refer to Figure 2), but applies by extension to otherapplications also.Phono PreamplifierThe appropriate input signal is coupled from the magnetic or ceramicphono input jacks, through switch SW2, to the grid of the first section of V1 (a 12AX7A vacuum tube) via coupling capacitor C101. Since this grid is at a substantial DC voltage above ground, resistor R101 is used to insure that the input is always at DC ground potential. Note that, as far as the input AC signal is concerned, this 100K resistor is effectively in parallel with R102 (also 100K), giving us the 50K input impedance required for most magnetic phono cartridges. The two triode sections of V1 are used as a differential amplifier.Note that the cathodes are tied together, and go to ground via a relatively large shared cathode resistance consisting of R104 and R105. This acts as a rudimentary constant-current source. If the current in either triode increases, a comparable amount of current will be robbed from the other triode. Therefore, if the voltage on the signal input increases (goes more positive), plate current increases and the plate voltage of that triode will drop, while the plate voltage of the other triode increases by about the same amount. However, if the voltage on the feedback input increases, causing an increase in current in that triode, the voltage on the plate of the first triode section willincrease and that of the other triode will decrease.A portion of the cathode resistor voltage drop is sampled by R104, low-pass filtered by R103 and C102, and provides the grid bias for the first section of V1 via R102. An interesting feature of this circuit is that this also sets the bias and operating points for the entire amplifier, as we'll see as we progress through the analysis.Experienced electronicists will be quick to point out that a simple cathode resistor is not an ideal current source. As a result, the "common-mode rejection ratio" (that is, the gain matching of the two inputs) of this circuit is quite low. (A great improvement results by using a pentode as a current source in the differential amplifier cathode circuit, a trick that's used in the driver stage **mon-mode reduction is more critical because we also require balanced outputs.)What we do instead, in the preamp modules, is "cheat the system" and carefully choose the operating points of the two triodes to be different, to help offset the error. Note that, even though there is approximately the same current flowing in the plate circuit of each triode section (about 500 microamperes), the plate voltage on the second section is considerably higher (by about 90 volts) than the plate voltage of the first section. This is because of the lower value of plate resistor R107, as compared to R106. This "trick" assumes that the two sections of the tube are reasonably well-matched, and will furthermore track as the tube ages. Tests with different tubes of varying manufacture and condition have verified that this assumption is indeed valid.3A-2: PREAMPLIFIER OUTPUT STAGEFigure 2 is a schematic diagram of the Hi-Fi Tube Stereo Preamp. Since both channels are identical, only one is shown. Please note that part numbers 100-199 refer to the left channel, and 200-299 refer to the right channel. We'll be assuming the left channel in this discussion.Both channels share a single power supply, shown at the bottom of Figure 2. Transformer T1 steps the 120 volts AC from the power line down to 12.6 volts, to supply the heaters of the three tubes. The center-tapped configuration is used to help reduce hum induced by the heater circuits.Transformer T2 steps the 12.6 volts AC back up to about 110 volts AC for our high-voltage plate supply. Diodes D1-D3 and capacitors C4-C6 are a voltage tripler circuit, providing about 450 volts DC open circuit, or around 380 volts under load. Note that D1, D2, C4 and C5 form the classic positive voltage doubler circuit. On negative half-cycles, C4 is charged through D1.On positive half-cycles, C4 is effectively placed in series with the transformer, and diode D2 transfers this doubled voltage to C5. D3 and C6 are a negative half-wave rectifier/ filter, so the total voltage across C5 and C6 is about three timeswhat would be obtained from a half-wave rectifier. This configuration is used instead of the **mon "cascade" tripler circuit because of its slightly better regulation.The tripled voltage is filtered by the low-pass network formed by R1 and C7. It is further filtered and decoupled by R2/C9 and R3/C8 to form the main supply for each channel. This eliminates any cross-talk between channels due to power supply coupling.Additional decoupling is provided for the critical first stage of each amplifier by onboard filters R117/C103 (left channel) and R217/C203 (right channel), reducing power supply hum injected into these high gain circuits.The output of our differential amplifier is direct-coupled to the grid of the second stage, V2, a 12AT7 dual triode. This tube was chosen over the **mon (and cheaper) 12AU7 because it sports about three times the gain (transconductance), yet is capable of almost the same output drive.The difficulty with direct-coupled vacuum tubes is that the grid of the second stage sits at a substantial voltage above ground (about 200 volts in our circuit). This is why we need a relatively high B+ voltage, since we have to insure that the plate circuit of the second stage has enough headroom. So why bother at all? After all, tube amps have been made for over half a century with good old RC interstage coupling. The answer has to do with dynamic stability as the tubes age. Unlike conventional multi-stage tube amplifiers, our circuit is self-levelling because its DC biasing is in a closed feedback loop.R115 in series with the grid of V2 introduces a high-frequency pole with V2's grid-to-plate capacitance, effectively limiting high-frequency response. This allows us to run the preamp with relatively eavy negative feedback (low gain) without worrying about oscillations caused by phase shifts. You can think of it in op-amp terms as "**pensation".Another reason for using direct coupling is because of the relatively large voltage swings at this point in the circuit. Capacitors (even good ones) can exhibit some non-linearity in capacitance vs. voltage -- a fact that is often overlooked in amplifier design. Direct coupling eliminates this capacitor, and as a bonus gets rid of one more pole in our transfer function that **plicate ourapplication of negative feedback for gain and frequency response control.In order to bias V2's grid at the proper voltage (about -1 volts with respect to cathode), we need a humungous cathode resistor R108. To avoid losing all our AC gain, this resistor is bypassed for AC by capacitor C106.3A-3: PREAMPLIFIER DC FEEDBACKThe rest of our **pletes the DC feedback loop. In case you're wondering about the presence of the three NE-2 neon bulbs in series, let's analyze the circuit without them. The plate of V2 will be sitting at about 315 volts, whereas the grids of V1 are at about 27 volts, or a factor of about 12:1. We could use a 12-to-1 voltage divider,which would give us a DC closed-loop gain of about 13. That is, it would require a 13 volt change at the output to compensate for a 1 volt change at the input.We can easily improve on this considerably. The lowly neon bulb can be viewed as the tube- technology equivalent of the zener diode. That is, the voltage drop across the bulb (typically about 65 volts) is reasonably independent of the current passing through it. The three NE -2's can therefore be viewed as a 200 volt "level shifter," allowing us to use a much lower voltage division ratio (about 4:1) in our DC feedback loop. The result is an almost 3 times improvement in DC operating point stability.The level-shifted and divided output voltage goes through a two-stage low-pass filter consisting of R111, C105, R112 and C104. This strips AC signals from our DC feedback loop, to insure that the amplifier will still have full open-loop AC gain. The resulting DC feedback voltage is applied to the inverting input of our differential amplifier via R113.The junction of R113 and C104 also forms a convenient "AC Ground" point for our signal feedback networks. Let's step through what happens if some change occurs in DC operating point. This change could be caused by tubes and **ponents aging, power supply voltage fluctuations, or input overdrive conditions. Let's assume that the change causes the output voltage to rise, as would be the case as V2's emission decreases. This would cause an increase of bias voltage (more positive) on the grid of V1B (the feedback input), causing that stage to draw more current and increase the voltage on **mon cathode. V1A (our input stage) would therefore draw less current, causing the voltage on its plate (and therefore the grid of V2) to increase. This would cause an increased V2 plate current, resulting in a decrease in plate voltage, tending to buck the original change. See how the overall circuit is self-regulating?Resistor R114 forms the plate load for V2, and C107 couples the output to the tone/line preamp module via the input and tape monitor switches.Capacitor C108 provides another pole of high- frequency attenuation (compensation) to prevent oscillation at low gain. (Before I added this **pensation, the first prototype became a dandy 11 megahertz transmitter at gains lower than about 3!) The original value for this capacitor was 1000 pF, but I've found since then that this can be considerably lower, depending on layout. In the schematic it's shown as 100 pF, if you get oscillation or other instability increase this as necessary.3A-4: PREAMPLIFIER AC FEEDBACKSo far we have a pre-amplifier with an open-loop passband gain of about 60 dB, with 3-dB corners at about 40 Hz and 2 kHz. (See Fig. 7.) While the low-frequency end isn't bad, the high-frequency end is pretty awful. This is partly because of **pensationintentionally introduced by R115 and C108 and partly because of tube electrode and circuit wiring capacitances. Not to worry, our bandwidth automatically increases again when we apply negative feedback, just as it does with solid-**pensated op-amps.Fig. 7: Preamplifier Open-Loop and Phono Gain CurvesAs hinted already, this circuit behaves very much like an operational amplifier (op-amp). But before we get on with designing feedback networks, we'll point out the ways in which it is not like an op-amp:a) Open loop gain, although quite high, cannot be considered infinite as in many solid state op- amp devices.b) The circuit exhibits a large output-to-input voltage offset (on the order of 290 volts). Any AC feedback elements between output and input therefore have to include DC blocking capacitors. The alternative would be level-shifters, which would in my opinion be an **plication (and expense) **mensurate rewards in terms of performance.c) The DC voltage at the feedback input is non-zero (about 27 volts in practise), so again there is a need for DC blocking. The point marked "ACG" (AC Ground) is provided for convenience, acting as a virtual ground for AC, at the same DC voltage as the inverting input.The not-quite-ideal Tube OpampKeeping these restrictions in mind, we can use the formula for the classic non-inverting op-amp to approximate our gain with feedback. Note that the inverting input (-IN) has a 47K resistor (R113) to "AC Ground". This is our "default" value for input resistance to the feedback input. Let's call that resistance Ri, though it can be considerably higher, as needed. The bare-minimum feedback network would consist of just a single resistance (we'll call it Rf ) in series with a DC blocking capacitor between output and -IN. The theoretical gain with feedback would then be:Av = ( Rf / Ri ) + 1For instance, let's compute our gain if we connect a "bare bones"feedback network consisting of a 430K resistor in series with a DC blocking capacitor between "OUT" and "-IN". That is, Rf / Ri = 9.15, so our gain would be 10.15, or about 20 dB.The feedback elements do not have to be pure resistances; the above formula could be generalized to **plex impedances.Av = ( Zf / Zi ) + 1The circuit's actual performance follows this predicted formula very closely, verifying that our gain-matching shortcut described earlier works just fine. See Figure 6 for an actual plot of the prototype. The slight curve at the low end is caused by that "+1" factor in the equation; as Rf / Ri increases, that factor becomes less significant, and the graph approaches a straight-line relationship. However, at gain settings above about 200 (46 dB), the relationship begins to fall apart as we approach the amplifier's open-loop gain. Incidentally, this gain setting is also the practical maximum as regards frequency response; the 3 dB corner at this gain will be on the order of 16 kHz.Figure 6 Preamplifier Gain Vs Feedback Ratio3A-5: PREAMPLIFIER PHONO FEEDBACK NETWORKSCeramic phonoThe feedback network for the Ceramic phono input is little more than our "bare bones" network described above. R118 in series with C109 forms our Zf . R119 is added as a refinement to insure that the negative end of C109 is always held at the DC potential of our feedback input, eliminating the massive pop that would otherwise result when switching modes. Note, however, that it is effectively in parallel with R113, lowering our Ri value to 38.7K. You can verify that our closed-loop gain would therefore be (150/38.7)+1, or about 5 (14 dB).Input resistor R123 attenuates our input signal by a factor of about 3:1, so the overall system gain is a little less than 2 (5 dB).The final element is C110, which introduces a 3 dB corner at about 20 kHz, rolling off ultrasonics that we aren't interested in. (Without this capacitor, the gain is actually flat to well beyond 100 kilohertz! See how feedback got rid of that open-loop corner at 2 kHz?)The magnetic phono feedback is only a little more involved. The straight thin lines in Figure 7 show the theoretical RIAA specification (asymptotes), and the curve。
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四、阐述拟选题的目的、意义、要完成的工作和预期结果
1．选题目的：为了能将自己学习的模电知识结合自己平时对音响的兴趣结合在一起，所以我决定结合工科基础和自己的兴趣来做出一个HI-FI高保真功率放大器。来实现理论与实践的结合。
至于我在设计中将用到的集成功放就是NE5532(前置功放)，后级为LM1875。
其中NE5532被认为是“运放之皇”，它的内部为JFET（结型场效应管结构）,声音特点总体来说属于温暖细腻型，驱动力强，但高音略显毛糙，低音偏肥。
NE5532虽然是一个比较旧的运放型号，但现在仍被认为是性价比最高的音响用运放芯片，是属于平民化的一种产品，被用于许多中底档的功放中。该功放技术已经相当成熟。
3．预期结果：做出的电路基本上满足上面我提及的参数，并且接上音源以及扬声器能发出优美的声音。
五、毕业设计所必需的实验、计算、加工等初步计划
本实验所需设备：
1.微机一台以及Protel 99se的软件；
2.低频信号源；
3.示波器；
4.万用表；
2．选题意义：可以让我感觉到我们学习理论知识对我们将来从事的工作起到的重要作用，同时也初步体验到了作为一个技术人员，需要很强的耐心，坚持的性格，才能做出一个令他人，令自己满意的硬件和配套的软件出来。同时，我觉得自己查找资料的过程便是对我本身，作为一个在信息海洋的现代社会生存的人的甄选知识能力的锻炼。同时，我也懂得了许多有关技术制作时涉及到的成本问题，也就是性价比的问题，这点很重要。
我想在我完成了这次毕业设计后，一定会学到很多技术的知识，不过我想不仅仅是技术的知识，应该还会学到一种韧劲，一种精神。
要完成的工作：做出一个具备额定功率大于双30w，总谐波失真小于0.5％，频率响应为40HZ到20KHZ，噪声电压小于5mv，整机效率大于60％的家用高保真音响电路，它包括了前级、均衡、功放、电源等。
[10]朱耀国.模拟电子线路实验[M].北京：高等教育出版社，1996
[11]王远.模拟电子技术[M].机械工业出版社,1991
[12]GB6800-86 0001—1986，中华人民共和国国家标准[S].
[13] M.Herpy.Analog Integrated Circuits[M].New York：Publishing House of Electronics Industry，1980：201～214
而LM1875是一个相当成熟的功率集成放大器，是美国国家半导体公司九十年代初推出的一款音频功放电集成电路，采用TO-220封装，外围元件少，但是性能优异，具有频率响应宽和速度快等特点,从九十年代初一直到现在还被广大音响爱好者推荐。最可贵的是其价格已从当初的十几元降至现在的八九元，最适合于不想花太多的钱又想过过发烧隐的爱好者业余制作。该IC最的优点是在小功率输出时的音质能直逼中高档音响的听音效果。
最近欧洲著名SGS-THOMSON意法微电子公司向中国大陆推出一款音色颇有新意的DMOS大功率集成功放TDA7294,一扫以往线性集成功放和厚膜集成功放生、冷、硬的音色,广泛用于Hi-Fi领域,如家庭影院、有源音箱。该器件为15脚封装。TDA7294内部线路设计以音色为重点，兼有双极信号处理电路和功率MOS的特点，具有耐压高、低噪音、低失真度、重放音色极具亲和力等特色；短路电流及过热保护功能使其性能更加完善。
[2]李东生.Protel 99SE电路设计技术入门与应用[M].北京：电ห้องสมุดไป่ตู้工业出版社，2002
[3]张义方.HI-FI音响放大器制作大观[M].武汉：湖北科学技术出版社，2001
[4]吴文波.高保真音响设计制作[M].北京：电子工业出版社，2000
[5]陈维伦.HI-FI音响技术手册[M].香港：万里书店出版，1981
[6]彭妙颜.杨志勇.周锡韬.高保真音响与家庭影院实用技术[M].北京：电子工业出版社，2000
[7]杨士毅.高保真使用全书[M].北京：电子工业出版社，2001
[8]张肃文.低频电子线路[M].北京：高等教育出版社，2003
[9]谢自美.电子线路设计试验测试[M].武昌：华中科技大学出版社，1992
二：调研及准备工作：
经过几周的网络和图书馆资料查找。基本上了解了高保真音响的原理以及其发展的状况，以及自己认真的去研究如何布线使信噪比提高等技术细节。以便自己做硬件设计中拿来参考，为今后的调试做下铺垫。
三、所选课题目前国内外科技发展动态如何？
人们对生活的质量要求随着经济水平的上升而愈加苛刻，尤其是对电子消费性娱乐的要求也越来越高。HI-FI音响便是其中的一例。
从我们儿时的收音机，三用机，到现在的HI-END的高级发烧音响组合，到结合HI-FI的家庭影院。我们都看到了HI-FI不仅在技术上愈加成熟，其应用层面也不断地扩展。随着电子科学技术的发展，用于音响系统的器材和材料都有长足的进步和发展。
现在HI-FI音响基本上还是有这两种阵营：真空电子管做前置的音响和用晶体管集成电路组成的音响，当然不乏综合两者优点的复合式的HI-FI音响。不过，我们都知道晶体管集成放大电路做出的很大情况下有所谓的“数码声”，高音的时候音量一大就容易干涩，有尖刺的带金属的声音；而电子管的由于其物理构造的原因造成的失真比晶体管迥然不同。电子管一般只产生低次谐波的失真，而晶体管却产生许多高次的谐波失真，如此造成晶体管产生的音乐的失真度远比电子管的大。所以电子管的声音更加恬美和温暖，高音也自然些。
计算机系毕业设计
开题报告
报告日期：2005年3月28日
姓名：刘鹏
学科专业自动化
论文题目：高保真音响设计制作
题目类型：工程设计
题目来源：导师提供
二、在选题过程中已查阅的文献资料（列出文献资料），还做了哪些调研、准备工作？
一：已查阅的文献资料：
[1]张维园.高保真放大器与音箱制作精选[M].北京：人民邮电出版社，2001