DIY PCM1738 DAC （参赛）

田雨

早就想搞台DAC玩玩了，直到前段时间，朋友送了两颗PCM1738芯片给我，于是就搞了这台DAC，没想到，一下子就被朋友们要求复制了几台，先让大家意淫一下
<img src="attachments/dvbbs/2005-11/20051126231626375.jpg" border="0" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onmouseover="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor=\'hand\'; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onclick="if(!this.resized) {return true;} else {window.open(\'attachments/dvbbs/2005-11/20051126231626375.jpg\');}" onmousewheel="return imgzoom(this);" alt="" />
设计：
    先看看PCM1738，这可是HI-END级的东东，性能不俗，117db的讯噪比和动态范围，已经赶超PCM1704了，但它也有个缺点，就是要通过软件来设定其内部的各种工作状态，默认状态下并不能发挥其最好的性能，为了榨干PCM1738的每一滴油水，决定加入单片机来对其进行设定。
完成设计的电路图：
<img src="attachments/dvbbs/2005-11/20051126233252556.jpg" border="0" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onmouseover="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor=\'hand\'; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onclick="if(!this.resized) {return true;} else {window.open(\'attachments/dvbbs/2005-11/20051126233252556.jpg\');}" onmousewheel="return imgzoom(this);" alt="" />
    数字接收解调使用的是CS8414，带同轴及光纤输入，解码芯片PCM1738外挂一片单片机，使用的是AT89C2051，配合8位编码开关，可设定PCM1738的各种模式，包括数据格式，数字滤波特性，输出反相，数字去加重，系统时钟输出控制等，并且在开机时由单片机输出一复位信号给PCM1738。为了防止开关机时对功放造成冲击，加入了继电器开关机静噪电路。
     在画PCB时，原本是打算做一台自己玩的，所以开始是布单面板的，准备用感光板做的，但一帮哥们听说我在搞DAC时，都表示有兴趣，于是干脆布双面，交给印板厂做，反正成本摊分，比自己做的好的多。一个星期，板子做好，一共10块，双面镀金的，花了几百大元。
<img src="attachments/dvbbs/2005-11/2005112623561256.jpg" border="0" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onmouseover="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor=\'hand\'; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onclick="if(!this.resized) {return true;} else {window.open(\'attachments/dvbbs/2005-11/2005112623561256.jpg\');}" onmousewheel="return imgzoom(this);" alt="" />
<img src="attachments/dvbbs/2005-11/20051126235628431.jpg" border="0" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onmouseover="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor=\'hand\'; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onclick="if(!this.resized) {return true;} else {window.open(\'attachments/dvbbs/2005-11/20051126235628431.jpg\');}" onmousewheel="return imgzoom(this);" alt="" />
装机:
    焊零件时，才发现有几个滤波电容的孔钻得小了点，电容的腿穿不过板，于是就用锉子整理一下几个电容的腿才行，无伤大雅。
<img src="attachments/dvbbs/2005-11/200511270193918.jpg" border="0" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onmouseover="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor=\'hand\'; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onclick="if(!this.resized) {return true;} else {window.open(\'attachments/dvbbs/2005-11/200511270193918.jpg\');}" onmousewheel="return imgzoom(this);" alt="" />

小钳子

<img src="attachments/dvbbs/2005-11/200511270431155.jpg" border="0" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onmouseover="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor=\'hand\'; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onclick="if(!this.resized) {return true;} else {window.open(\'attachments/dvbbs/2005-11/200511270431155.jpg\');}" onmousewheel="return imgzoom(this);" alt="" />
用了两个R牛，模拟及数字各一个，共六路电源，分别是+ - 16V，供运放用，PCM1738模拟+5V，数字+3.3V，CS8414 +5V，供单片机的+5V，
<img src="attachments/dvbbs/2005-11/200511270482536.jpg" border="0" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onmouseover="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor=\'hand\'; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onclick="if(!this.resized) {return true;} else {window.open(\'attachments/dvbbs/2005-11/200511270482536.jpg\');}" onmousewheel="return imgzoom(this);" alt="" />
电源部分
<img src="attachments/dvbbs/2005-11/2005112704936542.jpg" border="0" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onmouseover="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor=\'hand\'; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onclick="if(!this.resized) {return true;} else {window.open(\'attachments/dvbbs/2005-11/2005112704936542.jpg\');}" onmousewheel="return imgzoom(this);" alt="" />
DAC部分
<img src="attachments/dvbbs/2005-11/200511270562539.jpg" border="0" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onmouseover="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor=\'hand\'; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onclick="if(!this.resized) {return true;} else {window.open(\'attachments/dvbbs/2005-11/200511270562539.jpg\');}" onmousewheel="return imgzoom(this);" alt="" />
I/V变换及LPF部分
<img src="attachments/dvbbs/2005-11/20051127131525861.jpg" border="0" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onmouseover="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor=\'hand\'; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onclick="if(!this.resized) {return true;} else {window.open(\'attachments/dvbbs/2005-11/20051127131525861.jpg\');}" onmousewheel="return imgzoom(this);" alt="" />
滤波电容用了美国军用AeroM，输出耦合电容用了一对金宝，喜欢其中频甜润，堂音丰富
<img src="attachments/dvbbs/2005-11/20051127132223783.jpg" border="0" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onmouseover="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor=\'hand\'; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onclick="if(!this.resized) {return true;} else {window.open(\'attachments/dvbbs/2005-11/20051127132223783.jpg\');}" onmousewheel="return imgzoom(this);" alt="" />
<img src="attachments/dvbbs/2005-11/20051127132318559.jpg" border="0" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onmouseover="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor=\'hand\'; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onclick="if(!this.resized) {return true;} else {window.open(\'attachments/dvbbs/2005-11/20051127132318559.jpg\');}" onmousewheel="return imgzoom(this);" alt="" />
屁股
<img src="attachments/dvbbs/2005-11/20051127132949782.jpg" border="0" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onmouseover="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor=\'hand\'; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onclick="if(!this.resized) {return true;} else {window.open(\'attachments/dvbbs/2005-11/20051127132949782.jpg\');}" onmousewheel="return imgzoom(this);" alt="" />
单片机部分

试音：
   板子焊好，接着写mcu的控制软件，简单的程序，很快就写好了，将已编程的单片机插上，通电调试，无惊无险无烽烟，一切顺利。接着安装，只需转几个孔，也是很快完成。
   机子装好，先设定好PCM1738的各种工作状态，因为外挂了MCU，只需拨动编码开关，非常方便，然后通电试机，OK，声音出来了，也没仔细听，感觉有点木，不管它，先煲它几天再说，连续煲了六天，机子开始稳定，正式试听，先试了几种运放，最后决定I/V用OPA627,LPF用AD797。
   首先放入杨蔓莉的《亲密爱人》，第九曲“草原情歌”开始的清唱，那种人声的穿透力即时为之眼前一亮，声音甜甜的，很有质感，齿音很自然。接着是蔡琴的“月光小夜曲”，2:26秒时从右边声道发出的那微弱的蛙鸣声清晰可闻，定位准确，分析力很高。再用敲击卡门试听，动态庞大。一帮朋友听过的评价是：高频延伸很好，声音细腻，人声很甜，唯中低频稍差。
   此后的一个月，连续帮朋友们搞了几台，也不断的调整音色，也干翻了几台CD。那天，损友W君向别人借来一台解码器，音乐传真的A324，正好用的也是PCM1738 DAC，带升频，妙，正想找台有分量的来比试比试，急急呼朋唤友，到W君家中开坛。
试听器材：
<img src="attachments/dvbbs/2005-11/2005112723216111.jpg" border="0" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onmouseover="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor=\'hand\'; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onclick="if(!this.resized) {return true;} else {window.open(\'attachments/dvbbs/2005-11/2005112723216111.jpg\');}" onmousewheel="return imgzoom(this);" alt="" />

音箱：小旋风 M300，分频器已更换，两个低音单元各自独立的低通网络，将原来的18db/倍频程改为12db/倍频程，一改原来低频乱，蒙的 感觉
转盘：SONY CDP227ESD，变压器已更换，220V直入，晶振改4脚振荡器，加装BNC同轴输出座，其余未动
功放：DIY的全石合并机，带遥控，音量控制用的是CS3310，后级部分为全对称电路，带中点侍服，功率管每声道两对摩托的塑封MJL21193/21194。
<img src="attachments/dvbbs/2005-11/20051127232222911.jpg" border="0" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onmouseover="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor=\'hand\'; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onclick="if(!this.resized) {return true;} else {window.open(\'attachments/dvbbs/2005-11/20051127232222911.jpg\');}" onmousewheel="return imgzoom(this);" alt="" />
功放内部

<img src="attachments/dvbbs/2005-11/20051127232411426.jpg" border="0" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onmouseover="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor=\'hand\'; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onclick="if(!this.resized) {return true;} else {window.open(\'attachments/dvbbs/2005-11/20051127232411426.jpg\');}" onmousewheel="return imgzoom(this);" alt="" />
音乐传真A324 DAC ，带升频，I/V变换用5532，后面是晶体管输出电路

这次比试的是小弟搞的第三台的DAC，黑脸，运放也是用OPA627+AD797的组合，在金宝输出耦合电容上并联一只AUDIOCAP 0.1uf/200V 的电容，高频延伸更好

全部通电半小时，正式试听，先上音乐传真，用96KHz，听了几首，中频比较厚，但有点干，高频延伸较差，声音较粗，接着升频至192KHz，音场较宽，中低频一样的比较厚，但低频有点蒙，人声不够甜，高频延伸好了很多，但不够细腻，分析力差点，可能是用了5532的关系吧。
换上土炮，还是听那几首，感觉音场开阔，高频延伸的很好，但绝不刺耳，人声很甜很自然，聚焦、定位准确，分析力很好，中低频相比洋枪稍薄了点。
总体而言，洋枪土炮各有千秋，洋枪胜在中低频比较厚，土炮则在中高频的延伸，以及分析力、定位方面取胜，可谓半斤八两。
<img src="attachments/dvbbs/2005-11/2005112801837.jpg" border="0" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onmouseover="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor=\'hand\'; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onclick="if(!this.resized) {return true;} else {window.open(\'attachments/dvbbs/2005-11/2005112801837.jpg\');}" onmousewheel="return imgzoom(this);" alt="" />
试听软件

全部完，多谢钳版传授上传秘笈。

天涯羽飞

这个怎么没下文阿？

ronaldchiu

我知道田雨有好几款DAC作品，再罗几款DAC出来看看吧

kong2351

这是好东西，值得一玩。怎么没有下文啦？强烈关注！！！

31333

田大的东西的确不错

wttloon

精手精艺啊