出美国原装BEL CANTO DAC1 24/96K 升频解码 [复制链接]

Bel Cant DAC1 24/96K D/A 译码器 测试报告
作者 : 徐志伟

Bel Cant DAC1 24bit/96KHz 译码器(以下简称DAC1)笔者已使用了三个多月 ,  直接从美国厂方购得 , 当时该产品正找寻代理 ,笔者在完全没有试音,没有看过实物的情况 , 只从浏览网上杂志 Sound Stage时 , 发现 Bel Cant Design出了一部可将 16bit/44.1KHz CD数码输入提升至 24bit/96KHz 输出的译码器 , 实时登入 Bel Cant Design 的网站观看, 发觉价钱不贵 定价 US$2,000 特价 US$1295  及有10天试用保证 , 本来笔者正想购买 24/96K译码器Assemblage DAC-3.0 , 但当知到有DAC1后 , 笔者便改变原意 , 购卖DAC1 .

可能是世上第一部内置提升取样频率变换器的D/A译码器
       市面上装有 24bit/96KHz DAC芯片的译码器 , 一定要接上设有24bit/96KHz数码输出的DVD-Video , 回放小部份采用24bit/96kHz 两声道PCM录音DVD音乐碟时 , 才能发挥其优异特性 ,若果回放 CD , 新一代 24bit/96KHz DAC芯片的译码器便无用武之地 , 效果与旧一代译码器分别不大 .
以下是一般 24bit/96KHz译码器回放 24bit/96KHzDVD音乐碟的流程图:[ DVD音乐24bit/96KHz碟] -> [设有24bit/96KHz数码输出的DVD-Video机] -> [装有 24bit/96KHz DAC芯片的译码器] --> = 输出具 24bit/96KHz (* 频率响应 : 0 ~ 40KHz)的Analog讯号 *普通CD为 16bit/44KHzHz(频率响应 : 0 ~ 20KHz)
若果想将普通CD提升至 24bit/96KHz(频率响应 : 0 ~ 40KHz)质素 , 在DAC1出现之前 , 必需使用独立的取样频率提升变频器.
以下是使用取样频率提升变频器的流程图:[普通CD(16bit/44kHz)] --> [CD机 /转盆] --> 16bit/44KHz数码输出 --> [取样频率提升变频器] -->24bit/96KHz数码输出 --> [装有 24bit/96K DAC芯片的译码器] --> = 输出具 24bit/96KHz (频率响应 : 0 ~ 40KHz)的Analog讯号现在市面上巳有几款 , 取样频率提升变频器应市 , 例如:顶级的 dCS 972 (HK$55000元) , 中级的 Z-Systems Z-3src(约HK$1万多元) .
DAC1出现之后 , 想在普通CD回放中 , 得到 24bit/96KHz( 频率响应 : 0 ~ 40KHz)质素 , 将变得简单 , 及成本大大降低.
DAC1的工作流程图如下:[普通CD(16bit/44kHz)] --> [CD机 /转盆] --> 16bit/44KHz数码输出 -->[DAC1内置取样频率提升变频器和24bit/96K DAC芯片的译码器] --> = 输出具 24bit/96K (频率响应 : 0 ~ 48KHz)的Analog讯号.笔者认为DAC1是现在新数码时代中最低用的D/A译码器


DAC1内部结构 , 简单直接而精密 , 上层为主板 ,下层为电源部份 . 电源使用两个变压器 , 独立供应 "Digital"及"Analog"部份 , 再用两条 Kimber Kable 连接主基板 , 在主板上你会看到本机心脏芯片Grystal CS8420取样频率提升芯片 , 负责将16bit/44KHz数码讯号提升为 24bit/96KHz ,  96KHz 数码滤波器为Burr Brown DF1704 ,DAC Multi bit译码芯片为 Burr Brown PCM1704 24bit/96KHz . Analog 部份使用 Burr Brown OPA627A 和OPA2134PA  , 另外更使用十多枚昂贵而好声的Caddock电阻 . 厂方宣称大幅将以下三种译码器经常发生的失真和误差减至最低 : 1)DAC时钟的时间性 Jitter  2)EMI电磁干扰  3)数码 -> 仿真转换过程出现的量子化噪音 .同时, 具有缓慢滚降的48KHz数码滤波线路 , 完全消除传统砖墙滤波器(在 22KHz剧烈衰减100dB)在时间领域引起的扭曲

  为了使测试更为客观 , 及令读者更容易理解试听结果 ,特别借来一部 PS Audio UltraLink 2 来比较 , 为什么用UltraLink 2 作比较呢 ? 因为 , UltraLink 2 价位与 DAC1 差不多 , 约二万元 , 而且相信很多朋友也亲耳听过其表现 ,在A/B比较下试听了多张CD , 包括 :

RCA 09026-61795 Beethoven Symphony No9 Fritz Reiner .Chicago Symphony
Philips 416 821-2 Tchaikovsky.Sibelius.Violin ConcertosMullova.Boston Symphony Orchestra.Ozawa
Decca 417 459-2 Schubertrout Quintet/Death and The Maiden Curzon/Wiener Oktett
RCA 09026-61503-2 Rhapsodies- Liszt.Enesco.Wagner.Smetana STOKOWKI
JVC VDP-5182 Salena Jones
EMI CDC 5 55026 2 9     Sarah ChangPaganini: Concerto NO.1 IN D
Polydor 817 143-2  邓丽君15周年
点将唱片 DJCD-96108  民歌蔡琴
DAC1明显比 UltraLink 2 ,通透得多,最要命的是DAC1完全听不到有数码声 , 润滑柔美 , 但不失生猛活泼 ,结像力强 , 而UltraLink 2有明显的数码声 , 音色较为呆板 , 中高频有少许哑暗及干 , 结像较大 . 回放一些十多二十件乐器的音乐 , DAC1的表现起码高 UltraLinK 2 几班 .  DAC1的表现令我很难相信是出自一部一万元的译码器 , 如果是一年多前起码要三万多元的译码器 , 才有相同效果 ,至于 UltraLink 2 是否一无是处呢 , 这又未必 ,  UltraLink 2 始终也是一部二万多元的译码器 , 由于具有较强的电源供应 , 在回放极为爆棚的乐段时较为稳定及强劲(一般十几二十分钟的交晌乐可能只有十多秒大爆棚).

总结
DAC1 全频丰满厚润 , 感情丰富 , 结像力强 , 空气感接近 LP级数 (旧一代和没有提升取样频率的24bit/96KHz译码器很难做到 , 除非是五 , 六万元以上的顶级译码器),而其较弱一面是冲击力和爆炸力 , 相信是其电源供应的暇疵 , 厂方增值电源供应 改进其冲击力和爆炸力 , 音效更为完美 ! 研究室正在开会 , 如何用最少资源改善暇疵 , 一有结果笔者会第一时间通告 .

谢谢!!很好声的.

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PM了,诚意请来电13661671626

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Bel Canto Design DAC 1 D/A processor

Robert Deutsch


It's hard to know what the best strategy is for digital upgrades. Maybe you bought your first CD player when you became convinced that the format was going to succeed, and it seemed that players were about as good as they were going to get. Some time later, you tried one of the new outboard digital processors, and the sonic improvement was such that you just had to have it. Then you replaced the player itself with a CD transport, so you could benefit from improvements in servo control and digital output circuitry. At this point you were generally happy with your digital front-end—until you read about how 16-bit DACs (which is what your processor had) were old hat now that 20-bit DACs were available. But alas, your processor couldn't be upgraded, and was worth maybe 30% of what you'd paid for it. So you took a loss and bought a new-generation digital processor, and things were fine and dandy...for a while.



Now the rallying cry is "24-bit/96kHz!" It's possible to spend several thousand dollars on a digital processor that could become obsolete as rapidly as do today's cutting-edge computers. SACD and DVD-Audio are about to duke it out in the marketplace, and it's too soon to predict how this epic fight will turn out. The CD will likely continue as the dominant format for at least the next few years, so it makes sense to have your CD playback optimized. You'd like your CD playback equipment to be as up to date as possible, but you'd also like to stay in the moderate price range, so you won't lose too much in the inevitable next round of obsolescence.

The Bel Canto DAC 1 was designed for people like you.

Description & Design
If what you're looking for is a piece of equipment that will impress your audiophile friends with its milled-from-solid titanium case and array of flashing lights, the DAC 1 will not satisfy. It's a smallish black box, albeit with a classy gold-plated "Bel Canto Design" metal plate on the side. At one end are the inputs (one S/PDIF, one TosLink), at the other the analog outputs (RCA coax). There's an LED that changes from red to green when the DAC 1 locks on to a digital datastream, and a pushbutton inverts absolute phase.

As described in the "User's Guide," and in more detail in a white paper on the Bel Canto website, designing the DAC 1 involved attempts to reduce four sources of error in D/A conversion:

1) timing jitter in the DAC clock

2) quantization noise in the D/A conversion process

3) time-domain smearing

4) distortion from electromagnetic interference (EMI)

Without going into the technical details—which I understand at only a very general level—the DAC 1's design involves use of the popular Crystal CS8420 sample-rate converter chip, which converts all input sources to 96kHz and adds 8 bits of dither to bring the data depth up to 24 bits (unless the source is already 24/96), then sends this "upsampled" data to the Burr-Brown PCM1704 24/96 DAC. A crystal oscillator provides a buffered clock output that controls both the sample-rate converter and the DAC, thus reducing jitter. A slow-rolloff digital filter set at 48kHz produces what Bel Canto claims is a more "analog-like" impulse response than the 22kHz brick-wall digital filters used in some other processors.

EMI—which, as Bel Canto uses the term, includes radio-frequency interference (RFI)—has long been recognized as a significant source of distortion, and Bel Canto's white paper on the DAC 1 points out that the problems start with the radiation of high-frequency clock and data signals. "Radiation requires an antenna, which is any unshielded wire of sufficient length." It now becomes clear that the DAC 1 is made small not to save money (or not just to save money) on chassis costs, but because its design calls for short signal paths. Critical clock and data line lengths are a fraction of an inch, and the DAC 1's small size allows it to be placed close to the preamp or data source, requiring only very short cables. (The DAC 1 is also available in an "internal" version that can be part of a Bel Canto preamp or integrated amp.)

On the analog side, the DAC 1 uses all Caddock resistors and polypropylene film and foil capacitors, with separate power supplies (including separate transformers) for the analog and digital sections, and star grounding. The analog section's S/N ratio is said to be equivalent to 20-bit performance.

Getting Started
Connecting the DAC 1 is simplicity itself—the only decision is whether the coaxial S/PDIF or TosLink input should be used. And because my PS Audio Lambda II transport has no TosLink output, I didn't even have to make that decision. Linked by the excellent Kimber Illuminations D-60 coax, the Lambda II/DAC 1 pairing worked well except in one respect: with every CD, when the first track started playing, and whenever I changed tracks manually, there was a slight pop through the speakers. I've used this transport with a number of digital processors, and this has never happened, which made me suspect the DAC 1 was the source of the problem. However, when I used the Rotel RCD-991 as the transport, the pop was gone.

I discussed the issue with John Stronczer, designer of the DAC 1, who acknowledged that with some transports they've found this sort of interaction, which, he said, indicated momentary loss of lock. He suggested that I try one of the late-generation DVD players and use its TosLink output, which they've found to work better in this application than most CD transports. He also sent me a new sample of the DAC 1 that incorporated the latest revision of the CS8420, which was said to have better locking performance. Indeed, the new sample of the DAC 1 did not produce the pop when used in combination with the Lambda II (or any other transport I had on hand).

I was intrigued by Stronczer's suggestion to use the TosLink connection from a DVD player. The collective audiophile wisdom on TosLink is that it's inferior to coax S/PDIF, having lower bandwidth and being more prone to jitter. Stronczer admits that TosLink has relatively high jitter, but says that this does not present a problem with the DAC 1 because of this processor's ability to reject jitter. He likes the fact that TosLink can get rid of ground loops, and feels that the large (16MB) storage buffer built into DVD players is an effective way of suppressing low-frequency jitter components from the datastream that comes off the disc. In any case, I felt compelled to check out the suitability of a DVD player/TosLink as a source.

The DVD player in regular use in my home-theater system is a Sony DVP-S7000, a first-generation player; so I borrowed a Pioneer DV-09, a current top-of-the-line model. The first comparison I made was between the TosLink (AudioQuest OptiLink 2) and coax S/PDIF (Kimber Illuminations D-60) outputs of the DV-09, playing Chesky's familiar Jazz Sampler & Audiophile Test CD (JD37). The sound with the TosLink connection was fine in general terms, but compared to the coax it seemed subdued, slightly muffled, and subjectively slower. Comparing the DV-09 and the Lambda II, both using the coax outputs, there was not much difference; if anything, the Lambda II was a bit more detailed. I used the Lambda II for most of my subsequent auditioning of the DAC 1.

720304 在 2007-1-13 15:51:47 发表的内容 好东西，成色不错。声音很有模拟味。帮顶

谢谢，好声音。