请教各位大侠, 有用过DAC1的平衡直接耳机的么?

ruge

交易区新帖推荐

MOBIUS可以配平衡插口,  拿DAC1当前级,  从它的平衡输出直接连耳机
这样的效果,与直插耳机口相比会有什么区别?  请有经验的大侠指点, 多谢先!

fgpgp

看看这里：
http://www.headphoneclub.com/bbs ... light=DAC-1%2Bfgpgp

nadesicozhao

请看这里

http://www.headphoneclub.com/bbs/viewthread.php?tid=101531

慢慢往下看，50几楼，聚会上试验过，描述很详细了

ruge

多谢! 这就去看

渔歌

感觉推力不足 不推荐

ruge

这根线的作用是将左右声道的平衡输出转换成耳机输出，据说是某个国外阿枪首先在一个论坛上提出用DAC-1的平衡输出驱动耳机有着比耳机孔更好的效果。经过壳质C的实验，据他所说，对于普通版，结论是一致的。

聚会当天我们在USB版的DAC-1上实验了下这根线，首先有一点值得肯定，就是这根线本身的素质一听就是不错的，没有浪费了那两个瑞士产牛崔可平衡头。
经过我和小葛的试听，认为在驱动耳机上，明显的驱动力和密度不如USB版的耳机孔。如果使用前级功能调整音量，则整体的透明度不如耳机孔；如果使用前级直通，则推动力太小，声音单薄，大动态下有压缩（当时XLR跳线是-10DB）不过细节、乐器分离度和透明度要LL些。

这些结论其实早在我们意料之中，因为DAC-1做前级後明显不如直通来的通透和有灵气，这个我曾经反复在论坛上提起过。

另外老外的话也不是全错，因为相比USB版的耳机孔，老版的耳机孔推力也明显要小，整体素质可能是要比平衡线转出来推还差点，不过那天没有做实验，因为还有太多LL的东西等着我们比较
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把版主的试听结果复制到这来方便查阅. 我说的那MOBIUS是直接森海插口连左右耳机的. 但道理都是一样的

ruge

The XLR outputs on the DAC1 USB are not designed for driving headphones because they have a 30 ohm resistor in series. For a headphone amp, ideally, you would want 0 ohms output impedance, which is how the HPA2 is designed (the HPA2 is Benchmark's signature headphone amplifier which is featured in the DAC1 and other products.)

With that said, if one was to try driving balanced headphones from the XLR outputs, the DAC1 USB is much better suited for that then the DAC1. The DAC1 USB would be able to drive 300 ohm headphones to 28 dBu, but we have not tried nor measured the performance of such a setup. Therefore, we offer no claims or guarantees about the performance of this setup.
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BENCHMARK的答复1

ruge

I'd be interested in hearing the dual-active configuration, but I can't see how it would make a difference aside from having a signal with twice the magnitude.

Plus, they would have to be driven from a source with very low (near zero) output impedance.

The problem with using the DAC1 for such an application is the output drivers are designed to drive a line input device, hence the 60-ohm output impedance. With headphones, this output impedance will cause the damping factor to drop significantly, causing ringing, overshoot, and all sorts of distortion based on driver resonances. Let me elaborate on this further...

Damping factor is a ratio of [load impedance vs. source impedance]. In the case of the HPA2, the output (source) impedance is less then 0.11 ohms. Therefore, the damping factor with 300-ohm headphones will be near 3000.

The damping factor with a 30-ohm output impedance and 300-ohm headphones will be 10. The damping factor with 60-ohm outputs and 300-ohm headphones will be near 5.

As you can see, we lose the tight control over the drivers which is essential for the reactive load which a speaker presents.

Another problem with a significant (>1-ohm) source impedance: the headphones have frequency-dependant resistance. Therefore, the voltage divider that is created between the source impedance and the load impedance is now a frequency-dependent voltage divider. This means the frequency response is going to be anything but flat.

I would be hesitant to use this type of configuration. In fact, I don't recommend driving headphones with any source with an output impedance >1 ohm to drive headphones at all.

With that being said, it will not hurt the DAC1 to do this, so feel free to experiment with this setup without worrying about causing any damage. My philosophy is...if it sounds good to you...go for it!

However, don't evaluate the quality of the DAC1 based on driving headphones with the XLR outputs.
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BENCHMARK的答复2

ruge

看来还是少折腾为妙

nadesicozhao

我觉的
官方答复很多都是半通的客服问了工程师后（甚至没问，照读一些文档）做出的回复
特别是benchmark，当初几个同志问过的问题，他们的回复和实践下来明显相反（数字线、电源线、前级问题、跳线等）

有机会自己动手实践下好了

yolandacy