+4dBv or -10dBu?

[hugoo]

技术问题，

单端口line level都是-10dBu,
想知道一般Consumer hifi器材的平衡接口是+4dBv还是-10dBu? 器材的spec上没有标，有没有办法测出来？

如果解码模拟出口XLR出来是+4dBu的，进W4S STP-SE前级XLR input，如果W4S用的是-10dBu的，会不会有问题？据说会overload?

[hugoo]

作者: dalplex

很难统一这些量。
但是一般地讲有设置的地方来调节这些参考电平。

音箱可以调，W4S前级是肯定无法调，解码应该可以，就是不知道怎么调。
混搭就是麻烦，不玩了。

[hugoo]

作者: nattawa

放大器的输入电平指的都是所谓“灵敏度”，就是当得到额定输出电压或功率时的输入电平，对于增益可变的放大器，比如带音量控制的前级，是在音量放在最大时的指标。所以，你前级的输入电平可以用它的最大输出电压减去最高增益很容易的算出来。你的前级最大输出电压是9Vrms，相当于+21dbu，如果音量最大时放大器增...

隔行如隔山，我看了好几遍才看懂一点，汗
看来是担心的太多了，实际上只要音量别开太大，就不会有过载的问题。

[hugoo]

作者: silent_fish

不尽然， 我在用HUGO的SPL前级， 音源是DAC2, 耳机是AKG501，声音调到７，８点钟位置,换成＋４，声音变薄，动态不好，换成－１０就正常了.
我怀疑dac2和wyred stp se的搭配，是同一个问题

DAC2不是专业器材吗，SPL也是专业，专业对专业应该是+4才对，越来越糊涂了。
我现在接Apogee的解码进W4S前级，一个专业的，一个民用的，什么也没动，就这么接上去也没听出有什么问题。

这东西对我这种不懂技术太深奥了。

[hugoo]

作者: 老广

信号匹配问题，阻抗匹配问题。我说阻抗匹配不是指高频阻抗匹配那种定义: 输入阻抗=输出阻抗。而是音频的低阻输出，高阻输入也有一定匹配范围。线的阻抗影响，差太多了频响不行。

老广，请说中文好吗？

[hugoo]

作者: 老广

这不是中文？

开个玩笑，
你写的看起来像中文，每个字我都认识，不过就是看不懂你在说啥

[hugoo]

作者: nattawa

耳机监听输出有失真，不见得线路输出一定也有失真。
你说的SPL前级我不了解，但一般有耳机监听输出的设备，必然会有专门的监听音量旋钮，以适应不同阻抗和灵敏度的耳机，这个旋钮跟主音量旋钮如果配合不当，监听放大器有可能被驱动进入过载保护工作区，这时不管主通道的信号有无失真，耳机里面都会听到失真。这个...

好，专业人士来了

Spec在这里，
http://spl.info/hardware/monitor-con...fications.html

[hugoo]

作者: silent_fish

You could be right.

DAC2 has four different output level, adjusted by a rotary switch on back panel.
DC coupled, short circuit proofed output ci...

check out this:
Special +4/-10 Edition: More than you want to know about how dB's work
http://www.sweetwater.com/expert-cen.../d--04/14/2000

[hugoo]

作者: silent_fish

They are just voltage in different scale(log), but how does it explain the max input level of 21.3 dBu.

maybe it means you should not use a device with output level > 21.3dBu? as it will cause overload on SPL?

just guessing here..

[hugoo]

Then if set both DAC2/SPL to +4dBu, are you getting optimal performance from ModWright amp, comparing to other settings?

[hugoo]

作者: silent_fish

Since the source is still +4dBu, SPL is simply expecting +4dBu as max input level, I don't think there is an improvement. Unless there is difference i...

Yeah, as they say it's better to keep the line as hot as you can (without causing distortions) and only do attenuation at the last stage... in this case, at the SPL pre-amp.

[hugoo]

嗯，好像看懂了。
那用个-10dBV的pre-amp去feed一个+4dBu的amp,会是什么结果？

[hugoo]

作者: nattawa

无源前级（或带buffer的无源前级）

Thanks Nattawa, very professional!

I am using w4s stp-se which is a passive pre-amp with buffer, feed by an Apogee pro DAC with high output (over +4 for sure), drive a active pro monitor with +4db input sensitivity, sounds pretty good to me. If I use SPL, it sounds "aggressive" sometimes, and volume had to be kept down to very low settings, which can be a bad thing as you said..

[hugoo]

作者: silent_fish

I don't know your stp -se is passive, what kind of passive technology (transformer, resistors, others) it uses?

Not sure what technology it is using..
From its description, it's kind of passive-active design, when volume is <63, it's passive (no gain), when >63, gain stage kicks in. Its volume control uses only resistors and relays, I was told that it's better than a chip or volume pot, that's all I know about it technically