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Line6 DL4、MM4、FM4、DM4原装PX2电源的标称输出值是9伏交流、2000毫安；
Voodoo Labs Power 2和2 Plus都声称可以支持上述效果器，但它的输出是直流电。
这究竟是怎么一回事呢？
查了一下终于发现一篇帖子，很可能道出了内在原因：
http://line6.com/supportarchivenew/thread/55666
其中最重要的是这一段：
Re: DL4 power
by heyniceguy on 2011-02-08 15:13:54
Ok. Here's what's up.
The DL-4, as designed, expects a 9VAC signal, which is non-polarized at the jack. At the power input of the DL-4 is a rectifier/filter that turns the 9VAC into 6VDC. That 6VDC line is tapped to the battery line, which is 4 D batteries (4 * 1.5VDC per battery = 6VDC). That 6VDC is used to generate all the operating voltages within the unit (6VDC, 3.3VDC, 6.6VDC, and 5VDC). Notice that what makes the DL4 REALLY work are all DC voltages.
Now wouldnt it be nice if we could use a DC supply from our VDL Pedal Power to bypass that rectifier circuit? Pay attention.
Diode rectifier/filter circuits CAN accept a DC signal with no damage to the circuit. The rectifier circuit will just simply pass the DC signal (with a voltage drop because of the forward drop of the rectifier diodes). It will rectify an already-rectified signal. Because of the diode voltage drop, you have to feed it a slightly higher DC voltage to get the same output as you would with an AC voltage. That's why the VDL PP has a dip switch to up the DC voltage from 9V to something higher (12-14VDC, lets just say 12VDC for this argument). But because you are using a DC supply now, polarity matters! And in the case of this circuit, it must be center-positive to prevent from reverse biasing the semiconductors and blowing them up.
As far as current draw goes, a circuit will only draw what it needs. So most ratings are given as a maximum expected current draw times some safety factor (usually 50%). So in a worst case scenario, a circuit will draw 100mA, so a designer may recommend a 150mA rated adapter.
That said, you have 2 ways to power a DL4: 9VAC or 12VDC. Remember, AC and DC power draws are measured differently. Straight DC voltage is able to supply more current than an equivalent VAC supply. So at 12VDC, it may only require a max of 200mA, but at 9VAC it may require 1200mA. That's why the VDL guy and the DL4 guy give you different current draw ratings. Also, they both may be assuming 2 different safety factors!
When youre comparing electrical power, you have to make sure youre talking the same voltage levels, voltage types, load, etc. It happens all the time in pro-audio. A car stereo maker will take a peak to peak VAC measurement across some frequency range into a 16ohm speaker and calculate power from that. A tube amp maker will take it from an RMS measurement over a different freq range in an 8ohm speaker. And then the listener wonders why a 200W car stereo is no where NEAR as loud as a 100W tube amp.
我就不全文翻译了，只说其中的重点意思：
当DL4外接9伏交流电源时，内部有个电路把它转换成6伏直流，供其它部分电路正常工作。而当外接12伏直流电时，这个转换电路的输出端电压也正好落到了6伏直流，因此可以使用。由于交流与直流的功率计算方式不同，而且有转换电路的存在，所以在用9伏交流供电时，DL4的实际电流需求是1200毫安；但如果用12伏直流供电，则只需200毫安就够了。
如果外接9伏直流供电，则从这个帖子来看会出现故障：
http://line6.com/supportarchivenew/thread/41781
（见其中1楼：“... when i try stepping on the switches nothing happens. no lighting up, no delay, no nothing. its almost like its being bypassed totally. im not getting the effect from the pedal but when its plugged in to the amp im still getting regular sound...”）
这个故障描述与GC论坛里一些反应类似，因此看来比较普遍。
注意上述仅仅是我在网上看到的言论。我自己只有FM4，而且一直用原装的PX2变压器供电，没试过用直流供电，也没拆机验证过上述关于效果器内部电路的说法是否属实。而且上述翻译并非直译，只是大致意译其中一部分内容。因此请大家自行判断上述说法的正确性，并自行承担不使用原装电源所造成的风险。如果发生效果器及电源损坏、火灾、人畜触电、亡故、升仙、泡不到妞等等任何情况，本人概不负责。 |
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发表于 2015-1-25 01:43:13
