The DL4 actually uses closer to 1200mA of current. The PX2 AC power supply is capable of providing 2000mA of current, but the DL4 (or any PX2 compatible device) will only take what it needs.

  DL4's are not DC-powered devices. There is no fixed polarity on the center tip (AC = alternating current from negative to positive).

  The official answer from us (in terms of making sure you get the most out of your DL4 without running the risk of potential damage to it) is to use a power strip and the PX2 power supply we offer. Boss pedals are DC powered devices. Our 4-Button Stomps are not. They do in actuality require more than 250mA of current at 9V AC.

  Regards,

  L6Perry

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.