Lets understand the basics of what we KNOW a power cord does;
When we pull CURRENT through a power cord, any power cord, it will drop VOLTAGE onto the cord from the wall outler. That 120 volts won’t all go to the device at the other end based on the DC resistance of the cord, and the current drawn. Delivered voltage FLUCTUATES as the demand varies.
So if we pull 0.5 amps at an instant in time and our power cord has a resitance of 0.5 ohm, we will lose E=I*R= 0.5 amps x 0.5 ohms = 0.25 volts across the power cord as an example. This isn’t a deal killer but if you draw 20 amps in a HUGE amp that’s now 10 volts drop on the 0.5-ohm total resistance cord…maybe an issue. This is why big amps are harder to test, the wall voltage changes too much! It isn’t only the amp that is being tested anymore but the power delivery system.
The more power you draw the lower the cords DC resistance has to be to not modulate the power loss over a large voltage swing. The voltage modulation follows the power cords DC resistance for a given current. More resistance equals a larger voltage modulation at the end of the cord. The power cord is LOAD, too. No magic there. We lose some energy in the cord as it is in series with the wall outlet and the device. The voltage divider rule splits up who gets what voltage in a series circuit. Parallel circuit do the opposite, they split the current instead of the voltage.
The device’s power supply uses capacitors to smooth over these voltage fluctuations in the delivered voltage with a bunch of capacitors. The ability to hold what is called RIPPLE, or variations in the DC voltage based on current draw from the capacitors, is a spec that indicated how well the power supply can tolerate voltage fluctuations from the cord based on it’s resistance. The better the supply the less the DC will RIPPLE with varying voltage at the end of the power cord. All power supplies have to anticiate this modulate voltage and deign based on the CURRENT draw expected through the AC delivery “system”.
SOURCE devices don’t draw much current and don’t need larger cords (I use 14 AWG to all my SOURCES; T-Table, DAC, DISC Player ETC). The larger current draw devices, for the P20 and amps I use 10 AWG for better voltage delivery BUT, and just as important, to keep the GROUND point at the device and the wall as near the same as I can to minimize ground loop noise (hum). This is also DC resistance and current proportional. Bad ground differential is why we get HUM in our systems. Lower DCR cord help this not get WORSE if you have a high resitance junction somehere, they can’t FIX IT, though. series DC resistance all just adds up until we have a problem.
The passive RF properties of the dielectric are the same on all the BAV cords. As you go up in frequency the cord looks more and more high impedance and attenuates the unwanted signals going down the cord. This is backwards of delivering the power we want. Here, the cord should be the “device” that gets that voltage and not the device we are sending it to. I “trick” the RF signal into dropping voltage in the cord, not the device. In theory yu want the cord to look like an open circuit to RF. This is what those Ferrite collars do around a cord…they CHOKE the signal above a frequency. I do this without using a choke.
We want to waste that RF voltage in the cord so…I selected a dielectric that does that. Whatever is a higher impedance at a specific frequency will drop the most voltage. The Rs traces show the properties in the cord’s dielectric.
You all know by now about the P20’s output impedance being cut in HALF, right? Well, this is so we DO NOT lose power “inside” the P20! Yep, we want that power to go OUT to the devices and not be used up inside the P20…same kind of thing. So again, the devices IMPEDANCE is what determines WHERE the “signal” all ends up…eventually. All the decives in the chain steal some away and we want the right devices getting the goods.
A power cord isn’t magic as every cord does this. The differences are in the passive RF supression. We can use various methods to remove RF; dissipate the RF, shields to block and attenuate it external to the cord, do nothing and use capacitor shunt to ground in the power supply (yes, those are there, too) or use Ferrite CHOKES, or any combination. Some methods can interfere with low INDUCTANCE to allow current to flow INSTANTANEOUSLY in a wire. Keeping inductance low is important so watch that spec is good.
The BAV cords make sure we have a quality low DCR cord and connector with good passive RF absorption yet retain low inductance for varying instantaneous current draw. The fancyness is making sure I keep the cords WORKING well and at good price. Doing both is not easy, just a low price is easy. Just don’t pay any attention to the cords in-use properties and RF issues. Do that and the selection gets narrower and narrower for a quality cord. If that’s magic than OK, I did do that, select the best based on TESTING that anyone can do. Testing is not making the cord however, and I was lucky to find that Belden already had a really good cord and no one knew it. We win! Sometimes you get luck. That luck got you a nice well made cord that should work well and exceed the expectation for the price. We hope you like it. The market needed another option for the most of us in this hobby.
Best,
Galen Gareis (you know you can’t type if you mess up your own last name!)