Tried an interesting experiment with Hiface Two yesterday. After hearing about the "biblical" scale improvements an external power source could bring to the Hiface, and all the people raving about it, and after checking the retail prices of different power solutions (Aqvox USB power supply, JKSPDIF, Kingrex Li-ion, LiFePO4 batteries...), I decided to try and make a basic external power supply myself.
So, I found an old Samsung phone charger from like 2005 in one of my drawers, 5V 700mA, which seemed appropriate to power the Hiface. And a basic USB extension cable (USB A, Female to Male connectors) with fairly good quality connectors. Time to chop some cables!
I cut the phone side connector from the phone charger and cleared about 1cm / 1/2" of the core cable (+5V) and shielding (Ground), twisted them and tinned the ends. I chopped off both the male and female connectors from the USB extension cable, hacked my way through the thick plastic around the connectors, trying hard not to destroy the plugs, and eventually revealed the backside of the connectors with 4 very convenient slits to solder cables on each connector (where cables were soldered originally).
Alright, I now had a ready to solder power supply and naked USB male and female connectors ready to be soldered on. A USB plug and cable has 4 lines: +5V, D+, D- (the two data lines in the center of the plug), and Ground. Apparently, to use external power on a USB peripheral you still need to have the ground connected along with the data lines and only leave the +5V line disconnected (otherwise the peripheral is powered on but not recognized by the computer).
Next, since I needed to connect two data lines and the Ground between both naked USB connectors, I cut three 2.5 cm / 1" pieces of quality Mogami cable that I had left over from a previous project and stripped and tinned these. With both USB connectors facing in a complementary way (like if I were to plug one into the other, so that the lines can be soldered straight across and not have to be inverted, but not facing each other), I soldered the data lines and ground between plugs. Then I soldered the external power supply +5v and ground lines to the peripheral (female connector) side.
Tested, it worked (powered on the Hiface Two and it was recognized by the computer, unlike the prototype I made, which didn't have the USB ground soldered and was useless). Which just left the insulation and strain relief steps, drown the solder points and cable in hot glue (basically drown everything but the plugs in hot glue), add heat shrink over everything but the end of the male plug (so it can be plugged...), add even more hot glue wherever you still can inside the heat shrink (you can never have enough glue), apply heat to heat shrink until it, well, shrinks. And voila, you have a external power supply hooked to a USB cable for your Hiface! An inch and a half long, sturdy, and for free, not for $100 retail or whatever you paid for your Hiface in the first place...
Now, I wasn't expecting much out of this mod, it was meant more as a test to see just how much of an improvement I should expect to see on the Hiface Two using any other power than the "dirty" computer USB. Well, for an hour-long free essentially free mod, I was flabbergasted!
Not only did the external power supply work, it turned the Hiface into a totally different beast! We're not talking about minor improvements but something like a different product. Much better soundstaging and instrument separation, much better upper and low extension (outrageous low mids and bass), extra-detailed and natural presentation. Gone the ever-so-slight upper mid glare, replaced with a balanced frequency response and beautiful mids. And fast, fast, fast sounding too, decay is so unlike the plain vanilla Hiface I didn't even imagine you could get that kind of sound with the Hiface (this is a must-do mod if you use a Hiface with orthos, if not just for those gorgeous mids).
Anyway, I was not expecting a change that dramatic with a crappy 5V switching phone charger; now I'm wondering what kind of improvements I could get from a linear power supply or different kind of batteries (without hacking the Hiface itself, that's my limit). I strongly encourage anyone with a soldering iron, hands and a Hiface to try this. For an hour of work, it is more than worth it!
And again, I made no changes to the Hiface itself, so no warranty or reselling issues, you'll still have your plain vanilla Hiface afterwards. And you can reuse the USB external adapter for other devices!
Next I'll try to make another USB adapter that delivers 5V with batteries, again just to test and see the difference (if there is one), maybe a very basic 4 x 1.2V Ni-MH battery powered USB adapter. Ideas and suggestions are welcome!
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