I have read in several places that the audio output of the Akai AMX isn't very loud, and that this can be improved if plugging it into a powered USB hub (the AMX is bus powered). I have two USB 3 hubs, both of which have a socket to plug in a power supply, but I didn't have a 5V DC power adapter that would fit either.
So I purchased a 3-24V Regulated AC-DC adapter (model JDT-2402000 / JDT-001), and a selection of plug adapters. Checking with a multimeter and no load, it seems it goes from about 3.6 - 24V. It displays the voltage on a 3 digit 7 segment display, though I found the voltage measured with the multimeter was always slightly higher than that indicated on the unit.
So I went to test the AMX with my computer to compare volume plugged into the PC, the USB hub unpowered, and the USB hub powered. However, I found that whenever I connected the AMX to a USB hub or the front USB on the PC, Serato (the software I'm using with the AMX) would just say AMX hardware connecting. This can take up to one minute.
and never actually connect to the AMX. I tried 3 different USB cables.
Windows detected the AMX fine, but won't output sound via the AMX. Ableton Live will so long as you choose MMX/DX as the driver type and select AMX Wave (not DX) as the output device.
But when I plugged the power adapter into the USB hub, it showed up 4.99 on the adapter's LED, despite the adapter not even being powered on at this point. I adjusted the voltage dial up on the adapter, until I got to 5.02V, anything below this it still showed 4.99V.
With the power in or out there was no difference, the sound output from the AMX was exactly the same volume. This was with a Sumvision USB 3.0 Hub. With my other USB hub, an ipTIME UH305, the voltage with the power adapter off showed as 3.90. But with the power adapter off or at 5V, the volume seemed to be exactly the same.
So I'm not sure where this thing comes from about plugging the AMX into a powered USB hub for higher volume output. With my setup the AMX doesn't even work at all with Serato when plugged into a USB 3 hub, whether the hub is powered or not. And when using the AMX with Ableton, having the USB hub powered or not made no difference.
Maybe it depends on your hardware? Or what else you have plugged into the AMX (I didn't have anything plugged into the audio inputs).
Anyway, although the JDT-2402000 / JDT-001 power adapter isn't useful for what I bought it for, it still seems like a handy piece of kit to have around, especially with all the extra plug adapters I bought to accompany it. The only thing I don't have is an adapter to change it from positive tip to negative tip. However, I should be able to DIY one of these by cutting up a 5-way guitar pedal power adapter cable - just cut each end off, then reconnect them with the wires swapped over.
It would also be better if it did more than 2A (so you could use it power a laptop), but you can't have everything.
The power adapter, variety of tips, and AMX
