I decided to actually plug in the free amp I got on Saturday to see if it would blow up. I plugged it in, turned everything to zero, and then turned it on. The power light and some LEDs lit up. I slowly turned up the master volume, only to get this horrible growling sound. It was like a hum, but with some meat to it. And steady pops and clicks.
So I turned it off and unplugged everything. I then unplugged the effects unit from the rest of the amp. After hooking it all back up, I turned it on again. Same loud, steady noise. I tried plugging a guitar and a microphone in to the amp to see if I could get any sound on top of the loud noise. Nothing. I turned it on and off. Plugged and unplugged it. I unhooked different wires inside (since it is all PC boards with standard plugs for wires, it was easy to unplug and plug the obvious connections).
Nothing made an impact on the loud noise except the master volume knob and the phase button, which just made it louder.
Then I started looking at the power supply. Mind you, I am not an amp technician. This is my first time doing this and I was very nervous. I used a wooden chopstick to poke things. I was very careful to make sure everything was unplugged and turned the amp on and off multiple times just to make sure it was unplugged. I’m sure there was stored voltage somewhere in there, but I was not planning on finding it.
Finally, I unplugged everything and wondered if I was fooling myself. I don’t know what I’m doing. I can’t find any schematics on the web. So I went back to the internet and read the actual instruction manual for the amp.
There was practically nothing about the innerworkings of the amp. It was all about what to plug in and where to plug it and how to turn the knobs and how to use the footswitch and midi controller. Then I read this:
Please ensure that the ULTRACOUSTIC is set to the correct supply voltage before connecting the unit to the AC power system! Three triangular markings can be found on the fuse holder at the AC power connection socket. Two of these three triangles will be aligened with one another. The ULTRACOUSTIC is set to the operating voltage shown next to these markings and can be switched by twisting the fuse holder 180 degrees.
I thought it was pretty useless information, but I didn’t have anything better to do with my lack of knowledge, so I looked at the fuse. The arrows didn’t match up for 120 V. So I took it out, flipped it over, and plugged it back in. I then reset all the knobs and controls to zero. I unplugged my guitar and mic. I then plugged in the power chord and turned it on with the expectation that I would blow something up.
I turned up the master volume. A slight hum, but no loud noise. I turned it up more. That hum would be annoying if I had just paid for this amp, but it was not the loud noise…and I had not paid anything for this amp.
I turned everything off and plugged in my microphone. I turned everything back on and said “hello.”
I got an echoed “hello” from the amp that faded after eight or nine repeats. I turned off the effects. I said hello again and just got a simple hello. There is a hum, but the amp now works. Apparently the power supply fuse was set for the European/International 220 V. I just had to flip the fuse over. Could it really be that easy? Apparently!