The most important and most troubling issue for a lot of people getting started in amplified harp playing is feedback. Once you get the right equipment all put together feedback can be fairly easy to eliminate. There are a couple of tricks that really help. First, it’s very nice to have a volume control on your microphone. That way you can turn it down, step over to your amp to adjust the controls, and step away before you turn it back up. And of course if it starts to squeal when the band gets loud, you can turn it down easily. I have also found that adding a volume pot to my vintage Shure bullet has reduced the feedback tendency significantly. I don’t know exactly what the technical reason for this is, but it worked for me. Probably the most important factor on your amp is to turn the tone down to get less treble out of the speaker. It can’t squeal if the speaker isn’t sending out the very highest frequencies at full volume. The next thing you want to remember is to always stand to the side of your amp rather than in front of it or behind it, obviously because that’s where the sound from your amp is the weakest. Also, it helps if you set up your amp on one side of the stage and stand on the other side whenever possible.
The most important factor of all in eliminating feedback is selecting the right amplifier. Some amps work great for playing harp, and some are just terrible. Remember that if an amp is a beloved favorite of guitar players who like to play screamin’ lead guitar on rock songs, you may not like it much. You’ll probably prefer an amp that isn’t so responsive and edgy. Your best bet is to try lots of different amps until you start forming an idea of what works and what doesn’t. Try your friends’ amps, take your microphone to a music store, etc. Just don’t get locked into one microphone and one amp that gives you trouble. When you’re still fairly new to all of this, there is almost always something else that will work just a little bit better. Be careful, though. A lot of people will get the wrong idea of what makes one amp more useful than others. For instance, if a 4×10 combo with one type of circuitry performs better than a twin 12 with a totally different circuit, don’t get the idea that the speaker configuration is the sole determining factor. While the speaker configuration has something to do with how much punch an amp has in a room, the circuitry has a lot more to do with tone production. Don’t be one of those people who thinks that a red Ferrari goes faster than a blue minivan because of its red paint.