You can improve it somewhat by finding a microphone that breaks up slightly when you play into it. In other words, playing loudly with your harp right on the microphone is more than it can handle, and you end up overdriving the microphone. There are several stage microphones that are well known for this tendency. I want to point out right now that this article is not intended to be an equipment recommendation. That’s more in line with what the Review section of the website is all about. I’m just trying to let you know that there are stage mics that will overdrive and make your tone a little bit mellower while adding some expression to your playing. I have a jam session friend who got an old Electrovoice that sounds a lot better than the Shure vocal mic that the jam host band always has available. It’s also convenient that he can plug it into the same XLR cable and get right to playing. If you want to know more about this, ask around to find out which microphones sound good when played through the PA.
Another option is to get yourself a vintage microphone or a modern version of the vintage mics, most of which are high impedance microphones equipped with 1/4 inch plugs of the type that plug into guitar amplifiers. Most modern PA equipment also has high impedance inputs that you can plug these microphones into. I have always found that my vintage Shure bullet mic plugged into the PA sounds a lot more mellow and expressive than a modern vocal microphone. I have also found that the PA anti-feedback circuitry helps a lot when using my bullet microphone.
If you want to use your own amplifier you will have to take a few things into consideration. A vintage bullet-type high impedance microphone will plug right into the amp, but if you want to use a vocal microphone you will need an impedance transformer. You can get these easily enough from a music store or online vendors such as Musician’s Friend. Just make sure that it is a low-to-high Z transformer. Using your own amp gives you a lot of freedom to build your own sound. But it also requires you to think more about avioding feedack and making sure you are loud enough to be heard.
Using the right size amp is important for two reasons. If your amp is too small you will be drowned out on a noisy stage. If you plan to play in your own band you can try to get your band to keep the volume at a level that matches yours. Or if you prefer, it’s simple enough to play through your amp and put a microphone in front of it to send the sound through the PA and house speakers. I see professional bands doing that all the time. But I’ve found that when I try to mic a small amp at a loud jam at a club there is just too much noise all around and it sounds like crap. I have never gotten this to work. Obviously I need a bigger amplifier.