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Old 02-08-2014, 02:36 PM
Tony Conner Tony Conner is offline
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Mic noise

Aquired a sterlin condensor mic st51 with a phantom power supply. I never used a mic before so I don't know if im doing something wrong or wrong cables. I get a loud ringing noise that will be present all the time when I bring the volume to 5 on my acoustic amp ( im using a fender acoustasonic 30 amp). The cables came with the mic, but when I look online manual it says to always use high quality XLR cables and the only markings I can find the cables that I have are EXM3. If I don't plug the mic into the amp and just the acoustic I get no noise. Only when the mic is plugged in. I also get the noise when I touch the mic with my hand, it starts the loud ringing. Im sure this isn't normal, I have the power supply ontop of my amp, ill try to move it next time to see if it makes a difference..any input will be greatly appreciated..
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Old 02-09-2014, 12:45 AM
Slipin Lizard Slipin Lizard is offline
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Sounds like feedback... does it go away if you turn the volume down a bit? Plugging a mic and a guitar into a single amp is definitely far from an ideal setup, so you can expect to get some issues as you try to turn up the volume.

You say "when I touch the mic with my hand"... are you trying to hold the mic? A condenser mic is not meant to be held, touched or handled when active. If its going to be moved around, it needs to be supported in a shock-resistant mount because its very sensitive to handling noise.

The Sterlin ST51 uses a "Cardioid Polar Pattern", which in pure laymen's terms, means it picks up sound very well from sources its pointed directly towards, and poorly from sources that are directly behind it. If you place the mic on a stand pointed at the ceiling, so that you can stand and sing into it, its going to pickup the amp fairly well to... you can try moving the mic as far away from the amp as possible, and tilting it away from the amp if possible.

Dynamic mics are far better for "rough & ready" general purpose use. Like the Shure SM58 for vocals, or the SM57 which is pretty much industry standard for miking guitar amplifiers. If you're using the mic for live vocals, then I'd suggest the SM58 over the Sterlin. Large condenser mics work well for recording acoustic audio sources in isolation... in other words, in situations where a single source (an acoustic guitar, an accordion, a choir) is the only sound in the room. Not so much for live PA work, if that's what you're trying for.
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Old 02-09-2014, 12:14 PM
haghj500 haghj500 is offline
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You never want the mic in front of the amp. That will cause feed back.
Try moving it to different locations and as said you will want a mic stand.
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Old 02-09-2014, 01:28 PM
Slipin Lizard Slipin Lizard is offline
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Quote:
Originally Posted by haghj500
You never want the mic in front of the amp. That will cause feed back.
Try moving it to different locations and as said you will want a mic stand.


Actually, that is not true. Placing a mic in front on an amp does not automatically mean that you'll get feedback. When using a mic with a cardioid pickup pattern, the most important thing in avoiding feedback is to have the business end of the mic pointed away from the amp/speaker. Proximity will usually be the next factor. The closer the mic is to whatever its plugged into, the more likely the mic is to pick up its own signal and produce feedback.

Saying "you never want the mic in front of the amp. That will cause feedback" is not only overly simplifying the problem, its wrong. An amp takes the signal from the input source (in this case a mic) and amplifies it through its speaker. This is exactly how a stage monitor works. Stage monitors are speakers that are placed close to performers so that they can hear themselves as they perform. In the case of a vocalist, they are using the monitor to hear their own voice being picked up by the mic, so its essentially a more sophisticated version of plugging a mic into an amp. By necessity, the mic is in front of the speaker or "amp". The first and foremost way feedback is avoided is by using a directional microphone, such as a cardioid, that is pointed away from the monitor. There are othe ways to avoid or reduce feedback, but they are used in addition to using a directional mic pointed away from the amplifier or speaker.

I've plugged both a guitar and microphone into a small practice amp many times when practicing vocals. Placing the mic behind the amp would defeat the purpose... you want to be standing in front of the amp so you can hear it clearly. I would simply place the mic in front of the amp, pointed away from it, which allowed me to stand, play and sing and hear the amp clearly without feedback.
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