I messed around with mic placement again yesterday and I tried the old "45 degree pointing towards the centre of the cone" type placement.
While playing I noticed the sm57 had a really bad signal (my condensor a couple of feet away was fine btw).
During playback there was a lot of what sounded like line noise (like a serious ground loop buzz and no real volume), really bad and totally unuseable, I thought the mic was goosed but as soon as I put it back to my "straight on, an inch off centre" it worked fine.
I'm a newb when it comes to recording and I'm aware it's a steep learning curve but I'm interested to know what was the possible cause of this, what is the theory behind it?
Was it just bad mic placement, maybe needed moving up or across, like there is a band/position within which this technique will and will not work?
Is it this mic technique flawed or was I just doing it wrong?

For your information, I'm using a Peavery Vyper 75W (ok I know but it's what I have so don't go on about "you need a better amp ) with a Dean ML FBD Tribute, SM57 and Audio Technica ATM33a > Focusrite Scarlett 2i2 > Reaper.
Also, the finished recording with a small amounf of eq and haas effect was probably the best sounding recording I've ever achieved.
Don't think so mate, as soon as I put it to 90 degree to the amp it worked fine, could it be a phase thing or am I barking up the wrong tree?
I don't believe it's a phase thing but I really don't know just trying suggestions. The reason I thought it could be a grounding issue is because the ground could be loose so when you put it at angle it may move something on the inside and it becomes no longer grounded.
It's pretty difficult to diagnose without seeing the setup and hearing the result, but out of interest could you try to recreate the effect again and this time record it (and the on-axis tone too, for comparison). If you can't reproduce it, just put it down to some freak occurrence unless it pops up again, and don't worry about it. As long as your power source is clean and your cables are fine, you won't have any noise issues there as the XLR cable is balanced, thus meaning that (in theory) you won't suffer from signal interference, and grounding of the components in the interface or the mic wouldn't suddenly switch based on proximity to other devices and RF interference, so unless you were unfortunate and have a loose component like FireHawk said, that shouldn't be the issue.

If you were using the condenser at the same time, but didn't notice it when the condenser was muted, it's very possible that phase was playing some sort of havoc, but I would have thought that it would be hard to notice the difference of just turning the mic 45 degrees one way, as it is still almost the exact same distance from source to capsule.

Again, if you can record examples it would help, but if you don't get the issues again just let it go
Hey, look. Sigs are back.
Last edited by DisarmGoliath at Mar 25, 2012,
It's possible you have a bad cable and just moving the angle of the mic makes or breaks a connection. Also, I've had noise issues with dynamic mics even being properly grounded. The coil itself can pick up interference if it's angled the right way especially if you have the gain up pretty high. ( I was using an e906 to record acoustic- had to angle it just right to get it to not pick up noise from the power mains that are right outside my window.

So, if you're fairly certain it's not a bad cable or connection inside the microphone, try angle your amp differently so you can have the mic on axis but not pick up interference.