guitar phasing with a single mic?

[mephetic_exhumation]

Hey all, I've been lurking here for a while and I really like the place, learned some very awesome and useful stuff.

So I did read the stickies and searched through old threads but I still can't find the reason behind this:


I notice phasing on my guitars when recording multiple tracks and I use a SINGLE sm57, it's right against the grill of the cab and I don't move it between the takes.

I was thinking it may be because the area where I'm mic'ing the cab has shitty acoustics? Around the cab there are two walls that are ~10 feet apart from each other (but the other walls are way further though) so it's a narrow space and I have a feeling this is what's causing my trouble.

Also, I don't have any absorbers at hand to put on those 2 problematic walls (I'm really fucking broke) and I can't move the cab anywhere else in the room.


So I'd really like some input to know:

1- if I'm on the right track thinking the walls around are what is causing the phasing issue?

2- if there's a cheap ass ghetto way to reduce the impact of the walls (put a mattress on them?) if they are indeed my problem?

Any insight on this will be appreciated a lot!

thanks.

 

[crillemannen]

Has to be the room then? Seems strange otherwise to get phase issues. I would probably try the whole mattress thing. Just try to kill every reflection in the room and see what happens

 

[::XeS::]

But doesn't phase affect only 2 or more tracks on the same "level" (like 2 mono, centered, tracks)? If you pan 100% L/R 2 tracks you shouldn't hear phase problems....but I can be wrong

 

[Fbarre]

@Xes: He probably means that his guitar amp signal sounds weak, because the early reflections of his room mix up with the direct sound, which cancels our frequencies in a certain way for the signal to not sound good. Another thing might be that he doesn't pan his signals at all or I completely don't get it myself.

 

[bryan_kilco]

Yeah, first thing that comes to my mind is panning. You shouldn't have phase issues with a single mic on a single source.

 

[Uros]

Or it could be that there is a time delay between different takes? I don't get if he's getting that weird shit with one take, or with sum of few different takes.

 

[bryan_kilco]

mephetic_exhumation - what is your exact signal chain? Guitar? Interface/preamp? real amp/speaker? Impulses?

 

[mephetic_exhumation]

@Xes: He probably means that his guitar amp signal sounds weak, because the early reflections of his room mix up with the direct sound, which cancels our frequencies in a certain way for the signal to not sound good.

Yeah, that's what I meant. Maybe phasing wasn't the right word, but the signal does sound weak and I thought it may be cause the reflections off the wall are going in the mic, adding a delayed version of the original signal, therefore, creating some kind of cancellation.

I am panning the guitars and it doesn't sound massive like I think it should at all.

I'll post a short clip tomorrow. I guess it'll be easy from there for you guys to tell me what doesn't sound right.

mephetic_exhumation - what is your exact signal chain? Guitar? Interface/preamp? real amp/speaker? Impulses?

Les Paus classic----> ENGL savage 120 ---> Mesa 4x12 rectifier standard---> profire 2626, no external pre amp

Don't know what pick-ups are on the guitar, it is my friends' and he probably doesn't even know it himself.

 

[Nebulous]

Les Paus classic----> ENGL savage 120 ---> Mesa 4x12 rectifier standard---> profire 2626, no external pre amp

No wander you're broke

Try the matress thing, see if that helps IMO.
If it is the room that should make a positive difference. If not, start looking elsewhere.

 

[bryan_kilco]

Have you tried inverting the phase on one of the tracks? Maybe try putting some sort of absorbers around the cab?

 

[mephetic_exhumation]

Ok guys so here's the clip. That's a riff from immolation - into everlasting fire, if anyone's wondering.

I know there are a few flaws in the playing but I think it's clear enough to show that the tone is washy as shit.

I can't figure out how to post the clip directly in the thread so I'll put a rapidshare link for now (hope I'm allowed to do that). If anyone can tell me how to post it here, I'd appreciate that. I'll edit it after.

https://rapidshare.com/files/2206010480/ruined-tone-massacre.wav


So does that sound to you guys like it's a room problem or something else?

No wander you're broke

haha sadly the only thing that's mine in that whole chain is the profire. The Les Paul is my friends' and the amp/cab belongs to an other friend, but I think he stopped playing guitar and we aren't really keeping contact nowadays. It also seems that he doesn't even care at all that he's leaving 4k worth of gear at my place, as unbelievable as it is.

 

[Clark Kent]

Well that clip has no phasing. It's way too dark though. I'd say you mic placement is far from the point it should be. It's okay that it's close mic'ed... that's how I run things too but I wouldn't let it touch the cloth since it will affect the tone slightly. Secondly... if you are using a single SM57 on a loud cab, it doesn't really matter what room you are in, just make sure it doesn't get any early reflections.

1) turn off all noise gates and drive your amp with gain at full until your cab starts making NOISE
2) put headphones on so that you hear what the SM57 sounds like
3) move the mic with your headphones on and find a sweetspot (sounds stupid, I know, but you'll quickly get the idea when you try it)
4) tweak your amp so it sounds good in your DAW. NOT SO THAT IT SOUNDS GOOD IN THE ROOM!

No phasing in this clip IMO.

 

[Fbarre]

I'm not sure if it's a problem with the room. To me it sounds like the signal is slightly clipping. As far as the sound goes an overdrive pedal would help to get the sound to be tighter. I would try to using another microphone position and amp settings to get a more defined sound. Right now it sounds a bit dark and loose. Could it be the guitar pickups?

 

[Uros]

4) tweak your amp so it sounds good in your DAW. NOT SO THAT IT SOUNDS GOOD IN THE ROOM!

While your suggestion may sound sort of logical to some degree, I'd advise the OP to do exactly the opposite - to set up the amp so it sounds good in the room first, and only then to put the mic against the grill and sweep it around.
It will also help him if he starts to record other people some day, as it prevents 'fix it in the mix' philosophy, which many clients have.

 

[mephetic_exhumation]

Ok so there's no phasing in the clip? interesting.

What made me thought there was some was because the tone was dark, I thought it was a cancellation causing that. And also because I looked at the rendered file in adobe audition and the phase analysis tool indicated that the phase was changing. But I guess I'm probably not understanding it properly or that I shouldn't rely on it in this situation. For those that are familiar with it, well the ball was shifting from green to red like crazy and oscillating between the + and - area nonstop

here's some info on it

http://help.adobe.com/en_US/Auditio...=WS58a04a822e3e5010548241038980c2c5-7f5a.html

As for the dark character of the tone, I guess #1 problem is because I made a few notches in the 4-8k area to reduce some fizz and I'm pretty sure I made my cuts way too harsh. Perhaps not enough treble on the amp too, it's approximately at 1 o clock. And I had a LP at 10k but I guess it wasn't that which was killing the brightness that much.

And to give more details about mic placement, it's like just a bit besides the center of the speaker with a slight angle (bit less than 45 degrees). That's not a position notorious for making really dark tones AFAIK.

So yeah.. that's a lot of things that influence the tone, where should I begin with? Perhaps remove all cuts in the 4-8k area and post again?


BTW thanks very much for all the help so far!

 

[miche]

I wouldn't rely much on those phase analyzers for distorted tones.

Could you post your raw guitar takes, with no eq / compression / whatever? They will tell more than processed ones.

 

[egan.]

While your suggestion may sound sort of logical to some degree, I'd advise the OP to do exactly the opposite - to set up the amp so it sounds good in the room first, and only then to put the mic against the grill and sweep it around.

+1.

 

[Clark Kent]

While your suggestion may sound sort of logical to some degree, I'd advise the OP to do exactly the opposite - to set up the amp so it sounds good in the room first, and only then to put the mic against the grill and sweep it around.
It will also help him if he starts to record other people some day, as it prevents 'fix it in the mix' philosophy, which many clients have.

Well it all depends. Personally I suggest finding the perfect sweetspots for mics with static/noise. After that I would start tweaking the amp so it sounds good in the control room. The room sound is not the same thing as a mic'ed sound. F.ex. your room can sound dark or bright which can't be heard in the mic'ed signal... but hey, I'll use what works for me and you can use what works for you. There are no rules.

 

[B36arin]

You shouldn't have phase issues with a single mic on a single source.

That is true, but what many people forget is that the cabinets which most of us use have either two or four speakers. When the distance between the mic and the speakers varies you get phase issues between the different speakers. That doesn't have to be a bad thing though

 

[Omega_Void]

...I looked at the rendered file in adobe audition and the phase analysis tool indicated that the phase was changing. But I guess I'm probably not understanding it properly or that I shouldn't rely on it in this situation. For those that are familiar with it, well the ball was shifting from green to red like crazy and oscillating between the + and - area nonstop

Positive phase is when the recorded wave is above the centre-line. Negative phase is when it's below the centre-line.

The phase meter measures the phase correlation between left and right channels (i.e. if they're always positive/negative at the same time, phase correlation is positive. If one is always positive when the other is negative, phase correlation is negative.)

With hard-panned double-tracking, the small timing differences between the two different takes means that the phase correlation between L&R channels will never be perfect.

Hopefully that helps to clarify what the tool is telling you.

I wouldn't rely much on those phase analyzers for distorted tones.

Overdrive distortion has no effect on phase. The phase analyser would give the same results if there was no overdrive.