SDC spaced pair question...

[Rudy4]

Hi all,
I'm interested in distances / angles / spacing / where you point your mics when you are recording with a spaced pair cardiod SDC configuration for acoustic guitar in particular. I'm using Avantone CK1's with cardiod capsules installed in my particular case if that matters for your answer.

I'm aware of the 3:1 rule, so I'm interested in how ya'll deal with that. I'm wondering this because I've been playing with the balance between distance and spacing and lately I've been liking the mics set back a little further, in the 12"-18" range, but obviously at that distance it starts to become more problematic to space the mics far enough apart.

What's your solution? Thanks!

[rick-slo]

First off, ignore the 3:1 rule for recording solo guitar.

Second, there is no magic formula (except perhaps in part the best possible recording space).

Set up mikes using headphones and your ears, and/or record a little bit, listen back, record a little bit, listen back... Sitting in front of a pair of mikes turn your body a little (right or left) and listen - it can make or break a good sound.

I have heard good recordings from all kinds of mike setups, some which work for me and some that don't.

Different parts of the room (say six inches from where you are now) give different sounds and do best with different mike placement

[Scott Whigham]

Yeah, I'm with Rick - it just takes a lot of work + practice to find the magic spot. I have a new guitar and I bet I've spent 4+ hours in the past week trying to find the right distance + placement of my spaced pair.

1) Find good sound
2) Go to sleep
3) Wake up next day and listen with fresh ears
4) Arrrggghhhhh

haha

[ukejon]

Nice mics you have there. Rick is right in saying that there are no hard and fast rules for arranging the mics. I find that for any given recording session I need to play around a bit with setup. Sometimes spaced pair works (I do try to do the 1:3 rule but tend to do close-mic setup at about 6" or 8"), or X-Y aimed near the 12th fret, or ORTF (110 degrees splayed out). Listening on headphones through a good source (I use the Apogee Duet 2) makes a huge difference and really allows to you fine tune the sound.

Also there are some folks here like Fran Guidry, alohachris, and Doug Young who have offered great advice in the past on mic setups. You might search for some of their past offerings.

[Joseph Hanna]

Originally Posted by rick-slo

First off, ignore the 3:1 rule for recording solo guitar.

Second, there is no magic formula (except perhaps in part the best possible recording space).

Set up mikes using headphones and your ears, and/or record a little bit, listen back, record a little bit, listen back... Sitting in front of a pair of mikes turn your body a little (right or left) and listen - it can make or break a good sound.

I have heard good recordings from all kinds of mike setups, some which work for me and some that don't.

Different parts of the room (say six inches from where you are now) give different sounds and do best with different mike placement

I certainly agree with you in spirit here Rick. I do have a bug-a-boo I notice all too often here and elsewhere when it comes to duel mics setups. I've been cursed to hear even the slightest amount of phase problems. My head tilts like a dog hearing a dog whistle. For me it's an ugly, ugly sound that makes me grit my teeth. There are lot's and lot's and lot's of recordings posted that have obvious and major phase problems.

I guess I'd modify your statement (at least for my ears) to say..by all means there are no rules for mic placement and (as most of us have experienced) some unexpected great results have come from "creative" positioning. Phasing however, for some, is a VERY unpleasing characteristic that very often rears it's ugly head when ignoring the 3 to 1 rule. Obviously there are some that simply don't hear (or feel) the effects of a badly out of phase duel mic recording but it is most definitely an uncomfortable sonic reality for some. Ignoring it doesn't make a whole lotta sense as opposed to at least keeping in mind.

[rick-slo]

Originally Posted by Joseph Hanna

I certainly agree with you in spirit here Rick. I do have a bug-a-boo I notice all too often here and elsewhere when it comes to duel mics setups. I've been cursed to hear even the slightest amount of phase problems. My head tilts like a dog hearing a dog whistle. For me it's an ugly, ugly sound that makes me grit my teeth. There are lot's and lot's and lot's of recordings posted that have obvious and major phase problems.

I guess I'd modify your statement (at least for my ears) to say..by all means there are no rules for mic placement and (as most of us have experienced) some unexpected great results have come from "creative" positioning. Phasing however, for some, is a VERY unpleasing characteristic that very often rears it's ugly head when ignoring the 3 to 1 rule. Obviously there are some that simply don't hear (or feel) the effects of a badly out of phase duel mic recording but it is most definitely an uncomfortable sonic reality for some. Ignoring it doesn't make a whole lotta sense as opposed to at least keeping in mind.

.
The thing is that it does not apply to a solo guitar (it is more for two separate instruments) nor is it practical with spaced pair mikes. Also timing differences give a sense of space (there is pleasant phasing and unpleasant phasing).

[Joseph Hanna]

Originally Posted by rick-slo

.
The thing is that it does not apply to a solo guitar (it is more for two separate instruments) nor is it practical with spaced pair mikes.

I'm not understanding this Rick?!? Please explain.

[sdelsolray]

I see three things with the extent to which the 3 to 1 rule applies to recording solo acoustic guitar:

1) Whether the particular note/frequency from the guitar is a single point source;
2) The difference in amplitude each mic hears for a particular note/frequency; and
3) How much the two tracks are collapsed towards mono on playback.

As to #1, the more a particular guitar's sound (i.e., note/frequency) is a single point source, the less the rule applies.

As to #2, the closer in amplitude each mic is (for a particular note/frequency), the more the rule applies.

As to #3, the more a mix is collapsed towards mono, the more the rule applies.

[rick-slo]

Originally Posted by Joseph Hanna

I'm not understanding this Rick?!? Please explain.

I am at work so I will be brief.

Try some stereo miking of a guitar yourself. You will be in for some surprises. Post some clips.

Think about the 3:1 rule as it applies two separate instruments (it is about volume levels of one source at one mike versus the other).

Think about how you are miking a broad sound source versus a more nearly point source.

Gotta go.

[Doug Young]

Mic positioning is an interesting series of trade offs. The challenge with the 3-1 rule with guitar is that say you put the mics 16 inches from the guitar, to minimize proximity effect. Then the mics have to be 4 feet apart, which is basically at the tail block and the headstock! Probably won't work. I usually place spaced pairs about 15 inches apart, which would mean 5 inches or closer to the guitar. That may work, but its pretty close! I'm usually more like 8 to 10 inches these days, and that's still close.

Phase is worth paying attention to, but in practice I don't worry about 3-1 for spaced pairs on guitar. With that mic setup, some phase differences are part of the sound. I think the challenge with phase is knowing when it matters and when doesn't. The only way to be perfectly in phase is to be mono. Our ears even use phase as a directional cue in real life, so phase as a general thing isn't something that has to be stamped out. You just don't want "bad phase", a situation where an anomaly of how you are recording creates an unintended and bad sound.

[Joseph Hanna]

Originally Posted by rick-slo

Try some stereo miking of a guitar yourself. You will be in for some surprises.

I mic guitars for a living Have professionally here in Los Angeles and before that in Nashville for a whole bunch of years. I think (although I'm always willing to be schooled) I understand the variables and theories in duel micing and I'm certainly always on the look out for phasing. I dunno if there are any surprises left but I'm always hopin'!!

We'll talk more when you get off work!

[ljguitar]

Originally Posted by Rudy4

...What's your solution? Thanks!

Hi Rudy...

I'm not sure how the 3:1 principle applies to omnidirectional capsules which eliminate proximity effect, so closer mic placement is less tone affecting. Not sure if that removes phase issues.

My experiments with two small diameter mics (20mm capsules) have included using a Jecklin Disk which eliminates the 3:1 element and proximity issues since it uses a pair of small diameter omnidirectional mics separated by the disc. Quite nice binaural recordings with it.

I have also done mid-side recordings with a pair of 1 inch capsule mics head-to-head (one upside down centered head to head with the right side up forward facing mic) the side one in figure 8 mode.

Someone here had done mid side with a small diameter mic as the forward facing mic and a large diameter as the side (in figure 8 mode).

I have done A/B recordings spacing the mics less than 3:1, but I measure the two mics with a cloth sewing tape measure (my wife's which I borrowed rather permanently) to be sure the mics are exactly the same distance from the capsule at both ends and then insist the player sit still (which only works sometimes).

If they maintain the distance the chances of the phase shifting are minimized. It's more noticeable when players move around during recording sessions. If I get a hyperactive player, I go Jecklin Disk and back off a couple feet.

[Doug Young]

3-1 doesn't apply at all in MS, Larry. That's a co-incident mic setup, mathematically equivalent to XY. So no phasing issues. The mics are essentially in the same location, as close as physically possible.

I also wouldn't equate player's shifting positions to phase differences between the mics, that just a stereo balance issue, which you can have even with co-incident setups. I suppose they're slightly changing phase by moving, but they're also changing levels - so I'd tend to just think of it as a balancing/stereo image problem, which is different than the basic issue of phase cancellation between mics.

The whole phase issue with solo guitar gets kind of hairy - after all, not all parts of your guitar even vibrate perfectly in phase!

[rick-slo]

Originally Posted by Joseph Hanna

I mic guitars for a living Have professionally here in Los Angeles and before that in Nashville for a whole bunch of years. I think (although I'm always willing to be schooled) I understand the variables and theories in duel micing and I'm certainly always on the look out for phasing. I dunno if there are any surprises left but I'm always hopin'!!

We'll talk more when you get off work!

Great. If you have done much solo guitar stereo mike recording I would like to hear a clip.
Also see Doug's comments. I share those thoughts.

[ljguitar]

Originally Posted by Doug Young

3-1 doesn't apply at all in MS, Larry. That's a co-incident mic setup, mathematically equivalent to XY. So no phasing issues. The mics are essentially in the same location, as close as physically possible.

I also wouldn't equate player's shifting positions to phase differences between the mics, that just a stereo balance issue, which you can have even with co-incident setups. I suppose they're slightly changing phase by moving, but they're also changing levels - so I'd tend to just think of it as a balancing/stereo image problem, which is different than the basic issue of phase cancellation between mics.

The whole phase issue with solo guitar gets kind of hairy - after all, not all parts of your guitar even vibrate perfectly in phase!

Hi Doug...

I know there are no mid-side or Jecklin issues, and I'm talking/thihnking about passionate players who rock back and forth while they play or move radically side-to-side. I have actually switched chairs to keep one guy in place but he just swiveled his butt so that didn't work.

But when using A/B with "A" at the neck/body joint and "B" below the bridge or behind the bridge, I've had ''swingers'' move in/out 6 inches at one end of the chain, which doesn't translate as well in the recordings.

Levels change, and the tone shifts when mic is uni-directional. Maybe it's not phase that is the issue, but I resorted to different mic techniques to try to compensate.