mic placement on 1x12 combo amp (guitar)

[dainbramage]

Beat me with a verbal baseball bat if I'm wrong, but wouldn't panning the two mics 100% left and right eliminate the phase issue entirely at least when it comes to comb filtering?

 

[mixsit]

True that. Good catch.
Another thing to throw in there too maybe is the precedence effect- the closer mic will pull the image towards it (partial pan, you cound get results stronger than the pan pot' would suggest.
Anyway, a bit of stereo' effect in there as well.

 

[Greg_L]

Beat me with a verbal baseball bat if I'm wrong, but wouldn't panning the two mics 100% left and right eliminate the phase issue entirely at least when it comes to comb filtering?

Not really. One source into two close mics out of phase will still have an ugly hollow seashell sound, even when panned. Try it for yourself. The only DAW trick "someone" can do to make it sound clean and tight is to manually micro-slide one track into phase with the other. It's not a real stereo effect because it's not a real stereo recording.

Or, "someone" can have one mic significantly lower in level than the other.

Or, just live with the out of phase sound.

 

[Greg_L]

Here, I plugged into one of my wonderful Marshalls and did a quick little test cuz I'm such a nice guy and will always put my money where my mouth is. I like doing stuff like this and hopefully someone can get something useful out of it.

Here's two mics on one speaker - in phase - or really damn close to it. The amp and cab is a Marshall JVM410 into a 1960a 4x12. I've outfitted this cab with two Celestion Greenbacks and two Celestion G12-65s. For this test I used one of the Greenbacks.

The mics and placement:
Audix i5 - on axis, on grill, dead center of speaker.
https://copy.com/d6WuEvLcXlJSstwX

Shure SM 57 - on axis, on grill, at speaker edge..
https://copy.com/sypKU88rKEUsxfk6

These are just little wav clips recorded at 24/44100.

Here's what you do if you're interested: I've done the hard part for you, so just download both clips and bring them into your DAW of choice. They are in-phase, so just bring them in and you can hear how the two mic positions interact. As you'll hear, the centered mic is pretty dang bright, and the edge mic is pretty woofy. But that's okay. Play with the levels of each, mix and blend, play with some EQ on each, and pan them however you want and watch what happens. Then, slide just one of them a few milliseconds out of phase and watch what happens. It's drastic, and to my ears, pretty ugly. But you may like it.

Just give it a try at your convenience.

 

[dainbramage]

Greg, that is highly appreciated. I will play around with it first thing in the morning as I have the day off tomorrow. Awesome!

(Although I suspect you just needed a good excuse for posting yet another picture of your rig. Which is cool )

 

[Greg_L]

Greg, that is highly appreciated. I will play around with it first thing in the morning as I have the day off tomorrow. Awesome!

(Although I suspect you just needed a good excuse for posting yet another picture of your rig. Which is cool )

Haha, I'm not shy about a little bragging!

But really it was more for the mics. Honestly.

 

[bouldersoundguy]

Beat me with a verbal baseball bat if I'm wrong, but wouldn't panning the two mics 100% left and right eliminate the phase issue entirely at least when it comes to comb filtering?

Yes, until the mix gets played in mono.

 

[mixsit]

Coo.. Let's play
Here's some x-amples from Greg's cool tracks.
In all cases 'dark ('edge) mic panned 100% left, 'bright 100% right.

#1 is the two straight with the bright mic +3 to balance them L/R

#2 bright' has a 1ms delay (worth about a foot-'o offset gamers
THE first (or biggest) thing that happens is Haas pan / precedence effect kicks in. The effect is so strong it takes about 10 or so dB to overcome it...

#3 the non-delayed ('edge) mic -10 (and a few db global boost for some of the level lost)
Here you have the phasey 'sick feel, more than any terrible tone changes -crunch guitar with a different flavor of 'scoop. Who's to say this couldn't be a target' tone. Sum it mono and check it out.

#4 is the delay (and the -10) with the tracks swapped. For whatever reason having the bright mic 'lead (and the edge mic compensated) sounds cooler (YMMV..

#5 is 'bright delayed again but 8 ms. Now two things happen. One, it took way less level compensation on the non-delayed edge mic, and we're getting out of the strong Haas pan range and into a possibly useful 'stereo effect. Notice how there's some random L/R movement' now as the chords shift in their tone centers.

Not bad.
Lots-o-fun

 

[Armistice]

The rule of thumb is, closer to the edge more bottom, closer to the centre more tops, so I start about halfway.

This is how I miked my guitarists amp when we recorded the last album, all close kicked as we played the tracks live, guitar, bass and drums.

There is a fathead ribbon, a sennheiser ME20 omni pencil condenser and a Sennheiser 421. The 421 sometimes was swapped out to a sm57 depending on the track. All mics going to separate tracks on the recording.

Alan.

View attachment 86051

Nice rack of basses there Alan...

 

[witzendoz]

Nice rack of basses there Alan...

Haha my turn to show off, 1975 Precision USA (bought New by me), 1994 jazz fretless MIJ, 1989 Precision acoustic (hollow body) MIJ with factory fitted fretless jazz neck. Also own a Ibanez BTB 5 string extra long scale 35". and a ARIA SWB electric upright. Sold off my other basses last year.

Alan.

 

[jf.burman]

Try to put the two mic a close as possible to each other to be more phase accurate. If you invert the phase it should almost take out the sound completely.
A great and classic match is a sm57 with an MD421

 

[powpowmeow]

i have the at4050, which is pretty much flat until 9khz, sitting about a foot and a half in front
a 57 jammed in the grille pretty close to the edge of the speaker
mixing in the 57 dependent on how much meat i want
sounds pretty awesome

phasing starts when i pull the shure out a couple inches

just using one or 2 57's didnt do it for me. colored the sound way too much

 

[mixsit]

i have the at4050, which is pretty much flat until 9khz, sitting about a foot and a half in front
a 57 jammed in the grille pretty close to the edge of the speaker
mixing in the 57 dependent on how much meat i want
sounds pretty awesome

phasing starts when i pull the shure out a couple inches

just using one or 2 57's didnt do it for me. colored the sound way too much

'Phasing' you didn't like
Sorry to keep hitting on this.. but it is true

 

[powpowmeow]

'Phasing' you didn't like
Sorry to keep hitting on this.. but it is true

what?

 

[bouldersoundguy]

what?

i have the at4050, which is pretty much flat until 9khz, sitting about a foot and a half in front
a 57 jammed in the grille pretty close to the edge of the speaker

With this spacing there is already phase interaction. What you heard wasn't the difference between being in phase or not, it was the difference between phase shift you liked and phase shift you didn't like.

 

[mixsit]

With this spacing there is already phase interaction. What you heard wasn't the difference between being in phase or not, it was the difference between phase shift you liked and phase shift you didn't like.

This is kind'a along the line of spill'. When we don't like it - we call that 'bleed.
When we do like it, it gets recognized as 'adding ambience, and ‘depth..

 

[powpowmeow]

With this spacing there is already phase interaction.

mic 2 is a foot and a half from speaker.
mic 1 is a few inches away

i had assumed that i was breaking the 3:1 rule when pulling mic 1 out an inch or 2, because thats when i started hearing phase.

well, like most things in life, you dont need to fully understand "why" something "is" to appreciate "what" it "is"

 

[bouldersoundguy]

mic 2 is a foot and a half from speaker.
mic 1 is a few inches away

i had assumed that i was breaking the 3:1 rule when pulling mic 1 out an inch or 2, because thats when i started hearing phase.

well, like most things in life, you dont need to fully understand "why" something "is" to appreciate "what" it "is"

The 3:1 rule doesn't apply to a single source, it applies to multiple mics on multiple sources where you want to minimize bleed.

For a single source just use your ears and position things to sound good to you.

 

[mixsit]

mic 2 is a foot and a half from speaker.
mic 1 is a few inches away

i had assumed that i was breaking the 3:1 rule when pulling mic 1 out an inch or 2, because thats when i started hearing phase.

well, like most things in life, you dont need to fully understand "why" something "is" to appreciate "what" it "is"

The 3:1 rule doesn't apply to a single source, it applies to multiple mics on multiple sources where you want to minimize bleed.

For a single source just use your ears and position things to sound good to you.

True that- you don’t have to have ‘the rules, or ‘science’ of it.
I attempt to anticipate this- the mistaken notion of ‘3:1 / close-far mic’thing, back on post 17--

To cover again as it's a useful bit to get driven home- The only place where ‘two’ can be 'in phase’, is equal distance/equal time.

So the bottom line is for any 'second mic’ your choices are any position where your out of phase at some frequencies (in phase at others) tone -- make for pleasant useful combinations when blended together.

You can also have the case were one position makes for a very good tone picture (on its own), but the combined times don’t. Then the option is to adjust their relative times so they do work blended.

Another bit that might be helpful is the -9 dB rule;
The combined phase effect of any second signal attenuated by about that much are no longer oblivious- therefore making them not a problem.

In these ‘near + far mic’ questions this is often mistakenly applied / referred to / AKA as “The 3:1 Rule”.