Improvements to Mid/Side tracks - '56 Martin 00-18 + Neumann TLM102 + AKG C414 XLS

[howthewestwas1]

9/11/16 UPDATE
After getting lots of great advice from you fellow AGF'ers I took another stab at my Mid/Side techniques to correct for unbalanced stereo imaging. Changes since last time:

1. Combined both mics onto a single mic stand, positioned 14 inches from guitar, slightly off axis at center of guitar
2. Balanced both mics for equal gain in cardioid mode prior to M/S setup
3. Re-positioned the mics - TLM102 (mid) ontop near center of the guitar, at level of guitar's waist angled slightly down + AKG on the bottom.
4. Swapped out the C314 for a C414 XLS (and engaged the 80 hz HPF)
5. Still using dual Universal Audio Solo 610's for each mid

Here is the final product. I did apply a very subtle HPF to the Neumann to tame some boominess. I think it turned out great! What do you guys think?

"The Furrowed Brow"


"Mint"


The inspiration (see below the 18i8)


The new mic setup



Original Post:
I became a dad 7 weeks ago and part of our nightly routine of getting our son to bed is me playing guitar for him during his last feed for the evening. I've been working on a series of originals for him in the process and finally got some time this weekend on a retreat to the family farm to record them.

I have previously just been using single mic, mono techniques but have begun to experiment with the world of stereo. I decided to go with the mid/side technique and am quite pleased with the results!

http://imagizer.imageshack.us/v2/102...923/OFR4u2.jpg

Here's the setup:
- AKG c314 (side - figure 8, stock settings) -> Universal Audio Solo 610 (lo-cut engaged)
- Neumann TLM 102 (Mid- cardioid) -> Universal Audio Solo 610 (lo-cut engaged)
- Focusrite Scarlett 18i8
- Ipad Mini (Cubasis)

Mics were positioned at 12-14th fret, 12-16 inches from the guitar. Love the warm, buttery vibe from the solo610s. As always, it's fingerstyle and Martin Retro custom lights (11-52) for me.

Edited tracks - mid track panned slightly left + lowered sides to correct "lean"
"The Furrowed Brow"
https://soundcloud.com/user-95990230...ed-brow-1956-2

"Mint"
https://soundcloud.com/user-95990230...martin-00-18-2


Original, off center recordings (I have since taken these down)
"The Furrowed Brow"
soundcloud.com/user-95990230/the-furrowed-brow-1956-1

"Mint"
soundcloud.com/user-95990230/mint-1956-martin-00-18

[rick-slo]

Much better with two mikes. Spaced pair mic'ing is my favorite way to go.

[Doug Young]

Nice gear, nice playing, and nice overall sound, but you know that the right channel is about 8db hotter than the left? Getting left-right balance with MS can be tricky since your meters aren't helpful during mic setup.

Also, you're getting some boomy notes - not real bad, but at a few points it leaps out. Where are the mics placed? One thing I find works for me with MS is to have the mid mic placed at about the top of the guitar, well above the sound hole, but centered as far as L/R on the sound hole. Then I put the side mic below that, basically in front of the soundhole, but of course turned sideways so the soundhole is in the null. That seems to produce a nice wide sound, balanced L/R, and dodges the boom of the soundhole. It might also be that you need to back the mics up a bit to eliminate some of the boom

[howthewestwas1]

Thanks for the comments! I did notice the right channel was a little hotter. I assumded it was more of my right hand getting picked up. I am experimenting with the placement of the mid mic. Right now I just have it set up as if it were just a single mic technique, aimed around the 12-14th fret. I am about 14 to 16 inches from the mics. I think I tend to like the close mic sounds, less room ambience, hence the propensity for boom. Will keep working on it!

[Doug Young]

Originally Posted by howthewestwas1

Thanks for the comments! I did notice the right channel was a little hotter. I assumded it was more of my right hand getting picked up. I am experimenting with the placement of the mid mic. Right now I just have it set up as if it were just a single mic technique, aimed around the 12-14th fret. I am anew here from 14 to 16 inches from the Mics. I think I tend to like the close mic sounds, less room ambience, hence the propensity for boom. Will keep working on it!

That would do it - it's hard to get balanced stereo from the 14th fret - very little sound on the fretboard side! You might try that middle of the guitar spot and see how that works for you. Your iPad may not have the ability, but what I do for getting balance is setup my inputs with a MS-decoder plugin ahead of any metering while setting up the mics, so that I can see the levels as they'll end up. Then I shut off the decoder before I record. This is easy to do in Logic, no idea about your ipad app. Another thing you can do, depending on you physical mic setup, is set up as X/Y, get your balance, then just rotate your mics to the MS position. Looking at your photo, I think you could do that.

[jomaynor]

Originally Posted by howthewestwas1

Thanks for the comments! I did notice the right channel was a little hotter. I assumded it was more of my right hand getting picked up. I am experimenting with the placement of the mid mic. Right now I just have it set up as if it were just a single mic technique, aimed around the 12-14th fret. I am anew here from 14 to 16 inches from the Mics. I think I tend to like the close mic sounds, less room ambience, hence the propensity for boom. Will keep working on it!

I look forward to hearing your next recordings with the adjusted mic placement.

Even with the current channel dB discrepancies, you're already getting the delicious "warm and friendly," high quality sound that one gets with a first-rate guitar recorded thru a first-rate signal chain.

[howthewestwas1]

So the db issue may not actually be a position issue, but a phase one.

When I have the three tracks (1. Neumann mid down center, 2. AKG side panned left, and 3. AKG side panned hard right) with no phase inversion on any track, the sounds is thin and "out of phase". Note the equal L and R volumes on the master bus (bottom right)



When I flip the phase on one of the "side" tracks (track 3), the sound is fuller but notice the Right volume on the master bus is hotter. The same thing happens if I apply the phase switch to track 2, but the Left volume becomes the hotter one.



It appears that the "mid" track is producing an additive effect to the side of the phase inverted track and a subtractive effect to the other side. Is this normal? In watching some demos on YouTube I can see this occurring in other videos as well.

Thanks for the help

[Doug Young]

Are you sure the side tracks are panned? I don't know this app, so I don't see where the pan is being done. If you can post the raw 2 tracks, M and S, I'd be happy to decode them using an MS plugin (which is way easier, and more foolproof) and see what you have.

EDIT:

Actually, what you're seeing makes perfect sense. Before you flip the phase, you basically have mono - the mono M signal, and the S signal on both panned tracks, which identical. So you have a mono blend of the 2 mics. As soon as you flip the phase, the M/S calculation kicks in, and you have stereo, complete with whatever balance is there in the stereo image. BTW, if you want to verify this and see a bit of how inverted phase works, mute the mid signal, then listen to the two side tracks, with one inverted. It should sound pretty odd, but that's expected, it's just the side info. Now, if you have a master mono switch on your output, go to mono mode. What happens? Everything goes silent! The two out of phase signals completely cancel.

[howthewestwas1]

They are panned. If you look at the top of each bus there is a green bar denoted the side of the pan. There bar is graged out in the first track.

I'll email you the raw mid and side tracks. Thanks a bunch! They will be under my wife's email I am using her ipad :P. My email is [email protected]

[Doug Young]

Originally Posted by howthewestwas1

They are panned. If you look at the top of each bus there is a green bar denoted the side of the pan. There bar is graged out in the first track.

Ah, got it I missed that. Got the mid file.

[howthewestwas1]

I don't know how the mid file got through but I can't send the side file due to the size. I was able to upload both tracks to Dropbox though. Use these instead:

Side
https://www.dropbox.com/s/2anqroke7s...0side.zip?dl=0

Mid
https://www.dropbox.com/s/3xr2jq3pq1...20mid.zip?dl=0

[Doug Young]

Got them. Yeah, as I said in the edit to my earlier post, nothing's wrong, the mics are just not positioned to be balanced, so once you're in stereo you get an unbalanced L/R mix. I get the same exact behavior you see.

one thing I do notice is that the side signal is a bit hotter than it should be. When you use mismatched mics, you should calibrate the levels. Aim both mics forward, and use some signal source, even back up and hum or whistle, or better yet use a signal generator on your ipad or phone, and adjust the gain so that both mics produce the same volume. Then turn the side mic. The signal will drop about 6 db, which is expected, there's less volume in the side information. With what you have (ignoring the balance issue), it will work, but you will by default have an exaggerated width. When calibrated correctly, with the faders set the same, you will have the equivalent of X/Y. You can then go from there, to create a wider sound by raising the levels of both sides, or narrower, by decreasing them. With your current levels, the width will be pretty wide, which may sound nice, but ideally you want to start from a known place and deliberately choose the width.

[howthewestwas1]

Thanks, Doug for taking the time. This was very educational and helpful! I lowered the side volumes a bit based on your observation and it's does narrow the stereo field a little and in doing so seems to lessen the db difference on each side.

Thanks again!

[howthewestwas1]

Eureka!

I went back in post for my original recordings and just tweaked the levels for each track. Panning the mid track ever so slightly left and bringing down the side tracks a bit (more so on the right) brings the stereo image pretty close to center and I retain all the sparkle!

I have updated the original post with these tracks

[Doug Young]

Originally Posted by howthewestwas1

Well I tried experimenting with the mic positioning. I am finding that the mics have to be positioned more toward the center of the body of the guitar, and thus the sound hole. To minimize boominess and proximity effect I had to place the mid mic on top (so that it is not directly in front of the sound hole but above it) and the figure 8 mice on the bottom (the soundhole becomes the "node"). I am able to get a more balanced stereo image but I lose some of the sparkle. Interested to hear your thoughts. Maybe I need to be using spaced pairs...

That sounds very nice, balance-wise. That sounds like the placement that I was trying to describe, and what usually works for me. You might experiment with different heights and distances from the guitar. A few inches can make a big difference, for better or worse.

Did you EQ this? It's got a lot of high end, around 10K, but seems a little lacking in presence and punch somehow, and comes off as a tad muddy at the same time.

Every mic placement has its pros and cons, some work better with different guitars, and so on. My overall preference, given two mics, is for spaced pairs, but MS has it's benefits. I actually usually do both - spaced pairs with an MS pair in the middle, and then I can mix to taste, sometimes one, sometimes the other, often both, with the mix tending one way or the other.