Level matching acoustic guitar recording in ORTF and NOS

[Joost]

Ok, so I tried a few mic techniques with my stereo pair of Gefell M300s for my solo acoustic guitar recordings in the past few weeks (M/S, xy, ORTF, NOS, 3-1) and it turns out I like NOS the best, but with all those setups (except M/S) I have one problem:

I setup the mics and sit facing the mics straight:

mic 1 / \ mic 2
. . ._______ guitar

Then mic one is pointing towards the 12th fret and mic two is pointing towards the bridge. Then I set the levels on my preamp to the exact same setting and play. Then, of course, one channel will be louder than the other (mic1 picks up less energy than mic2).

I can correct that by changing the distance to mic one and until the levels are matched and thereby probably introducing phase issues, because mic 1 will be much closer to the guitar than mic 2, or I can change the level on channel 1 until I have a close enough match. I would say that the second method is better, but it still feels wrong.

I know this is probably a dumb question, but what should I do?

[Joost]

Anyone?

[Timothy Lawler]

Well I don't know what you should do but what I'd do is move the mic's back a few feet so they're picking up the whole instrument in a balanced way L/R to get a more true stereo rendering. I usually record in ORTF for acoustic and classical gtr and if the mic's are too close it comes out, to my ear, more as just 2 channel close mic'ing rather than a real stereo soundstage. Just my 2c.

Tim

[TheReal7]

Originally Posted by Timothy Lawler

Well I don't know what you should do but what I'd do is move the mic's back a few feet so they're picking up the whole instrument in a balanced way L/R to get a more true stereo rendering. I usually record in ORTF for acoustic and classical gtr and if the mic's are too close it comes out, to my ear, more as just 2 channel close mic'ing rather than a real stereo soundstage. Just my 2c.

Tim

I am about to do some acoustic tracking and I am a total noob. Could you explaing what ORTF is?

Thanks
scott

[mmyohane]

I can correct that by changing the distance to mic one and until the levels are matched and thereby probably introducing phase issues, because mic 1 will be much closer to the guitar than mic 2, or I can change the level on channel 1 until I have a close enough match. I would say that the second method is better, but it still feels wrong.

I know this is probably a dumb question, but what should I do?

Of course you can change the gain on channel 1. There's nothing wrong in matching the gain to get balaced stereo image.

[Timothy Lawler]

Originally Posted by TheReal7

I am about to do some acoustic tracking and I am a total noob. Could you explaing what ORTF is?

Here's a good description:
http://www.dpamicrophones.com/page.php?PID=131

Tim

[zakco]

Originally Posted by Timothy Lawler

Well I don't know what you should do but what I'd do is move the mic's back a few feet so they're picking up the whole instrument in a balanced way L/R to get a more true stereo rendering. I usually record in ORTF for acoustic and classical gtr and if the mic's are too close it comes out, to my ear, more as just 2 channel close mic'ing rather than a real stereo soundstage. Just my 2c.

Tim

Bingo!

Get a few feet back and move L/R and up/down until you like how the instrument fills the soundstage. If it sounds good then ignore how it looks, just listen....

-Z-

[TheReal7]

what would be a good pair of mics for this appication?

[Joost]

Thanks guys! Of course that would do the trick, why didn't I think of that.
As for which mics work for this application, you should look at Small Diaphragm Condensor mics and a (matched) stereo pair would be very preferable. I got a stereo pair of Gefell (old Neumann) M300s and they sound really good!

Here you see some pictures of the Gefell M300s in ORTF stereo setup
http://www.gefell-mics.com/images/M3...eview-540w.jpg
http://store1.yimg.com/I/mercenary-audio_1869_32304509
http://www.gefell-mics.com/images/M3...inbox-540w.jpg

"Gefell M300 pencil begins with a 21mm gold evaporated Mylar diaphragm assembly with a temperature-constant ceramic housing. This technology was borrowed from Gefell's Test & Measurement division whereby when testing rockets for aerospace; it was found that temperature shift would cause metal expansion and performance shift. Ceramic components are proven to provide a more stable and uniform platform when the microphone is subjected to changing environmental conditions.

To reduce self-noise, an innovative DC to DC optical converter eliminates spurious electrical currents and noise typical of 48V phantom powering, thus providing a pure DC voltage to the capsule. This results in the quietest operation levels while delivering a full 80-volt plate voltage, for an unprecedent ed 147dB signal handling without the use of an input attenuation pad. This makes the M300 an ideal candidate for the demands of today's advanced analogue and digital recording formats."

[Timothy Lawler]

Originally Posted by TheReal7

what would be a good pair of mics for this appication?

small diaphragm condensers with cardioid or hypercard pattern and good off-axis response.

Tim

[TheReal7]

Thanks for the recomendations. Now, since I don't have any mics and am going to be renting for this up coming weekend. What mics would fit the bill? Keep in mind the store isn't a high end audio so whey won't be caring any super slutty gear. Mostly AKG and the sorts. Would a pair of C1000s fit the bill?

[mmyohane]

I like Neumann KM184s in vertical CAP pair 1-2 feet away from the point where body and neck join. Nice and wide stereo guitar with no "bass on left and highs on right"-thing. I do mostly folk music though so a rock guy might think otherwise.

[TheReal7]

Thnkas mmyohane, but unfortunately, this store doesnt carry Neumann stuff :(

[mmyohane]

You could basically try any small diaphragm condencer microphone. If you're on a budget AKG SE300 series with cardioid capsules could work. AKG C460 / 480 could work also. Even Rode NT5 and Oktava MC012 could work.

[zakco]

If they carry shure, you could try a KSM141 or even an SM81 would work well in this application.

-Z-

[Timothy Lawler]

Originally Posted by TheReal7

the store isn't a high end audio so whey won't be caring any super slutty gear. Mostly AKG and the sorts. Would a pair of C1000s fit the bill?

I'd avoid those, personally. Unless the playing is very mellow they're likely to give you a screechy high end. What else does the rental store have?

Tim

[TheReal7]

Thanks again. I talked to 2 different stores. My options for mics and preamps are as follows:

Mics:
apex 180 and 190
Audio Technica AT3031
Rode NT4 (stereo mic)
Neumann U87
AKG C1000, C2000 and C3000


Preamps:
Avalon 2022
Avalon VT737SP (x2)
and of course I have me Mbox pres.


Please let me know what the best combination is from that list. Unfortunately, this is all I have to go with.

Thanks
Scott

[Timothy Lawler]

Originally Posted by TheReal7

Thanks again. I talked to 2 different stores. My options for mics and preamps are as follows:

Mics:
apex 180 and 190
Audio Technica AT3031
Rode NT4 (stereo mic)
Neumann U87
AKG C1000, C2000 and C3000


Preamps:
Avalon 2022
Avalon VT737SP (x2)
and of course I have me Mbox pres.


Please let me know what the best combination is from that list. Unfortunately, this is all I have to go with.

Thanks
Scott

Now you've really got my interest. I used a U87 through an Avalon 737sp recently at a studio and it was fantastic on flamenco guitar. Tracked mono at 4 ft distance in cardioid mode... rich and detailed w/no other processing except a little stereo verb needed for a finished track. Haven't used it on steel string acoustic though. If they have two U87's personally I'd go with those and the 737's. Haven't used a 2022 but have heard excellent tracks done with it. The Rode NT4 is a good mic also but surely very different.

Good luck with the recording.

Tim

[TheReal7]

Thank Tim. You confirmed what I was thinking. They have 2 and 2 737s as well and the XY mic stand. Gonna pick this up next weekend and giver.

thanks

[Timothy Lawler]

Originally Posted by TheReal7

Thank Tim. You confirmed what I was thinking. They have 2 and 2 737s as well and the XY mic stand. Gonna pick this up next weekend and giver.

thanks

That gives you LOTS of options too since they're multi-pattern mic's. When I was using the 737sp I wasn't engineering, I was playing, so didn't tinker with the compression or EQ on it. We just tracked without needing them. You should be in store for a fun session. Hey, I didn't know there was a stereo bar setup for mic's that size. I figured you'd need to put them on separate stands/booms/shockmounts.

Tim