ORTF on acoustic - your kind thoughts please

[adventureboy]

Originally Posted by ukejon

Certainly not in the same league as Doug, but his advice has been a big help to me and in the few recording I've done with ORTF the results seem rather inconsistent and a bit distant sounding, sort of imprecise without sounding muddy or anything like that. The 110 degree configuration does indeed present some real problems in terms of finding the sweet spot. And then the angle of the mics is a bit odd relative to the instrument, whether pointed towards the neck or the bridge (I'm speaking about close mic placement here, which is my only option).

Conversely, the spaced pair seems to offer a better ability to really dial in on the neck tones and body tones that are most desirable for a given song. There is better tonal breadth but also an immediacy to the sound that I don't seem to get with ORTF. Sort of the best of both worlds. As for XY, that certainly is a very reliable setup and a good direct tone (I like it for ragtime/Travis style tunes). But, to my ear, it is not as rich or dynamic as the spaced pair, which offers some nice flexibility when mixing and panning.

Interesting stuff there Ukejon, thanks for taking the time to explain it. I'm just about to upload some more soundchecks on the subject

[adventureboy]

Ok, I've done some fingerstyle samples today focusing on the main guitar body using ORTF stereo mic configuration again at 50cm, 45cm and 40cm using between the bridge and soundhole as centre point first, then the actual Soundhole as center point and finally between soundhole and the neck as centre point. Seagull S6 guitar, 2 x Rode NT1A mics and Focusrite pre.

https://soundcloud.com/adventureboy/...cm-40cm-bridge



I've really appreciated and taken onboard all your comments and advice so far, it's been really helpful and would be likewise extremely grateful if any of you would care to listen and compare the different samples I've done today and offer any comments. Thanks again
Rob

[sdelsolray]

The sonic result of ORTF with (fairly) close mic'ing for acoustic guitar significantly depends on the off axis frequency response of the microphones, and the room. Mics with poor or uneven off axis response color the sound of the recording when used in ORTF.

[Doug Young]

These all sound pretty nice to me, I think you're on your way. I like the 1st example at 40 cm, but it may just be because that one sounds most balanced to me.

[Fran Guidry]

Originally Posted by adventureboy

Thanks, Fran
were you referring to ORTF configuration there?
I monitor on Sennheiser HD280 Pro headphones which are fairly well sealed. I'll bear in mind your advice when I do some more soundchecks later.

I was referring to an ORTF array but it applies to any kind of stereo mic technique.

Fran

[adventureboy]

Originally Posted by Doug Young

These all sound pretty nice to me, I think you're on your way. I like the 1st example at 40 cm, but it may just be because that one sounds most balanced to me.

Thanks, Doug
I liked that between bridge/hole example myself and it seemed to sound ok when I was monitoring too. I'm not sure if I prefer 45cm or 40cm.
Interested to hear what anybody else thinks

[adventureboy]

Originally Posted by Fran Guidry

I was referring to an ORTF array but it applies to any kind of stereo mic technique.

Fran

Fran,
it seems you were right about shifting the ORTF mics towards the bridge side of the soundhole, that's where I think is sounding best on my uploaded clips today.

[ukejon]

Doug or Fran, is there a difference in the effectiveness of ORTF between small and large diaphragm mics?

[Fran Guidry]

Originally Posted by ukejon

Doug or Fran, is there a difference in the effectiveness of ORTF between small and large diaphragm mics?

ORTF is unusual among mic patterns because it is a very very specific arrangement based on extensive experimentation by the French national radio system. It specifies not only the angle and distance between the mics, but also specifies that the mics be small diaphragm cardioids.

Obviously this doesn't mean that setting up LDs in this configuration won't work, it just means that it won't be _true_ ORTF.

Now, on the difference between LD and SD mics, based on my experience there is no general characteristic that that can be assigned to one or the other. There are theoretical differences, specifically greater narrowing of the pattern at high frequencies for LDs and higher self noise for SDs. But in practice, any two SDs are likely to be more different than any SD vs LD. It's only on the internet that there is an "LD sound" or an "SD sound."

Fran

[ukejon]

Thanks, Fran. Regarding the differences between SD and LD, I've had trouble finding a LD that doesn't seem to have a ton more self-noise than my Shure KSM 137s. And when I record with LD there seems to be more of a need to do rather aggressive high-pass filtering to remove low end noise and rumble/hum.

On the other hand, I keep wanting to believe (probably without any rational justification) that blending an LD and a SD in my recording will yield a mix of big warmth and brighter presence.

[rick-slo]

Originally Posted by ukejon

Thanks, Fran. Regarding the differences between SD and LD, I've had trouble finding a LD that doesn't seem to have a ton more self-noise than my Shure KSM 137s. And when I record with LD there seems to be more of a need to do rather aggressive high-pass filtering to remove low end noise and rumble/hum.

On the other hand, I keep wanting to believe (probably without any rational justification) that blending an LD and a SD in my recording will yield a mix of big warmth and brighter presence.

Just keep looking. It varies by specific mike but in general LD as a class of mikes have lower self noise than SD mikes. For example my TLM 103 self noise is 7 dB-A. Your mike's self noise is 14 dB-A. Mixing a LD and SD for stereo recording does not guarantee any specific results - it is still more about mike placement.

[Fran Guidry]

Originally Posted by ukejon

Thanks, Fran. Regarding the differences between SD and LD, I've had trouble finding a LD that doesn't seem to have a ton more self-noise than my Shure KSM 137s. And when I record with LD there seems to be more of a need to do rather aggressive high-pass filtering to remove low end noise and rumble/hum.

On the other hand, I keep wanting to believe (probably without any rational justification) that blending an LD and a SD in my recording will yield a mix of big warmth and brighter presence.

When I started comparing mics 10 years ago I always "heard" what I was told I would hear by internet "experts." Of course, those comparisons were completely uncontrolled and sighted.

As I learned more about mics and audio technology and comparison testing, I realized that I was not comparing the mics at all, I was comparing the results of placement, level setting, and performance differences all filtered through unavoidable subjective bias.

The solution, the only meaningful solution, is to reduce the variables by careful level matching, using the same performance, and blinding the result. This is a pain the rear, it takes some tools and some time and some care, but I was amazed at how many of the "obvious" differences I had heard before disappeared when my comparisons were controlled and blinded.

These days these tests are easier than ever if you have a smart phone, because the signal generators and SPL meters are available in a low cost app.

In your specific case I can think of two issues that could impact what you're experiencing. If your LD mic is cardioid dual diaphragm, which many are, these tend toward omni response at low frequencies. And LD mics as a class are more sensitive than SD mics as a class, so at the same gain level they will capture a higher signal level. Small differences in level are often interpreted by our hearing system as a difference in tonal balance and audio quality.

Fran