K. Margaritis 2/21/20 K. Margaritis 2/21/20

Three M/S Setups for Classical Guitar

Capturing the natural room sound of the guitar.

The Mid/Side microphone technique has almost a century of history. Developed by Alan Blumlein in the early 1930s, it became popular in the broadcast studios because of its compatibility with mono. Even in the recording studio, it appears to have many advantages over the most commonly used stereo techniques.

With small instruments like the guitar, it is easy to capture a too wide of an image, resulting in an unrealistic and often a blurry reproduction, especially with ORTF and AB techniques.

The "Mid" microphone of M/S provides a solid capture of the instrument, while the "Side" microphone is responsible for picking up the ambience of the room. The right balance of the two microphones allows for a truthful image of the guitar realistically placed in the sound field.

The M/S technique gives you the most control over the stereo spread, but the best part is that you don't have to commit to any balance until the mixdown, as you can always change the balance long time after the recording is finished.

Things to consider

As the "Mid" microphone is responsible for capturing the actual sound of the guitar, it is essential to take the time and make sure that it's placement is optimal. Otherwise, there is not a lot you can do to fix it. Also, if the room ambience is not pleasant there is not a lot you could do to improve it, so you are better off with a close AB technique and using artificial reverb in your DAW during mixing.

Here is one of several M/S setups that I've tried this week. I placed the "Mid" microphone at a distance of 55cm from the top of the guitar, aiming at the midpoint from the bridge and hole. With the capsule being at 96cm high, slightly angled downwards, placing it on-axis with the angle the I hold my classical guitar.

The "Side" microphone with a Figure-8 pattern was simply placed on top of the other at 90 degrees, aligning the capsules as close together as possible, minimizing phase issues. The whole setup was angled slightly to the sidewalls of my room. The room is medium-sized, with a wooden floor, high ceiling and a few interesting angles on the wall, making it relatively live-sounding.

Austrian Audio OC818 in M/S Setup

In this first example, I used an Austrian Audio OC818 pair with the "Mid" microphone was set to cardioid. The response of the Austrian Audio microphones is fairly natural, especially at the low and mid registers. A slight boost is present at the higher frequencies, but it retains the very smooth character of the classic ceramic capsule, making the classical guitar recording to sound polished and vivacious, without any sign of harshness.

Gefell UMT70s in M/S Setup

The second example utilises a Gefell UMT70s pair, these mics have a unique appearance, an incredibly small grill and an unquestionably satisfying feeling to the touch, the craftsmanship is second to none. The UMT70s shows a distinct bright character with slightly recessed lows in its cardioid pattern. The Gefell microphones offer coloured pickup but maintain a smooth quality. In a way, this combination produces a somewhat more finished recording, with nostalgic charm, it reminded me of some Julian Bream albums. The result is pleasing but differs from the sound that I hear when I play my guitar, in my room.

Neumann TLM193 and AEA N8 in M/S Setup

An often overlooked aspect of the M/S microphone technique is that it doesn't require a matched pair of microphones. So for the last test, I decided to combine the Neumann TLM 193 with a ribbon microphone for "Side" duties, in this case, an AEA N8.

The TLM 193 has a natural pickup, with good low-end extension, flat mids and unhyped high-end. The most gratifying aspect of the Neumann is that it captures all the nuances of the classical guitar without emphasising any frequency. Additionally, it is dead silent which enhances dynamic playing styles as it allows the notes to fade to complete silence.

The AEA N8 offers an extended high-end in comparison to more traditional ribbons and a very juicy low end. This combination in an M/S setup produces a bigger soundstage and a sound that is reminiscing of the what I hear when I play.

Conclusions

All three setups can produce high-quality recordings, although the perspectives of their designs are different. I'm used to the Neumann sound, and I gravitate towards that, together with the N8 I think they produce the purest and calmest recording, but with the expense of some definition and the higher noise floor of the ribbon. The Austrian Audio microphones are the most versatile and they take EQ well. They are detailed, without sounding overly analytical, and offer an elegant and smooth sounding result. The Gefell combo sounds like an excellent record from perhaps a different era, but if you love that sound, it is impossible to get it with the other microphones.

Coda

The M/S Stereo technique has the potential to create outstanding recordings, captures a full-bodied and defined sound while eliminating phasing issues. Larger halls and resonant spaces are where it excels as it allows us to concentrate on the recording and fine-tune the balance of ambience and close sound during mixing.

Austrian Audio

Neumann Berlin

Microtech Gefell

K. Margaritis 2/20/20 K. Margaritis 2/20/20

Austrian Audio OC818 and the PolarDesigner plugin

What if you could set-up the microphones, record your classical guitar and configure the best polar pattern your room after the recording is finished?

Polar pattern selection on large-diaphragm condensers is not a new thing, a few microphones intergrade continuously variable selectors that allow in-between pattern selection, or allow the two capsules to be recorded in separate tracks. Austrian Audio expands the possibilities with the PolarDesigner plugin.

The most important feature of the plugin is that it enables us to craft the perfect polar pattern responses across up to five crossover bands, at any time after the recording is finished. To make the plugin even more useful, Austrian Audio has packed a lot more into the PolarDesigner to perfectly fine-tune your sound.

Usual suspects

I decided to try it first on an M/S setup, I used the two output method only on the Mid microphone, I positioned it at 96cm high and around 60cm from the top of my classical guitar with a slight downward angle so that it is on-axis with the spruce top. I placed the second OC818 on top of the first in Figure-8 pattern.

Basic sounds

With the Side mic muted, I concentrated on the Mid mic for a while.

The unprocessed track, with each capsule recorded at a different track, is unusable without the PolarDesigner plugin, but that was expected.

First, I wanted to see how the basic patterns would behave. So, I enable the plugin, as well as some lean low-cut and high-cut filters.

Tweaking the patterns

After playing around with the controls for some time, I found that the Omni pattern assigned to the lower frequencies gives a beautiful body sound to my guitar. Cardioid and Wide-Cardioid patterns were chosen for the mids, to bring tones of the guitar in focus. And for the highs, I used more of a Wide-Cardioid pattern to add some room ambience.

I also used the free-field equalization preset, which I'm not exactly sure what the underneath processing is, but gave more depth and definition to the overall sound. I boosted the lows a little with the proximity control bar.

And finally, I added the Mid channels to the mix and balanced all three to get a natural room sound.

Conclusions

As you can see, the possibilities are endless, and you only have to position the microphones once, record a couple of takes and then figure out the perfect polar response during mixing.

Additionally, on remote location recording, lugging up monitors to accurately check that the microphones are placed in the most desirable position can be quite unattractive. Headphones, on the other hand, are never the best option to judge stereo spread and overall tonal balance. The PolarDesigner plugin allows for fine-tuning to take place with the speakers and room you know and trust at your mixing room.

Click here for the full review of both the Austrian Audio OC818.

PolarPilot App

Austrian Audio designed an App that allows for real-time wireless control over the analogue bias voltages of the OC818, allocating 255 discrete polar patterns for us to choose. Plus access to high-pass, and pad in realtime via Bluetooth. Unfortunately, they didn't send me the OCR8 Bluetooth dongle that is required for this to work, so I couldn't test it out.

The judgement day

The plugin allows uses some sort of AI that determines what is important and not and provides a spill terminator or maximize target algorithm which should in principle reduce unwanted spill from other instruments But, I didn't get to use.

Austrian Audio