Earthworks: PM40 PianoMic System

I like gear that makes a statement. The long, narrow aluminum briefcase of the PM40 PianoMic System certainly makes one. That of, "I've got an upscale rifle here" — an impression that can come in handy at times. But back to recording...

People have been mic'ing acoustic grand pianos in much the same way for decades. If you're recording in a studio and have no issues with acoustic bleed from nearby instruments, then many traditional approaches are just fine. Close or mid-mic'ing with condenser or ribbon mics can be a great way to go. However, in the studio or on the stage, things can get much more complicated when acoustic isolation becomes a requirement. Closing the piano lid can minimize bleed, but that is impossible, or at best problematic, if you are using traditional mic'ing techniques. Front-address mics won't always allow the lid to close, and the sonic coloration resulting from closing the lid is a liability even with side- address mics. Some people have addressed this issue by using either pickups mounted on the soundboard or a boundary mic (like a PZM) inside the lid. In my opinion, both of those options can be rather hideous, sonically. Often, a huge amount of EQ is required to make the sound barely passible. To me, that tradeoff is not acceptable. So, Earthworks has attempted to create a system that delivers the best of both worlds: acoustic isolation, and excellent sound quality.

The Earthworks PM40 PianoMic System utilizes a pair of high-quality omnidirectional condenser mics mounted to a telescoping bar using miniature goosenecks. The bar fits across the case of the piano and allows the lid to be completely closed. However, there is a little more to it than that. The mics have a very wide frequency response (9 Hz — 40 kHz!) and are a type called random-incidence. Now, I must admit, I was not previously familiar with this type of mic. After doing some research, I learned that a random-incidence mic is designed to have a flatter frequency response in situations where the sound is arriving from many different directions simultaneously. This supposedly helps the mic smoothly cover the entire range of the piano. Another impressive specification is the ability to handle sound levels up to 148 dB SPL.

In order to keep a low profile and allow the lid to easily close, both channels of audio are carried over one rather thin cable that exits one end of the bar. This cable is plugged into an aluminum breakout box. The output of the box is a pair of standard XLR connectors.

Installing the system takes moments, not even minutes. Telescope the bar to span the width of the piano, and tighten down the fittings to lock the bar at that width. Run the cable out of the side of the piano, and plug it into the breakout box. That's it. There are a few choices and adjustments that are possible. Since the support bar can adjust to the width, it is possible to move it to vary its distance from the front of the piano. Earthworks suggests positioning the mics 2''-3'' away from the dampers as an initial starting point. Also, although the mics are locked at a spacing of 16'' between the capsules, you can slide the pair left or right as needed to favor a lower or higher string emphasis. The short goosenecks also allow some alterations of mic positioning.

My first experience with the mics was a rather clinical setting, rather than a practical one. We set up a listening session with solo piano, just to get an idea of the overall system performance. The piano used was a Steinway Model B. I set up the PianoMic System along with other conventional mic'ing approaches. These included AGK C 414 XLII, Neumann U 87 Ai, and Earthworks QTC40 mics. The QTC40 is an omni mic with similar specs to the PianoMic, but are not random-incidence mics. However, I wanted to see how they would perform compared to the PM40 mics. All were fed into Millennia HV-3R preamp channels.

We first started with the other mics closer to the soundboard than I normally would place them, because the PianoMic System positions the mics pretty close. For this first listen, the mics were set in similar spacing to the 16'' PianoMic System. The '414s and U 87s were about 12'' above the soundboard. However, the QTC40s were placed right next to the PianoMic capsules to see how they performed with a similar placement.

When listening back to the recorded files, all of the results were not entirely compelling. While they weren't bad, it was obvious some position changes would be required. The best results in this initial setup came from the U 87s. They exhibited the best overall image and tonal balance. The '414s weren't bad, although they lacked the definition in the midrange that I heard from the U 87s. The PianoMic system had great response in the low- frequency range of the piano, but it lagged slightly behind the U 87s in detail and imaging. The Earthworks QTC40s came in last initially, but remember that we placed them very close to the soundboard, right next to the capsules in the PianoMic System. This is not how the QTC40s were intended to be used, but we were experimenting.

We then repositioned all of the mics, backing them off a bit into a more traditional placement. As for the PianoMic System, we slid the bar a bit farther away from the hammers and adjusted the goosenecks to position the capsule a little higher. We heard a huge difference in all of the mics.

Listening back, it was obvious that we had found the sweet spot for the PianoMic System. They now slightly surpassed the U 87s in terms of detail and clarity, as well as body. While the U 87's imaging was still slightly wider, the PianoMic System's was in no way narrow. It was coherent and balanced. The '414s had more top end sparkle, but sounded a bit less natural in the midrange by comparison. Now positioned towards the edge of the piano case, the QTC40s were similar to the PianoMic System in terms of clarity, but lacked the slightest amount of body in comparison.

With these mic positions, it might be a toss-up as to whether your preference would be the U 87s or the PianoMic System. But that is assuming that we are talking about a situation that allows the lid to remain open. Obviously you can't close the lid on a pair of U 87s.

I was able to test the performance of the system with a closed lid in a live setting. We mic'ed a 9 ft Kawai EX concert grand for a jazz performance, splitting the mic lines and feeding both the FOH console and a Pro Tools rig. The stage was fairly well occupied with musicians in close proximity, including a drum kit and amplified bass. The approach in the past had been to use a pair of '414s while putting the lid on the short stick. This was far from ideal, as it still allowed a good amount of bleed from the drums and created some nasty issues with the back capsule being so close to the bottom of the lid. After positioning the PianoMic System, we were able to close the lid fully. This greatly reduced the unwanted stage bleed, and the design of the PianoMic System meant that the interaction with the closed lid was minimized. Now, I'm not going to say that the closed lid made no difference at all sonically — because it did — but we had nowhere near the issues that arise in that scenario from a closed lid with traditional mics. Although there was a definite boxiness to the midrange stemming from the closed lid, it was very manageable. A slight bit of EQ cleaned things up very well. One thing I should mention: I was using the PM40 studio version of the PianoMic System in this live concert setting. There is a PM40T touring version available that is specifically designed for live use; it's hinged in the middle to allow it to collapse into a package that's more easily transported... and less likely to be mistaken for a rifle.

So is this system worth the investment? I think it depends upon your individual needs. If you are fortunate enough to possess an arsenal of fantastic mics already, and you never have the need to acoustically isolate a grand piano, then this may not interest you. However, if you've been searching for a piano mic'ing approach that works for you, especially in a closed lid situation, then this kit is certainly worth looking at. The PianoMic System provides excellent sonic character in an easy to set up package that can yield repeatable results. Once you determine the best position for your piano and desired sound, it is very quick and easy to recreate that setup and sound on any session. If you need to minimize bleed from adjacent instruments, this is the best system I've seen for recording piano with the lid closed.