Comparing a Rode NT4 to two DPA 4060s with train passes

Lavalier Microphone Techniques For Field Recording

Of all my microphones I probably use my lavaliers the most often. Whilst there are lots of good ones out there, like many recordists I invested in a pair of DPA 4060s. I find these tiny omnis to be pretty rugged microphones with crisp, balanced highs and extremely smooth, rounded lows. Since getting them I have been experimenting with various setups and recording techniques for stereo field recording. 

The Coat Hanger

Back on my first ever recording trip to Iceland in 2013, it was environmental recordist Chris Watson who first taught me that you can simply mount lavaliers to each end of a coat hanger. This provides a wonderfully straightforward, lightweight and cheap mount for a spaced pair. The hook means that you can hang it up or bury it in the ground. I still use the coat hanger when carrying my equipment for long periods such as multi-day hikes and when weight is the biggest factor. However it does have its limits. You can’t attach it to a boom pole or stand and some environments simply have nowhere to hang a coat hanger. It also makes you look like a ufo hunter from a low budget sci-fi. This can definitely cause unwanted attention in populated environments!

Wildlife recording with lavaliers on the Camino de Santiago in Northern Spain

Two DPAs recording sounds of the Camino de Santiago in Northern Spain, attached by coathanger

The Binaural Technique

Next I started using lavaliers for my audiobooks as a binaural setup. The recordings with the DPAs were way clearer than the other purpose made binaural mics on the market. We found that we got the most realistic results from literally taping the microphone to the auricle (by the earhole) This produced some really nice 3D binaural spatial effects. However I wouldn’t recommend it for use outside of the studio (or with anyone else’s microphones for that matter).

The Quasi-Binaural Rig

For stealth recording outside of the studio I’ve often used a quasi-binaural setup. I took a cheap pair of sports earphones, removed the speakers and melted a small hole in each earphone, just big enough for the capsule of the lavaliers. From there I attach a Bubblebee windshield and tape the cable to keep it all in place. A readymade solution would be something like BudFitsThis technique allows you to record almost anywhere without anyone realising. I once managed to make a recording in the Panthéon, Paris, only for security to tell me I wasn’t allowed to listen to music! I still use this technique often as it requires the least amount of kit and is truly stealth. My biggest issue with this technique is that you capture every breath, every slight movement, even the sound of you gulping. To do a good job requires that you behave like a statue. Another drawback is that you can’t monitor your recording. I once did try bluetacking the lavaliers to the outside of a pair of normal earphones, but the results were not great. So in all some of the joy of recording is lost with this technique.

The Camera Arm Rig

Moving forward from the spaced pair coat hanger technique, I started using Colin Hunter’s setup for any environmental recordings. The lavaliers are on two flexible camera arms, attached to a Rycote portable recorder suspension, which attaches to a stand. The suspension removes all handling noise, and having a stand means you can leave the mics out in the open at whatever height you please. The flexible arms also means you can adjust the distance of the spaced pair. Whats more you can fold them in, making for easier transportation. My hangups with this technique are that the camera arms are stiff to adjust and a bit flimsy. Its also not that compact and little heavy. I’m quite unorganised with cables so find myself getting tangled as well. Not to mention that you’ve now progressed to a high budget and frankly alarming ufo hunter – Definitely something to be avoided in public places. Colin has just worked out a V2 which uses the stubby Gorillapod arms instead and looks to be a much improved setup.

 

Field recording of a Dawn Chorus in the Pyrenees with Lavaliers

Recording a dawn chorus in the Pyrenees using dual camera arms to create a spaced pair

The Baffled Blimp

The blimp mounted technique is widely used with lavaliers. It might be just the right balance for compact spaced pair recording, especially in public places. Every time I’ve seen it used, its been in medium sized blimps, as distance between the two mics is vital to having a wide stereo image. However I only have the Rycote WS1. This is their smallest blimp and comes in at a total length of just 280mm. Whats more, the microphones would be mounted at the end cap intersection, leaving just 170mm between the mics. Whilst it comes down to taste, a typical AB pair will be spaced between 400mm and 600mm apart.
In order to improve channel separation I wanted to try using a baffle, or Jecklin disk between the two mics. The idea is to isolate the mics and block sound coming from the opposite side. The principles for a traditional Jecklin require an acoustically absorbent material be placed between the two mics, which should be 165mm apart, so ideal for me! However the disk should be around 3 times bigger than my blimp’s diameter. Whats more, Jecklin later revised his original specifications. He concluded an optimal distance to be a much wider 360mm apart. I was therefore uncertain as to how my setup would perform. For the disk I used Plastazote foam which at 28mm is a little thicker than the typical disk.
Unsure as how best to mount the mics I asked the Facebook Field Recording Group. It turns out everyone has their own method, from a wire strip of cut down coathanger that spans the length of the blimp to a wood dowel. My method is to simply use dental floss, which can be hooked around the end cap mounting clips. Not thick enough to block the caps, but strong enough to hold the mics with a little tape.
 The result is a windproof, lightweight, clean and compact setup which can be handheld, boom or stand mounted. Plus it doesn’t make you look quite so crazy!

 

DPA 4060 lavaliers suspended in a Rycote WS1 Blimp

I used dental floss to suspend the microphones in the Rycote WS1 blimp. No handling noise!

The Blimp Test

Yesterday I took the rig out into the Toulousain sunshine to get an idea of how it sounded. Recoding train passes seemed a good subject as the left/right separation of a flypast is always revealing. Whilst I would have liked a second pair of DPAs to test it against, my only other field microphone to hand was the Rode NT4. The stereo mic has 2 cardioid capsules in an XY configuration. At least this would give some spatial comparison. The mics were aligned, with the Rode being just 50cm closer to the sound source. You can listen to the results (MP3) below.

 

Rode NT4 – Short Train

 

DPA 4060 – Short Train

Rode NT4 – Long Train

DPA 4060 – Long train

In listening back, the results between the two mics seem almost incomparable – I asked myself if I had high-passed the Rode by mistake, as the low frequency difference was enormous. Its clear that the DPAs do excel with this kind of bass-driven sound. The omnis also naturally sounded much, much wider than the Rode. In hindsight I should have set the Rode further back behind the DPAs. The real question was whether the stereo image would be as natural as the XY arrangement. At this point I must say I’m impressed, to me it really did sound natural. The disk seems to be adding a great deal of separation, despite it being on the small side. If anything I felt that the disk was doing too good a job. The sound attenuated very rapidly on the blocked side once the train passed. I’ll be using this technique whilst recording the French city of Toulouse over the coming months, so will update this post with further analysis in different recording environments.

Other Techniques for Lavaliers

There’s still several techniques I haven’t used much. One of the best things about lavaliers is just how tiny they are. It means that you can place them in all sorts of nooks and crannies that we usually couldn’t get to. They are often used in film sound on vehicles to close-mic the engine, or the inside of the cab. I read somewhere that they were buried in the desert on the Mad Max set and driven over! In an environmental setting you can hide them under rocks and leaves to get up close and personal with wildlife. There’s also surround sound which is a whole other topic on its own. I’ve already seen 4 channel blimp mounted 4060s for 4.0 playback, and DPA have their own baffled 5.1 solution which is regularly used for live sports and pro game audio.
In all we can see just how useful lavs are for field recording. Inevitably the 4060’s self noise is higher than in many larger diaphragm mics, but for its price and sound quality (especially in the low end) its a tough one to beat. The lavs are a vital component of my field recording toolkit.

 

Bicycle with lavaliers attached by coathanger

Whilst cycle touring I attached my DPAs using the coat hanger technique, leading to some interesting recordings!

Comments

  1. Really interesting article. Have previously had good results with Sennheiser Mke2 s taped to my ears. Will definitely try out these other techniques. Thanks.

    1. Author

      Hi Dinesh,

      The suspension mount is the Rode SM4 Microphone Shock Mount

      As for the windscreen, it is home made. I used a baby’s toy called an Oball along with the Rycote Baby Ball Gag windshield. You can see a picture from my twitter here

      Hope that helps!

  2. “The Baffled Blimp” is the very inspiring idea.
    Solid and portable set for sound hunters.
    Thanks a lot Ben.

  3. A railfan from India here. I have experience with PCM-M10, H4NPRO, MKH8060, NT4 and 4060. I feel the 4060s worn around ears beat all others in naturalness. If I were starting today, I would have bought just a mixpre-3 and a stereo 4060 kit, passing all others. Trains are loud and noisy, so mic self noise is not a big issue when recording close passbys. But transient response and bass extension are, and the dpas excel there. 4060s are not much sensitive to wind, so I can get usable recordings of not so fast trains with zero wind protection on calm days(by standing like a statue). 4060s can also handle high spl with ease, after I dial down gain to about 15 on Mixpre-3.

    A comparison of the above kits from an amateur’s perspective:

    PCMM10: Good bass extension (comparable to 4060s), good wind resistance with deadkitten, but bass is boomy and loose at times, overwhelming other subtle hf details. Transient response is so so, it cannot handle high spl at all (some digital distortion occurs when gain is reduced to avoid clipping). Abysmal stereo separation due to two closely placed omni mics. But the most portable and practical setup for quick recording.

    H4nPro/NT4: They are very similar in sound. Very weak bass extension, yet insanely senstitive to wind and handling noise. NT4 has much lower noise, but also slightly darker. Both of them sound harsh when recording high spl train horns, but while NT4 is usable, H4n is not. I found H4nPro stereo separation to be much better, even at 90 degree mode. At 120 degree mode, centre suffers (i.e the cardioids sound dull when 60 degree off axis response).

    8060: Sounds dull if off axis, has a very narrow angle of sweet spot. On axis sound is slightly honky (hyped midrange).However, it has low noise, good transient response and reasonable bass, good hf rejection from back and sides that become lifesaver in noisy areas and recording targeted sounds (e.g. just the loco, not the carriages).

    I am still using all of them regularly except the bulky NT4.

    1. Author

      Wow thanks so much for your input! I’ve had experience with a lot of the same equipment, just not specifically with Trains as the subject.

      Im surprised that the H4n and Nt4 sound so similar, but agreed about the weak bass extension. The 8060 is also my only shotgun. Whilst I think all shotguns tend to sound dull of axis, the good thing about the 8060 is the sound remains pretty neutral and uncoloured.

      Just about to post an article looking at a cheaper pair of lavs, the LOM mikroUši. Whilst the transient response and upper mids aren’t as good as the DPAs for the price they are impressive. I’m personally interested in buying 4 to experiment with some 4 channel surround recordings.

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