3D Immersive Microphone Arrays

Over the years, I've recorded with many types of microphone arrays. I started with stereo, then moved to various surround sound arrays. Here's the rough progression of the arrays I mainly use: 

1. Stereo: Mid/Side
2. Stereo: ORTF
3. Stereo: AB
4. Stereo: Tree-ears
5. Surround: Double Mid/Side
6. Surround: Quad (Spaced Omnis)
7. Surround: Quad (Tree-ears)
8. Surround: Double ORTF
9. Surround: IRT Cross

In 2024 and 2025 I began experimenting with 3D immersive arrays. These are not out-of-the-box setups like Schoeps ORTF-3D or Ambisonics microphones. These are experiments of my own design, that sound lovely to my ears. 

These setups were used to record the strong vertical component of tall Redwood forests. Here's and overview: 

4.0.4 ARRAY – IRT CROSS CUBE: 

This is the largest 3D rig I've used. The .4 vertical channels (5-8) can be mapped to the .4 speakers of a 7.1.4 Atmos setup. This cube array of 8 microphones is fabulous. It array excels at recording incredibly quite environments because of the extremely low self noise of 4 dBA.

• I built this setup with eight Lewitt LCT 540 S microphones. 
  
• The 540 S mics are placed in the the shock mounts that come with the mics. 
• The foam wind guard that come with the mics is used. 
• Eight Radius blimp furries are wrapped around the mics. This is not ideal, but works for light winds. This is not the rig you want to use to record stormy winds anyway, it is to record the subtle sounds of almost silent ecosystems. 
• I arranged these microphones in a cube using Manfrotto Dado mounting balls and extension rods. 
• Dado ball + one extension rod + 540 S shockmount = excellent spacing for a roughly 25 cm square IRT Cross setup. 
• Stack 3 Dado balls and two extension rods to space channels 1-4 & channels 5-8. This gives you a roughly 25 cm square for an IRT Cross Cube array. 
• This heavy rig is sitting on a Manfrotto 5001B stand. This rig is extremely heavy, but this stand will barely hold things. I'd recommend a heavier duty stand if you already have one. 
• I tried a few different cardioid orientations that produce different imaging depending on how you tilt the cardioids. 
• Variation 1 – all cardioid mic capsules are oriented parallel to the ground. 
• Variation 2 – the top 4 mics (channels 5-8) are pointed up at 45 degrees and the bottom 4 mics (channels 1-4) are pointed down 45 degrees.
• Variation 3 – the top 4 mics (channels 5-8) are point up at 45 degrees and the bottom 4 mics (channels 1-4) are parallel with the ground. 
• This setup works, but is very bulky and difficult to setup. It only offers light wind protection and no rain protection. I'm working on better ways to weatherproof the Lewitts for use in the field. More on that in a future update. 
• Recordings from this array are included in AMB91, AMB92, and AMB93. 

4.0.2 ARRAY – QUAD TREE-EARS + ORTF

This is smaller 3D rig I've tested. The .2 vertical channels (5-6) can be mapped to the .2 speakers of a 7.1.2 Atmos setup. This rig is fully weatherproofed. 

1. LOM Usi (x4) and Sennheiser MKH8040 (x2) - Quad AB + ORTF
2. Step one. Climb to the top of a Redwood tree. 
3. Mount four LOM Usi microphones in Cinela LEO20 blimps. Mount two MKH8040s in LEO25 blimps. Read my blog post on how to do that – here. Once that's done your mics are weatherproofed. 
4. Use electrical tape to mount the Usi (channels 1-2) mics on opposite side of a tree branch about the width of a human head. The branch acts as a baffle and gives you a quasi-binaural image. 
5. Space channels 1-2 and 3-4 about 1 meter apart on the branch.
6.  Repeat step 4 with channels LOM Usi for channels 3-4
7. Mount two MKH8040s in ORTF using a stereo bar above the lower set of Quad mics. 0.5-1 meter vertical is a good place to start. 
8. Mounted the MKH8040s (channels 5-6) directly over the LOM Usi (channels 1-2). 
9. This gives you a 3D immersive array that can be recorded using the six channels of a Zoom F6. 
10. Recordings from this array are included in AMB91, AMB92, and AMB93. 

Here's a video showing how I assembled this rig at the top of a Redwood: 

4.0.2 ARRAY – SPACED OMNIS + ORTF

This is smaller 3D rig I've tested. The .2 vertical channels (5-6) can be mapped to the .2 speakers of a 7.1.2 Atmos setup. This rig is fully weatherproofed. 

• Sennheiser MKH8020 (x4) and MKH8040 (x2) - Quad AB + ORTF
• Mount four MKH8020 microphones in Cinela LEO25 blimps. Mount two MKH8040s in LEO25 blimps. Read my blog post on how to do that – here. Once that's done your mics are weatherproofed. 
• Use a Manfrotto 5001B stand
• Build a square using Insta360 Invisible Selfie Sticks (44.9") and some adaptors. 1 meter square spacing. 
• Use a 5th Insta360 selfie stick to go up 1 meter. 
• Add and RODE stereo bar, then mount two MKH8040s in ORTF for channels 5-6. The ORTF array is centered over square of channels 1-4. 
• This gives you a 3D immersive array that can be recorded using the six channels of a Zoom F6
  
• Recordings from this array are included in AMB91, AMB92, and AMB93. 

GOING FORWARD: 

You can find all the other blog posts and media from my Redwoods Climbing Expedition – here. 

I hope you have found these setup examples helpful. I'll add more experiment to this blog post as I do them. In the near future, I plan to try out:  

• 3D Tree-ears: 8 omni microphones strapped around a large tree. The tree body acts as a baffle. Then the channel 1-4 and 5-8 are separated verticall on the tree. Like the photo below, but with another Quad array stacked on top (one meter higher) for channels 5-8. 
• Spaced Omni Cube: 8 omnis at the corners of a 1 meter cube.