This thread gave me extra incentive to get my binaural recording project underway, so I'm adding my (single day of) experience here.
Locating Microphone Capsules
I had been planning to get into binaural recording for several weeks but found it impossible to purchase Panasonic (or any other) microphone capsules here, even in Akihabara which is supposedly the electronics mecca of the world. Everyone sells the same four or five brands of made-up microphones at identical prices. Chasing Matsu****a/Panasonic directly revealed that I would be able to purchase microphone capsules provided I wanted to order at least two- or three-thousand. Maybe next time...
So I decided to buy a consumer mic and plunder its capsules. I had wanted to avoid the cheapest tie-clip microphones if possible since they are only rated down to 100 Hz and I already have an old Sony tie-clip mic which is seriously lacking bass. However, I figured the capsules in Panasonic's tie-clip mic may be identical to the WM-61A which everyone raves about and which
supposedly goes down to 20 Hz. [Maybe the difference depends on how it is mounted]. At about the same time, Audio-Technica released a new tie-clip microphone with a back-electret condenser capsule so I went to an electronics store where there were subwoofers in action and helped myself, unwrapping one of each of the majors' tie-clip microphones and recording them on my portable MD.
Testing Tie-Clip Microphones
There was a Sharp MC-TS1,
the Audio-Technica AT9830,
a Panasonic RP-VC200
and an Aiwa CM-S220,
in increasing order of price from around 1,000 to 2,000 yen.
I found a quiet place to listen back to the recordings and evaluate the microphones (using a demo set of Sony R10's at a different store, but that's another story
). The A-T mic was the most sensitive and had a darker tone, seeming to pick up the low freq's well, but there was something a bit harsh in the top end. [No such thing as burn-in for microphones, right?] In fact there was only one mike which didn't seem rough in the treble, and it turned out to be the Panasonic. Somehow it caught the ambience of the store unlike the other mic's, but what really jumped out at me, even on the first hearing, was how well it captured my voice. During the recordings I had made a little announcement for each mike to prevent confusion over which was which. This turned out to be a great idea, since your own voice gives perhaps the best reference point for how natural a microphone sounds. Concerns about bass response were discarded for the realistic sound of the Panasonic, which I went back and purchased.
Removing the Capsules
Next problem though was to get the capsules out of the casing. Not trivial! Let's just say that the photo above would be the "before" picture.
I had to pry away (and destroy) the metal screen first. Inside, the capsules looked quite fragile in their thin aluminium housings, which were firmly glued to the plastic casing with contact adhesive. I had to basically slice the casing away with a modelling knife, which was a thorough pain-in-the-@ss. [If you can get capsules separately, don't even think about dismantling an off-the-shelf microphone].
The capsules are 9.5mm diameter and 7mm deep, and are stamped "WD" on the side. [Definitely
not the WM-61A which is only 6mm x 3.4mm]. Any larger and these would not go in my ears. I desoldered and modified the cable into a Y shape and taped the cable along the side of each capsule, with an appropriate bend to go up and over the ear to reduce cord microphonics.
Test Recording
Let the fun begin! I did all the normal things you might do at this point - wandered around the house, put some music on the stereo, pulled the cat's tail (joke
), went for a walk outside, etc. All I can say is that if you have ever wondered about making your own binaural recording, you simply must do it. Do it right now, this week! It is that good. I managed to get the felt covers of the capsules almost flush across my earholes and the imaging was truly superb. I tried covering the backs of the capsules with foam pads (from earbuds). This gave a more comfortable and secure fit but seemed to increase the cord microphonics and bass noise as I was walking about, and also made my voice sound muffled. There are vents in the back of the capsules. I might try blocking them off, which I imagine will fix the funny voice effect but may also alter the bass response.
Which Headphones?
Here's another tip. I found that earbuds (MX400) recreated the 3D sound sensation much better than full-size cans (HD580). My theory is that you only want to allow your ears to shape the sound once. If you play back on cans then you get secondary ear effects telling your brain that there's a pair of headphones on your head. Just a theory, but I'd recommend earbuds or canal phones for best binaural imaging.
Can't wait to get a chance to record some acoustic instruments, a street festival, whatever.
