I have a Tetramic, as well as some decent other mics (Sennheiser, Beyer, Oktava, Avenson).
My experience with it is this: It can really sound good. Like, spooky realism. But...it is going to have some of the same limitations of any coincident pair. You cannot just place it anywhere and expect to fix it all in post. Coincident cardioids usually don't sound very spacious, so it usually needs to be decoded to something between hypers and Blumlein to reach its potential. As such, the distance to the source is important. You have to try to keep the source in the 90-degree recording angle as if you were using Blumlein. Too close gives you wierd image problems, and too far gives you too much reverb. Yes, you can fix that in post - but the further you are from proper placement usually requires fixing that by dialing out more of the rear lobes that provide the spacious sound. You will be left with something closer to coincident cardioids. Most of us would prefer near-coincident cards to that, I'm sure.
In sum - think of it as a flexible Blumlein or hyper pair that lets you tweak it in post. If you are in a situation where you would never use Blumlein or coincident hypers, you would not like an ambisonic mic either. If you dig Blumlein or coincident hypers and know how to use them, this mic will make you very happy. You will have much more margin of error with this than with a pair of fig. 8's or hypers. Just not as much as with near-coincident cards. But if it's right, it will sound way better than near-coincident cards. Make sense?
With regard to the quality - it's all about placement. If the mic is in the right spot, it will sound outstanding. You will need to make no excuses.
I also have a Tetramic and this description is spot on. I hesitate to say anything else but I will, simply in an attempt to help fully explain what its real world values are for me, and also what it isn’t. Now it seems I've typed way too much..
First the ‘in the field side’-
Like leddy, I find it useful to think of it primarily as a very good, compact, coincident hyper/blumlien pair with fine-tuning. If a coincident hyper or bumlein pair works for the situation, then this mic can do the job very well. Both the Tetramic and it's associated cabling (mini-xlr based) is amazingly small, lightweight and compact. With the foam windscreen on it looks like a simple single point stereo mic with one thin mic cable. It is pretty discrete appearing.. a visual sleeper. It is very easy to use when recording, and hides the complexity of decoding and file management until after you get home. I’ve configured it for my girlfriend and she has taken it to a show without me and run it without any problems. She simply clamped to a rail, attached the mic with its single cable, powered up the recorder and rolled. Microphone location is as important as ever, but pointing it accurately is not at all, since that can be completely adjusted for later. Pretty simple to setup one mic and cable, then press record.
Understand that I’m primarily a spaced/baffled omni guy and like time-based information, especially in my surround recordings. The limitation to coincident patterns is a pretty big constraint for me, and the primary constraint of any ambisonic mic. If and when I can, I often try to run additional spaced omni outriggers, but if the situation is perfect for Blumlein, they aren’t really needed. I think this thing would work quite nicely with the Tascam DR-680 now that the most recent firmware apparently allows linking of input gain controls, but also because of the possibility of running an additional pair of spaced mics, synced on the same recorder.
I’m running it into an R-44 which powers the mic via four phantom powering adaptors. The need for the bulk of the phantom adapters in the recording bag, the additional steps to assure matching channel gains on the R-44 and the post processing are somewhat of a PITA, but if the quality of the recording is more important to you than making those extra efforts, that may be a worthwhile tradeoff. It is for me. Honestly it’s amazing that the rig is as small as it is, but still, I’d really like to be able to ditch the phantom adapters.
The ‘back at home side’-
Much is said about the decoding and virtual mic aspects of an ambsonic recording system. I’m focusing solely on stereo playback here. I have yet to explore the surround decoding options (it’s decodable to standard 5.1, 7.1, etc. type configurations, as well as true 3-D ambisonic playback systems which I and most others have never seen or heard), even though I do significant surround recording using other, time based mic arrays. I’ll explain why that is some other time if anyone is interested.
For stereo, I think it helps to think of this as simply a more tweakable Mid/Side technique, like a more advanced mid/side plugin. Like Mid/Side, there is usually a relatively small range of settings where things actually sound best. That usually means hypercardioid/fig-8’ish patterns, plus making slight adjustments to mic angle, rotation and elevation. Unlike standard stereo Mid/Side, the mic pattern and angle are independently adjustable, which helps in optimizing the settings, but again the key is dialing it in an optimizing it, rather than some ability to point a virtual mic of any 1st order pattern in any direction. Tweaking the overall mic rotation and elevation (point up toward stacks or more straight at stage from farther back, horizontal at floor level amps or up at the the musicians holding the instruments themselves from stagelip) is quite useful in that optimization as well.
The only gross-level adjustment that is really applicable for stereo is the rotation/elevation control. If there is a rather narrow practical range of settings for dialing in the specifics of the virtual stereo mic array itself, that array itself can be pointed in any direction at all. The first time I ran the mic I had it pointed 90 degrees to the side instead of ahead and simply rotated everything 90 degrees when decoding. As mentioned this is the exception to the ‘mostly useful for fine-tuning, but that fine-tuning is important ’ aspect of the thing.
Why I went with it-
I looked at it cost wise and usage wise similarly to Brian. His analysis is right on.
I record multichannel already, but I’ve been moving to more compact and easy to run rigs. This is compact and very easy to run and I can use it in conjunction with my spaced techniques. I like the technical stuff, experimentation with different techniques, surround recording and options and it certainly fits those descriptions. I like playing around with different ways of using my multi-channel recordings and don’t feel pressure to track and upload swiftly so the post work isn’t an issue for me. I’ve read a lot about ambisonics and this it a relatively inexpensive way of getting into it and exploring it. I also feel like using this mic has helped deepen my real world understanding of how 1st order microphones actually behave acoustically, as well as the limitations of coincident and spaced techniques.
I like the approach of using specific measurement corrections to match the capsules in each individual Tetramic and see that as one of the real technical strong points of the system, leveraging the use of software in addition to doing the A to B format conversion and specific stereo mic decoding. I feel that helps offset many of the potential drawbacks of using less than premium grade mic capsules and may be an advantage of the Core approach over Soundfield’s in maxizing performance vs cost.
I talked with both Soundfield’s US reps and with Len at Core. Soundfield couldn’t answer many of my questions or point me to anyone who could, they assured me they could order a mic from England, but that was about the extent of their support. Len was quite helpful and went out of his way to get the mic to me very quickly before a recording opportunity. I realize this might not reflect the experience of others here, but it’s my experience.
Why don’t more tapers use it? Compared to typical mid grade stereo rigs it’s not inexpensive, it’s conceptually complex and not well understood by most people, and it requires more post work. Ambisonic mics are only available from a few manufacturers, and relatively afforable examples have only recently become available, plus it’s a bit of a leading edge technology, even if it has a 35+ year history behind it. For me it's a great way to explore my interests in sound and its reproduction as well as a simply being tool for making great recordings.
Topic: Soundfield and Coresound Tetramic (and ambisonic mics generally) (Read 24724 times)