Aaaah....good thing I caught this one then from Peter and Ty. So if I can have only 1 good quality mic for indoors and outdoors compromise on a Mkh50 or CMC-641.

Ok, i'm going out to rent and try them out.

Dan, very useful indeed. The 2nd one was a really good read and explained lots in a real-world and practical way. Your tests on the mkh50 revealed a very interesting performer. Thanks for the links.

Why will an MKH-40 work well for booming indoors but an MKH-416 not, when both are Super-cardioid?

Hi Sherif:

I am so glad that you found them useful. Good luck in your search for the right mic although in my opinion, we all mostly need to own two or three to get it right.

Dan

The MKH40 is not a super-cardioid; it's a plain vanilla cardioid. But be that as it may, the inddor outdoor thing is not due to the pattern but rather the exact acoustic principles the mic uses to achieve its pattern directivity. The 416 is an interference tube mic, as are most shotguns, and the problem using it is due to the way the direct sound and the reflected sound interact with each other when you use it in an environment where there are a lot of off-axis reflections such as a normal interior.

Hi Steve,

do you know any source to read a bit more about this concept?

Regards,


Andres Montana

Trying to remember the references- will check my bookshelf when I get home and let you know. In general, the directivity of interference tube mics is concentrated in the mid-range ... the 416 becomes almost omni at low frequencies. Direct sound from the source arrives along the axis of the tube. Reflected sound arrives from off-axis, slightly delayed due to the longer path. The higher frequency components of the reflected wave are rejected but the lower frequencies are still audible as low frequency reverb, changing the character of the recording and giving it a hollow, recorded in a culvert, kind of sound. Couple that with the comb filtering that can result when the incoming direct sound wavefront and the slightly delayed indirect reflected wavefront collide and mix within the tube and you can have marked changes in the timbre of the sound. Hypers are not so frequency dependent in their directionality so even if there is some reverb audible it doesn't change the character of the sound as much.

Polar diagram of MKH-416
 

This is the Sennheiser information on the MKH-416 T. The polar diagram, which bears out what Steve has said about polar pattern varying with frequency, is identical in Phantom powered versions. Anyone wanting to find out more about T powering need only read other parts of this leaflet. NB, the first part is in German, but a few pages later there is an English version.

Ah, I understand. A certain large name online store needs to update their description then. They have the MKH40 listed as a super-cardioid.

LOL - it happens. Here's the details straight from the horse's mouth ... Sennheiser USA - MKH40 - Product Details

Thanks Steve. I'm still learning the technical aspects about sound and find this fascinating. I would like to help others understand this concept. I think a side by side video showing a shotgun vs a hyper/super cardioid in action would help a lot of people. Can anyone think of a clear way to replicate this concept on purpose? Maybe with a highly reflective surface/room and some kind of boom box that would output certain frequencies? What do you guys think about having a little video/audio demonstration? If you'll help me script it, I can shoot it.

Even easier Andres,

I explain it on camera and you can hear and see why.
Go to my online archive,
.Mac - iDisk
Look in the Video folder and download the Ty Ford Mic Tutorial.mp4 file. It's a 28 MB file.
Use the arrow to the right of the file to download.
Regards,

Ty Ford

Well the pattern, itself, is not the issue. The Schoeps lists the cmc641 as a supercardioid. I think they (and Sennheiser) know the differences. The issue, as Steve explained, is the interference tube.

When is an interference tube not an interference tube? The Sanken CS-3e LOOKS like an interference tube mic, and it is....sort of, but unlike traditional interference tube mics, the main capsule is at the tip of the mic and not halfway down the tube or more. Instead there are other capsules below the Sanken CS-3e tip that help it be more directional. As such, the CS-3e does not behave like a traditional interference tube mic with one capsule halfway down the tube.

Ever been inside an interference tube mic? Below is a Sennheiser 416 and Sennheiser NTG-3 out of their skins for everyone to see. The capsule ends up being about halfway down the slotted tube.

Regards,

Ty Ford

Prssure gradient Microphones
 

Ty, very many thanks for that picture of a 416 separated from its tube. I had vaguely taken in that it was a pressure gradient mic from the literature, but hadn't really devoted much thought to the obvious consequence - that as the diaphragm is exposed to pressure differences existing between both sides of it as the waves pass, therefore the interference tube should be roughly symmetrical on both sides. Never too old to learn.

Well, the real deal is that as directional as interference tube mics are at high frequencies, they are way less directional at mid and low frequencies.

How could they possibly have been used all these years? Historically, there was always someone to yell, "Quiet on the set.", before rolling. That meant there was a set; a space that had been designed (or treated) to reduce sound bounce and that there wasn't much if any other noise around the mic.

Regards,

Ty Ford