Question about hyper's rear lobe

[leddy]

Since hypercardioids are halfway between fig. 8 and cardioid, would they offer something a little closer to Blumlein when used in XY?

Can someone describe how hypers in XY might differ from cardioids or fig. 8 in XY, or when you might choose hypers over the other two options?

I've used XY cardioids and Blumlein. I don't own hypers at the moment.

I've always thought of them as tools for minimizing spill. I have not given thought to their stereo characteristics.

Thanks.

[David Rick]

Hi Larry,

Coincident arrays use only Interaural Intensity Differences, not Interaurual Time Differences. Therefore you can analyze them using the same math as for stereo pan pots. If you do this, you soon find out that hypercardioids are a lot more useful than cardioids in coincident pair stereo arrays.

The trouble is, you have to rotate a cardioid by a large angle to get enough intensity difference: at 90 degrees off axis, they are only down 3 dB. Consequently, coincident cardioid pairs tend to scrunch everything into the center, even if you deploy them back-to-back It takes a very wide ensemble (or a very close placement) to fill up the soundstage when using cardioids. That may be one reason why most people gravitate towards near-coincident arrays such as ORTF or NOS.

Hypercardioids work a lot better for coincident stereo. In fact, one of the common M/S setups can be shown to be theoretically equivalent to a coincident pair of hypercardioids. Figure eights are useful too, but have well-known limitations with the maximum recording angle.

Sennheiser's Manfred Hibbing published a classic paper on these topics.

David L. Rick
Seventh String Recording

[RobAnderson]

I think hypercardioids tend to have a better off-axis response than cardioids as well - another important consideration in a coincident array since most of your sound sources are picked up off-axis. As a result, I think you can angle them a little wider and get a wider stereo spread, while still maintaining the clear image and mono compatibility.

One downside is that most hypercards tend to be even lighter in the bass response than cardioids.

[JEGG]

Originally Posted by RobAnderson

I think hypercardioids tend to have a better off-axis response than cardioids as well - another important consideration in a coincident array since most of your sound sources are picked up off-axis.

Yes, they tend toward having (much) more uniform patterns.

Originally Posted by RobAnderson

One downside is that most hypercards tend to be even lighter in the bass response than cardioids.

Generally true, depends on the mic. And sometimes this is just what is needed, if you're in a largish room with bad resonances; all depending on what is being recorded.

I think hypercardioids are under utilized and largely unnoticed.

[leddy]

Thank you guys. I think I am going to join the AES and start reading through these things more.

I have been let down by XY (too bunched up as you said), and the nature of recording I do (mostly small jazz groups in clubs) does not let me do Blumlein because of the recording angle (can't have the mics far enough out front because of audience issues).

I've been thinking about hypercardioids and maybe even boundary mics. If nothing else, it's an education...

Thanks again.

[fifthcircle]

When I use my stereo mics, I cross hypercardiod mics at 90 degrees all the time. In my case, the AKG 426 and 422 sound fantastic in blumlein. However, I find that many rooms just cannot support the sound that the rear lobes of a blumlein give you. I'll go one or two clicks toward cardiod (hypercardiod pattern) as a way to minimize the room, but still get the spacial imaging that the Blumlein pair gives me. Works great and gives you the best of both worlds.

--Ben