Topic: two way mics?

[cybergaloot]

This may be a stupid noobie question but here goes. Since most stereo speakers are made up of two or three raw speakers, each designed to best delivery a certain frequency range, does anybody do anything similar with mics? Say two or more coincident mics for each "channel" (for lack of a better term), each chosen for their ability to best capture a frequency range?

[digifish_music]

This may be a stupid noobie question but here goes. Since most stereo speakers are made up of two or three raw speakers, each designed to best delivery a certain frequency range, does anybody do anything similar with mics? Say two or more coincident mics for each "channel" (for lack of a better term), each chosen for their ability to best capture a frequency range?

Not a stupid question, however the physics of making sound (where large volumes of air need to be shoved around) and sensing it, where small pressure fluctuations must be tracked, are quite different. Diaphragm size does not correlate with frequency captured, i.e large diaphragms don't capture low frequencies better than small ones, the WM-61A proves that (@ ~ 4 mm diameter). Large diaphragms are usually more sensitive overall and small diaphragms pick up transients more accurately. I am sure someone out there has made a mic array using several diaphragm types, but I am equally sure the technological complexities of doing so far outweigh any real advantage.

Indeed speakers would have only 1 driver too if they could make them stiff enough.

That said, I have made matrix recordings using a pair of cards (for the stereo image) and omnis (for the bass). However that's about pickup type, not diaphragm size.

digifish

[Krispy D]

Indeed speakers would have only 1 driver too if they could make them stiff enough.

exactly

[notlance]

The AKG D200E microphone was a 2-way dynamic mic.  I know it was available in the 1970s, but I don't know when it went out of production.  It was OK for its day, but not worth seeking out today, IMHO.

[digifish_music]

The AKG D200E microphone was a 2-way dynamic mic.  I know it was available in the 1970s, but I don't know when it went out of production.  It was OK for its day, but not worth seeking out today, IMHO.

Interesting and here it is...

http://www.coutant.org/akgd200e/index.html

and here's how it sounds...

http://www.coutant.org/akgd200e/akgd200e.mp3

[cybergaloot]

The AKG D200E microphone was a 2-way dynamic mic.  I know it was available in the 1970s, but I don't know when it went out of production.  It was OK for its day, but not worth seeking out today, IMHO.

Interesting and here it is...

http://www.coutant.org/akgd200e/index.html

and here's how it sounds...

http://www.coutant.org/akgd200e/akgd200e.mp3

Dynamic mic. Still an interesting idea in my mind. It would just seem that you could tailor each element to work best at a certain range rather than a one-size-fits-all solution. But then the more parts you throw in the more chances for failure and other problems. I could see possible phase type problems but then you see folks running multiple pairs of mics and mixing them together.

But then, what do I know. All I know is that my Jimmy Thackery & the Drivers recording from last night that I'm editing at the moment SMOKES! Too bad they don't want me to share it yet. Talk about badass guitar playing!

[heyitsmejess]

cant recall the model, but last time i was at guitar center, they had an AT mic that (to my understanding) had a dynamic super cardioid, and a powered cardioid cap both on one mic.  i believe it was an instrument mic, tho for what i dont specifically recall.

actually, this is it right here

http://www.audio-technica.com/cms/wired_mics/4359efa46266c7e9/index.html

[John Willett]

The AKG D202, D224 and D222 were all dual capsule designs with the entry slots for the bass frequencies being at the bottom.  These all had a reduced proximity effect because of this design.

[lino]

The D224 was by far the most sophisticated one with a crossover circuit ,
these mics are still great for studio work even by todays standards

[DSatz]

cybergaloot, you might begin by asking yourself why full-range dynamic loudspeakers have multiple drivers at all. Mainly it's because each driver has to have a small diameter relative to the wavelength of the sounds it's generating, or its dispersion will suck. So a midrange driver has to be medium-sized, and a tweeter has to be small. But small drivers can't move large volumes of air, so for that reason among others, it's fortunate that the high frequencies in music and speech aren't generally equal in intensity to the midrange and lower frequency energy.

Similarly, the diaphragm of a microphone has to be smaller than the wavelengths it's picking up, or else its polar pattern (the complement of a loudspeaker's dispersion) will suck. But as digifish_music points out, the way microphones operate doesn't involve a lot of air motion. Even at very high sound pressure levels the membrane excursion and the acoustic power involved in moving that membrane are vanishingly small.

So a microphone is just not analogous to a loudspeaker in those respects. For pressure transducers, even a 1/8" diameter microphone can have flat response down to as low a frequency as you like--certainly well below the range of human hearing.

--best regards

[Roger Gustavsson]

Schoeps have their LP40U for combining cardioids and omnis.

Roger

[Church-Audio]

This may be a stupid noobie question but here goes. Since most stereo speakers are made up of two or three raw speakers, each designed to best delivery a certain frequency range, does anybody do anything similar with mics? Say two or more coincident mics for each "channel" (for lack of a better term), each chosen for their ability to best capture a frequency range?

Its not a stupid question it has been done before more then a few times by AKG once with a dynamic mic and once with a mic called the AKG C3000 the original version of this mic has two capsules one is a 6 mm capsule the other is a 1 inch capsule they are combined to change the polar pattern the small capsule was also used to extend the top end response of the microphone and there is a low pass filter on the small capsule at 500hz or so. AKG quickly dropped this design and changed it to a single capsule design because there was phasing issues that could not be corrected. 

[Petrus]

Indeed speakers would have only 1 driver too if they could make them stiff enough.

Not so. Speaker cone diameter has to have the same ratio to wavelength thoroughout the whole frequency range to keep the radiation angle constant. A 12" stiff tweeter piston would radiate only to a few degree angle + have a bunch of out of phase side lobes. Totally unusable design even if possible.

Even large (6-10") midbass drivers have cones where the higher requences are supressed by the cone, they do not travel far from the voice coil area. This makes the dispersion angle constant; the higher the frequency the smaller the radiating surface. Great polymeer engineering!

[run_run_run]

Figure 8 sorta works 2 way correct?

[cybergaloot]

Figure 8 sorta works 2 way correct?

Not the way I was referring to. What I was wondering about was a two way mic with one element for one frequency range and one for another, think tweeter and woofer but in the mic world that may have nothing to do with diaphragm size and maybe more to do with internal mic design. I'm not say that's the case, its just my thoughts. Figure 8 or bidirectional mics from what I've read are essentially the same element pointing in opposite directions, no difference in frequency response.