I read every response in this thread, and nobody said SDCs have no bass.
Shadow_7 said:
And an SDC might lack the low end needed.
Supercreep said:
I'd use an LDC to grab as much bass response as I could.
Instead of being cryptic, why don't you share some of your knowledge?
Well the search function seems to have taken the night off, but here is the big thread:
http://www.itrstudio.com/MIC_CHAT.PDF
Harvey quotes David Satz on pg. 4 describing transducer design, also on pg. 3 Harvey discusses diaphragm size vs. low-frequency response. Important point for pressure mics: their low-frequency response is not limited by operating principle, since they are just responding to changes in pressure. Their lower limit is set by their pressure vent--could be as low as 5 Hz or so.
Pressure gradient mics are more complicated. Remember that pressure gradient mics create their polar patterns via signal difference between the sides of the diaphragm. If there is no delay or attenuation, there is no response.
Let's think only about low frequencies: when you have no delay, then the pressure on either side of the diaphragm from a faraway source (in other words, the source is effectively planar) will be the same--therefore, no response. As you get closer to the source, the path length difference creates a difference in magnitude (inverse square law), and you get a response. This is proximity effect.
Of course cardioid mics aren't pure pressure gradient transducers, they are blends of pressure and pressure gradient, so real-world will be in between. Still, the bass response of any cardioid mic, whether large or small diaphragm, is always going to be a function of distance to source, and not a function of diaphragm size.
Except for teensy tiny cardioid condenser capsules, they generally don't have very good bass response, that's because their delay chambers are so small that they can't generate a very effective path length difference. Such capsules are generally designed for special purposes, such as close-micing drums, so far-field use isn't anticipated.
But any of the common SDC cardioids, say the SM81-class or equivalent, I don't think there should be a problem with them. And of course, any directional mic a few inches from a didg is going to have plenty of proximity effect. You might actually be struggling with too much bass . . . so position the mic according to the bass response you want.
What do you get with an LDC? Well, larger variations in response, which maybe you like, which is fine. You also get less high-frequency response. That could create a psychoacoustic impression of more low-frequency response, but that's not actually true. So use an LDC if you like, no harm, but please don't say, as Shadow_7 did, that SDCs might lack bass response. Maybe crappy ones do, but that's not a principle of physics. Crappy LDCs could lack bass response for the same reason.
Oh, and p. 29 talks about didg.
More on this topic:
on omnis, from DPA:
http://www.dpamicrophones.com/en/Microphone-University/Technology-Guide/Large Diaphragm.aspx
or a version of the DPA document that also discusses directional mics:
http://www.sengpielaudio.com/LargeVsSmallDiaphragms-TwoParts.pdf