Timeline for A question on the meaning and model of microphone impedance
Current License: CC BY-SA 4.0
6 events
| when toggle format | what | by | license | comment | |
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| Apr 16, 2019 at 21:51 | vote | accept | user16307 | ||
| Apr 16, 2019 at 21:07 | comment | added | Dan Mills | Assume Xl is say 20j at 20KHz and work your values from there, but note that 600 + 20j is pretty much the same as just 600 ohms resistive when driving into a few k ohms of load impedance which is the usual design. 2mH would be VERY large for an air cored coil having maybe a 20mm diameter, I for example make a 20mm diameter, 100 turn single layer coil, 5mm long, right about 300uH (Wild guess, but it feels reasonable). | |
| Apr 16, 2019 at 20:40 | comment | added | user16307 | Please see my edit. I tried to model a dynamic mic as L and R. If correct at 100Hz audio to neglect the inductive part coil needs to have 2mH inductance. Does that make sense? So I took the DC resistance of the coil is 600 Ohm. Im also asking whether I can model this way. | |
| Apr 16, 2019 at 20:10 | comment | added | Dan Mills | Real low impedance mics are generally a few hundred ohms (mostly resistive, reactance is usually <20 ohms across the audio band) and are intended to drive a load of a couple of k ohms in parallel with maybe up to a nF or so of cap (cable plus input RFI suppression) which is what most modern mic input stages look like. High Z mics are about the same but seen thru somewhere between a 1:3 and a 1:10 transformer or thereabouts (Yea there is a reason nobody goes there these days). | |
| Apr 16, 2019 at 19:55 | comment | added | user16307 | I dont get the part about why we can model it as Rm instead of Zm. You saying small enough but the document is talking about a value betwern 600 Ohm and 10k. Can you show it with a model example with a source and a reactance? | |
| Apr 16, 2019 at 19:46 | history | answered | Dan Mills | CC BY-SA 4.0 |