Another noob microphone question. What would happen if..

...and how to do so...
jp008
KVRist
44 posts since 15 Oct, 2010

Post Sat Nov 09, 2019 8:56 pm

What would happen if I took the capsule out of a condenser microphone and put a dynamic capsule into it instead ? I'm aware dynamic mics don't use phantom power, so I wouldn't use that, but what would happen? Anything ? Would the dynamic capsule be able to produce sound through all the components on the condenser's circuit board without any power applied ?

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BertKoor
KVRAF
11335 posts since 8 Mar, 2005 from Utrecht, Holland

Re: Another noob microphone question. What would happen if..

Post Wed Nov 13, 2019 5:16 am

When I was about ten years old, I learned about electricity, difference between Decent Current and Alternating Current and so on. So I heard a loudspeaker needs alternating currents to make sound. And guess what, there's a handy source of AC at the wall! So I took this old loudspeaker, plugged it into the mains power wall socket, and indeed it made a loud sound! But just for a very short while. And it made a lot of dust as well, and it smelled quite funny. I won't do that ever again, at least on purpose...

Now what you're doing is much much safer. I'd almost suggest you try it, if it weren't that you need a bit of theoretical understanding before you try to validate your theories. And I'd have to warn you it's all at your own risk and I don't take any responsibility. But if you can afford every thing involved in the experiment blows up, oh well...

Can the circuitry of a condenser mic work without phantom power? Hmmm... Why would you not use phantom power in the first place? Because of the dynamic capsule? Worst case: putting 48V DC on the voice coil would make it make a plop sound, but otherwise doesn't do much.
No, that phantom power is needed to amplify signal of the capsule. It needs to be converted from very high impedance to quite low impedance.

If you read the wikipedia article on condensor mics, they'll throw in terms like voltage, current, impedance, charge... You know what those terms mean?
In short: power (in Watts) is Volt * Ampere (current) while impedance is Volt / Ampere.
Very high impedance means very low power. Lower impedance means more power at the same voltage.

Now an experiment... Given:
* Line level signals are around one Volt and have an impedance of say 1000 ohm. So the current is 1/1000 = 1 mA.
* Headphone signals are about 100mW at 16 Ohm. Reworked with my VawoCalc it's 1.26 V and 0.08 A.

Can you plug a headphone into a line input? Maybe, but there's not enough power to make the coils move, so you hear nothing. Come to think of it, the 16 Ohms you put on it might be so low that it acts as shortage, so things might indeed blow up like I did with my speaker and the power socket. But here it will be whatever provides the line output that has to suffer.

Reversed: can you use headphone outputs as line outputs? The voltage is roughly right, and there's power enough. So why not. With nothing plugged in it also works fine, so loading an output with less than it provides is OK. All the power sockets can provide 16A, but using less than that is also fine. But ask for more and fuses will blow.


Now back to the mics: replace the very low impedance capsule with one with higher impedance. Me thinks the delivered voltage is too low (they usually need quite some gain from the preamp) but the high current would not really be a problem. I think... So no, it won't really work.

But go ahead and try if you want to test whether something blows up or not. At your own risk ofcourse. If you want to blow stuff up, then plug a speaker into the wall socket. But have a fire extinguisher close by please :-P
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vurt
addled muppet weed
54790 posts since 26 Jan, 2003 from through the looking glass

Re: Another noob microphone question. What would happen if..

Post Wed Nov 13, 2019 7:13 am

decent current?

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Forgotten
KVRAF
6007 posts since 15 Apr, 2019 from Nowhere

Re: Another noob microphone question. What would happen if..

Post Wed Nov 13, 2019 7:34 am

vurt wrote:
Wed Nov 13, 2019 7:13 am
decent current?
Current should always be appropriately dressed.

Small correction to the above - it’s not entirely accurate that:

impedance = voltage/current

That’s the formula to determine resistance, which is a component of impedance.

Impedance is the sum of resistance, capacitive resistance and inductive resistance.

jp008
KVRist
44 posts since 15 Oct, 2010

Re: Another noob microphone question. What would happen if..

Post Thu Nov 14, 2019 12:39 pm

Decent current
Obviously this was a typo, meant to mean Direct Current.

jp008
KVRist
44 posts since 15 Oct, 2010

Re: Another noob microphone question. What would happen if..

Post Thu Nov 14, 2019 12:52 pm

BertKoor wrote:
Wed Nov 13, 2019 5:16 am
When I was about ten years old, I learned about electricity, difference between Decent Current and Alternating Current and so on. So I heard a loudspeaker needs alternating currents to make sound. And guess what, there's a handy source of AC at the wall! So I took this old loudspeaker, plugged it into the mains power wall socket, and indeed it made a loud sound! But just for a very short while. And it made a lot of dust as well, and it smelled quite funny. I won't do that ever again, at least on purpose...
Now what you're doing is much much safer. I'd almost suggest you try it, if it weren't that you need a bit of theoretical understanding before you try to validate your theories. And I'd have to warn you it's all at your own risk and I don't take any responsibility. But if you can afford every thing involved in the experiment blows up, oh well...
Funny how you would use a speaker as a comical example about a question pertaining to a microphone because a speaker is basically what a microphone is. Maybe just try plugging the speaker into a preamp instead ? :idea: Hmmmm..
Now an experiment... Given:
* Line level signals are around one Volt and have an impedance of say 1000 ohm. So the current is 1/1000 = 1 mA.
Correct me if I'm wrong, but I believe 1000 mA would be 1A, same as 1 volt/Ohm. So 1000 Ohms would be 1,000,000 mA or 1000A. Of course, that would have to be stepped down considerably before usage..
Now back to the mics: replace the very low impedance capsule with one with higher impedance. Me thinks the delivered voltage is too low (they usually need quite some gain from the preamp) but the high current would not really be a problem. I think... So no, it won't really work.
Wouldn't a simple matching impedance transformer XLR adapter do the same thing? For example, instead of plugging the mic into a mic preamp input, plug it into a DI input with an impedance matching adapter on the end of it.

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Tj Shredder
KVRAF
3380 posts since 6 Jan, 2017 from Outer Space

Re: Another noob microphone question. What would happen if..

Post Sun Nov 17, 2019 9:39 pm

A condenser mic membrane (the part that is moved by the vibrating air) is part of a condenser. The membrane of a dynamic mic is like the membrane of a speaker, moving a magnet within a coil. (you can use a speaker as mic and vice versa, it just does not sound good, but could be good enough for spies in the living room).
Without knowing how things work, such experiments don't lead too far. Its easy to learn that "how" nowadays, just google it...
Complete capsules actually contain all circuits already, Its not worth to make them fit to whatever you would hold in your hand...
What is the basic idea behind your question? What do you want to achieve??? This is eventually the more important part of your inquiry which is missing...
If you just want to know how a mic look inside, go ahead and disassemble that pricy Neumann...; - ) (Though burning money directly seems easier...)

xtp
KVRian
862 posts since 4 Jun, 2006

Re: Another noob microphone question. What would happen if..

Post Tue Nov 26, 2019 2:36 pm

BertKoor wrote:
Wed Nov 13, 2019 5:16 am
So I took this old loudspeaker, plugged it into the mains power wall socket, and indeed it made a loud sound! But just for a very short while. And it made a lot of dust as well, and it smelled quite funny. I won't do that ever again, at least on purpose...
:lol:

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