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Topic: USB Microphone To Analogue? (Read 6276 times) previous topic - next topic
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USB Microphone To Analogue?

I wonder, is it possible to mod a USB Microphone so i can uset he sound card as the ADC instead of the internal hardware in the Microphone?

I am not that technological, but if i understand thing right, it works like this:

Mic input (Analogue) -> Internal ADC -> USB -> PC + Decoding

So wouldn´t it be possible to just do something like this.

Mic input (Analogue) -> 3.5mm -> Soundcard(ADC) -> PC + Decoding

Hope you get what i am trying to explain here.

Thanks

USB Microphone To Analogue?

Reply #1 –
Sure, cut the wire from the microphone into it's ADC and replace it with your amp + ADC.

USB Microphone To Analogue?

Reply #2 –
Quote from: saratoga on
Sure, cut the wire from the microphone into it's ADC and replace it with your amp + ADC.


http://www.youtube.com/watch?v=pNj3as390AY

Looked at this, and as said, i am not that technical.

But is there an easy way to know which cable does what?

I mean, the sound is just mono, so i guess it´s 1 wire that does the sound, and the others are for LED and functions?


And couldn´t i just connect it directly to the Sound Card?

As it should have internal Amplifying?

USB Microphone To Analogue?

Reply #3 –
Quote from: zerowalker on
But is there an easy way to know which cable does what?

I mean, the sound is just mono, so i guess it´s 1 wire that does the sound, and the others are for LED and functions?


It takes two wires to make a signal.  If you watch that video theres 2 wires coming out of the transducer.  Those are the ones that go into the mic jack on an amp. 

USB Microphone To Analogue?

Reply #4 –
Quote from: saratoga on
Quote from: zerowalker on
But is there an easy way to know which cable does what?

I mean, the sound is just mono, so i guess it´s 1 wire that does the sound, and the others are for LED and functions?


It takes two wires to make a signal.  If you watch that video theres 2 wires coming out of the transducer.  Those are the ones that go into the mic jack on an amp.


Are you talking about the red and white?

http://jumperone.com/2011/10/samson-c01u-teardown/

When i read there, he shows 3 wires at a photo, and writes:

Which connected with three wires to the main board. The wires is GND, +5V, MIC_OUT.

Which makes me a bit confused to what you are saying.


USB Microphone To Analogue?

Reply #5 –
Ah didn't see the power line, so I guess the signal is the two lines that aren't power.

USB Microphone To Analogue?

Reply #6 –
Quote from: saratoga on
Ah didn't see the power line, so I guess the signal is the two lines that aren't power.


Okay,

So, is it as easy as to, breakdown a 3.5mm cable on one end, and connect the cables to the mic cables?

USB Microphone To Analogue?

Reply #7 –
Okay it seems that mine doesn´t look exactly like that, even though it is pretty much the same model.



USB Microphone To Analogue?

Reply #8 –
I can't watch youtube so I don't know what is there, but the discussion so far hasn't seem to make clear that power has to come from somewhere to make things work. As designed, that is from the USB connection.

What is the point of this anyhow? I have nothing else to occupy my time so I will destroy a functioning microphone and try to make it work again, in a different way , just to pass the time?

USB Microphone To Analogue?

Reply #9 –
The thing i am trying to do is use my Soundcard ADC instead of the USB microphone, as it has bad noise floor.

http://jumperone.com/2011/10/samson-c01u-teardown/

There it is in text and pictures.

USB Microphone To Analogue?

Reply #10 –
Both the microphone preamp and ADC are in one chip. You need a microphone preamp, so you must add one in between the microphone and soundcard if you take the chip out of the circuit --  or use just the preamp part of the AK5371. I don't know if the later is a practical possibility. In either case, you need power to the microphone and any part of the rest of the circuitry you keep. As designed, that power comes from the USB line.

Maybe I didn't read some part of the article, but I did not see anything that suggested it is possible to get an improved noise figure. Is that what the youtube piece is about?

USB Microphone To Analogue?

Reply #11 –
But what happens if i connect it to the SoundCard mic port?
I know that my line in won´t work as the signal is to low (as a preamp is needed).
But a mic port should amplify the signal right, or is there a reason why it won´t work?

The youtube or the guide does not have anything to do with what i am trying to do, which explains why you don´t find it.

But the mic itself has an internal noise (did a topic on that a while back), and it exist no matter what, even if i mute, it´s pretty much like you have 2 channels, 1 with noise and 1 with the actual sound, and then they join.

But from my understanding, the noise comes from either the pre-amp or the ADC, meaning the Mic itself isn´t the problem.

So if i can use my SoundCard as a ADC, that should solve it.

USB Microphone To Analogue?

Reply #12 –
Many microphones need phantom power to function. If yours does, it is provided from the power coming in on the USB line. The microphone in that article contained a JFET. That does not work with out some electricity of the correct specifications.

All other things working, if your soundcard microphone preamp is better (less noisy) than the one on the USB ADC chip, you may end up with less noise. I suspect it is the mic preamp part, not the ADC part, that has the most noise, but that is only my suspicion. The spec sheet does not break it down.

USB Microphone To Analogue?

Reply #13 –
That power should be able to be provided from the Soundcard form the microphone port (not Line In, which does not amplify the signal with power).

Hmm, is there a way to try the sound cards preamp, to see the noise floor and compare it?

Cause isn´t a Preamp supposed to be noise free?
Of course that ain´t possible, but i mean, it should´t ad noise that is audible?

I am guessing the Preamp (if it´s the cause) is low end?
Or is this natural on all Preamps?

USB Microphone To Analogue?

Reply #14 –
If a microphone preamp provides phantom power, it will be in the specs. Normally there is a way to turn if on and off, for use or not, depending on the type of microphone used. There are many microphone preamps that do not provide anything to the microphone (i.e. from preamp to microphone). I don't think any MB mic inputs do. Obviously these preamps are not meant for mics such as condenser microphones that require it. There are also separate power supplies for microphones, to allow them to use a wider range of preamps.

Microphone preamplifiers are one of those audio devices that can still be fairly expensive with good cause. Very low noise microphone preamps must be carefully designed and carefully constructed and thus are more expensive to produce. They also must be matched with a microphone proper to their design to get the most out of their potential noise performance.

Most microphone preamps are fairly low noise at low gain but with lower priced preamps the noise may becomes quite noticeable above 60% or 70%  gain. I don't know for sure, but I doubt that any of those in MB soundcards are low noise. To plagiarize a guide on microphone selection: microphones and preamps each have their own noise floors. When selecting a mic preamp you want to know to what degree the preamp's noise degrades the noise of your microphone.

There are also preamp considerations such as input impedance (which can have an adverse effect on noise) and overload headroom that are important considerations when determining what preamp to use with a given microphone. Also important, depending upon the type of microphone, is whether or not the preamp provides enough gain to always be able to insure a good recording.

USB Microphone To Analogue?

Reply #15 –
I see, didn´t know that.

But when you say, Expensive, what are we talking about, what prices?

And this makes things a bit harder for me, How can i determine what Preamp to choose?

As, let´s say i buy one. I wouldn´t want it to be limited to work good with one microphone, i would like it to work with, well a many as possible, so if i want to upgrade/change microphone, i am able to do that.

USB Microphone To Analogue?

Reply #16 –
Is there a reason why you want to use this particular microphone? There are many inexpensive microphones available that are designed to plug directly into the microphone input of a soundcard (for Skype etc in conjunction with a webcam).
Regards,
   Don Hills
"People hear what they see." - Doris Day

USB Microphone To Analogue?

Reply #17 –
The topic is multi-dimensional. It depends on a variety of factors. This might provide some overview.
http://www.rane.com/note148.html

USB Microphone To Analogue?

Reply #18 –
Quote
I am not that technological...
This sounds like a VERY BAD IDEA to me, unless you consider this a "throw-away" mic...    I assume you don't have a soldering iron or a multimeter?    I have the equipment & experience, but I wouldn't want to "mess-up" working mic.

The mic preamp built into most soundcards is low quality, so you may end-up with worse quality.   

And you can't use a "better" preamp, because your mic doesn't have the proper hardware/electronics to interface with a normal (stage or studio) preamp, mixer, or interface which will have balanced (3-wire) low-impedance connections and XLR conectors.    Plus, your mic won't operate from "studio standard" 48V phantom power.

The main idea of a "studio style" USB mic like yours is to bypass the "cheap" consumer soundcard with something better without requiring a separate USB interface with good mic preamps and XLR connectors.

USB Microphone To Analogue?

Reply #19 –
Quote from: splice on
Is there a reason why you want to use this particular microphone? There are many inexpensive microphones available that are designed to plug directly into the microphone input of a soundcard (for Skype etc in conjunction with a webcam).


Not exactly, but as i own it and the sound is good, i thought it would be nice to just get rid of the noise.
But it seems it was harder or not possible at all.