How to connect a microphone to a computer...
I once thought about this myself and didn’t know who to ask... Time has passed, I’m sharing the article.
GO!!!
Computers and computer technologies are increasingly becoming part of every person’s life. A microphone, as a device that converts sound into an electrical signal and allows a computer to “hear,” perceive, analyze, store and transmit sound, is an indispensable companion and participant in the evolution of computer technology. Almost any modern laptop has a built-in microphone, and any desktop computer is necessarily equipped with an integrated sound card with a microphone jack (MIC).
Today, a microphone is connected to a computer for communicating via Skype, for recording speech and speakers, recording noise and musical instruments, lectures and conferences, for conducting acoustic measurements, for broadcasting on the Internet and for a number of other tasks. The improvement and specialization of microphones has led to their diversity and different connection options.
Modern microphones are divided into several groups according to their purpose and type of transforming element: multimedia (for voice communication via a computer), professional (for various professional uses), dynamic (use a dynamic transducer), condenser (use a membrane transducer), USB microphones (adapted for connecting to a computer directly via USB) and a number of others.
Multimedia microphones - mainly used for voice conversations over computer networks (for talking on Skype, etc.) are connected to the computer directly into the MIC input of the built-in or multimedia sound card.
Behringer XM 8500 Dynamic microphones - typically used at concerts, rehearsals and for recording loud instruments in the studio, do not require additional power. They are connected to the computer via a mixing console (mixer) or preamp (microphone preamplifier), then to the line input of the sound card. If the sound card has a microphone input (that is, the sound card has a built-in preamp), then a dynamic microphone can be included in such a sound card directly into the MIC input.
The most famous and popular dynamic microphones: Shure SM58, Behringer XM 8500 Ultravoice, Electro-Voice C05 and others.
ART Tube MP Studio v3 Examples of preamps include: ART Tube MP, ART Tube MP Studio V3, M-Audio AudioBuddy, Behringer MIC 200 TUBE ULTRAGAIN.
You can read about sound cards in detail in our article “Sound card for a home studio.”
Rode NT1-A Condenser microphones - used for recording voices and most instruments, for vocals and a number of instruments at concerts, for conferences and reporting. To operate, condenser microphones require additional power, which is usually supplied to the microphone from the preamp or mixing console through the same wire that connects the microphone to the console or preamp (this is called phantom power).
Condenser microphones are connected to the computer through a mixing console or preamp with phantom power, then the sound signal is sent to the linear input of the sound card. If the sound card has a microphone input with phantom power (that is, the sound card has a built-in preamp), then a condenser microphone can be connected directly to the sound card in the MIC input.
Typical representatives of condenser microphones: Audio-Technica AT2020, Behringer C1, NADY SCM 1000, Rode NT-1A.
AT 2020 USBUSB microphones are condenser microphones that have in their housing everything you need to connect directly to a computer via the USB bus. They have a preamp, a microphone power supply, and a sound card on board. Used to record speech, vocals, musical instruments, etc. Extremely mobile and easy to connect.
The most famous USB microphones: Infrasonic UFO, Audio-Technica AT2020 USB, Behringer C-1U, RODE Podcaster.
In practice, for high-quality sound recording into a computer, condenser microphones are usually used (as they have a wider frequency range), but for recording sources with extremely high sound pressure or a limited frequency range (drums, percussion instruments, electric guitar, bass guitar, etc.) etc.) choose dynamic microphones.
In general, the connection diagram for a condenser or dynamic microphone to a computer has the following form: microphone, microphone cable, microphone preamplifier (or mixer) with phantom power, compressor (optional), other processing devices (optional), line input of the sound card (for digitization of a sound signal), sound card driver, program for recording sound into a computer.
The modern trend is to simplify this scheme: sound cards with microphone preamps on board, mixing consoles and preamps with a built-in sound card and connection to the computer directly via USB or FireWire, and USB microphones that are simply connected to the USB input of the computer are produced.
In conclusion, let me remind you that before connecting for the first time it is always (!) important to study the instructions for the microphone and the devices with which it works - specific models may have non-standard connection options and a special activation procedure. Knowing the manufacturer's recommendations will keep your microphone, computer, and everything in between in top working shape.
Almost all headsets that are designed to work with a PC have such “pathetic” characteristics that if you try to use the microphone from such a headset for recording or karaoke, you will get nothing but disappointment. There is only one reason here - all such microphones are designed for speech transmission and have a very narrow frequency range. This not only reduces the cost of the design itself, but also promotes speech intelligibility, which is the main requirement of the headset.
Attempts to connect a regular dynamic or electret microphone usually end in failure - the level from such a microphone is clearly not enough to “boost” the sound card. Additionally, ignorance of the input circuit of sound cards affects and incorrect connection of a dynamic microphone completes the matter. Assembling a microphone amplifier and connecting it “wisely”? It would be nice, but it is much easier to use an IEC-3 microphone, which was once widely used in wearable equipment and is still quite common. But, of course, you will have to connect “wisely”.
This electret microphone has fairly high characteristics (the frequency range, for example, lies in the range of 50 - 15,000 Hz) and, most importantly, it has a built-in source follower assembled on a field-effect transistor, which not only matches the high impedance of the microphone with the amplifier, but it also has an output signal level that is more than sufficient for any sound card. Perhaps the only drawback is that the microphone requires power. But its current consumption is so small that two AA batteries connected in series will last for many months of continuous operation. Let's take a look at the internal circuit of the microphone, which is located in an aluminum cup, and think about how to connect it to a computer:
The gray color indicates the aluminum glass, which is a screen and is connected to the common wire of the circuit. As I already said, such a microphone requires external power, and minus 3-5 V must be supplied to the resistor (red wire), and plus to the blue one. We will pick up a useful signal from white.
Now let's take a look at the computer microphone input circuit:
It turns out that the signal should be supplied only to the very tip of the connector, marked green, and the sound card itself supplies +5 V to the red one through a resistor. This is done to power headset pre-amplifiers, if used. We will not use this voltage for two reasons: firstly, we need a different polarity, and if we simply “turn” the wires, the microphone will produce a lot of noise. Secondly, the PC power supply is switching and the interference at these five volts will be considerable. The use of galvanic elements in terms of interference is ideal - pure “constant” without the slightest pulsation. So, the complete diagram for connecting our microphone to a computer will look like this.
This question is usually asked by those who do not understand anything at all about microphones and musical equipment. Such people face a number of problems, they often make purchases without understanding the item and it turns out that they either buy something unnecessary, or simply do not realize that what they bought will not work the way they want and in fact need spending a lot more money than they expected to make everything work as it should.
Let's give instructions, so to speak, for complete laymen.
So, rule number one - never buy microphones in electronics stores like M-Video, Eldorado, in shopping centers or, God forbid, in Auchan. Nothing travel-related is ever sold there. At best, you will buy a karaoke microphone that sounds disgusting and is incompatible with normal equipment.
Rule number two - never buy a microphone that comes with a microphone cable attached by default. This is generally taboo. Both the cable and the microphone will be lousy. However, you vote with your ruble and buy what you buy. Everything has its price, just don’t say later that you weren’t warned.
If you want to sing karaoke songs after a feast, that's one thing. You don’t mind getting this microphone dirty in Olivier salad. If you want to record your voice on your computer, read on.
The first and easiest option for connecting to a computer is to buy a USB microphone. You connect via a USB port with a regular USB cable and immediately get decent sound. USB microphones come in both cheap and expensive varieties. This option has long ceased to be a compromise and the sound quality of such microphones is quite decent. Considering the convenience of connecting to a computer, their price is justified. Naturally, a USB microphone will cost more than a karaoke microphone from Auchan. But it will sound as it should.
If you provide voiceovers for computer games, record podcasts, or conduct training sessions on the Internet, then a USB microphone is your option. Our consultants will help you choose the right model taking into account your budget - call or write to us.
Well, the last and coolest option is a studio microphone for recording vocals. Don't be intimidated by the word "studio". Studio doesn't mean expensive. Prices for such microphones vary greatly. There are very inexpensive models and there are top-end items that, in our opinion, are not justified in using at home.
The advantage of a studio microphone is primarily in sound quality. If sound is a fundamental point for you, then there are no options, you need to assemble a home studio.
First, let's decide on the type of microphone you need. For vocal recording, it is best to buy a condenser microphone with a large diaphragm. Dynamic microphones are an option for concerts, while small-diaphragm condenser microphones are an option for recording musical instruments. Ribbon microphones are generally a topic for a separate article and they are not suitable for us.
In general, we take a condenser microphone with a large diaphragm. It looks something like this:
There are a million options and prices. Again, our consultants will help you choose the right one. Don't hesitate to ask.
Buying a microphone alone does not make you a rock star. A condenser microphone will not work on its own. And you won’t be able to connect it directly to your built-in sound card. even if you try, it won't work. Because a condenser microphone requires phantom power. And such power is available either in external audio interfaces or in specialized microphone preamplifiers.
Therefore, if you want to use a condenser studio microphone and get cool sound, in addition to a microphone, at a minimum, you also need an external USB audio interface with a microphone input. In common parlance - an external sound card.
For example this one:
There are also more expensive options and solutions, but we will not touch on them in this article, because... This is already equipment for professional studios and the approach to it is completely different.
Now let’s conduct a short educational program on microphone cables and the connectors into which they are connected. Because This is what causes most problems and questions among ignorant people.
So, all professional microphones (not karaoke or USB) use XLR connectors. The XLR connector on the microphone looks like this:
In turn, the connectors on the microphone cable will look like this:
You will not buy such a microphone cable at any Auchan. They are sold in specialized music stores like ours.
Sound cards and microphone preamplifiers usually use either XLR inputs for connecting a microphone cable or combined Jack / XLR connectors. A standard XLR input looks like this:
The Jack/XLR combo connector looks like this:
The combo connector can accommodate both a microphone cable with an XLR connector and an instrument or stereo cable with a Jack connector. The Jack connector in professional equipment looks like this
There is also a mini-jack, but it has nothing to do with professional music equipment - this is a solution for portable players, etc.
If you bought a microphone for karaoke and are trying to plug it into a jack/xlr combo jack, you may be disappointed. Why? Because, as a rule, combined connectors are designed in such a way that when connected via a jack, the signal preamplification is much less. This is done so that you can connect musical instruments or linear signal sources such as an mp3 player, synthesizer or computer via the jack. And when you connect an XLR cable, another chain is triggered, which is designed to amplify the signal coming from the microphone.
In Russian: if you plug your microphone with a jack connector at the end of the cable into such a combined input, the signal will be very quiet, and the problem is not in the microphone or in the device you plug into, but in incorrect use and lack of understanding of how your equipment is working.
A computer is a universal machine capable of performing many different tasks, including recording and processing sound. To create your own small studio, you will need the necessary software, as well as a microphone, the type and quality of which will determine the level of the material produced. Today we’ll talk about how to use a karaoke microphone on a regular PC.
First, let's look at the types of microphones. There are three of them: condenser, electret and dynamic. The first two differ in that they require phantom power for their operation, thanks to which, using built-in electronic components, you can increase sensitivity and maintain high volume levels when recording. This fact can be both an advantage, in the case of using them as a means of voice communication, and a disadvantage, since in addition to the voice, extraneous sounds are also captured.
Dynamic microphones used in karaoke are an “inverted speaker” and are not equipped with any additional circuits. The sensitivity of such devices is quite low. This is necessary so that, in addition to the voice of the speaker (singing), a minimum of unnecessary noise gets into the track, as well as to minimize feedback. When we directly connect a dynamic microphone to a computer, we get a low signal level, to strengthen which we have to increase the volume in the system sound settings.
Using a Preamp
When choosing a preamplifier, you need to pay attention to the type of input connectors. It all depends on what kind of plug the microphone is equipped with - 3.5 mm, 6.3 mm or XLR.
If a device that is suitable in price and functionality does not have the necessary sockets, then you can use an adapter, which can also be purchased in a store without any problems. The main thing here is not to confuse which connector on the adapter the microphone should be connected to, and which the amplifier should be connected to (male-female).
DIY preamplifier
Amplifiers sold in stores can be quite expensive. This is due to the presence of additional functionality and marketing costs. What we need is an extremely simple device with one function - amplification of the signal from the microphone - and it can be assembled at home. Of course, you will need certain skills, a soldering iron and consumables.
To assemble such an amplifier, you need a minimum of parts and a battery.
Here we will not describe step by step how to solder a circuit (the article is not about that), just enter the request “do-it-yourself microphone preamplifier” into a search engine and get detailed instructions.
Connection, practice
Physically, the connection is quite simple: just insert the microphone plug directly or using an adapter into the corresponding preamplifier connector, and connect the cord from the device to the microphone input on the PC sound card. In most cases, it is pink or blue (if pink is not available) in color. If all the inputs and outputs on your motherboard are the same (this happens), then read the instructions for it.
The assembled structure can also be connected to the front panel, that is, to the input with a microphone icon.
Conclusion
Proper use of a karaoke microphone in a home studio will allow you to achieve good sound quality, since it is designed specifically for voice recording. As is clear from the above, this requires only a simple additional device and, perhaps, care when choosing an adapter.
This document contains electrical circuit diagrams and information on how to power electret microphones. The document is written for people who can read simple electrical diagrams.
- Introduction
- Introduction to Electret Microphones
- Basic power circuits for electret microphones
- Sound cards and electret microphones
- Plug-in power
- Phantom power in professional audio equipment
- T-Powering
- Other useful information
1. Introduction
Most types of microphones require power to operate, usually condenser microphones, as well as microphones similar to them in operating principle. Power is required to operate the internal preamplifier and polarize the mic capsule membranes. If there is no built-in power source (battery, accumulator) in the microphone, voltage is supplied to the microphone through the same wires as the signal from the microphone to the preamplifier.
There are times when a microphone is mistaken for a broken one only because they do not know about the need to supply phantom power to it or insert a battery.
2. Introduction to Electret Microphones
Electret microphones have the best price/quality ratio. These microphones can be very sensitive, quite durable, extremely compact, and also have low power consumption. Electret microphones are widely used; due to their compact size, they are often built into finished products, while maintaining high performance characteristics. According to some estimates, the electret microphone is used in 90% of cases, which, given the above, is more than justified. Most lavalier microphones, microphones used in amateur video cameras, and microphones used in conjunction with computer sound cards are electret microphones.
Electret microphones are similar to condenser microphones in the principle of converting mechanical vibrations into an electrical signal. Condenser microphones convert mechanical vibrations into a change in capacitance of the capacitor, obtained by applying voltage to the membranes of the microphone capsule. A change in capacitance, in turn, leads to a change in voltage on the plates in proportion to the sound waves. While the capsule of a condenser microphone requires external (phantom) power, the membrane of the capsule of an electret microphone has its own charge of several volts. It needs power for the built-in buffer preamplifier, and not for membrane polarization.
A typical electret microphone capsule (Fig. 01) has two pins (sometimes three) for connection to a 1-9 volt current source and, as a rule, consumes less than 0.5 mA. This power is used to power a miniature buffer preamplifier built into the microphone capsule, which serves to match the high impedance of the microphone and the connected cable. It should be remembered that the cable has its own capacitance, and at frequencies above 1 kHz its resistance can reach several 10 kOhms.
The load resistor determines the resistance of the capsule, and is designed to match the low noise preamplifier. This is usually 1-10kOhm. The lower limit is determined by the amplifier's voltage noise, while the upper limit is determined by the amplifier's current noise. In most cases, a voltage of 1.5-5V is supplied to the microphone through a resistor of several kOhms.
Due to the fact that the electret microphone contains a buffer preamplifier, which adds its own noise to the useful signal, it determines the signal-to-noise ratio (usually around 94 dB), which is equivalent to an acoustic signal-to-noise ratio of 20-30 dB.
Electret microphones require a bias voltage for the built-in buffer preamp. This voltage must be stabilized and not contain ripples, otherwise they will arrive at the output as part of the useful signal.
3. Basic power supply circuits for electret microphones
3.1 Circuit diagram
Figure Fig.02 shows the basic power circuit for an electret microphone and should be referred to when considering connecting any electret microphone. The output resistance is determined by resistors R1 and R2. In practice, the output resistance can be taken as R2.
3.2 Powering the electret microphone from a battery (battery)
This circuit (Fig. 04) can be used in conjunction with household tape recorders and sound cards, originally designed to work with dynamic microphones. Once you assemble this circuit inside the microphone body (or in a small external box), your electret microphone will have versatile applications.When building this circuit, it will be useful to add a switch to turn off the battery when the microphone is not in use. It should be noted that the output level of this microphone is significantly higher than that obtained with a dynamic microphone, so it is necessary to control the gain at the input of the sound card (amplifier/mixing console/tape recorder, etc.). If this is not done, high input signal levels may result in overmodulation. The output impedance of this circuit is around 2 kOhm, so it is not recommended to use a microphone cable that is too long. Otherwise it may act as a low pass filter (a few meters won't have much effect).
3.3 The simplest power supply circuit for an electret microphone
In most cases, it is acceptable to use one/two 1.5V batteries (depending on the microphone used) to power the microphone. The battery is connected in series with the microphone (Fig.05). This circuit works as long as the DC current supplied from the battery does not adversely affect the preamplifier. This happens, but not always. Typically, a preamplifier acts only as an AC amplifier, and the DC component has no effect on it.
If you don't know the correct polarity of the battery, try turning it in both directions. In the vast majority of cases, incorrect polarity at low voltage will not cause any damage to the microphone capsule.
4. Sound cards and electret microphones
This section discusses options for supplying power to microphones from sound cards.
4.1 Sound Blaster variant
Sound Blaster sound cards (SB16, AWE32, SB32, AWE64) from Creative Labs use 3.5mm stereo jacks to connect electret microphones. The jack pinout is shown in Figure 06.Creative Labs provides specifications on its website. which a microphone connected to Sound Blaster sound cards must have:
- Input type: unbalanced (unbalanced), low impedance
- Sensitivity: about -20dBV (100mV)
- Input impedance: 600-1500 ohms
- Connector: 3.5 mm stereo jack
- Pinout: Figure 07
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| Fig.07 - Pinout of the connector from the Creative Labs website |
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| Fig.08 - Microphone input of the Sound Blaster sound card |
4.2 Other options for connecting a microphone to a sound card
Sound cards from other models/manufacturers may use the method discussed above, or may have their own version. Sound cards that use a 3.5mm mono jack to connect microphones usually have a jumper that allows you to supply power to the microphone or turn it off if necessary. If the jumper is in a position where voltage is supplied to the microphone (usually +5V through a 2-10 kOhm resistor), then this voltage is supplied through the same wire as the signal from the microphone to the sound card (Fig.09).
The sound card inputs in this case have a sensitivity of about 10 mV.
This connection is also used on Compaq computers that come with a Compaq Business Audio sound card (the Sound Blaster microphone works well with the Compaq Deskpro XE560). The offset voltage measured at the Compaq output is 2.43V. Short circuit current 0.34mA. This suggests that the bias voltage is applied through a resistor of about 7 kOhm. The 3.5mm jack ring is not used and is not connected to anything. The Compaq user manual says that this microphone input is only used to connect an electret microphone with phantom power, such as one supplied by Compaq itself. According to Compac, this method of power delivery is called phantom power, but this term should not be confused with what is used in professional audio equipment. According to the stated technical characteristics, the input impedance of the microphone is 1 kOhm, and the maximum permissible input signal level is 0.013V.
4.3 Applying bias voltage to the three-wire electret microphone capsule from the sound card
This circuit (Fig. 10) is suitable for connecting a three-wire electret microphone capsule to a Sound Blaster sound card that supports bias voltage (BC) to the electret microphone.
4.4 Applying bias voltage to a two-wire electret microphone capsule from a sound card
This circuit (Fig. 11) is suitable for interfacing a two-wire electret capsule with a sound card (Sound Blaster) that supports the supply of bias voltage. |
| Fig. 12 - The simplest circuit working with SB16 |
4.5 Power supply for electret microphones with 3.5 mm mono jack from SB16
The power circuit below (Fig. 13) can be used with microphones whose bias voltage is supplied along the same wire through which the audio signal is transmitted.4.6 Connecting the handset microphone to the sound card
According to some news articles on comp.sys.ibm.pc.soundcard.tech, the circuit can be used to connect a handset electret capsule to a Sound Blaster sound card. First of all, you need to make sure that the microphone in the selected handset is electret. If this is the case, then you need to disconnect the tube, open it and find the plus of the microphone capsule. After this, the capsule is connected as shown in the figure above (Fig. 13). If you want to use the RJ11 connector of the handset, then the microphone is connected to the wires of the external pair. Different handsets have different output levels, and some may not be at sufficient levels for use with a Sound Blaster sound card.If you want to use the handset speaker, then connect it to the Tip and insert it into the sound card. Before doing this, make sure that it has a resistance of more than 8 Ohms, otherwise the amplifier at the output of the sound card may burn out.
4.7 Powering the multimedia microphone from an external source
The basic idea of powering a multimedia (MM) microphone is shown below (Fig. 14).
The general power supply circuit for a computer microphone designed to work with Sound Blaster and other similar sound cards is shown in the figure below (Fig. 15):
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| Fig. 15 - General power supply circuit for a computer microphone |
Note 2: Typically, the supply voltage for microphones connected to a sound card is about 5 volts, supplied through a 2.2 kOhm resistor. Microphone capsules are generally not sensitive to 3 to 9 volts of DC current, and will operate (although the level of applied voltage may affect the microphone's output voltage).
4.8 Connecting a multimedia microphone to a regular microphone input
The +5V voltage can be obtained from a larger voltage using a voltage regulator such as the 7805. Alternatively, you can use three 1.5V batteries in series, or you can use one 4.5V battery. It should be turned on as shown in the figure above (Fig. 16).
4.9 Plug-in power
Many small video cameras and recorders use a 3.5mm stereo microphone plug to connect stereo microphones. Some devices are designed for externally powered microphones, while others supply power through the same jack that carries the audio signal. In the characteristics of devices that provide power to capsules through a microphone input, this input is called “Plug-in power”.
For devices that use the Plug-in power connection for electret microphones, the diagram is shown below (Fig. 17):
Technology for connecting Plug-in power microphones from the point of view of the circuitry of the recording device (Fig. 18):
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| Fig. 18 - Plug-in power connector circuitry |
Notes
An electret microphone buffer preamplifier is also simply a preamplifier, voltage converter, repeater, field effect transistor, impedance matcher.