How to convert an old telephone receiver into a lo-fi mic

telephone receiver into a lo-fi mic

Home recording is always exciting. For that we have many low cost recorders, but a lo-fi mic is better than a hi-fi mic. A lo-fi mic helps in a clean recording which also includes free from sound reflection and free from noise. A lo-fi mic was a great hit with rap music where the drum sound had boomy kick. It gives us a range which was mid range. A telephone speaker works as a fantastic microphone. This can be prepared at home and it is easy to do.Read on to know how to make your own lo-fi mic at home.

Difficulty level

For a beginner, it would be difficult as it involves soldering and drilling and with out practice it could be tough. But with little help from a hardware store or a mechanic, it could be easy and simple. If you would be doing the drilling and soldering on your own, then be cautious as it could be dangerous.

Time required

The time required to make a lo-fi mic from a telephone is variable. It could vary from two hours to four hours. With out experience, drilling and soldering could be difficult and also risky. But if you take help, it could be only two hours or so.

Resources required:

  1. Hook up wire (about 20 inches) to connect the speakers.
  2. Soldering iron with solder to place the wire.
  3. Small cloth piece or towel to reduce noise level.
  4. Screw driver to unscrew the screws in the phone
  5. Audio jack (quarter inch size).
  6. Old phone handset.
  7. A 5/16″ drill to make room for audio jack.
  8. A headphone/speaker.

Estimate cost

The cost for this entire process could be a bit expensive if you do not have the necessary materials. Like, if you have to purchase the telephone from the second store, it would cost a few cents. Mostly people do not have a drill or a soldering iron at home. So while renting it out, it could cost a few cents. For the beginners, who cannot handle a drill or a solder, hiring an electrician will also cost a few cents. Over all the cost of this project could be around two to three dollars or could go even to ten to fifteen dollars.


    Step 1: Remove the innards by unscrewing the microphone caps and speaker. You simply have to unscrew the covers. Take out everything including the jack of the telephone. Only the speaker must be still inside as it is essential to prepare a mic.

    Step 2:

    In order to place an audio jack, you need to drill and enlarge the hole of the telephone hole. So, you need a 5/16″ drill. Drill the jack hole enough to make enough space for 1/4″ audio jack.

    Step 3:

    Solder a 20 inches wire and install it in the enlarged hole to install a 1/4″ audio jack. The wire should be long enough so that you can attach it to the speaker.

    Step 4

    Screw the wires to a speaker. Some of the phones have resistor for the speaker, let it be there.

    Step 5

    In order to reduce the air noise, you can use a small piece of towel below the cap that is fitted on the speaker. Once you are done with those, screw the caps back on to both the speakers of the telephone.

            Frequently asked questions

            1) What should I do if I do not have the old phone handset at home? Where should I find one?

            Ans: An old hand set is a bit rare in this world of smartphones. Some people like to collect old phones, so you could borrow it from your friends or neighbors who have the old telephones. It will also be available in some of the second hand shops or even antique shops.

            Q2) How does the speaker here pick up the sound?

            Ans: A speaker usually has 4,8,16 or some similar amount of ohms. The sound waves, when they cause the driver to vibrate, a signal is created which transmits to pre amp and then to amp. Higher the ohms, higher the signal received. So, use a pair of head phones, which works as a mic. Raise the input and also talk closely to the mic as lower the ohms, lower the signal transmitted. In order to improve the quality of the speaker, you can use woofers in the speakers.

            Q3) Could you elaborate on the experience with the microphone made thus?

            Ans: This microphone made at home can be used for many purposes. It could be used for skits, bands, DJ, etc. You can directly plug your guitar straight in without the need of the DI. Mice up the speaker so that you can get a more filtered sound. You can also use the Copperphone mic, it has the same limited tone needed for a band, but at the same time has a good clarity.

            Quick tips:

            1. Try taking the help of an electrician for drilling and soldering. That would reduce your time and also it would be less risky.
            2. While soldering the wires, first install the audio jack and then screw the wires to the speaker, or else the audio jack will not fit into the body of the phone.
            3. Make sure the you do not remove the resistor from the speaker.
            4. Keep the wire long enough so that it reaches the speaker.

            Things to watch out for:

            1. Sometimes, the frequency distributed by the speaker is not what you would have expected from a microphone. By making some simple adjustments to the characteristics of the material. But it will be very expensive to make it like a professional microphone.
            2. Mostly a speaker acts only as passive microphone. So, only if you include additional amplifying circuit, the signal of the microphone will be strong.
            3. Be very cautious while drilling the the receiver. If you are not careful, you could break the receiver.
            4. While soldering, make sure to have a protective lenses or else it could blind the eyes.

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