# Simple Way to Convert Stereo to Mono

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## Introduction: Simple Way to Convert Stereo to Mono

This is going to be a tutorial on how to take a stereo audio source from a phone for example and convert it to a mono signal to use with a mono amplifier or a two channel amplifier( I'll show you how to do this), and anything that needs a mono signal. This is a cheap alternative for a stereo to mono circuit costing less than 3\$, that works surprisingly well for its simplicity, even though this is not really the best way to do this. Enough of me blabbering boring stuff, onto the theory and tutorial!

## Step 1: When Do I Use This Circuit?

You use this circuit if for example if you have a homemade boombox with a two channel amplifier that has a sub-woofer on one channel and a tweeter and a mid-range on the other. On some songs that alternate between channels, the sound will get cut off and you will not hear that part of the music, which can be frustrating. The thing to do is to make a Stereo to Mono circuit that will convert stereo to mono to play equal sound through both channels and not get any sound cut-off. This will give the boombox more range of frequencies heard through the tweeter and mid-range and not through the subwoofer which cannot be heard well. It seems confusing at first, but you will hear a difference if you are having the problem like the example above. You can also use this circuit for a mono amp like the Lm386 class ab amplifier.

## Step 2: Theory Time!

The way this works is if you just join the two source stereo wires together, you will cause shortage problems as he audio sources are fighting over each other and possibly break or blow the source device, and you will have a BAD day! To counter this fighting, you put resistors on each source +, and join the two resistor ends together to have a Mono signal. This works by how the audio signals have something to pass through like a filter to prevent the audio signals from fighting like Rocky Balboa and Apollo Creed, nobody wants that.

## Step 3: What You Need?

Audio source(iPhone, MP3 player, phono plug)

2 resistors of equal value(For LINE OUPUT, use 470-1000Ω resistors.)

(For PHONE OUTPUT, use 33-100Ω resistors)

( Although anything between these values should be good)

## Step 4: Time to Build It!

To build this, refer to the circuit diagram that I have provided, you get a phono plug or your source and connect your resistors then connect your mono output to a mono amp or put two wires or rca from ground and two wires or rca from the output to your 2 channel amp as I explained in the example. This is an extremely easy circuit that works very well for the simplicity and the price.

## Step 5: Closing

So, I hope you liked this tutorial and got this circuit working, ask questions in the comments and me or anybody else will help you hopefully as soon as possible. As for the two channel example, after you hook it up, look up a left and right stereo test, if it works the sound should sound like its coming from the same speaker ans sound equal. Hope you like this tutorial and try this for your self if you need it. Thank You

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• ### Block Code Contest

You know what you're doing and I don't, so I'm asking:

As a guitar player, I'm interested in how to use a simple yet powerful stereo amplifier (Search Amazon: Nobsound NS-20G 200W Mini Bluetooth 5.0 Power Amplifier) as an inexpensive guitar amplifier between a guitar effects processor (Search Amazon: Zoom G1 FOUR Guitar Multi-Effects Processor Pedal) and a passive 8Ω guitar speaker cabinet.

The output from the pre-amp/processor is typically 1/4" mono (or 3.5mm headphone jack) and the speaker cabinet jack also is typically 1/4" mono.

To maximize the output from this amplifier, I'd like to tap both channels into mono output at 8Ω to the speaker. If it's not too kludgy, maybe I could fit it in an Altoids box and velcro it to the amplifier.

If this can work, I'd be able to fit loud clean guitar amplification into a briefcase at low cost.

Any advice would be appreciated, even if it's to tell me to give it up.

Thanks for considering this.

I'm not really clear about the phone/line output. (I'm an audio novice at best) I've thought line (out or in) is the same level as the aux input on most Bluetooth speakers, amps, your car etc. But you connect the phone to those, so I just se this confusing love triangle between aux, phone and line XD. Or is it phono you mean? As in a vinyl player? I could trial'n error this but a clarification here would make my day!

Thanks!

Hello! There, I have a question regarding the use of it. Can we use this method for the input of lm386 module (which runs 3W single speaker)?

My project is a DVC subwoofer (4+4 ohm) powered by a 50W x2 RMS stereo amp. My idea is to combine the stereo signals to mono and use a Y splitter for input to the amp so the DVC's don't fight each other. How many watt resistor is needed for each line? Thanks!

I know this is an older post. But I have seen how this works when you have a Bluetooth to amp configuration. But I can't seem to find anything on an amp with built-in Bluetooth. Is there a way to create stereo to mono, or are you just basically stuck with a Right or left channel? Great explanation of the pre-Bluetooth(or signal) to amp configuration!!!

Like you said, " I know this is an older post", but try this: TPA3110 Bluetooth 4.2 Digital Amplifier Board Audio Stereo 2x15W Output Power. It sells on ebay for as little as \$4.39, with \$2.99 shipping. It's still stereo, and you still have to convert to mono for the subwoofer, but the Bluetooth is built in to this amp. I hope this helps.

They ought to sell stereo-to-mono adapter plugs with resistors built in as shown here. I think the ones they do sell simply short the inputs together, which (as described here) is not good.

Hi

Can I use this principle to build a cable to combine a mono input to stereo output?

Combine two capacitors at negative terminal and use the positive terminals as two channels. Capacitor value 4.7uF probably at 63V.

The circuit is mostly to go from Stereo to Mono. for Mono to Stereo you can most often just connect the mono-channel to both stereo inputs without resistors.

Using a 2 channel chip amp with built in Bluetooth to drive a woofer and tweeter, so I need a mono signal. Could these resistor(s) be used on the stereo volume pot to combine the channels to mono?

Нужно подключить предварительный стерео усилитель к моно усилителю. Оба питаются от двухполярного питания. Сейчас подключены по этой схеме, но без R5. R3=R4=600Ом. Звук тусклый. Что нужно добавить или убрать?

can i just combine the outputs of a preamp together and put that signal into a mono amp using a simple y connector?

Hi,
First I want to thank you for this tutorial :-)

I have a question about the resistors, how to choose the right value ? why 33-100 omhs for phone and 470-1000 for line ? Is there a way to calcul it based on some measures?

Hi,

I have small radio that has 1 speaker with no auxiliary so it's a mono. Can I use this same principal to built a cable that will wire from the mono speaker and convert the output to stereo ?

At the radio I have + G (mono)only, at the other end I have +G, +G. (Stereo)

NB. This is a very small BT speaker that does not have auxiliar output I want to utilize the BT capability use the mono ouput and wire to sterio amplifier.

Thank you .