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Questions tagged [audio]

Questions about designing electronics for measuring, processing, and amplifying audio signals.

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263
votes
3answers
36k views

What is it that strips vocals from audio when a 1/8" audio jack is partially unplugged?

Every once in a while, my eighth-inch audio jack will slip loose and I'll seemingly lose only the voice part of a track -- leaving somewhat of a "karaoke" version. What I would guess about how audio ...
18
votes
3answers
27k views

DC biasing audio signal

I have seen a few different ways of adding DC bias to an audio signal. I have simulated them and they all give me similar results, but I cant Figure out is why choose A over B or C. My audio source ...
42
votes
6answers
162k views

What is the voltage range of a standard headphone jack from a phone?

I want to connect the output from the audio jack of an iPhone to an Arduino. What voltage range can I expect to see on the audio lines from the iPhone? I assume that turning the volume up on the ...
52
votes
3answers
67k views

How important is impedance matching in audio applications?

How much will reflected signals matter in audio applications (say between an amp and a speaker, or a pre-amp and an amp)? Mostly with regards to fidelity and not power transfer. What are the ...
18
votes
3answers
97k views

Using a microphone with an Arduino

EDIT: I have been investigating in this problem for quite some time. It turns out to be a way more difficult project than I thought and not something for beginners. This requires expensive hardware (...
3
votes
2answers
1k views

Can I use a UA741 here?

I need to pass a domestic -10dbV audio signal (it should oscillates between -447mV and +447mV) to a microcontroller's ADC which only accepts signals that oscillates between 0V and 5V. I think that the ...
2
votes
3answers
3k views

Playing sounds on an AVR MCU [closed]

I never had to deal with sound and I am pretty sure some of you guys have some experience in that kind of application. My question is more about getting some tips on the different ways to implement ...
15
votes
2answers
18k views

Single supply op-amp audio amplifier

I am trying to create an op-amp amplifier that would work from single 5V supply, and would be able to amplify -100mV to +100mV audio signal to around a 1V peak-peak or so. I've came across this ...
22
votes
6answers
7k views

What makes a “balanced” audio signal?

What is "balanced" audio exactly, and why is it useful? I've read that it means there are two voltages, with one being the inverse of the other. A balanced audio receiver looks at the difference ...
16
votes
5answers
60k views

Simple Audio amplifier Using Transistors

I would like to build a simple audio amplifier using transistors. I know there are IC designs specifically for the task. But i want to use transistors so i can learn how to use them for amplification. ...
17
votes
4answers
12k views

How could you transfer data over an audio line?

I'd like to pass some data over an audio cable (i.e from audio card to my cellphone) with a short cable. I'm looking for some ideas for algorithms for achieving this. They of course should include ...
15
votes
5answers
48k views

How does the phone detect if 3.5 mm jack circuit is closed?

I have an android phone to which i have plugged an earphones. So at the top of the phone, I get the headphone symbol which indicates that the earphone is connected (In other words, the circuit at the ...
12
votes
2answers
21k views

Naively mixing two (or perhaps more) audio signals

this is my first question and I am very much a beginner in electronics so I apologize if this is a too stupid question. I have Atari punk console and another small homemade audiomaking circuit. These ...
22
votes
5answers
10k views

What's the best cable to transfer audio signal?

Sorry if this is the wrong place but I'm interested in a scientific and electrical explanation and not some HiFi voodoo magic. I guess you all have seen the discussions about expensive audio cables ...
9
votes
4answers
12k views

Can I use a PNP Transistor with an Electret Microphone to get an non-inverting output for my Arduino?

I'm looking to simply read the generic sound level from an Electret Microphone. I've seen a number of schematics with NPN transistors, that will provide an inverted output (~5V when quiet, ~0V when ...
5
votes
2answers
22k views

How to make my own volume control for headphones?

I have headphones that don't have volume control built in on the cable, so I thought why wouldn't I try to make one? However, I don't know where to start. Is it enough to just use a logarithmic ...
4
votes
2answers
10k views

line-level audio into an iPhone headset jack?

What level and/or impedance matching (or pre-amp) circuits should be used to send a line-level audio signal into the mic input ring of an iPhone headset jack with minimal distortion and/or loss?
5
votes
3answers
9k views

How to read an audio signal using ATMega328?

I was trying to use the ATMega328 ADC port A0 to read a signal. The hardware I used was: Seeeduino Stalker Electronic Brick Shield Microphone Electronic Brick (I found a link to the original ...
5
votes
2answers
20k views

What is the typical max voltage for sound card line in? [closed]

What is the typical max voltage rms, peak and peak to peak for a sound card line in?
4
votes
2answers
2k views

What component to use for audio signal switching?

I'm looking to build a guitar pedal switcher based on a Raspberry Pi or Arduino (have not yet decided, but I have an unused Raspberry around and I lean towards that). Anyway, digital logic. Now, I ...
2
votes
3answers
360 views

Single supply op amp to convert 0-5VDC to +/-2VDC (microcontroller to line level)

I am generating a 0-5 volt sine wave using an arduino with a DAC. I would like to level shift this signal (DC bias?) by -2.5 volts and have a gain of .8, so that I end up with a line level sine wave. ...
37
votes
6answers
37k views

Can an audio circuit be powered by a switched-mode power supply?

Most audio circuits are powered with large, heavy transformers and a small ripple after smoothing. SMPS are smaller and more efficient. EMI can be shielded by a metal enclosure and the output filtered ...
17
votes
9answers
6k views

DSP recommendation for beginners [closed]

I am considering a project involving a fair share of digital signal processing. As far as I know, the best type of IC suited for this are the Digital Signal Processors. I have never worked with them ...
10
votes
7answers
22k views

LM386 audio amplifier not amplifying

This is my first attempt at making a really simple audio amplifier. The schematics are below:- First I tried connecting the circuit to a 9V battery. (Multimeter reads around 8.3 Volts, which is in ...
8
votes
2answers
32k views

Connect speaker output to microphone input

What exactly is the difference between a microphone signal and a speaker signal? I want to make a simple cable to connect a PC speaker output to a microphone input. Does anyone have a good idea or ...
6
votes
6answers
23k views

MOSFETs or BJTs for using as switch for audio signals

I was wondering which component is better for using as voltage controlled switch for audio signals (e.g. music signal from mp3 player). Should I use MOSFETs or BJTs? The max rail voltage is ...
6
votes
1answer
14k views

Using diodes to mix 2 audio signals into one set of speakers

I have the audio output of 2 computers connected to only one set of speakers. Each computer uses one of these external USB sound cards: And I use this splitter cable to wire the signals together: ...
4
votes
3answers
2k views

My Atmega328 seems to be overkill, what should I use instead?

I'm using an Atmega328 chip with the arduino bootloader in a very small circuit. The sketch simply plays a tune using the tone() function to play a melody through a piezo speaker on a single pin. ...
12
votes
2answers
12k views

Audio delay using discrete components

I would like to make a circuit that causes an audio delay using discrete components. I know I can do small phase shifts using an opamp, but I am looking for something in the millisecond or second ...
5
votes
3answers
9k views

Ground loop? Switch mode power supply noise

I have a single 12V supply powering a 12V class D audio amplifier (Tripath TA2020 based, model 'SMSL SA-36') (C) and a very cheap 12V to 5V 2A rated switch mode converter (A). The 5V is used to power ...
14
votes
2answers
38k views

What wattage should a headphone amp be?

I was at a local surplus store today and I got two LM386N ICs. I thought I could make a really simple headphone amp out of these. But I have no idea what the wattage of a normal headphone amp is. ...
11
votes
8answers
14k views

Maximum sample rate of Arduino Duemilanove?

G'day all! I have an Arduino Duemilanove hanging around spare at the moment and thought I might try a few audio interfacing projects. I'm just wondering what sort of sampling frequency I can achieve ...
7
votes
4answers
1k views

Isolating audio ground between devices

I'm planning a build for a guitar amplifier with 2 stages, the first being a tube pre-amp and the second stage being a solid state amplifier. Both amplifiers will be powered from the same source, a ...
7
votes
3answers
8k views

How do I amplify a dc voltage that is too weak to trigger the base in a transistor?

I'm trying to take the voltage output from a 3.5mm audio jack and have it light up an LED according to it's voltage. I was going to attach the left audio cable to the base of a 2222n transistor which ...
6
votes
2answers
16k views

Driving LEDs from audio signal

I am making this very simple hobby circuit and I need help. This utilizes the sound (variations) from the device through the jack to provide light (intensity) variations in the LEDs using TIP31. ...
2
votes
3answers
3k views

Using a 1.5V battery to increase the voltage from a headphone jack so it can switch a transistor at lower volumes

I recently built a circuit using a 2N3904 BJT transistor with the hopes that when connected to a headphone jack, it would light a LED whenever an audio signal was passed through. However, I found ...
9
votes
3answers
4k views

How can I effectively reduce the voltage needed to activate a transistor?

I have built a circuit which basically connects the line out (audio output) of a music playing device to a set of LEDs (actually a huge strip of around 200 LEDs), so they flash in time with the music (...
8
votes
3answers
2k views

Function of Specific Capacitor in Audio Amplifier's Negative Feedback

The audio amplifier that I am referring to here consists of three stages. Among others, the amplifier also includes negative feedback (NFB) that is made of two passive resistors. From the base of TR3 ...
5
votes
2answers
4k views

How to store audio data for AVR project?

I see a lot of projects for AVR-based audio players that use an SD card to store the audio data. In fact, I am currently doing the very same thing on an Arduino and its Wave Shield, which has an SD ...
4
votes
1answer
2k views

Convert Digital and Analog values to dB SPL

I am trying to create a sound level meter. I want to use an analog MEMS microphone (INMP510) and a digital microphone with I2S output (SPH0645LM4H). The sensitivity of the INMP510 is -38 dBV and for ...
2
votes
2answers
5k views

What is the low frequency limit for ferrite cores in audio applications?

I've searched high and low through the ferrite magnetics catalogs and this list for an answer and can't find data on ferrite core permeability below 10kHz. My application is for audio use and I need ...
2
votes
1answer
6k views

Mono jack output to stereo headphones : how to send the mono signal to both sides?

I have a 3.5mm jack mono output. I'm plugging standard stereo headphones into this jack, and it plays only on one side. I want the sound to come out on both sides in the headphones (same signal, but ...
1
vote
1answer
303 views

Microcontroller GPIO in audio circuits

I'm designing an analog synthesizer, which is controlled by an STM32 -microcontroller. In several parts of the circuit, I intend to use a GPIO pin to control switches in the circuit, and in two ...
9
votes
2answers
8k views

Power supply noise in audio

I have what is surely a classic problem with regard to power supply switching noise and audio but I am unable to sort myth from reality with regard to what I found so far on the topic. Setup: I have ...
8
votes
2answers
2k views

What is the purpose of the capacitor and resistor in this op-amp circuit?

Here is the op-amp circuit, which is found in this datasheet on page 5: I have boxed, in red, the part of the circuit that I am confused about. What is the point of having this? Thanks in advance.
6
votes
3answers
56k views

How to determine appropriate speaker cable gauge?

When wiring speakers to a 100W consumer-grade amplifier, how do I select an appropriate gauge cable (for 8-ohm speakers)? Also, if 14 gauge cable is sufficient, what harm is there in using a heavier ...
3
votes
1answer
620 views

How to boost audio volume coming from a telephone

So I have this circuitry Purpose is to connect the soundcard with a telephone to also play computer generated samples over phone. It works with one drawback: The Headset's speaker is low volume. How ...
3
votes
3answers
323 views

What should the minimum voltage rating of replacement power resistors be?

I'm looking for four power resistors of the same type to replace R87, R88, R89, and R90 in the POWER AMP section of the amplifier of Klipsch SW-12 subwoofer shown below: What should the minimum ...
2
votes
1answer
873 views

What is “Power Supply Pumping”?

I recently came across the term "Power Supply Pumping" in an answer provided to me in return to one of my questions. Although I tried googling I didn't have good luck with it. I would appreciate if ...
2
votes
5answers
2k views

Any truth behind “multipole” technology in audio signal transmission?

After reading this question about ultra-expensive audio cables, I was reminded of a product that we sold at a company I used to work for. MIT Cables makes these "audio interfaces" which go a step ...