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Questions tagged [audio]

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

257 questions with no upvoted or accepted answers
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53 views

How to create a Bluetooth audio streamer that receives and transmits at the same time?

I want to create a Bluetooth streamer that wirelessly receives audio from a Bluetooth audio player (like smartphone) and then transmits the received audio to a Bluetooth speaker, with no wired ...
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1answer
300 views

Dolby HX PRO implementation on existing tape recording deck

I'm experimenting the implementation of Dolby HX PRO's IC into an old stereo Fostex tape deck to improve high frequency and headroom capabilities. HX PRO works as a dynamic processor with the BIAS ...
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0answers
334 views

Audio DC Offset

I want to make an audio processing device using a Teensy and I want to run an analog signal into it. My background is in audio programming, so electronic circuits are new to me. I realise audio is an ...
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0answers
74 views

Can this circuit be simplified?

The circuit is a LPF with a buffer stage in front of it that uses a linear pot. to control gain & attenuation. The setup is such that the response of the linear pot. is similar to a log. pot.. A ...
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1answer
123 views

YM2612 Circuit Audio Signal Noise

I'm working on a project where I'm controlling a Yamaha YM2612 with an Arduino MEGA. I can communicate with the chip just fine, but I'm having problems with the audio signal the chip is outputting. I'...
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0answers
240 views

I2S Fundamentals

I'm trying to get a good understanding of the I2S protocol for a project I'll be working on. My current goal is to take a 24bit, 2 channel .wav file with known, repeating bytes (ex: x00/x00) and view ...
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1answer
253 views

Can anybody help me modifying a reverb circuit on a guitar amp to an FX loop circuit?

I have a solid state guitar amplifier with a reverb tank. I have done a bit of research as to how these work. I now want to replace the reverb tank with an FX loop for normal pedals (instrument level)....
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2answers
85 views

Configuring Frequency Bandwidth and Input Signal for Bandpass filter circuit

How do I set and configure the frequency bandwidth I want the filter to output to a device? I am using a physical passive bandpass filter which I intend to take the signal in and filter it and output ...
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1answer
389 views

Using an audio splitter when using Arduino to read from an aux cable

I am currently able to feed a 3.5 mm aux cable into my Arduino and read its values, but I'm not able to hear the sounds being played. I wanted to solve this problem by using an audio splitter and ...
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1answer
322 views

Common audio signal voltage range on Line out connector

What is typical audio signal voltage range on Line out connector of consumer electronic devices? (Vmin/Vmax) I need specify Input voltage range to calculate op-amp. ...
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1answer
150 views

Buffer, amplify, filter, sample - In which order?

I'm trying get an audio signal from a high impedance source (guitar or mic) to an ADC. Some casual research suggested that I should filter my signal before amplifying it. My current mental design is:...
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2answers
192 views

Why does it take over 4 seconds to eliminate audio popping in this circuit?

I made a simple audio mixer circuit with its output going to headphones. Right now I'm only testing with a single audio signal at the input, which is music from a smartphone. I hear a pop sound after ...
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0answers
188 views

Audio op amps - what do they do to the audio I hear from the speaker?

I have a simple DC circuit which outputs audio from a ESP8266 attached via 2 wires and a NPN transistor to a simple speaker. It uses this library : https://github.com/earlephilhower/ESP8266Audio/ to ...
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0answers
87 views

how to connect Capacitor in audio circuit

I am making an audio amplifier circuit using TDA7297 which I got from an old tv circuit. At the input I have connected two capacitor in series with pin 4 and 12. Also two capacitors are connected to ...
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0answers
856 views

Connecting audio line to ESP8266 / ESP32

I don't know how to correctly connect audio line to ADC input of ESP32 board. The audio line is common stereo output from phone, PC or audio mixer. I didn't find any schematic or advice how to do that ...
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1answer
125 views

Splitting Audio Out - are there any issues I am not seeing?

first post, so I hope this isn't TOO stupid a question. I am planning on building this circuit: https://github.com/trash80/Ym2149Synth/blob/master/Ym2149SynthSchematic-V29082016.pdf which eventually ...
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0answers
271 views

Audible Ticking in Audio Opamp Circuit

I'm experimenting yet again with the following audio mixing circuit: On the scope with signal gen as source, everything looks great. When hooked up to the input of a mixer with a laptop as the source,...
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0answers
137 views

Switching Inputs on Audio Mixer

I am experimenting a bit and have built the circuit shown below to mix two input signals. It works great across the full audio spectrum. Now I’m trying to figure out a way to switch the signals so ...
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0answers
190 views

Audio reactive lights - DMX vs I2C

I need to build a system to control lights using line-level audio signal. My idea is to acquire the signal from my mixer using a microcontroller (or FPGA), apply some filters and finally drive 5 leds ...
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0answers
438 views

How to remove noise between raspberry pi PWM0 and SIM800L mic pin?

In my project SIM800L module(GSM Module) is interfaced with raspberry pi zero. Whenever user call Pi zero play an audio so that user can hear it. To send audio signal from pi zero to SIM800L, PWM0 pin ...
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1answer
145 views

Driving Lights with Audio Amplifier

I'm working on a project where I want to have christmas lights (or LED strips if needed) react to music. In this case, the end goal is to have them pulse to the beats/bass of the music. There's a lot ...
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3answers
697 views

Reduced gain with ground loop isolation with car aux head unit

How to suppress ground loop hum without reducing audio gain? I added an aux input to my car's factory head unit by soldering wires onto pin 4 (right channel) and pin 33 (left channel) of the M62490FP ...
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0answers
618 views

Audio input: stereo to mono and filtering DC

I have to get an audio input from a PCB 3.5mm jack and summing right and left channel into one (mono). Then, I have to filter any DC noise from the input. Resistors are 1kOhm each. This, for now, ...
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0answers
417 views

Audio Switching Circuit - Ground Loop Noise Problem

I'm building an adapter to connect an RJ9 headset output to a 3.5mm jack output(TRRS, mic included). I have designed it so far to use DG409 (4:1) analog multiplexers to choose what lines are connected ...
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0answers
475 views

Replacing trim pots with potentiometers?

I have been looking at and considering building the following circuit from Beavis Audio Research. Their explanation of the circuit: Around 1965, Marshall introduced a few amps built around an 18 ...
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0answers
223 views

Calculate distance between two vehicles without using GPS

I am trying to understand if there is any way to measure the distance between two vehicles, possibly moving, without the aid of GPS. I want to measure a distance of more than 50 meters but less than ...
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0answers
272 views

Is it possible to get audio tone from STM32405RG off PB7 pin?

I have been doing some software work on an open source hardware/software project that produces a video overlay, but also offers an apparent audio out pin that is so far unused. The original developer ...
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0answers
252 views

Thru-Hole Works, SMD Does not

I have been working on migrating a through-hole circuit design that works to a surface mount version. It is a preamp designed by an engineer named Ritter. Here is his schematic: www.ciphersbyritter....
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0answers
515 views

conversion dB into dB SPL

I'm using a sound calibrator (1kHz, 114dB SPL, GRAS Type 42AB). When I got my data from my scope, the signal has 5mV. In spectrum mode, it is -50dB at the peak of 1kHz. I'm using this preamp: GRAS ...
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0answers
409 views

Piezo speaker driver not giving full differential voltage - why?

I am trying to drive a piezo speaker at 20kHz with maximum voltage swing from a 10V source. Previously I had used a square wave plus its inverse to give the equivalent of 20V across the speaker but I ...
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0answers
126 views

Speaker designed for ultrasound operation

I've created a transmission protocol in order to transmit information bits between a PC speaker and a smartphone, or between 2 smartphones using ultrasounds. I've implemented a QFSK system which uses ...
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0answers
81 views

perfect square wave cannot be played back

If I produce a square-wave by creating a sine wave first and then doing, if x >= 0 return 1, else return -1 this produces a "perfect" square wave(python code). Like this the audio signal cannot even ...
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0answers
330 views

hijack project microtransformer doesn't work well

I am working on a project that need to get energy harvest from smartphone headset jack.I find hijack project has a solution.the energy harvest circuit of it is below: it use coilcraft transformer ...
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0answers
1k views

Noise-cancelling headphone concept

Inexpensive noise-cancelling headphones use a single microphone located in a little lump between the plug and the earphones. They seem to work fairly well for ambient noises, but not for handling ...
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0answers
170 views

Best possible specs for a MEMS mic in 2014?

I want to use the best MEMS mic that's on the market today (June 2014) in terms of audio quality. Since I know that "shopping" questions are forbidden, I'll phrase it like this: What are considered ...
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0answers
12k views

STM32f4 discovery audio sampling above 16kHz not working

I'm trying to use digital microphone (MP45DT02) on stm32f4 discovery and just forward data to audio DAC and amplifier (CS43L22). The problem is that at sampling frequency higher than 16kHz thing ...
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0answers
1k views

USB battery charger noise in an audio amplifier

As the title says, I'm having some issues with battery charger noise and an audio amplifier. The PCB with the charger and amplifier is connected to a GSM device, and that's where the audio signal for ...
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0answers
2k views

IRDA Through Audio Jack

I'd like to know if it is theoretically and/or practically possible to enable a smartphone (iOS or Android) to communicate with another device via IrDA (IrCOMM) using a simple infrared transceiver ...
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0answers
699 views

Problem with impedance matching on DIY 4 pole 3.5mm audio splitter

I built an audio 4 connector 3.5mm splitter. The goal is to play a sound clip through a phone's mic input across a call, while recording the same sound clip on the computer. I used the TRRS ...
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1answer
28 views

Audio playback information when pressing buttons (school project)

My son is making a display (about A1 sized card) about space for school and I am trying to find out a simple way to add some buttons, that when pressed plays an audio recording with info about ...
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1answer
104 views

How does headphone volume correspond to driver excursion?

I was curious about how driver excursion in a headphone corresponds to the volume that music is playing at. For this question, let's use my current headphone as an example. It's the Audio Technica ...
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1answer
299 views

Audio attenuator has audible pops

I'm copying the recommended circuit (the 'Higher Performance' one, actually) from the LM1971 audio attenuator datasheet but there are audible (loud) pops on the output. I'm using OPA227s for all op-...
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1answer
159 views

Understanding Audio Amplification with OpAmp

I have what I believe to be a fairly simple schematic, as shown below, to take either a PWM signal from an AVR board to play a song/alarm, or radio signal. I'm connecting both of these with a ...
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25 views

Difference in output between digital codec and analog filter

I'm working on a project which deals with filtering audio signals with a Low Pass Filter and amplifying the output. Currently, we are solving this using the TLV320AIC3111 audio codec by Texas ...
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0answers
20 views

Advice required re audio output stage for UM3561

I'm OK with digital electronics, fully capable of popping a 2n2222 and a suitable base resistor onto a GPIO pin but analogue is still quite a mystery to me, hence I'd appreciate some design advice ...
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1answer
61 views

how to increase output power of multistage audio amplifer?

In the circuit given below, I'm working on an audio amplifer. It is driving a 4-Ohm load (speaker.) Input : 1.1V peak-peak sine wave of frequency 1Khz. Input dc = 12v Output : 4-Ohm load. Gain = (8 ...
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0answers
64 views

What do I need to make an Auto-Decibel Recorder?

I want to rig up a decibel-level sensor to an automated script that will record the times and decibel levels of door slams when I am not present, for later evaluation. I am a capable programmer and ...
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1answer
95 views

Audio amplifier with strange open loop, is it an oscillator?

straight to the problem. Here is a picture of frequency response of my amplifier in the simulator (LTspice or Pspice both give same results). Normally, in the open loop i see a phase of 90° which ...
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1answer
76 views

Do passive RC filters need ground?

So, after a bit of searching I can't seem to find an answer to this anywhere, at least not in an easy to understand manner. Ok, lets set a scenario, if we have an audio input (in my project it would ...
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0answers
27 views

How do I convert this ADC code for STM32F3 to STM32F4 for colorchord?

I am currently trying to make the ADC driver code for the STM32F3 version of the colorchord https://github.com/cnlohr/colorchord code work on an STM32F4, as my F4 does not have an on board microphone. ...