Questions tagged [audio]

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

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56 views

Why can you simply short a line-level output to ground? [duplicate]

I've read that one of the ways to sum two line-level outputs into mono is to simply ignore the right channel and connect the left channel to the mono input. In doing so, it has been said that you can (...
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2answers
62 views

Why is it safer to not short left and right audio jack outputs together?

I've read that the best way to "mix" two left and right line-level stereo jack outputs is to first connect each to a 1k resistor and then to your mono input. Why is this preferred over just ...
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1answer
828 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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3answers
92 views

Audio Amplifier using an Op-Amp

I am experimenting with Op-amp for making a audio amplifier. I am using this circuit. I want to know if the values of C424 and C118 are correctly chosen here or do they need to be change? I hear ...
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2answers
421 views

using the mcp42010 for audio attenuation

I would really appreciate some help here, I've spent a lot of time on this and can't get it right. looking at datasheets and answers here actually made me even more confused... I'm trying to control ...
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3answers
100 views

Audio amplifier components

I want to understand the purpose of capacitors and variable resistor in the following audio amplifier circuit. Here is its datasheet. C118 at amplifier output pin. C424 between amplifier input and ...
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1answer
204 views

Would it be ok if I try to measure an audio signal using a 15m BNC Cable?

I would need to use a 15 meters BNC Cable (RG58) in order to measure an audio signal that goes directly to a pair of earbuds. This means, the test point would be exactly before the balanced armature ...
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1answer
359 views

Start/ stop 5v motor from headphones jack

I would like to make the jaw of a plastic skull open/close based on words spoken by a Raspberry Pi. I can make the Pi send the audio to the headphone jack, and would like to use this output to run 5v ...
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1answer
211 views

Repair lifted ground pad on power amp

I'm repairing a 250W bass power amp board and one of the problems is that the pads for two ground wires have lifted off the board. It looks like it has had something of a bodge repair done before and ...
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1answer
42 views

Virtual ground supply for audio-applications

The most common solution to provide positive and negative voltage to supply an OP-amp would be to use a voltage divider and another OP-amp. In this way the voltage "on the top" of the ...
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1answer
27 views

How does a channel know to drive in I2S TDM mode?

I'm learning I2S right now and am curious how to work in an environment where 8 or so audio devices could be in the setup. I understand TDM mode would allow the Controller (Master in legacy terms) to ...
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0answers
51 views

Connecting MAX9814 to Speaker

I am trying to build a fetal heartbeat sound detection using Adafruit AGC Electret Microphone Amplifier - MAX9814. I attached the MAX9814 mic to the hole of wood fetal hearbeat stetescope (picture ...
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2answers
1k views

Output coupling capacitors in dual-supply op amp circuits

Consider a dual-supply op amp circuit used to process (but not amplify) line level audio; for the sake of simplicity, imagine a unity gain follower. With the input AC coupled and referenced to ground, ...
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1answer
217 views

THAT4315 audio analyzer - capacitors getting hot

I have designed a audio spectrum analyzer circuit with THAT4315 and a drivers for IN-13 bar graph nixie tube to visualize the signal level. To supply +-12V to the opamps, the Meanwell NSD15 module is ...
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1answer
46 views

Building a voltage adjuster circuit

I've been trying to build an op amp circuit that takes an analog signal from my electric guitar of around -1.5 to 1.5 V to a voltage level of 0 to 5 V, so that I can put it into the ADC of a ...
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2answers
1k views

Is it possible to use a dual rail power system to power op-amp which is designed for a single supply?

I am designing an amplifier circuit using the LM386 amplifier. I am using the schematic below as a guide. I have access to 3 pins: +5V, virtualGND and -5V. Is it possible to power this amplifier using ...
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2answers
373 views

Mechanical vibrations picked by an audio amplifier (Strange microphone efect when there is no microphone)

I opened today my Philips audio system (30W woofer + 20w satellites) because it has a lot of noise. There is something weird with that amplifier: when I knock into the circuit board with my finger ...
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2answers
737 views

Solving Op-Amp Instability

Basically, I began modding my Soundcraft Ghost sound board and wanted to put in a different op-amp that would sound more "colored" in the preamp stage. From everything I've read, the OPA2134 is the ...
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2answers
49 views

Terminating an audio line-in signal when source is disconnected

I've been trying to DIY a home audio setup. We have a pair of speakers in the ceiling of an upper floor (previously installed), and a new TV on the same floor. We wanted the sound of the TV to come ...
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1answer
172 views

Please help me identify this noise on my ADC

I have a CS4270 codec hooked up to a Raspberry Pi more or less according to the "recommended layout" in the datasheet (P7), shown below. This device sinks power from three different places (VA = power ...
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2answers
4k views

Replace vintage speaker connection by modern one

So, I have a vintage Pioneer hi-fi installation and I want to use it in a recording studio. It features two passive speakers and one amplifier. My problem is that the speakers need to be connected to ...
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1answer
100 views

Using an LM358 as line level buffer

Recently, I've acquired an old SNES, specifically the SNSM-CPU-1CHIP-03 model, with no audio output. I traced the issue to a dead S-Mix chip, essentially a buffer between the audio DAC and the line ...
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3answers
15k views

Cost Effective Solution to using PAM8403 as a headphone amp

I've just bought a PAM8403 pre-built circuit board for $1 on eBay, I was going to use it to drive a set of headphones but I neglected to consider that this is a Class D amplifier and will not take ...
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3answers
439 views

LM386 no output with input signal below 2V

I'm trying to implement volume control using a digital potentiometer (LM386) and audio amplifier (MCP4131). The way I have it setup, I'm outputting square wave audio signals out of a PWM pin on the ...
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1answer
56 views

2 channel audio splitter passive

I have a Scarlett solo like the one above and I need a way to split the output of the Mix boards Auxiliary output into two level controlled signals. This Scarlett puts the Instrument on the left ...
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1answer
168 views

Trigger PTT on Baofeng UV-5R with Arduino

A current project of mine is to have the Arduino Uno play an audio file off an SD card module. The audio file would come out of the Arduino and into a Baofeng UV-5R handheld transceiver. The first ...
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2answers
63 views

Do class D headphone amplifier ICs typically contain integrated step-down converters?

Headphones can range in impedance from 8 ohms to a couple hundred ohms, and many only require a few milliwatts. This means that - for a low impedance headphone - only a few hundred mV RMS will be ...
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1answer
66 views

How should microphone impedance relate to input impedance?

I have: a Boya BY-MM1 microphone which has a nominal impedance of 300 ohms a Steinberg UR-12 with a balanced microphone input that has a nominal impedance of 4 kOhm I connect the microphone to the ...
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0answers
67 views

Why is the STM32 reference manual stating the wrong sample frequency for I2S?

This could be a misunderstanding but everything I have gathered and seen it looks like there's a disconnection on what the reference manual says. On Pg. 2212, in the STM32H753ZI it states: "The ...
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1answer
287 views

Damaged solder pads on FX-Audio DAC-X6 Alternate solder locations?

I've tried to remove a faulty 6.5mm headphone jack from a FX-Audio DAC-X6 and ended up removing the solder pads from the board. I'm trying to save this instead of trashing it and buying a new one for $...
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0answers
72 views

Audio mixer on battery power

I have an audio mixer which can run on two 9V batteries in series. I'd like to run it off a single 12V supply. Can I use two 12V-9V DC-DC converters both running off a 12V battery? Will the ...
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2answers
344 views

Can't find the datasheet of cheap Bluetooth audio reciever

The chip says JL AP24186-26A4, but I can't find datasheet anywhere. Everytime it takes me to dead end. If someone know about it then please help. Update: Found that it's Bluetooth 5.0 based audio ...
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4answers
110 views

Audio output voltage range

I'm working on a synthesizer project and I'm confused on what the final audio output voltage should be. The idea is that I would send the audio to a speaker or headphone amplifier, so I don't have to ...
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4answers
100 views

Can you reduce audio noise by decreasing input impedance with a resistive load?

First asked this over at sound stackexchange but they pointed me over here as a better place for it. A general question but inspired by a specific example so framed as such. I have powered studio ...
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1answer
45 views

Debugging Signal Distortion/Oscillation

Finally built up the circuit below that I've been designing/toying with in LTSpice and its working OK but I'm wondering if an experienced eye might be able to quickly label what/why the oddities are ...
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1answer
613 views

Inverting Second Order Filter

I am working on an audio filter, and my goal is to filter out noise below 90Hz and 20kHz (the range of my speakers). I will have some nearby circuits running at 25 to 30kHz, so I have decided to go ...
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1answer
297 views

Microphone with LM386

I am trying to build an audio amplifier circuit based on this design using an LM386 opamp. On the output side (pin5) an Arduino is connected constantly reading out the pin ...
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2answers
91 views

Click-and-pop suppression when circuit is not yet powered

Problem description: Power supply, for some reason, false-starts on power on of the device: the red is system +5 V supply rail, and yellow is my device's 3.3 V buck converter powered from the system'...
4
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1answer
152 views

How can a marginal connection become “good” by just applying a little more voltage?

"On the side" I do a fair amount of repair work to guitar gear -- Amplifiers, pedals, guitars, etc... I've had a similar symptom occur on different repairs, and found the same root cause for ...
2
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1answer
521 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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0answers
24 views

AV Receiver playing music using RCA Analog input (AUX) from Mobile 3.5 mm stereo source

I have a pioneer AV Receiver VSX-832-K with RCA AUX INPUT "input (Sensitive/Impendency ) 200mv/47K ohm" issue : when i am trying to play music from mobile using 3.5 mm headphone jack using ...
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1answer
707 views

Piezo speaker equivalent for circuit simulator

I am using Falstad's circuit simulator to test a design of an Op-Amp based microphone-speaker system...kind of like a megaphone, but the speaker is going to be a piezo plate. Falstad does not have a ...
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1answer
100 views

Why does this cable have 3 wires to PCB on one side but only 2 wires on the other end? [closed]

I am working on a stereo receiver and was going to resolder some wiring. When I went to strip one wire on the 3-wire cable, the whole wire pulled out that was bare except for the half inch I was going ...
4
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1answer
352 views

Ultra low power audio recorder

I'm trying to design an ultra low power audio recorder, in order to monitor ground noise in rural areas. The circuit I'm working on is based on a microcontroller (STM32L100RC) and an audio codec (...
5
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3answers
1k views

Do DSL / ADSL modems have an ADC with ~ 2 MHz sampling rate?

For fun and no real practical use, I'm trying to design a DIY modem that can transmit data over an audio line, like old 56k modems did. I'm studying how to pack bits of data efficiently in a 1k-15k ...
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2answers
399 views

DC voltage ripple help

I am new here and I realy need your help. For diplome at the end of my studying I am making the audio amplifier module (power amplifier, preamplifier, tone control, power supply, linear regulator) all ...
4
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1answer
92 views

The relationship between bit depth and SNR in ADC

An 8-bit audio signal has a theoretical maximum SNR of 48.16 dB (20log(2^8)). My question then would be, does this work in reverse, i.e. would an analogue audio (or video) signal with an SNR of <=...
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1answer
204 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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1answer
531 views

Sound Chip Audio Amplification Circuit YM2612 + TDA1308

I've been working on a project for connecting a Yamaha YM2612 to an arduino and triggering sounds to be played from the chip. I'm having trouble on the audio part of the circuit. I've worked out a ...
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1answer
320 views

PCM1789 DAC direct connection to TPA6138A2 headphone amplifier?

Is it possible to directly connect PCM1789 DAC to TPA6138A2 headphone amplifier? According to datasheet PCM1789 output are differential outputs and the input of TPA6138A2 is also differential inputs. ...

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