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

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1answer
28 views

DIY Multi-Input Audio

What would be the best method for preventing damage to multiple audio input devices that are connected to a home made audio patch panel? Im wanting to make a device or cable where I can connect ...
1
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1answer
67 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 ...
0
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1answer
30 views

Smartphone microphone frequency response, ADC and SNR

I'm trying to find on the web if there's an example of smartphone that records with low quality (which introduces lot of background noise) and an example of phone that records with good quality, maybe ...
0
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4answers
85 views

Connect LED from audio output without it blinking?

I have a circuit in which I want a pre-built stereo amplifier kit (with + and - outputs for each speaker) to drive a speaker and an LED in parallel. The circuit works, however is there any way to stop ...
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0answers
42 views

Modify Si4703 FM Tuner evaluation board to add an external antenna

I have this Si4703 evaluation board which I would like to modify to attach an external antenna. The board usually uses the plugged in headphone cable as the antenna. Here are the relevant schematics:...
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1answer
54 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 ...
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0answers
46 views

What causes periodic noise with LM386 amplifier

I am trying to use a LM386 to amplify an audio signal so that I can listen to it using a speaker. I am using the recommended circuit from the data sheet: When I connect my audio source to the input,...
2
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2answers
72 views

viability of idea for low voltage signal clipping (distortion) for guitar effect

I want to create an guitar distortion effect. What I want is a unity gain buffer op-amp that clips the signal. In the drawing below there is a circuit found on this forum here which will clip a very ...
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3answers
69 views

Convert PWM to Analog using a DAC chip in order to emulate a Potentiometer for audio

I'm trying to control audio level/gain (from line or amplified signal) using an Arduino. I do not want to use SPI, for this project I can only use the PWM outputs, thus I do not want to use a digital ...
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1answer
93 views

Choose DAC for audio

I am trying to play music from a PIC microcontroller using a DAC. I have seen other similar questions, but they use parallel interfaces and I am hoping to save pins with SPI as the interface. I saw ...
0
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3answers
70 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 ...
2
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2answers
63 views

When should an audio pre-amp use a differential input

As a guitarist, very familiar with the various types of noise that can wreak havoc with electric guitars, I've been mystified at how infrequently guitar amplifier inputs have employed differential ...
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1answer
27 views

audio mixer - is ground isolation needed for each channel?

In every audio mixer schematic that I have found, the signal circuit is described extensively. Here are a few examples: However, these diagrams do not show any considerations for the ground ...
0
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1answer
78 views

eliminating audio hum

I'm working on a circuit that feeds a microphone into the ADC of the STM32F4 Discovery and then outputs that exact signal out of the microcontroller's DAC and then to a headphone jack. I am able to ...
0
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1answer
59 views

Fixing a headset, TRRS [closed]

First of all I'm not sure if this is the correct site for this question but: I am trying to fix a head phone jack for my headset with a TRRS headphone replacement. This is the connections of the ...
2
votes
2answers
81 views

How to minimize hash noise in amplifier mounted near boost regulator

I've designed an audio low power (20W) guitar amplifier circuit whose pre-amp section has somewhat high input impedance, as is best for a magnetic guitar pickup. Since it operates from a battery ...
0
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1answer
30 views

Beaglebone PRU PWM to Audio Signal

I was wondering if its possible to convert the high frequency PWM output from a Beaglebone Green's PRU into an analog audio signal. I was looking at building a low pass filter and I was wondering if ...
0
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1answer
64 views

How to improve gain of class A amplifier

I constructed the following two circuits: Fixed bias amplifier. simulate this circuit – Schematic created using CircuitLab Voltage divider bias circuit. simulate this circuit ...
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3answers
105 views

How to design an air core transformer to operate in audio frequency range (20 Hz to 20 kHz) [closed]

Impedance matching has become a very annoying problem for me in my project of designing an audio amplifier. Here in my locality, audio frequency transformers are not available. I've browsed for ...
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2answers
90 views

Can i get continuity in the inputs of Op Amp (TL072)

Hello everyone, I have 1 doubt, i made in a protoboard an audio sequencer to provide CV(control voltage). The circuit is from [MFOS][3]. What happen is that the inputs of the op amp (TL072) are ...
2
votes
4answers
986 views

What does “600 : 600 Ω” mean for an audio transformer?

I found audio transformers online having the following specification: 600 : 600 ohms. My question is what does it mean? Does it mean that it is simply an isolation transformer? Or is it in some way ...
0
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1answer
40 views

Can an ordinary transformer be used for coupling the speaker with a transistor amplifier

Audio transformers are not available in my locality. However, I have bought an ordinary transformer. It has the following specifications: Primary voltage: 230 V Secondary voltage: 6 V Current rating: ...
7
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2answers
833 views

Audio using PWM, what is the principle behind it?

I have seen a schematic of a PIC board which uses filtered PWM to provide audio output signal to an audio jack. It shows PWM output filtered using 3 stages of passive RC filter followed by an LM386 ...
1
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3answers
83 views

Correctly powering amplifier and speakers

I have a few speakers that I salvaged from broken electronics and I plan on buying an amplifier board to drive the speakers. I'm currently looking at an amplifier such as this one and have sketched a ...
0
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1answer
64 views

stm32 audio levels

I'm using an STM32F746G for exploring embedded audio DSP. My experiments sound great in headphones but when I connect the audio output to external amplifiers, the signal level is low and there's a ...
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0answers
26 views

Adding a 2nd AUX input with switch to a Car Factory Head unit

let me begin by saying my electrical knowledge is very limited, so I apologize in advance if my questions sound stupid. Here we go, ... in the car in question, the OEM aux jack is designed with a jack ...
0
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1answer
48 views

Finding the short in my receiver (AMP circuit)

I will be glad to get your help to solve the mystery in my MARANTZ-SR4500 receiver.. The problem is that after turning on the AMP I got PROTECT MODE and it turned off. I find out that the source of ...
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2answers
51 views

Running microphone signal through stereo jack

I've recently mounted a 3.5mm connector onto a walkie talkie, so that I can plug in a headset. It works really well, though I've had the idea that since it's a stereo jack and the singal is mono, I ...
1
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2answers
54 views

Do narrow-band single-chip bandpass filters for audio frequencies exist?

I am looking for a single-chip implementation of a bandpass filter for audio frequencies, but unsure if they even exist. All the filters I've seen seem to be at least in hundred KHz range. So my ...
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2answers
61 views

Skype Phone Project - Help with Audio Amplifiers Selection

I am doing a project that involves using a landline phone to work as the speaker and microphone for Skype calls. A representation of the final design is given below. I have a landline phone in ...
0
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0answers
40 views

Remove mains hum out of amplifier

I have a headphone amplifier that is afflicted by mains hum 60 Hz and upper harmonics, below is an FFT of the spectrum with nothing connected to its inputs. In headphones you can clearly hear a buzz-...
0
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0answers
36 views

question on “Intercom” circuit I am planing to build

I am using Voice Record Module to save messages and then play them to one from selected outputs ...some kind of weird intercom system. My OA is LM386 [can only do 2 links but I'll post image relevant ...
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2answers
77 views

Single double triode vacuum tube for headphone amp at high voltages

I'm planning to build a single double triode vacuum tube as I have seen many schematics even though most of them are low voltage (20-40v). However I didn't seem to find a high voltage single double ...
1
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3answers
82 views

DIY mixer - use diodes to prevent input potentiometers influencing each other

I've builded a simple amplifier (just stereo audio in, two speaker outs) and I'm building a mixer for it. There are some audio inputs, which goes through stereo potentiometers (volume for each input)...
0
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1answer
50 views

Switch audio from one source to another one

I am currently working on a project where I have two GSM modules in a single product. Those modules have each one a mic port and speaker port. They will not be used simultaneously but they will be ...
4
votes
1answer
320 views

Identifying this "IC”, Trying to reverse engineer a board

Part 1: the board and how it's connected I'm looking at a headphone sound amplifier that is used to help experts detect pests in palm trees when a microphone is placed on the trunk of the palm tree. ...
0
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1answer
71 views

Wy are speakers rated by impedance instead of inductance?

Audio speakers contain coils which product sound by vibrating a cone. Why are speakers rated by impedance instead of inductance?
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3answers
62 views

How to remove noise from power adapter

I am making an audio amplifier using an LM2879. I am using the schematic provided in the data sheet. For a starting point, this design works pretty well, although the base cutoff point could be a ...
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1answer
31 views

Would anyone help these various latency? [closed]

This may not be suitable for electrical engineering stackexchange. The problem may not be in hardware at all. Basically I have omni 10 speakers. If I use bluetooth to connect to the speaker there is ...
5
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2answers
219 views

Why do audio op amps require such high rail voltages?

This might be a silly question, but I haven't been able to find it addressed directly anywhere on the internet yet. I also have a handful of related questions in-line, which I hope don't stray too ...
0
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0answers
47 views

STM32 Discovery dev platforms [closed]

I'm still researching this but though I'd post asking about experiences. Looks like st.com offers a variety of STM32 Discovery dev boards for ARM CPUs to, among other things, play with DSP. But ...
1
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1answer
71 views

How many stages of transistor amplifiers should be used in order to produce an audible output

I have constructed this amplifier as shown in the circuit diagram: simulate this circuit – Schematic created using CircuitLab I have made a few inferences: Reducing the value of ...
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0answers
51 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 ...
1
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1answer
108 views

Old radio amplifier circuit explanation

could somebody explain me how does this audio amplifier circuit from old radio is working ? I understand role of last transistors 413,417 and 415,419 but what is the point of T409 and T411 and other ...
0
votes
1answer
59 views

how to solder MEMS microphone to PCB at home? [closed]

I would like to experiment with audio applications using MEMS microphone. The problem is i cannot think of a way to solder these microphones on a pcb as PCB prototype manufacturers that i know won't ...
0
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3answers
43 views

Audio Signal Noise: Understanding & Troubleshooting

Today, I'm wearing a pair of active headphones for a change.. ( Running on 2x AAA batteries ). I've hooked them up to a synth and noticed this really annoying monotone buzz / hum in the background. ...
0
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1answer
11 views

Sound fader control source select

I'm trying to add second source to an amplifier. It uses TEA6320t sound fader control chip which takes in multiple sources and outputs one. The source selector selects one of 4 stereo inputs or ...
1
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1answer
33 views

Does any RCA connector work for S/PDIF interface?

I'd like to work with this chip : http://www.cirrus.com/cn/pubs/proDatasheet/WM8804_v4.5.pdf The S/PDIF Input mentioned in the datasheet states that the input impedance is 75Ohm. So I think that it ...