Questions tagged [audio]

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

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1answer
61 views

What were the transfer curves of major recording technology from Wax cylinders to HiFi electronics? [closed]

I am interested in the evolution of the quality / fidelity of audio recording. Specifically in the actual frequency response curves and dynamics behavior of those technologies, not just rough ideas. ...
3
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2answers
233 views

Enhancing the bass response of an audio isolation transformer

Below is a simple buffer circuit using an isolation transformer : The green trace is the output of the transformer and the blue trace is the input signal (20hz to 20Khz sine wave). As you can see the ...
2
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1answer
81 views

Hi fi speaker impedance

I'm currently working in a charity shop. We have a range of hi-fi units, radios, CD players etc. We also have a range of speakers to go with them. Some are marked with their nominal impedance, ...
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2answers
151 views

Shutdown amplifier when headphones are connected

I'm designing a board for a diy synth, one of the circuits consists in a audio amplifier that drives a small 1W speaker. The amplifier takes the signals from a Raspberry hat(a Fe-Pi Audio V2) and I ...
0
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1answer
96 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 ...
21
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3answers
28k 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 can't figure out why choose A over B or C. My audio source will ...
1
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1answer
59 views

Help identifying connector on vinyl shellhead

I'm working on a DIY project where I'm basically creating/connecting my own vinyl record player arm. I have one of these shellheads in the picture below. Ideally I wan't to be able to use this, and ...
5
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2answers
596 views

What does the FPGA do with unreferenced I/O pins?

Here's one thats been puzzling me for a while. I have an FPGA design in Altera, driving an audio chip and programmed through its serial interface. I monitor and debug this with an oscilloscope/...
22
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5answers
7k views

What set the speed in a cassette tape recorder?

I was wondering what set the rotational speed in a cassette recorder? I assume that the speed must be constant, but that means that the tape data would have different effective densities depending on ...
0
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1answer
208 views

Troubleshooting noisy FET buffer for contact mic

I'm trying to follow the schematic on this page to create a preamp/impedance matcher for a balanced piezo contact mic. I've reproduced the schematic below. I've built it on a breadboard and I'm ...
2
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3answers
58 views

Can I replace a dual section capacitor in a tube amplifier design with two single capacitors?

I was planning on building this schematic, but found it hard to source their 20/20 dual section cap (C3/C4). Could I replace this with two single 20uF caps, or is it a dual-section for a reason?
0
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1answer
186 views

MOSFET analog switch, Transmission Gate, Bilateral switch circuit questions

Below is an LTSpice simulation of two attempts at a Mosfet bilateral switch or 'transmission gate'. The plot shows the switch (onoff) going from 0 to 5v (in blue) and a sine wave audio signal being ...
0
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1answer
159 views

Impedance matching for analog audio from aircraft (high impedance) to USB audio IC

I'm working on a project where we're recording audio from the intercom output of an aircraft. Essentially, this lets us record air traffic and cockpit audio. Aircraft audio is stereotypically high ...
2
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0answers
57 views

How to connect Electret Microphone module and OPAMP?

I am trying to build a circuit that gets electret microphone input and maps into 0-1V for utilizing in ADC. The microphone module suggests using such circuitry When I tried that circuit and talked ...
0
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1answer
48 views

Cannot connect microphone using audio jack

I have a microphone and a female 3.5 mm audio jack. I want to use the jack to get the signal from the microphone for a project with an arduino. To test if the microphone works or not, I'm trying to ...
0
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1answer
56 views

Audio Amplifier Clipping

I designed a PCB with the following audio amplifier on it: https://eu.mouser.com/datasheet/2/302/TFA9896_SDS-1381317.pdf According to the data sheet, the amplifier is able to deliver 2.1W RMS into an ...
1
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1answer
29 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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3answers
159 views

741 Op Amp Audio Amplifier with Noise

I have a project to build an intercom using op amp 741, because it is easy to find and is the only one that currently has access because of my location. Below the schematic diagram which I designed. ...
14
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6answers
57k views

Over what frequency range can the microphone of smartphone receive the sound?

I have a project in which I am considering using the microphone from a smartphone for the reception of inaudible signals (> 15khz). What is the frequency range that such a microphone of receive sound?...
1
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1answer
179 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 ...
1
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1answer
128 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 ...
0
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1answer
197 views

Studio Mic --> 3.5mm jack not working

I have created a system to plug my studio mic (MXL 990) into my MacBook's 3.5mm headphone jack that consists of the following system: Mic -> AC Power supply for the mic -> 3-Prong microphone cable to ...
0
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1answer
100 views

How to record a speaker?

Complete noob here. I don't need a ready to implement solution, pointers on what to read upon and ideas for even simpler projects to gain experience first are perfectly fine. I'm trying to feed both ...
1
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1answer
153 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
88 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 ...
3
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1answer
229 views

Amplify Raspberry Pi Zero W Audio with 60s Tube amplifier circuit

First of all, thank you for taking a look at my question. Electronics is not my field of expertise, and I have found myself a bit stuck. I have been restoring some old 50s and 60s tube amplified ...
2
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1answer
345 views

Opamp Design for Low Impedance Sources?

I am terribly confused ... I tried myself at building a low impedance guitar pickup some time ago. Quick LowZ Pickup Intro Basically just two loops of aluminium with two magnets, a humbucking guitar ...
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0answers
51 views

Can I make this Bluetooth speaker stop cutting off its speakers when audio signal goes silent?

I have a simple Bluetooth speaker that always seem to cut off its speaker circuit when the audio stream goes silent. This makes an audible popping noise, which is repeated when the stream starts ...
1
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1answer
83 views

What type of audio output does this symbol represent?

I have this picture. I want left, left ground, right and right ground output. Pin. But I can't understand it. Can somebody please help me. Thanks.
2
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1answer
161 views

Can I connect a MEMS mic directly to this spectrum analizer chip?

I have a ICS-40181 MEMS mic and want to do basic spectral analysis using the popular MSGEQ7 chip for the purpose of a sound reactive project. Can I simply connect one into the other (with cap/res as ...
1
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0answers
28 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 ...
0
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4answers
137 views

Is there a data transfer limit for virtual serial ports

I want to record 5/10 seconds of audio using an electret microphone and an STM32 nucleo development board and send it to my computer in real-time to be processed. I'm a beginner so I'm sure I'm making ...
0
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1answer
41 views

What does changing the volume on a Bluetooth audio device really do?

For example, when playing audio from a smartphone through car speakers, you can change the volume on both the phone and the car. It makes sense that when changing the volume on the audio controls in ...
2
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1answer
228 views

Why would this Class D Audio Amplifier have low current draw?

Disclaimer: Saying I have very little knowledge of electrical engineering theory is an overstatement. I very much appreciate your help and patience. I'm not finding any questions similar to mine, but ...
1
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2answers
399 views

How can i replace a electret mic input with headphone output as input

I'm using a SIM800L GSM module for my project. In this module there is a electret mic input pin but I want to give audio to this module from headphone output from a mobile (There is no line in pin ...
0
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1answer
52 views

Downsides to terminating a line level audio signal into an amplifier without an output resistor

I'm using a PCM5122 to output audio to a line level output as well as a PAM8406 amplifier. If I connect the PCM5122 to the PAM8406 AFTER the output load RC filter, then there is noise introduced ...
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0answers
21 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 ...
0
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3answers
114 views

8 ohms and 4 ohms speakers wired in series - volume issues

I have two identical sets of ceiling speakers connected to a cheap 2 channel Chinese micro amp - one 8 ohms and one 4 ohms, wired in series per channel. The 8 ohm speaker is too loud when the volume ...
0
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2answers
65 views

3.5mm Push to Talk Switch

I am looking to take a 3.5mm microphone line, insert a press button switch (a foot pedal in my use case) between the headset and the computer. I would like the switch to mute the mic connection when ...
0
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1answer
186 views

Op-amp control theory

back at it again trying to use your genius brains. I have been trying to teach myself audio amplifier design. The big road block I am getting into is the control theory part of it, meaning how does ...
1
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1answer
29 views

Audio codec output detection

I am looking for guidance on audio functionality test over USB audio codec. This audio output serves as Alarm to indicate certain events. The signal flow is ARM processor USB port --> USB Codec --> ...
0
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0answers
69 views

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

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 ...
0
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1answer
70 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 ...
1
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1answer
136 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 ...
1
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1answer
173 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 ...
0
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3answers
77 views

AC to DC rails sag excessively when loaded

I'm just experimenting with rectifying a 120v to 12v dual winding transformer and smoothing it out two a dual rail power supply while I work towards attempting to build a clean power supply. I ...
21
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6answers
5k views

Where do overtones in a 555 generated square wave come from?

I have built a 555 oscillator and connected it to a speaker. Using an oscilloscope I adjusted the 555 to generate a 2.5kHz square wave. I then held a microphone up to the speaker and fed the input ...
0
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2answers
173 views

Audio ADC voltage level SNR question

I keep looking for Audio specific ADCs and the majority of these devices work at low voltages on the analog circuitry (5V for example). Lets say we want to process an higher voltage audio input ...
0
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1answer
77 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 ...
0
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0answers
28 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. ...