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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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1answer
207 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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46 views

What's the maximum supply voltage for a OPA2134PA?

I built a MOSFET driver using a TI 741 op-amp, sounds like garbage - because you know... its a 741. I decided to continue my endeavors and purchase some better preamps and settled on a half-dozen TI ...
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1answer
347 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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2answers
268 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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0answers
101 views

MOSFET amplifier using single rail DC

Back in the day I built high power push-pull audio amplifiers using a few MOSFETs and a split-rail DC supply (12-0-12v, 16A) - and I fully understood the circuit. What I’m tying to understand is how ...
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1answer
248 views

MICBias Ground in audio codec

MICBias is the voltage required for microphone to power and record signal at full levels. What will happen if we ground MICBias, is it means we are disabling microphone.
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52 views

Speaker Cross-Over Network and Power Design

I have some speakers I want to drive from a single output: a 4Ohm 300W Subwoofer, a 6.44 Ohm 60W Midrange, and 2 8Ohm 3W Tweeters. All ratings are RMS. I know that if I were to wire all of these in ...
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57 views

Can I create a uniform magnetic field with an n52 magnet?

I want to build a ribbon speaker and I've read that one of the greatest sources of distortion in these types of speakers is the non uniform magnetic field along the length of the magnet. I've also ...
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3answers
766 views

Amp troubles - noisy TEA2025

Recently I got my hands on a small amplifier board containing two TEA2025 ICs. Not sure what had it been used in previously, but the sound was acceptable, at least when removing some resistors that ...
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1answer
120 views

How to prototype analog audio processing?

How to prototype analog audio processing? Should I merely trial with analog electronics or should I simulate the circuits in software first? Particularly, I'm interested in discovering new forms of ...
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1answer
19 views

Boombox extending power autonomy

Hi Im building a boombox and I am looking for ways to extend the power autonomy. I am using this stereo(https://www.amazon.com/gp/aw/d/B0091V0A9U/ref=mp_s_a_1_3?ie=UTF8&qid=1514153185&sr=8-3&...
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159 views

Interfacing a phone's microphone to a MCU

I am doing some speech recognition, and my phone is my microphone. I have used it to collect data for PC and would like to do the same on my Tiva C launchpad. I planned on using an app,such as this ...
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1answer
190 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 ...
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2answers
162 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 ...
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0answers
245 views

Digital pot leaking and vcc/2 impedance doubt

I have been trying to use a digital pot to control the volume of an audio signal. I am aware that most digital pots don't take negative voltages and also that digital pots have a high wiper resistance ...
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1answer
161 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
250 views

Line level detection using ADC from a passive summing box

I was looking for a way to detect a line-in device transmitting audio. I got the idea to use ADC for this from this question: How to detect line level audio signal? I already have a 4-channel ADC (...
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0answers
51 views

Doubling RC circuit frequency: troubleshooting

This is a followup to Is it possible to double the resistance of a potentiometer?, which solved my AB problem of adding a half-tempo switch to an existing beat generator by suggesting that I add a ...
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0answers
798 views

calculating current draw for opamp circuit

I am trying to understand how to estimate the current drawn by the following opamp circuit and how much current the regulators for the +14/-14 rails should be able to deliver. The opamp used is the ...
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0answers
442 views

When is it safe to ground DC- (specifically audio output)?

With regard to audio devices, if all equipment is unbalanced and there are no DC- connections to earth ground, equipment will generally operate hum/noise free despite large common mode voltages ...
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1answer
238 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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3answers
2k views

TDA7492p 50W+50W

I'm thinking of making a portable Bluetooth speaker using this module. I have some speaker and tweeter combos from a cheap old 5.1 home theater system (cjc 690r). I want to be able to connect any ...
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0answers
77 views

Polling interrupting my codec reads and USB writes?

Another USB question here... same as last time; USB Audio on an ARM microcontroller. I have both endpoints (input and output) as isochronous/asynchronous transfers. In addition I have Timer Counter (...
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0answers
145 views

Sallen Key filter for audio applications (guitar)

I am building a custom guitar effects pedal. This is a digital pedal where the microcontroller handles all the effects. The guitar signal enters the silicon domain through the ADCs , the effect is ...
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1answer
58 views

Troubleshooting Noise/Quirks in Audio Circuit

I am working on a project that takes in a single line-level audio channel and outputs 2 balanced/unbalanced +/- outputs from that channel. I have read a number of the excellent published articles ...
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235 views

What causes 1000Hz (and multiples) electromagnetic interference?

When recording old analog synthesizers (different brands and models) I'm getting interference in the audio. This started suddenly about two years ago (I thought the synth I was using was ...
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0answers
69 views

What factors determine the shortest audio signal a common DAC IC can play back?

I am using a PCM5122 clocked with a 24.576MHz oscillator in an application that must produce fairly short bursts (<5ms) of broadband, ultrasound (15-90kHz) audio at 192kHz sample rate. The design I'...
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2k views

Can a ferrite choke/bead suppress unwanted audio signals (maybe mobile phone induced)?

I use a headset with a normal 3.5mm audio cable (not USB). Most times I have excellent audio quality, but in a large office building, I sometimes get very bad signals injected from an unknown source. ...
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2answers
248 views

Audio Transformer Selection

I have a line-level audio output stage with an output impedance between 100-600 Ohms and an input stage with an input impedance of 10-20kOhms. I am looking to use an isolation transformer to connect ...
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2answers
189 views

Op amp zener clamp design

What are the drawbacks of this design vs a design like the TI one here? Should the feedback be on the other side of R2? Are there any other gotchas using something like this, vs limiting using a 7v+-...
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3answers
906 views

TDA7262 Audio Amplfier's SVR/MUTING pin (pin3)

What exactly is the SVR/MUTING pin on the TDA7262? I've done my research on it but I cant find much. I found something that said its to eliminate the thump the speaker gives off when power is applied ...
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0answers
180 views

Connect Analog Audio Line to analog Amplifier IC

I have a SoC that uses an Amplifier IC to Output Audio to a 8Ohm Speaker. I want to take the Audio Signal from the IC and give it on the Audio Line of another Circuit. I am not sure if my circuit is ...
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0answers
109 views

Unusual power consumption - audio amplifier

I bought a 50W*2 stereo amplifier from eBay (i believe the values are overrated, though) and i wanted to use it on my motorcycle. It works just fine, but then i wondered about the power consumption: I ...
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0answers
96 views

Strange noise in audio background

I've set up an audio amplifier using TDA7297 and Raspberry Pi's 3.5 mm audio jack. And I'm using omxd, a daemon for omxplayer, and playing mp4 video files. The audio output has been set to jack. But ...
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0answers
43 views

Having trouble converting an audio signal to be usable by a mic input

So to start, to say that I'm a little out of my depth would be an understatement. I have a single channel audio signal coming from a building intercom system (data sheet). This audio signal is ...
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1answer
43 views

Convert Audio output signal to a switch

How could I evaluate the signals from the audio input so that it acts as a switch to turn on my Bluetooth Speaker?
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2answers
105 views

A TDA2822M earphone driving problem (Hot earphone)

Recently I built a circuit to drive loudspeaker and earphone. The circuit was the same as the reference design (Fig. 1 of Page 4) of datasheet. It works fine with 8 ohm loudspeaker but makes earphone ...
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0answers
286 views

Unity Gain Clipping Circuit

Please see the image below: This is an idea for a unity gain clipping circuit to be used in a guitar effects unit as a 'distortion' pedal. Some percentage of a peak detector output voltage feeds ...
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0answers
73 views

Individually modulate two lasers diodes using sound - while using the same power suppy and preventing signal “bleed over”

I'm trying to individually modulate two lasers diodes using the same power supply. The modulation for each laser module is created by the left and right audio channels. Is there a way to do this ...
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0answers
353 views

Do LCD monitors emit high audio frequency noise?

I held my ear up to an ultrasound probe today and heard a high pitch noise. I am trying to deduce it's source. Someone told me it could be the LCD monitor generating the tone and the energy hopping ...
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0answers
517 views

DC blocking capacitors in a powered microphone?

I want to build a power adapter for a condenser microphone that I own. The normal camcorder that I use the microphone with provides plug in power of 2.5v. The microphone uses a TRS 3.5mm jack. The ...
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0answers
340 views

Pre-amplifier to drive LM324 Op-Amps

I want use Electret microphone Pre-amplifier described in TI document, with Color light organ. Will the output level of this pre-amp enough to drive LM324 Op-Amps on Color organ? Input signal goes to ...
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0answers
387 views

PT2314 Audio IC AT89C2051

How can I interface Audio IC PT2314 with 8051 series micrcontroller (AT89C2051). The audio IC requires SCL SDA (I2C Interface) to control. But in datasheet of AT89C2051, there is no hardware I2C pins. ...
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1answer
193 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 ...
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0answers
241 views

Audio POT with FET and PWM

I've been trying to build a simple audio pot to be controlled with PWM with an arduino, but I'm not sure why it doesn't work. I could do it with a LED (not directly which is simple, but with a FET), ...
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1answer
638 views

How do I calculate expected output voltage of car audio amplifier with given conditions?

I have a 4-Channel Amplifier rated at 800 Watt RMS per channel @ 2 Ohm load. Channel 3 and 4 are preset to operate a subwoofer speaker while Ch 1 and 2 are set to operate mid-range speakers at ...
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1answer
151 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 ...
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1answer
205 views

How do I wire a Shure WL 185 to to iPhone or iPad?

I have this old but very nice mic. Old days I recorded audio to the camera or recorder. Nowadays I record to iPhone so I do not have extra recording device and cameras are action cameras usually ...
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1answer
39 views

TDA1904: Output volume is not amplified

I have created this circuit on the breadboard. Circuit Page no.4 of this TDA1904 datasheet: Supplied voltage 10V from pin2 and supplied signal from 3.55 mm jack to pin8. I have connected the wires ...
-1
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1answer
46 views

3.5mm, 4 conductor, in-line, plug

I am struggling to find pictures of the plug I bought to figure out where to connect speaker wire to. It is a TRRS 3.5mm plug ...