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Questions tagged [audio]

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

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5 votes
3 answers
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What is the purpose of this diode in the gate of a JFET

I am studying how the bypass circuit of the Tube Screamer pedal works. It is dependent on two JFET transistors that are used as switches. I am not great at understanding JFETs as switches, as I have ...
Juan Aldrey's user avatar
-1 votes
0 answers
55 views

What do the pins on this audio amplifier PCB mean? What I would need to connect to them to get my speaker working? [closed]

Running down the upper left corner are all the pins that go in and out of the board. I'm still a novice at things like this and I would like some help identifying what each pin is for and to what it ...
Lexi Mcvay's user avatar
-1 votes
0 answers
23 views

How can I increase the volume of this video intercom device? [closed]

I recently moved and the video intercom device is faulty. Given building conditions a repair cannot be performed and my device rings and sounds at a very low volume. I have to be at a meter's distance ...
Sergio Basurco's user avatar
-2 votes
0 answers
61 views

Audio amplifier for a physics experiment, how do I make it? [closed]

The experiment includes a mic taking in sound(2KHz-4KHz) and sending it to a DSO. I need an audio amplifier circuit in between that to amplify the signal so it would be visible properly. The ...
Aether Void's user avatar
1 vote
1 answer
58 views

Coupling/decoupling power supplies: how? [closed]

I'm adding a hi-Z adapter to a solid-state amplifier that is powered from the mains through a transformer and regulator. The hi-Z adapter is powered by 24 volts DC, so i need an external power supply ...
delt's user avatar
  • 113
0 votes
1 answer
53 views

Audio Codec Input/Output Channel Stages

I am planning to build a PCB for a Eurorack Modular Synthesizer, incorporating an STM32 for DSP and a bidirectional Audio Codec like the TLV320AIC3104 to handle the ADC/DAC. Eurorack audio signals ...
95lux's user avatar
  • 1
0 votes
2 answers
73 views

How can I record with this old fashioned mono microphone? [closed]

I have this microphone that comes with a 3.5mm mono jack connector. When I plug it in to my laptop or my phone it won't work, and I believe the "mono" part is the problem. What do I need to ...
I. Haage's user avatar
  • 103
3 votes
2 answers
381 views

How do you choose an audio isolation transformer for a microphone?

I found a few SE Q/A's for audio transformer characterization, but they neither address calculating the impedance match, nor consider signal loss for weak audio sources (like those from a microphone). ...
KJ7LNW's user avatar
  • 2,190
2 votes
5 answers
439 views

Do audio impedance mismatches cause reflection (ie, 8-Ohm output to 20kOhm input) ? Does it matter?

I understand that audio source⇒input impedance mismatches are normal, and this answer provides a good reason as to why. However, having worked with RF more than audio, mismatches cause reflection that ...
KJ7LNW's user avatar
  • 2,190
0 votes
2 answers
55 views

Why does 9.7Vrms == 27 Vpp? I thought it was 9.7/0.707 == 13.72!

At first, I thought this calculator was wrong, because I have always used an RMS to peak-to-peak conversion as \$ V_{RMS} = \frac{V_{pp}\sqrt{2}}{2}\$: https://benchmarkmedia.com/blogs/calculators/...
KJ7LNW's user avatar
  • 2,190
3 votes
2 answers
373 views

What type of cap would you use to block DC on a microphone-level audio line (unbalanced)?

I need to block a DC voltage on a microphone line, and a bit of research shows that MLCC is a bad idea because they can mechanically ring from vibration. Question: What type(s) of capacitor could be ...
KJ7LNW's user avatar
  • 2,190
0 votes
2 answers
87 views

What is the maximum dBu I can send into a microphone input in this schematic?

The schematic below is from the Icom 9700 radio service manual (page 80). I would like to feed this input from a mixer board's ALT-3/4 outputs, and I want to avoid blowing the TS462 microphone preamp ...
KJ7LNW's user avatar
  • 2,190
1 vote
0 answers
68 views

Bipolar 15 V DC from 9 V DC

I’m looking to get a regulated ±15 V DC @100mA minimum from a 9 V DC source. It’s for an audio circuit, so it needs to have a switching frequency well above audio range, and it needs to have a small ...
Connor Moore's user avatar
0 votes
1 answer
53 views

How can I make an adapter wiring for a TRRS microphone to TRS?

I'm making a sound level meter using a Raspberry Pi as part of my thesis. My professor has given me a TRRS microphone to work with. I tried to make the TRRS microphone work with the Raspberry Pi ...
Χρήστος Παρασκευάς's user avatar
8 votes
7 answers
2k views

What is the reason for using decibels to measure sound?

If the decibel represents a gain ratio, why do we use it in sound measurements? Yes, since we have an input signal in audio amplifier circuits, we can understand the behavior of this system according ...
kaan's user avatar
  • 377
0 votes
2 answers
30 views

Measuring voltage from the aux cable signal

I wanted to make a bjt amplifier circuit to get used to analog circuit design. My plan was to use an AUX cable connected to my phone. I cut the cable and stripped the 3 wires inside. I wanted to see ...
kaan's user avatar
  • 377
2 votes
2 answers
96 views

What is the function of the inductor in this Bluetooth audio module?

I found the circuit below for a Bluetooth sudio module that included a 100 mH inductor in series and then a 10 uF capacitor in parallel to the power input. Image source: Iranian electronics seller ...
adam_Barfi's user avatar
0 votes
0 answers
22 views

Audio project converting TSH-4 headset to 3.5 mm audio jack

I've been trying to connect this TSH4 headset to a 3.5 mm audio jack. The headset has kind of a weird setup, with Mono audio + and - being the top pins (I don't know which is which, but the polarity ...
Emily Kramer's user avatar
1 vote
0 answers
68 views

Making audio signals imitate USB flash drives [closed]

If there is a USB port designed for USB flash drives that plays the audio files in that drive when it is connected --such as the ones commonly found in cars-- is there any practical way to turn an ...
adam_Barfi's user avatar
0 votes
1 answer
107 views

Modifying TI schematic to learn more about amplifiers

Let me start off by saying that I'm a complete beginner. I've watched some videos on amplifiers and read about them but it's hard for me to analyze circuits that don't match exactly to the examples I ...
Ivory's user avatar
  • 1
4 votes
3 answers
477 views

Audio engineering: amplifying two different sources

I've started a small project to renovate/rebuild an old record player for my wife. I have a degree in Electrical Engineering, but it's been almost 15 years since I last had to project/build a circuit, ...
Yuri Oliveira's user avatar
1 vote
0 answers
80 views

Can an audio isolation transformer between a preamplifier and an amplifier cause the amplifier's fuse to blow? [closed]

I'm building a microphone preamplifier. I was having problems with hum (intermittent ground hum when touching the case) and decided to try adding an audio isolation transformer (600 ohm : 600 ohm) ...
steev's user avatar
  • 111
1 vote
2 answers
61 views

Inline volume control for analog audio signals with push buttons [closed]

I want to build something to control the amplitude of analog audio signals between the source (line level analog audio output already extracted and decoded from an HDMI source) and the AMPs. In ...
Deling Ren's user avatar
1 vote
0 answers
64 views

PCB digital sound input and output

I've designed a simple 3-band equalizer circuit. I've used 3.5 mm audio input connected with computer via 3.5 mm audio jack for input, and basic small speaker for output. In all my references, many ...
GL Park's user avatar
  • 31
7 votes
3 answers
515 views

Audio amplifier for school project

For a school project, we have to explain this design of a audio amplifier. We have only been able to understand to parts marked with colored rectangles. The design comes from the book audio power ...
hgfg hfghgfh's user avatar
1 vote
1 answer
36 views

Identify and substitute f1404zs

I need help understanding which chip I need to buy. First, I hope this is the correct community; if not, I apologize. My intention is to repair a Mark Levinson 86280-0w690 audio amplifier, inside ...
user_0's user avatar
  • 113
1 vote
0 answers
65 views

How to generate a 50-100 Hz 12 Vac sine wave for audio tone from 5 VDC (PB0 pin) atmega164p microcontroller [closed]

I have programmed to ATmega 164P to make PBO high when PC1 is low. In programming, I'm adding other peripherals as well. But I am facing one issue regarding generating a tone. I have drawn low pass ...
Traffic t's user avatar
0 votes
1 answer
46 views

How to replace microjack on stereo earplugs with microphone [closed]

I broke a microjack connector. It is attached to a set of stereo earplugs with built in microphone. I know how to solder, but I am not sure how to find the correct replacement plug and how to identify ...
Jostein Trondal's user avatar
-1 votes
2 answers
65 views

Boost or buck audio input to minimum and maximum levels

Similar to Simple circuit to boost line-level audio Background: Some songs start out really quiet - Queen is notorious for this - and then eventually ramp up to passable audio levels. To hear them, ...
Aaron M.'s user avatar
0 votes
5 answers
97 views

How does one add a volume control to this circuit?

My uneducated guess is to add a potentiometer at R6. Can anyone confirm? Image courtesy : amplifiercircuit.net
AlphaSixSierra's user avatar
-1 votes
2 answers
85 views

How to modify frequency of an analog signal [closed]

I want to create my own pcb. First step is to design my circuit. I thought about a voice modifier. So, in the breadboard I should put: a microphone (an electrostatic electret microphone) followed by ...
void_brain's user avatar
0 votes
1 answer
33 views

switchable summing audio mixer volume troubles

Consider this audio mixer. There are 3 sources that may play any kind of audio (the sine generators are just illustrative). You can switch any of them to either of 2 outputs using the SPDT switches. I ...
one_three_three_seven's user avatar
0 votes
1 answer
76 views

Mains hum in TDA7265-based active loudspeaker

The old pair of M-Audio Studiophile AV40 active speakers (one box containing all the amplifier parts and the second is just a passive box) I have have developed a clear low-frequency hum. This hum is ...
paulus's user avatar
  • 1
0 votes
1 answer
41 views

Best practices for combining dual mono to stereo? [closed]

I have two old-style telephone pickup coils, each of which has a 3.5mm mono (TS) male output. I made a simple adapter that just runs together the grounds from both inputs and connects each positive to ...
Michael's user avatar
0 votes
0 answers
125 views

Audio amplifier cutting off and clicking PAM8304

I have designed a PCB with a PAM8304 Mono Class D Audio Amplifier and MAX1708 5v step converter to drive a 4 ohm speaker. The device will be battery powered with 3.3v battery hence the step up ...
CADman's user avatar
  • 1
1 vote
2 answers
62 views

Synchronizing multiple I2S codecs on stm32f405

I am designing an audio device that requires two CODECs to be connected to the MCU - two stereo outputs, two stereo inputs. When working with a single codec, no problems with synchronization occur ...
sx107's user avatar
  • 1,109
0 votes
1 answer
59 views

what is the source of this noise when recording to raspberry pi using USB soundcard

I connect aux out from my laptop to USB soundcard mic in and use arecord to record audio. But I am getting noise even recording at CD quality. The nature of the noise is really strange as it seems to ...
Vrisk's user avatar
  • 376
0 votes
2 answers
55 views

Can the impedance of the source affect the response of a high-pass filter?

Having a simple RC high-pass filter, can a high signal impedance change the cutoff frequency response? Or more practically, should a resistor before the capacitor be included in the calculation for ...
boromyr's user avatar
  • 53
1 vote
1 answer
88 views

Audio visualizer: What can I improve in this circuit?

Being a beginner in electronics, I embarked on designing and building a sound visualizer, turning bass, mid, and high frequencies into red, green, and blue light in an RGB LED strip. I designed the ...
Matthias's user avatar
  • 169
0 votes
0 answers
69 views

Noise in audio amplifiers when touching the smartphone touchscreen as an audio source

While observing the audio output of my smartphone on the oscilloscope, I noticed a signal being generated when I touch the touchscreen. This signal is around 500Hz and appears in groups of 3 peaks, ...
boromyr's user avatar
  • 53
0 votes
0 answers
50 views

How do you diagnose a fault with a tweeter?

I have a Pioneer XPRS 10 at work that isn't producing any high frequencies; the 10" woofer working fine, but the 1.75" tweeter is not producing any sound at all. It's a 50W, 8 ohm tweeter. I ...
Sputnik's user avatar
  • 101
0 votes
0 answers
79 views

PAM8403 weird clicking / banging noise

I'm using an ESP32, a PCM5102, and a PAM8403 to output a 3.5mm Audio Jack output. In my circuit, I'm sending the Audio Signal via I2S to the PCM5102, where a quieter output can be picked up. If the ...
Tom's user avatar
  • 1
0 votes
3 answers
122 views

Why is there a greater lag in Bluetooth headphones compared to wired?

The Usual Answers and Responses: Encoding, Compression, and Buffering The typical answer to this on the internet is because Bluetooth headphones require the conversion of one form of data information ...
Curious Layman's user avatar
18 votes
2 answers
4k views

What is the purpose of these fat copper coils wrapped around … something?

Dissecting 20-year-old outdoor speakers (SpeakerCraft OE8 One), found this electronics board inside. I recognize the capacitors, but what are the big custom coils of copper wire, and what is their ...
Phrogz's user avatar
  • 293
0 votes
0 answers
30 views

Radio mic and speaker as camera mic input

I want to add radio comms to in car action camera audio. I am a total amateur in analog circuits. I understand that i can't just feed headphone out and mic into camera. That will trip PTT (Push-to-...
Tomas Mazukna's user avatar
-1 votes
2 answers
89 views

Why can I hear a radio station when probing with oscilloscope? [duplicate]

I assembled this on a breadboard: and am hearing a faint buzzing sound... My first question is, what could be causing this sound? It does not go away if I connect VIN to ground. With or without VIN ...
brooksbp's user avatar
  • 129
0 votes
1 answer
61 views

CB style PTT Mics to USB circuit

I need to design a circuit that takes the input from 2 different CB style (4-pin) push-to-talk microphones and pipes them out to USB. CB mics I have confirmed use regular XLR balanced level output. ...
Muscle Nerd Jerry's user avatar
1 vote
2 answers
86 views

Disabling microphone when secondary one is connected

I'd like to add a 3.5 mm female jack to this circuit so that I can add a better external microphone while keeping the internal one for convenience. What would the circuit look like? Putting both ...
Jess's user avatar
  • 11
0 votes
1 answer
80 views

TRS headphone output socket that may be used with a TS mono jack: how to prevent short to ground?

I'm using a TPA6132 headphone amplifier connected to a stereo (TRS) output socket. In my application, the output will usually be used as a line output, and only occasionally with headphones. The audio ...
one_three_three_seven's user avatar
0 votes
0 answers
73 views

Automatically Vary LFO Speed Resistance Value

I have a basic tone generator circuit with LFO speed controlled by a 50K pot (variable resistor). I would like this resistance to fall (or rise, but I guess fall might be easier) after the circuit has ...
Jeff's user avatar
  • 1

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