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

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0
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1answer
30 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
308 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
67 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?
1
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0answers
28 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 ...
-1
votes
1answer
28 views

Would anyone help these various latency? [on hold]

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
votes
2answers
197 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
41 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
vote
1answer
65 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 ...
1
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0answers
42 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
vote
1answer
101 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
50 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
votes
3answers
39 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
votes
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
vote
1answer
31 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 ...
1
vote
2answers
72 views

How can i create a mic preamp with variable slew rate? [closed]

How can i create a mic pre amp with variable slew rate that is dialed in with a button and have a wide range from very slow to very fast !
0
votes
2answers
79 views

How do you get rid of hum in audio?

I built a circuit for a simple amplifier that can use both bluetooth or a 3.5mm connector. The problem is that I am getting noise when I use the bluetooth module. There is no noise when I use the ...
-3
votes
2answers
63 views

How to extend a pair of RCA cable and not lose too much audio quality at the same time? [closed]

I have a 2.1 speaker system that I have been using for over 6-7 years or so. Recently I have decided to mount the two satellites on the wall, but there is a problem with the length of cables. I have ...
0
votes
2answers
31 views

Low amp/volt relay for microphone switching

Its that time of year when I revisit one of my old projects and try to improve it. Currently I have a small 12v PA system that has a microphone and I've added an 3.5mm auxiliary input to play music ...
1
vote
1answer
36 views

Thin film SMD resistor reliability

I am hoping someone can point me toward some clarity regarding the durability of thin film SMD resistors. Google pointed me toward a number of pages that indicate they are sensitive to humidity and ...
0
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0answers
22 views

Short period of noise after audio stops?

I am building an audio amp based on the TPA1517. I added a bluetooth module to it and I noticed that now wired or bluetooth, once the music is paused, there is a few seconds of noise, a pop, and then ...
3
votes
1answer
171 views

“Stopping” sound after a certain frequency

A friend has a condition that can cause seizures when listening to frequencies over 1500Hz. To help her out I made a passive first order (RC) low pass filter with a cut-off frequency at ~1300Hz but ...
0
votes
1answer
35 views

generating a 10mVpp signal from computer

I have an input to a system that requires a 10mVpp max signal. I have to use my computer to input it due to constraints out of my control. I am well aware an audio card cannot go down that low. I ...
-1
votes
3answers
46 views

Signal loss over distance

What diameter size copper wire is needed to send 30KHz audio at 50 watts over to high power tweeters 120 feet away without losing too much signal over the wire?
1
vote
2answers
55 views

Impedance matching for piezo element

I am trying to boost audio signal from around 3V to around 60V for a piezo element with a component as small as possible. I found audio transformer MET-23 that reflects 1.6 kOhm impedance on primary ...
0
votes
1answer
67 views

What resisters for inverting op-amp should I use?

I am not an electrical engineer by any means so go easy on me here. I am simply experimenting with a speaker amplifier. My situation: I have a Clarion xc1410 4-channel amplifier with a 10k input ...
-3
votes
1answer
38 views

Solder old Home-Cinema wire to Audio Jack Plug [closed]

So I have this ancient Home-Cinema (Panasonic SA-HT540) and the main unit appears to be broken. The speakers should work just fine though. I'm planning to solder the speaker-wire (which is a simple ...
0
votes
1answer
43 views

Audio Amplifier Design (CE Amplifier - Class AB Power Amplifier)

I am trying to design a Audio Amplifier which provides a gain of 20db (10V/V). I have managed to design the following circuit but the output voltage gets clipped and clamped. Please find the schematic ...
0
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2answers
35 views

CE Amplifier Design for Audio Amplifier

I am trying to design an audio amplifier which provides a maximum gain of 20dB (or) 10V/V . For the circuit I designed the lower half of the amplified signal is being clipped. I am also attaching the ...
-2
votes
1answer
53 views

Why Can't I get a Smooth Sine Curve in PSPICE

I am trying to simulate a Volume Control Circuit in PSPice Student Edition. I am unable to see a smooth sine curve at the output. Could you check my circuit. Find the Schematic below Thanks
3
votes
1answer
72 views

AM335x FPGA Memory Integration

I'm currently designing a digital mixing console. We have a somewhat large number of ADCs and DACs (more than the multi channel audio serial port on the processor can handle). We decided the solution ...
0
votes
2answers
53 views

Connecting and soldering audio cable of several earbuds, but none is working

I have about 10 sets of earbuds accumulated over the years, where just one of the two is working or the jack is broken, so I thought to try to fix them. I've tried mixing several of them, in example ...
0
votes
2answers
53 views

Op-Amp decreasing amplitude of audio signal

For a final project for an electrical engineering course I am taking (my first), we have been tasked with combining input from a small microphone and an aux cord, amplifying it, transmitting it via a ...
0
votes
1answer
29 views

Modifying Voltage Controled Amplifier to become attenuator [duplicate]

https://www.fairchildsemi.com/application-notes/AN/AN-6603.pdf Page 3 top left of this also shown in this screenshot: http://i.imgur.com/rp3lYsl.png How would you modify Figure 11 to make a voltage ...
0
votes
2answers
55 views

Is there a circuit that amplifies current or voltage relative to signal frequency?

I am trying to create a circuit that outputs a higher voltage/current as the frequency of the signal input (such as an audio input) gets higher - such as to allow all frequencies to bypass a capacitor ...
0
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0answers
34 views

Floating Ground Adapter for Car audio line level signal?

I have a an Audi that uses the Bose external amplifier. Bose/Audi designed the system to use a single common between the head unit line out and the Bose amplifier line input, so it is four wires (FR+, ...
0
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0answers
48 views

vhdl code to do ramp-up & ramp-down for audio

I'm trying to learn more about VHDL and audio. I generated sine wave data using matlab. I want to generate three different type of audio output so I thought of doing ramp up and ramp down for my ...
6
votes
3answers
535 views

Audio transformer: What to do with an unused winding?

For the purpose of impedance matching and floating a single-ended, ground-referenced signal, I am planning to use an audio transformer like this one. Here's the schematic from the data sheet: My ...
0
votes
4answers
61 views

Can I efficiently monitor sound card line in with a vu meter?

I'm trying to monitor some audio input to my desktop pc with a vu meter. I've connected to the line in, and it's just a bog standard on-the-motherboard sound card. I'm having a problem understanding ...
0
votes
4answers
78 views

Audio transformer for 12V light emitting circuit

I'm working on transmitting audio through light using amplitude modulation of an LED, received by a solar panel connected directly to an active speaker. Something like this: simulate this ...
1
vote
2answers
62 views

Using a LM311n in a class D amplifier as comparator

I'm making a class D amplifier as a school project, and we are currently at a stage where we simply need to add the comparator. But the comparator (LM311n) does not seem to run as intended. My ...
0
votes
2answers
42 views

How to increase speaker max input power

I have a tiny 8 ohm speaker rated to accept a maximum of 0.5W. The docs explicitly say adding 1.5W or more will "blow it out". However, I'd like to use this speaker with a 1.5W amplifier (PAM8302A). ...
2
votes
1answer
59 views

How to increase an output of opamp in this noise generator?

I'm working on a noise generator for my analog synthesizer and have problems with current design I built. As a noise source I use NPN-transistor in avalanche mode with only base and emitter connected. ...
2
votes
1answer
47 views

Variable Input Voltage Power Measurement

I've looked around the site for suggestions, but think this question is a unique one and would love some conversation. I need a method to measure the average power in to a transducer. This method ...
0
votes
2answers
84 views

XLR to Microphone wiring

I have an XLR cable that I am trying to wire directly to a microphone that did have a Micro XLR connected to it. I have cut the male micro XLR's from each side and am left with the following wires - ...
1
vote
2answers
38 views

Audio Mixer Passive Attenuator Circuit

I'm currently designing a digital audio mixer. One common thing found on audio mixers is a optional 20dB pad on the input. I've seen some attenuator circuits but all of them require you to know your ...
1
vote
2answers
99 views

Missing low frequency tones from bluetooth audio output

Currently I'm working on a project which uses a bluetooth module (Bluegiga WT32i) to get audiostreams from my iphone to a 3.5mm stereo jack input for a car AUX input. The problem now is that I have ...
0
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0answers
25 views

How to use switch in line-in audio jack connector to (de)activate electret microphone?

I have a megaphone with an electret microphone. The voltage at the microphone is about 3.1V and the microphone has a resistance of about 1 kOhm: I replaced this microphone with a little circuit to ...
0
votes
1answer
46 views

enclosure fabrication resources for the upscale hobbysist [closed]

I recently saw a beautifully made 1RU 8Ch microphone pre-amp that was in a beautiful enclosure with a very pro looking faceplate and so on. The engineer wouldn't share who made it for semi-obvious ...
0
votes
1answer
66 views

How do I get rid of speaker static?

I made the basic TPA1517 circuit as shown on page 11 of the datasheet. When there is nothing plugged into the input, there is a lot of static. When I do plug something in, there is less static, but it ...
1
vote
1answer
33 views

Add line in to electret microphone and mute the microphone when plug is connected

I have a megaphone with an electret microphone. I want to modify the megaphone so that I can optionally conntect a notebook's headphone out to the megaphone. So I want to add a line in connector to ...