Author Topic: Audio spectrum analyzer  (Read 1988 times)

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Offline t_jason_tTopic starter

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Audio spectrum analyzer
« on: January 19, 2018, 12:22:17 am »
I have a question am trying to figure the easiest way build a IN-13 spectrum analyzer. I just want to know if I use band pass filters for each stage on the low input audio then us and Inverting op on that filter single to change the level form AC to 0-5 v dc signal. Then use a MJE 340 through a 270K resistor to ground will that not work to drive this display. I have been looking around on the internet and seen some much more complicated solutions so am just asking will this work.
 

Offline t_jason_tTopic starter

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Re: Audio spectrum analyzer
« Reply #1 on: January 19, 2018, 12:24:30 am »
Non inverting I mean
 

Offline Audioguru

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Re: Audio spectrum analyzer
« Reply #2 on: January 19, 2018, 01:05:32 am »
Your non-inverting opamp circuit will not change its AC input to DC. It is a simple AC amplifier with a voltage gain of 11 times.
You need an active peak or average detector circuit instead.
 

Offline danadak

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Re: Audio spectrum analyzer
« Reply #3 on: January 19, 2018, 02:38:28 am »
Close to free approach -

You can start with a PC sound card based scope for free. Will give you basically
audio rang scope, spectrum analyzer, and function generator all using your
PC sound card.


https://www.zeitnitz.eu/scope_en


http://www.zelscope.com/


http://www.ledametrix.com/oscope/


http://www.virtins.com/downloads.shtml


But first build a simple circuit to protect sound card inputs so you do not
ruin from transients, overvoltage. Google "protect sound card input".


For example   http://makezine.com/projects/sound-card-oscilloscope/



Regards, Dana.
Love Cypress PSOC, ATTiny, Bit Slice, OpAmps, Oscilloscopes, and Analog Gurus like Pease, Miller, Widlar, Dobkin, obsessed with being an engineer
 
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Offline t_jason_tTopic starter

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Re: Audio spectrum analyzer
« Reply #4 on: January 20, 2018, 06:55:37 pm »
If there is no polarity flip how is it AC the whole wave is above 0v.
 

Offline Michal Mytnik

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Re: Audio spectrum analyzer
« Reply #5 on: March 30, 2018, 10:42:58 am »
HI t_jason_t

I am basically building same thing. Have tried few approaches. Analog way with bandpass filters seems like first choice but starts to be pretty costly if you are looking for something like 22 or more bands. FFT with MC seems to be the cheapest options. I have also considered doing that with switch capacitor filter IC that is swept through audio frequency. Wondering what's your approach. I can share my design if you are still after that.
 

Offline ogden

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Re: Audio spectrum analyzer
« Reply #6 on: March 30, 2018, 11:38:24 am »
I have a question am trying to figure the easiest way build a IN-13 spectrum analyzer. I just want to know if I use band pass filters for each stage on the low input audio then

... then it is very hard way to build spectrum analyzer. You need loads of quite steep filters each containing at least two or even four opamp stages and capacitors/resistors which may not fall into usual "value grid" of nominals, shall be quite precise as well. Such "filter way" is crazy complex and expensive.

Easiest way (today, in 21st century) to build spectrum analyzer - using powerful enough for the task microcontroller and doing FFT (fourier transform) of digitized audio. Also it is not easy to build your own design from ground-up. For beginner it is advised to copy first. When you finished copy and it works - then you can think how to improve it or make your own design.

Start here for example:

http://www.instructables.com/id/Arduino-Spectrum-Analyzer-on-a-10x10-RGB-LED-Matri/

If it is not what you are looking for, then check this:

http://lmgtfy.com/?q=fft+spectrum+analyzer+microcontroller
 

Offline rhb

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Re: Audio spectrum analyzer
« Reply #7 on: April 01, 2018, 12:38:55 am »
Aside from better resolution, a PC sound card & FFT will let you display a waterfall display.  If you do this with a 4K TV you'll have a resolution of less than 10 Hz.  It's almost hypnotic to watch.
 

Offline MasterT

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Re: Audio spectrum analyzer
« Reply #8 on: April 01, 2018, 01:42:26 am »
Arduino UNO (Atmel's AtMega328) is capable to split audio into 256 (!) bands. Done a small project a little while ago, have a look:
https://youtu.be/Ra4Yx8nkENs
 

Offline ogden

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Re: Audio spectrum analyzer
« Reply #9 on: April 01, 2018, 12:34:43 pm »
Arduino UNO (Atmel's AtMega328) is capable to split audio into 256 (!) bands. Done a small project a little while ago, have a look:

Very cool project. Especially fact that you managed realtime(?) FFT256 on Uno. Could you possibly share more than just video?
 


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