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[on:]

hello!
im from chile, im part of TALLER DINAMO...
 sorry for my english i'll try to make myself clear....

i'm developing an art installation with an arduino one and 8 spacializated 2"speakers. I want to distribute one only sound throw these speakers controlling each volumes with an individual pwm signal, drive by an shiftregister (74595), so can move smoothly move the sound throw the space...

my question: wich system, circuit or componet can i use to control only the volume of each of my speakers, considerating that i will use an external mp3 player to generate the only one sound????

any help will be we welcomed!!!

thank you!!!!

Rodrigo Costa MAluk
santiago chile!

[Reply #1 on:]

I would feed the MP3 signal into the equivalent of potentiometers  before it goes to the speaker amplifiers.
You could look into digital potentiometers
http://www.maximintegrated.com/products/digi_pot/
 to control the volume that each speaker amplifier sees.

[Reply #2 on:]

thankyou crossroads!

i,will check the digital potentiometeers deapply, but in the overview, i've found that its control "only by up and down signals (im searhing for a component that convert direcctly the pwm that i get from arduino, to control the "digital potentiometer" but just cant findit...  , and i don't complexing a lot the code. plus the are hardly find here in chile, i have not much time for this time.
i think that i will use an 8 chanels demultiplexer, that only shicthes, but this way i can save time to bring all sistem togeder and get the best interacctions with the users...

thankyou!!!

[Reply #3 on:]

To use the PWM output as a voltage you need to smooth it with a filter.
http://provideyourown.com/2011/analogwrite-convert-pwm-to-voltage/

Then connect the filter to a  voltage controlled amplifier.
http://hackmeopen.com/2011/04/voltage-controlled-amplifier/

http://www.analog.com/en/specialty-amplifiers/variable-gain-amplifiers/ssm2164/products/product.html#product-documentation

[Reply #4 on:]

If you chop up the audio signal and then smooth it out with filtering, you will end up altering the sound itself instead of just changing its volume at different locations. If you do anything besides change the gain (amplitude) of the signal, you will end up with a different sound.

[Reply #5 on:]

Arduino is controlling the VCA via the PWM and the low pass filter, audio goes direct to the amp.

[Reply #6 on:]

That'd be okay then. Reply#2 didn't read that way to me.
Altho re-reading it, switches &  multiplexers could be used to have sound on or off at each location.