Two beeps before sound is played

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christhorn
 
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Joined: Mon Oct 18, 2010 1:58 pm

Two beeps before sound is played

Post by christhorn »

Hi there, thanks very much for taking the time to help.

Having searched the forum (and other sources online) I can't find an answer to my problem.

I have an Arduino Duemilanove and a Wave Shield, and I have a 10W 8 ohm speaker connected to the Wave Shield. To this I have connected a 1W audio amplifier (http://www.maplin.co.uk/module.aspx?moduleno=220054, product code N48FL).

I have programmed the Arduino to play a sound when a switch is flicked, using the WaveHC library. Without the amp connected, the sound played fine. There was a slight pause (0.5 - 1 second) before the sound played, but I'd not really noticed it before. Now with the amp connected there are two distinct beeps before the sound is played - a high note followed by a low note.

Depending on the input attenuation of the amp and the output volume of the Wave Shield, these beeps become louder or quieter.

At the current setting (full Wave Shield volume and about 50% amp input attenuation) the beeps are barely audible and everything is fine, but I'm curious to know what might cause these beeps as if I reduce the attenuation (thus making the sound louder) the beeps become more noticeable.

Thanks again for your help.

Chris

adafruit
 
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Re: Two beeps before sound is played

Post by adafruit »

sounds like digital noise from the arduino coupling in. this is not easy to get rid of, make sure you have the highest volume coming out of the wave shield and a clean power supply to the amp

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christhorn
 
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Re: Two beeps before sound is played

Post by christhorn »

Thanks for the reply. I guess I just wanted to check whether there was a simple fix, or whether it was something inherent like you mention.

The speaker begins to distort before the beeps are particularly noticeable, so that's something I guess!

suopo
 
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Re: Two beeps before sound is played

Post by suopo »

Hi,
I´m new here so hello everybody and thanks for ada and all you other making this forum such a great asset for a starting arduinist. Just a thought that occurred, have you checked your soundfile? Seems to me that there might be some silence/garbage in the beginning. That would also account for the pause before the sound begins to play.

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