giving Arduino ears- Spectrum Analyzer Shield

Projects General Guidance
1

Hi,

Does anyone know if you can plug in a 3.5mm jack microphone into the spectrum analyzer shield?? Trying to allow my arduino to listen to it's environment and analyse the sounds. Had no luck so far :frowning: any help would be appreciated.

Thanks,
Emma

2

Why not just look at the product description?

http://www.bliptronics.com/item.aspx?ItemID=116

"Stereo audio can be input using a 3.5mm headphone jack. Two jacks are supplied, so you can route the audio through to your stereo or speakers. "

3

Thanks for the reply. I did read the description before, and not just on the bliptronics site, but also the sparkfun version too. I just wasn't sure if it meant direct connection between an audio source into the jack. e.g cable connecting an ipod into the audio jack.

I've tried plugging a mic in, but the analyzer values don't seem to be changing. However, they do change when I connect an iphone via audio cable into the jack and start playing music. Hence the confusion here.

4

The signal level on an iPod headphone output is much higher than the signal level on a microphone. To use a microphone you will need an amplifier like this kit from Sparkfun for $2.95: http://www.sparkfun.com/products/8872

5

It's worth noting that the Sparkfun shield gave me TERRIBLE results compared with the reference circuit as shown on the MSGEQ7 data sheet. Even when using $.03 caps and cheap resistors, the msgeq7 in a protoboard isolated from the arduino was VASTLY superior.

I'm going to be designing a single channel MSGEQ7 shield in eagle this week and will post the resulting files to the arduino playground after I've had a chance to test it fully.

6

Thanks for all the help here. Thought the shield would be easy to use. guess i was wrong :frowning:

righto, so the shield will never work with a microphone in a plug and play sense?
It will always need a pre amp?

7

echee:
Thanks for all the help here. Thought the shield would be easy to use. guess i was wrong :frowning:

righto, so the shield will never work with a microphone in a plug and play sense?
It will always need a pre amp?

It's not necessarily hard all that hard... It's more a matter of approaching it knowing the limitations. The MSGEQ7 is a great little chip - just have to figure out what you're needing from it.

Are you trying to get directional audio? What's the actual application?

Note that the MSGEQ7 applies approximately 20dB of gain, and some people have been able to use VERY small mics with it unpowered. This is NOT reliable or good.

How about building a couple of these suckers?