Teensy 4 Audio Project Speaker

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DW99

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Hi all,

I have a T4 and Audio shield, and I need to connect it to a speaker using the line out of the audio shield. I am planning on using the LM4861MX/NOPB power amplifier to amplify the audio shield line out output and using a 3.3V supply rail, but I need a speaker to play the sound. The requirements for the speaker are that it should be able to play recorded speech clips loud enough to sound like someone speaking. The speaker needs to be relatively small in size. I am not quite sure how the wattage of the speaker translates into volume, so I am not sure what I should be looking for with regards to power, hence the question. From my searches on part stores so far it would seem that most speakers have a frequency range of >200Hz. The male speaking voice is about >100Hz, which makes those speakers unsuitable. I can't seem to find a speaker with a low enough frequency range.

Could anyone recommend me a suitable speaker for the project?
 
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You are perhaps selecting only small speakers, in general small speakers don't do low frequencies, you'll need a larger one -
a key specification is efficiency (aka sensitivity), usually given as dB for 1W at 1m.

Power the amp from 5V, not 3.3V, if you want more power from it.

There is a trade off between size, bass and efficiency meaning that if you want good efficiency and bass you cannot
choose a tiny speaker box. This is why laptop speakers have no bass at all.

The normal vocal range for comms is 300 to 4kHz, nothing is needed below 300Hz for intelligibility, the ear fills in the fundamental
from the overtones in speech waveforms.

BTW are you looking for a complete speaker unit, or just a driver?
 
Sorry for only coming back now, I finally received the power amp IC and can only now actually start working on it.

I've decided to power the amp from 4.5V. That's the power supply I'll be using to power the T4 as well. I've got the amp up and running, and the speaker working. The speaker I used is this one: https://www.digikey.co.za/en/produc...973691?s=N4IgTCBcDaICwGYEFoCMqAMdkDkAiIAugL5A.

I am not looking for base, the speaker needs to be tiny with sound that is relatively noise-free and audible to a mobile phone while in Playing back audio, it has a rather bad buzzing quality to it. Is this due to the sensitivity of the speaker? Or, more likely, I am powering everything form USB at the moment. Could it be the USB noise that's translating into the power amp and thus into the audio?

I am looking only for the speaker itself, ie the part that actually emits the sound. The link above will show what I need. But that specific one has rather bad sound quality, though I believe the volume is acceptable for my purposes.
 
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