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I like to hear speech with a cutoff at 15kHz or higher. Old deaf people cannot hear frequencies higher than 1kHz.
Do you hear an old telephone well that cuts frequencies above 2700Hz?
I looked in Google for Arduino text to speech and found many circuits. Here is one using an ordinary LM386 linear amplifier and a 2nd order lowpass filter with a cutoff frequency as low as 230Hz. It must sound awful.
Do you hear an old telephone well that cuts frequencies above 2700Hz?
I looked in Google for Arduino text to speech and found many circuits. Here is one using an ordinary LM386 linear amplifier and a 2nd order lowpass filter with a cutoff frequency as low as 230Hz. It must sound awful.
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So would I, but it is unlikely that the PWM frequency is high enough to achieve that with a simple RC filter, that is why I am going for telephone quality. A 15 KHz cutoff would likely require a multi-pole active filter, as I had observed earlier in the thread. The OP does not know what the PWM frequency is, which would help a lot.
Bob
Bob
I want to let you guys know how much I appreciate your help with this subject, I truly have learned a lot from you both!
Here is the product as of now. I tried to make it as compact as possible. The out of the amp board goes into the resistor and capacitors, and the input of the speaker is connected to the ground of one of the caps. I connected the ground cap to the ground of the input. Is this correct? It should be common ground.
Your speaker (squeaker?) gets hot because it is tiny. Also it might not be loud enough.
It looks like you have the filter at the output of the amplifier but instead it must be at the input.
This audio amplifier has two bridged outputs. Then each wire of the speaker has its own amplifier and the speaker is not grounded. Then the voltage swing is doubled which causes the current swing to also be doubled which results in about 3.5 times more power than a simple amplifier that drives a grounded speaker.
The speaker and amplifier will get hot if you connect one of its outputs to the circuit ground.
It looks like you have the filter at the output of the amplifier but instead it must be at the input.
This audio amplifier has two bridged outputs. Then each wire of the speaker has its own amplifier and the speaker is not grounded. Then the voltage swing is doubled which causes the current swing to also be doubled which results in about 3.5 times more power than a simple amplifier that drives a grounded speaker.
The speaker and amplifier will get hot if you connect one of its outputs to the circuit ground.
Ok, I'll be sure to fix that. The squeaker shouldn't overheat with the additional resistance, right?
A speaker never has a resistor in series with it and it never has DC in it like yours will have if one of its wires is grounded. The DC causes the speaker cone to move toward one side making its sounds faint and causes a lot of heat in it.
I agree with everything @Audioguru says above. The filter must go between the Arduino and the input to the amplifier. The idea is that the Arduino puts out a series of pulses that encode the audio and the filter turns them into actual audio that you can run through an amp and speaker.
Bob
Bob
Alright cool. I will do some changes and report back to you guys
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