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The audio frequency of low A on a piano is 27.5 Hz.<p>When I use my function generator to send a 27.5 Hz audio signal to a speaker, the speaker just clicks in and out at that frequency. It isn't until I increase to a higher frequency that the speaker starts to produce a "tone".<p>Two Questions:<p>1. What does a low frequency audio tone generator (like a synthisizer) do that my sine wave generator doesn't?<p>2. Is there a kit available for a low frequency audio tone generator?. I would like to generate the lower tones of a piano/organ (25 Hz or so).

I would appreciate any replies, this has puzzled me for a while now.<p>Thank you

On a piano you are hearing overtones of 27.5
To produce 27.5 Hertz with a speaker, you need a large speaker enclosure and a large room.

You don’t have enough power to drive the speaker, at that low frequency. At higher frequencies less power is required, [impedance] and so what you need is a audio power amp. They come in chip form from a few watts to dozens of watts and the external circuits are minimum. The tone generator out put goes into the input of the amp, [and may need to be balanced?] the amp drives the proper impedance to the speaker. <p>A LM 386 or TDA 2002 should do?

If all your speaker is doing is clicking "in and out" at that low of a frequency, I'd bet a dollar to a donut that you're feeding it a square wave rather than a sine wave. All it'll do is "tick".<p>Dean

The audio amp you are using probably does not have a response that extends below 60 Hz due to coupling capacitors and an intentional design to reduce hum.

And let's not forget that your ear is MUCH less sensitive to 27 Hz than midband (500 Hz - 5 kHz or so) frequencies. Something like 60 dB less sensitive. So, for you to hear a 27 Hz tone, it will have to be a LOT louder than a 1 kHz tone.<p>Do a search on "Fletcher-Munson curves" if interested in learning more on this. For example:<p>Link to Fletcher-Munson Equal Loudness Contours explanation<p>Regards,
Todd

Also, your speaker probably has poor response that low. Therefore, it may only respond to the higher harmonics of a square wave input.