Hi,
im speakers for my phone i need some help
its a dual stage amplifier circuit using a TL071, to form an active low pass filter with an upper cut-off frequency of between 18 and 25 kHz with and gain matched to the output for my phone, and an OPA551 current amplifier with unity gain.
I checked the datasheet for the OPA551 and found Max current out is 200mA
Speaker impedance is 8 ohms
i loaded a continuous tone on my phone and measured,
Max volume = pk-pk 2.68V
Medium volume = pk-pk 100mV
Low volume = pk-pk 10.30mV
how will i work out the gain? i tried this
200mA x 8 = 1.6V
max volume gain = 20xlog(1.6/2.68) = negative 4.4dB
im not sure if this is right
and then on medium and low i did the same thing and got 24dB and 43dB