|28th October 2012, 05:35 AM||#31|
Join Date: Jul 2008
Two issues: Power vs bandwidth (i.e. audio spectrum) of audio amplifier
Power: If there is no electricity, battery operated audio system normally requires low voltage and high power output , the impedance of speaker is very low (e.g. 1-ohm) in comparing to home HiFi audio system (4 or 8 ohm). Typical examples are audio system for transportation such as car, boat, airplane or railway without electricity. Please visit Perry’s website, he does a good job to explain it. But, I don’t understand why impedance of headphone is designed at so high impedance such as 16-ohm to 600-ohm?
Bandwidth: It must widely cover the human audile frequency from 20Hz to 20Khz
For direct coupling audio amplifier, the bandwidth is limited by the transistor, usually above Mhz at unity voltage gain. For power amplifier with voltage gain normally less than 20, the bandwidth is at several hundred Hz which is far above the human audile frequency at 20Khz.
For capacitive coupling amplifier, the bandwidth is limited by the analog filter. In my experience, I use a “Quantitative and Qualitative” approach to design analog filter.
Quantitative approach is to calculate the cut-off frequency of analog filter which must widely cover human audile frequency. Once cut-off frequency is determined, there are many combinations to meet same cut-off frequency of a typical RC filter (i.e. f = [R1,C1], [R2,C2], etc…) Beside, one capacitor can be replaced by several capacitors in parallel at same capacitance value. It causes sound difference due to different charging and discharging rate of capacitor. For this reason, it is hardly to predict the sound quality by theory (i.e. mathematical calculation). Qualitative approach is done by practical listening test to select RC value at different scenario to get the best sound quality.
"To work smarter, but not to work harder." by alant4321
|28th October 2012, 08:29 AM||#33|
Join Date: Jun 2012
A 12 volt 2 amp power source will not work !!!!!
Buy a cap will do nothing to help you at all !!!!!
The amp draws current the more you turn the volume up the more current it will draw...
A car amp will draw more then 2 amps of current ...
Im not sure if you playing games here to get people going or you do not have the knowlegde ..
Not trying to be mean at all Theese people are here to help you out not to give u the wrong info ..
If you hook this up to a 12volt 2 amp supply you are likely to cause a fire ..
Ask the people on here they have many years of knowledge about this kind of stuff..
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