I have an amp 200W.@4ohms with a sensitivity of 1V,
with feedback resistor values of 27K and 1K , there by making the gain of 28...which is fine but when I connect the amp to speakers I hear a hiss if I go very near to the speakers , can this be avoided if I use lower value resistors say 10K and 370ohms or 5.6K and 207ohms?
I understand that power dissipation can and will be a issue ? What's the way to eliminate this hiss and this only happens when the amp is connected to my PC.
with feedback resistor values of 27K and 1K , there by making the gain of 28...which is fine but when I connect the amp to speakers I hear a hiss if I go very near to the speakers , can this be avoided if I use lower value resistors say 10K and 370ohms or 5.6K and 207ohms?
I understand that power dissipation can and will be a issue ? What's the way to eliminate this hiss and this only happens when the amp is connected to my PC.
If the hiss is gone when shorting plugs are inserted into the amplifier's inputs,
then the noise is not from the feedback resistors.
then the noise is not from the feedback resistors.
With a feedback divider impedance <1kOhms there is not much you can improve in real life.
Standard PC soundcards are generally good quality and reasonably low noise (i.e. including the hiss) but cheapest possible Laptop and PC types are often low grade - only for voice and general audio reproduction as defined by the on-board audio output chip and the DAC circuitry driving it. In other words, don't expect high quality audio from budget grade program sources or mis-matched impedance ones either.
It may be that you can add say, a PCI sound card from another PC to compare the quality with your existing soundcard or buy a good quality replacement type soundcard that you can install yourself. First though, I would check that your present system is comparable to others and working correctly by (for example) asking a friend to use the amp with their PC audio source or just compare the amount of hiss from any other, decent quality audio source available .
It may be that you can add say, a PCI sound card from another PC to compare the quality with your existing soundcard or buy a good quality replacement type soundcard that you can install yourself. First though, I would check that your present system is comparable to others and working correctly by (for example) asking a friend to use the amp with their PC audio source or just compare the amount of hiss from any other, decent quality audio source available .
What on earth gave you the idea that the feedback resistors would be the cause?
Didn't this ring any bells in your mind?