Hi,I'm planning to build an audio amplifier and for the crossover, I've been looking in to using resistors instead of inductors?I know what each one does. Simply put resistors do not hold an electrical charge like inductors in an electromagnetic field.What is the role of the inductor in this circuit? I'm not asking for the definition, I'm asking what it's doing to the actual audio signal.Also I've put a capacitor in series for the top frequency and after trying it out with different caps, the audio gets distorted in the speaker component (the cone moves to its maximum rating). Am I right in saying that I'd need a bigger speaker, well a bigger speaker cone in fact, to increase the rating of volume and power of the signal to reduce distortion/noise?Thanks,Rish
Perhaps your concepts of capacitors and inductors need to be ascertained. Resistors cannot replace inductors or capacitors. In such a case, why would one have inductors and capacitors in the first place. And as was told in another answer, resistors have more or less same resistance or impedance at all audio frequencies capacitors have impedance inversely proportional to frequency and inductors have impedance directly proportional to frequency. A 100mH might mean a reactance of just 31.4 ohm at 50 Hz but its reactance is 314 ohms at 500 Hz, and 3.14k ohms at 5kHz. Such a variation is essential to shape the spectrum as is done in cross over networks. See what happens when this inductance is in series with a resistance of 314 ohms. And inductors alone will not do. It will be like attempting to walk in frictionless floor. You need a resistor, as in this case, 314 ohms. So we use RL combinations for cross over networks. Trying is something you can do. If successful let everybody know. But according to theory this is just not possible and attempts may be termed as waste of time and effort. But remember failures are path to success. The failures will enable you to remember the results much better just as a child may recall when it hurt itself by touching the burning end of an incense stick!!
Best to get building instructions (radio shack used to have books on this). I changed my home theater to all 4 ohms to get the full spectrum as I like at moderate listening levels. 8 ohm speakers have to be driven hard to sound right in my opinion. Using a crossover I salvaged from a passive subwoofer (with a dual magnet speaker so I got two separate crossovers, they were 8 ohm design) by using 4 ohm 10 subs I got a crossover of 115 Hz. that's about where my 6 1/2 mid woofers go down to without crossover, and I found some really cheep tweeters from China that I double up on because you have to take in mind high freqs don't travel well but these tweeter were high enough that they don't double up with the mid woofers which would create too brilliant a sound. Car speakers at 4 ohms work great but watch for overheating the reciever/amp. My new amp has no problem handling 4 ohm. When using two tweeters keep them vertically in line for clear separation. I added cooling fan (computer case fan) in old amp.
capacitor resistor combinations are used as high and low pass filters networks, to shape a frequency response i;e you may want sounds up to 50hz amplified 200 times whereas above that you may want to attenuate them as higher sounds are obtuse to the human ear, so in an op amp circuit using a 10k going into a 2.2meg feedback resistor would achieve a theoretical gain of about 220, putting a 1.5 nfd capacitor in conjunction with a 220k resistor above the feedback, could be used to achieve this cut off point and reduce the gain at higher frequencies. be advised that the Xc of the capacitor used would reduce the overall gain down to 155 from the calculated 220 when ac is passed through an inductor the output voltage leads the current by up to 90 dergees, whereas a capacitor has the exact opposite effect. inductors are used in a parallel resonance circuit to produce a very high gain over a narrow bandwidth, it would be useful to see a circuit diagram LC circuit - Wikipedia, the free encyclopedia
