| Electronics > Beginners |
| Tweeter bass blocker |
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| symbianas:
Hi, I want to add tweeter speaker to my car, it came with factory 15v 4.7uF inline capacitor crossover capacitor. When connected it seems that I still hear bass "squawking" sometimes. I would like to clarify: will increasing or reducing capacitor size make it speaker to ignore lower frequencies? If I change to 15uF it will get more lower frequencies than with 4.7uF? So it means I should try <4.7uF it would get less lower frequncies? Could it be volts which are bad? or maybe an old capacitor? radio is producing 4x15W so not that much. |
| Whales:
If the capacitor is wired in series with the speaker: lower capacitances will give you less bass. You will want to use non-polarised capacitors. Polarised capacitors (such as most electrolytics) can be made non-polarised by using two of them in a certain way, you can find details (including photos) on the web. |
| Zero999:
Two electrolytic capacitors of equal value, connected back-to-back will make a non-polarised capacitor of half the value. Yes, the capacitance needs to be reduced to cut the bass more. Don't remove the existing capacitor, just add another capacitor in series with it. The total capacitance of two capacitors in series can be calculated using the following formula: CTOTAL = (C1*C2)/(C1+C2) |
| themadhippy:
Assuming its a 8 ohm driver the capacitor is crossing over at around 4.2Khz,instead of moving the crossover point you could try making the cut off rate steeper by wiring an inductor in parallel with the tweeter. The back of a fag pack calculator says a value of around 0.30mH should do the trick. |
| Zero999:
--- Quote from: themadhippy on September 26, 2019, 11:05:22 am ---Assuming its a 8 ohm driver the capacitor is crossing over at around 4.2Khz,instead of moving the crossover point you could try making the cut off rate steeper by wiring an inductor in parallel with the tweeter. The back of a fag pack calculator says a value of around 0.30mH should do the trick. --- End quote --- If there is enough room in the speaker enclosure, then an air core coil will do. I threw in some figures into the calculator linked below. A 40mm former diameter, such as a toilet role tube. Inductance = 300µH Wire diameter of 0.63mm which is 22AWG. http://www.circuits.dk/calculator_single_layer_aircore.htm Results: 144 turns wound over a coil length of just under 91mm I confirmed the results with this calculator: https://m0ukd.com/calculators/air-cored-inductor-calculator/ It gave a wire length of 18.1m. The resistance 22 AWG wire is 52.96mΩ/m, so the ESR of the inductor will be just under an Ohm. The self-resonant frequency is 1.85MHz, which is nearly 100 times the audio bandwidth. https://en.wikipedia.org/wiki/American_wire_gauge Space can be saved with a multilayer coil. I just chose a single layer because it made the calculations easier. |
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