DizRotus Posted April 22, 2015 Share Posted April 22, 2015 (edited) Can anyone help me understand how they work, as well as the similarities and the differences? The Internet is awash with notch filters to tame the harshness of Fostex FE103 drivers in single driver enclosures. I understand the need and the goal, but I don't understand how they work. Frequently an inductor, a capacitor and a resistor are wired together in parallel and then wired in series in the positive lead to the driver. While I understand the function of each component, I don't understand how it works in that parallel then series configuration. Some electrons go through each component before reuniting at the driver terminal. How can such a device target a specific frequency range to tame harshness? It reminds me of the joke about how a Thermos can keep hot things hot and cold things cold. "How does it know?" Edited April 22, 2015 by DizRotus Quote Link to comment Share on other sites More sharing options...
cradeldorf Posted April 22, 2015 Share Posted April 22, 2015 (edited) A zobel will keep the resistance "level" throughout the spectrum, as far as a notch filter I never got that far. Do you belong to the DIY audio forum?, that is where the fostex people are. Edited April 22, 2015 by cradeldorf Quote Link to comment Share on other sites More sharing options...
djk Posted April 22, 2015 Share Posted April 22, 2015 An inductor and a capacitor in parallel have an impedance that goes very high at their resonant frequency. The resistor in parallel passes full-range signal. An inductor and a capacitor in series have an impedance that goes very low at their resonant frequency. The parallel combination is used in series with the driver to reduce power at its resonant frequency. The series combination is used in parallel with the driver to reduce power at its resonant frequency (there had better be some resistance in the circuit ahead of this or the impedance can drop to virtuall zero ohms at resonance). The first is usually used to put a broad dip in the midrange, the second to flatten impedance peaks in horns. 1 Quote Link to comment Share on other sites More sharing options...
DizRotus Posted April 22, 2015 Author Share Posted April 22, 2015 (edited) Thank you both.Dennis-I was hoping you'd shed some light on this.Cradledorf-I belong to DIY forums, and have searched and read the topic, but this forum is more active and I know and respect the opinions more. Edited April 22, 2015 by DizRotus 1 Quote Link to comment Share on other sites More sharing options...
pzannucci Posted April 22, 2015 Share Posted April 22, 2015 Another good reason to use a zobel is that it flattens the impedance so that a passive crossover can be designed more closely to text book to work correctly and provide better crossover slopes. If you look at the typical crossover tied to the driver without the zobel, the rising impedance of the driver, especially woofers, will negate the crossover function giving unexpected results. That causes a crossover builder pain in the crossover design and makes it harder to have a predictable impedance going back to the amp at the crossover point. This is why when you look at a Klipsch crossover, you can't really figure out based on normal formulas where the crossover point is (no impedance management - deemed bad and power robbing by many). Much will be trial and error along with the subsequent voicing. The parallel or series notch filters are used for taming impedance or response peaks. Good information here http://www.diyaudioandvideo.com/Calculator/SeriesNotch/ Pretend the driver is a resistor and then read up on capacitive and inductive reactance. Then substitute the driver's impedance (variable resistance at frequency) and you closer. Quote Link to comment Share on other sites More sharing options...
DizRotus Posted April 23, 2015 Author Share Posted April 23, 2015 Does anyone know the values of the components in the notch filter used in the now discontinued Tekton 4.1? Quote Link to comment Share on other sites More sharing options...
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