Hi everyone, I've been reading this site for a little while now, but this will be my first post. I'm pretty new to speaker building, but I'm really enjoying it!
I've built some small bookshelf speakers with the 3" Fostex FE83En drivers. I want to put in a zobel network on the speakers. I was planning on using a 7.5 Ohm 10W Resistor and a 0.33uF 250V Polypropylene Capacitor. Does that right? or did I totally mess up the calculations?
Thanks, for your help.
I've built some small bookshelf speakers with the 3" Fostex FE83En drivers. I want to put in a zobel network on the speakers. I was planning on using a 7.5 Ohm 10W Resistor and a 0.33uF 250V Polypropylene Capacitor. Does that right? or did I totally mess up the calculations?
Thanks, for your help.
Are you driving the speaker through some sort of passive filter/crossover or just directly connected to the amplifier ? If it's just direct then a zobel network will make no difference to the response as it's purpose is to flatten the impedance curve seen by a passive crossover/network.
(Edit: to be thorough, this is only true if the amplifier has a low output impedance, as in the case of nearly all solid state amplifiers, if you're using a valve amp with an output impedance as high as several ohms, there will be a difference)
In any case I find calculations for zobel networks based on the DC resistance and nominal inductance figures of the driver are only approximate, as the inductance is not a "pure" inductance due to the solenoid and motional effects of the driver. It's always best to fine tune the values by actually measuring the resulting impedance curve of the driver and zobel together.
(Edit: to be thorough, this is only true if the amplifier has a low output impedance, as in the case of nearly all solid state amplifiers, if you're using a valve amp with an output impedance as high as several ohms, there will be a difference)
In any case I find calculations for zobel networks based on the DC resistance and nominal inductance figures of the driver are only approximate, as the inductance is not a "pure" inductance due to the solenoid and motional effects of the driver. It's always best to fine tune the values by actually measuring the resulting impedance curve of the driver and zobel together.
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A series notch filter will also dampen the Resonance peak in impedance
but you would need an impedance graph of your driver in open air.
Notch filter are of three types
1.Series
2. parallel
3. Band stop
bandstop is used on Frequency response but can also kill the surrounding frequency of your peak if not designed properly
parallel is hard and very variable even after calculator and need a good component(it is a series filter with parallel filter)
Series notch is used to correct impedance peak, much better and stable, least expensive and also correct phase.
I have done Zobel and series notch in Knowles RAF driver for in ear monitor and it nailed the response
Sound less grainy
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