Inductor values for parallel drivers

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AndrewT

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Joined 2004
To get the LR filter to work as a single pole filter, the R part needs to be reasonably constant for a range of frequency either side of the intended crossover frequency.

If the driver goes from 75% of the 8ohms (say 6ohms) @ around 200Hz and has risen to 11ohms @ 1500Hz, then it will keep rising in the octave from 1500Hz to 3kHz.

The Inductor will only see the 11ohms at 1500Hz.

You should look at using a speaker Zobel to flatten the driver impedance around the crossover frequency.
The Inductor can attempt to create that single pole roll-off.
 
Inductor

Inductor

Member
Joined 2006
Mentioning the brand and model of the drivers (references) plus the frequencies and other details (like the type of enclosure/speaker) you are aiming at, will help members much better to help you with comments or links to similar layouts and applications. For many newbies it is desirable being more specific in post#1.
 
J

JRO2298

Member
Joined 2014
Inductor said:
Mentioning the brand and model of the drivers (references) plus the frequencies and other details (like the type of enclosure/speaker) you are aiming at, will help members much better to help you with comments or links to similar layouts and applications. For many newbies it is desirable being more specific in post#1.
Click to expand...

Sorry for not providing specifics. This is for an older pair of commercial speakers that I own and I prefer not to mention the brand. I am trying to tune out some peakiness around the XO frequency. If I can tame the problem with the current speaker, I may gain the confidence to take on a kit build. It's how I started all my DIY projects - take a product that I'm not afraid to break, try to improve it, learn the circuits, components and interactions and go from there. As I said - Newbie.

The current speaker uses paralleled SEAS P17REX crossed at 1500 Hz. I have isolated (by ear) the problem at SEAS drivers and want to make changes to the 1st order low pass filter.

I am trying to understand the inductor values - have no way to measure, but rather calculate, buy new coils and test. I don't mind a small amount of trial and error, but would like to come close.

Thanks to all for the responses.
 
S

sreten

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Joined 2003
Last edited:
J

JRO2298

Member
Joined 2014
I was able to borrow an LCR meter and now able to read 1.5 mH for the inductor, although I'm unable to calculate why this would result in 1500 Hz low pass filter for paralleled SEAS P17REX.

Going to try 1.6 and 1.8 values to see if I can tune out the peakiness I'm hearing. I'll also increase coil gauge from 18 to 14 and see how lower DCR impacts sonics. Will post results.

Thanks to all for the help.
 
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