Could do it line-level, as well...
Parts-Express.com:FMOD Crossover Pair 50 Hz High Pass | rca PA ir high pass fmods fmod f mod Crossovers air active crossover
Parts-Express.com:FMOD Crossover Pair 50 Hz High Pass | rca PA ir high pass fmods fmod f mod Crossovers air active crossover
How is this calculated?
Like a normal filter. You just use the input impedance instead of the speaker impedance.
It's also called a PLLXO.
How is this calculated?
by much maths! see attached. The formula at the end is probobly the only bit of interest but I felt like showing why this works. Disadvantage of first order filters are there very slow roll off (-6dB/octave).
higher order filters must be constructed out of inductors and capacitors to be practical or be at line level.
Attachments
a capacitor at speaker level can increase excursion though interaction with impedance peak(s) - - -do it line level
I cant go that way, I have to go speaker level.
Can you explain that interaction simply?
by much maths! see attached. The formula at the end is probobly the only bit of interest but I felt like showing why this works. Disadvantage of first order filters are there very slow roll off (-6dB/octave).
higher order filters must be constructed out of inductors and capacitors to be practical or be at line level.
So i just have to use the same calculator that can be found for a first order filter to find the capacitor value, right?
-6dB/octave is exactly what I want.
By the way I have tried it with 1000uF and this does a wonderfull job. I will try diffenrent values to find the best value. But I think Im pretty close of my goal.
cap at speaker will work in some instances - but not all - here's a little horn with lower resonance 6" speaker and 36uF highpass - with just the cap it was trying to play bass way below its cutoff (imageshack lost my impedance graphs) and distorting badly - adding a impedance compensation network made it behave correctly
here's a sealed box woofer - look at the effect of a 500uF cap in series and
also look at the impedance curves - where the boost occurs in this case is from a lower impedance in that area with the cap
-the box is now a 3rd order sealed box with the 500uF cap
An externally hosted image should be here but it was not working when we last tested it.
here's a sealed box woofer - look at the effect of a 500uF cap in series and
also look at the impedance curves - where the boost occurs in this case is from a lower impedance in that area with the cap
-the box is now a 3rd order sealed box with the 500uF cap
An externally hosted image should be here but it was not working when we last tested it.
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yes that is a problem speakers arn't actualy resistive but you can easily make an |impedance|/frequancy plot using a multimeter, signal gen and resistor. Infact if you made a phase plot aswell you should be able to completly describe the speakers electrical transfer function.
I just put a 1000uF capacitor on the + lead on each channel, that right?
No. Get 2 caps each 1000uF. Connect their negative terminals together, then wire the amp red wire to one side and the speaker red wire to the other side, connect the amp black wire as normal direct to the speaker.
Repeat for the other channel.
No. Get 2 caps each 1000uF. Connect their negative terminals together, then wire the amp red wire to one side and the speaker red wire to the other side, connect the amp black wire as normal direct to the speaker.
Repeat for the other channel.
Ok i will try this. What is the reason to connect them like this instead of just one?
Thanks
electrolytic caps wired back to back as "non-polar" are usable with AC
Actually they are connected single and it seem to work fine?
It will until you turn it up, then the cap will literally explode, making a loud bang, firing the cap into the ceiling like a bullet and spraying electrolyte slime all over the place. I've only ever seen this happen with a 100uF cap, would not like to see a 1000uF cap do it at all!
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