Hello,
I've a pair of replica JBL 4345 which I've been 4-way actively bi-amping with the DEQX Pre-8.
I'd like to add 2 subwoofers to the mix, and that means I'll have to free up 2 of the 8 channels from the Pre-8.
My idea is to make a passive crossover for the horn (JBL LE 85, 8 Ohm) and tweeter (JBL 077, 8 Ohm), and then run them off of 1 amplifier.
Trouble is I don't have any experience with such activities, so I hope someone here can teach me a thing or two to get started.
What I think I know so far is as follows:
From the JBL 4345 manual they state that the crossover frequency from the horn to the tweeter is at 10kHz, 18dB per octave.
I understand that there are different types of crossovers from 1st to 6th order? They have different names along the way?
After reading around a bit I gather that my crossover needs to be a 3rd order (Due to the 18dB?)
Then I used the link below to calculate what I think is correct:
https://www.diyaudioandvideo.com/Calculator/SpeakerCrossover/
And the result is as follows:
In the calculator I had 2 options for a 3rd order, Butterworth and Bessel, what are the differences between these? Which would suit my case the best?
Am I on the right track here? Or is there something I should know about?
How important are the values? Is it okay to be a bit over or under, in case I can't find a capacitor or inductor with the exact value stated?
I hope someone will enlighten me a bit and maybe give some tips if possible.
Best regards,
NavnFugl
I've a pair of replica JBL 4345 which I've been 4-way actively bi-amping with the DEQX Pre-8.
I'd like to add 2 subwoofers to the mix, and that means I'll have to free up 2 of the 8 channels from the Pre-8.
My idea is to make a passive crossover for the horn (JBL LE 85, 8 Ohm) and tweeter (JBL 077, 8 Ohm), and then run them off of 1 amplifier.
Trouble is I don't have any experience with such activities, so I hope someone here can teach me a thing or two to get started.
What I think I know so far is as follows:
From the JBL 4345 manual they state that the crossover frequency from the horn to the tweeter is at 10kHz, 18dB per octave.
I understand that there are different types of crossovers from 1st to 6th order? They have different names along the way?
After reading around a bit I gather that my crossover needs to be a 3rd order (Due to the 18dB?)
Then I used the link below to calculate what I think is correct:
https://www.diyaudioandvideo.com/Calculator/SpeakerCrossover/
And the result is as follows:
In the calculator I had 2 options for a 3rd order, Butterworth and Bessel, what are the differences between these? Which would suit my case the best?
Am I on the right track here? Or is there something I should know about?
How important are the values? Is it okay to be a bit over or under, in case I can't find a capacitor or inductor with the exact value stated?
I hope someone will enlighten me a bit and maybe give some tips if possible.
Best regards,
NavnFugl
Well that has the midrange and woofer on it as well, which in my case isn't needed. Can't I get away with making a more simple design for just the horn and tweeter?
Sure just use the legs for the 2 drivers. You want the lowpass on the mid and the crossover on the tweeter. That's charge coupled network which you can simplify buy using single capacitor values. To convert C1XC2/C1+C2 same as parallel resistor values. So paired 2uf becomes a single 1uf. That 077 is really about a 10 ohm driver.
Rob 🙂
Rob 🙂