This all started for me last summer when an AK pal
@nedseg finally convinced me to replace the LF drivers in my speakers (he has the same exact model JBL I do and also has owned them since new) with a true modern day driver out of the
JBL 4367 in fact. They were a "perfect fit" for the L200' from a physical size bolt pattern way and to a cab volume/port size diameter and length the size similarity between the L200 and 4367 was really close.. Anyway it all worked way better than either of us could have dreamed!
But the 2216Nd1 was not fully happy with the existing passive crossover in the L200. That was when I decided to biamp using at the time the MiniDSP 2x4HD. The results were pretty outstanding, especially for the LF driver which was finally not being veiled by the old passive crossover anymore. I was able with some PEQ manipulation, get the frequency response down th 24hz and flat (+/- 4db to 20khz)..
After the MiniDSP 2x4 was added I ran them for months, with just the MF and HF playing off the same amp with the passive xovers in place. But then I decided to switch over to 3 separate amps (triamp) and that required a new DSP. I went with the MiniDSP 4x10HD although there are a few others in my price range I could have gone with, I knew more about the MiniDSP interface, so was a bit more familiar to me from my experience with the 2x4HD.
One thing that is vital important for triamping and eliminating passive crossovers without destroying a driver or drivers by sending it the wrong frequency is a good way to ID speaker cables so a mixup is much less likely.. Here is how I did it: Using heat shrink in different colors is probably the best way although electric phasing tape in different colors would work too. All cables are marked the same on each end. In the picture, the blue shrink tube closest to the end indicates which amplifier goes to which driver, and the red and green indicates left and right speaker. In my case blue means the mid range. I have green as the HF, and black as the LF with the same red and green for left/right speakers.
Then of course the same level of vigilance is needed to make damn sure the RCA cables (in my case) were coming from the correct output on the DSP to the correct amp it is meant to go to. But that is a lot easier than speaker cables as in my case the MiniDSP is right there within a few feet of the 3 amplifiers.
Then the passive crossover is taken out of the system and protection caps should be installed.. I found help in a JBL chart and from a helpful member here as to which size is needed to protect the driver from harm, without filtering out the normal lower frequencies that is within the drivers range.. In my case these caps were used based on driver inpedence, and frequency. A 50uf on the mid range compression driver filters somewhere down around 1000hz which is just below my planned crossover point. The 6uf cap is for the tweeter. The resistors go parallel across the driver to shunt a reactive component (as JBL describes it).
Then once the caps and resistors were in place, it was time to set up the crossovers in the DSP. This is done with all amps switched off! Before that can be accomplished, the routing (which input goes to which outputs) has to be set up.
In this case I used Analog in Right channel to have its outputs connected to output 1 (LF) output 3 (MF) and output 5 (HF). And out 2, 4, and 6 are the corresponding lleft channel outputs for LF, MF, And HF.
Now to the crossovers.. This clip shows the LF crossover for channel 1 which is the Right side showing the cut off frequencies for high pass and low pass. The "link enabled" box is checked so all settings are linked and copied to channel 2 (Left side LF driver)
This is done for each driver, with the HF having its low pass filter disabled.
Once the crossovers are set up, and everything is triple checked for being hooked up correctly, its time to switch on the amplifiers and rough set their outputs if your amps have them, or the outputs can be set within the DSP if they don't. The way to do this is with a calibrated mic at the listening position.
Then using software and the mic (I use REW) set the output level of the input to the DSP such that it is within the range of the calibrated mic so that REW can make a good distortion free frequency sweep from 20 to 20,000 (since my speakers are full range). Then by using the PEQ,s you can manually set them to better flatten the frequency response, or let REW come up with PEQ's for you. If you let REW do the PEQ's it will be a good start but likely you will want to do more manually at that point by editing one, run the sweep, see if it helped.. IOW, trial and error..
I am still not quite finished but here is my latest FR curve showing +/- 5db from 23hz to 20khz. The good news is I don't have to try to sneak a pair of subs past the wife into the living room! These speakers are now capable, thanks to the new woofers of frequencies well into what is considered sub range!
