Reading on from post ................
This is a new thread dedicated to a DIY Passive Crossover for the M2 DIY clone
Its a lead in starter for anyone planning an M2 clone or those wishing to simplify from an active to a passive set up.
This is not a completing alternative to the DSP crossover specified by JBL.
I will continue to post some measurement as a means of zeroing in on the passive crossover network.
Today I measured the 2430 driver on the M2 horn withe the voice coils wired in parallel.
The acoustic response is compared to the 2216dn in a grouped screen shot.
The test conditions are identical to my previous measurements:
The DBFS reference test level for the REW Analyster was set at 75db.
Distance = D = 1 metre
Notes:
The purpose of today’s measurements was to ascertain the difference in sensitivity of the parallel wiring of the 2430 driver voice coils.
Based the the curves below the 2430 driver with its voice coils wired in parallel is between 10-12 db more sensitive than the 2216nd.
Back in post 859 of the M2 diy thread l noted with the 2430 driver voice coils wired in series (32 ohms ac impedance) the 2216nd woofer was about 5 db less sensitive.
So what’s the deal?
There are advantages and disadvantages with wiring the voice coils either way. In a dsp scenario there will be 6 db less noise due to the lower driver sensitivity.
In a passive crossover the additional sensitivity of the 2430 can be used to an advantage in the passive network for matching the sensitivity to the 2216nd woofer after normalising the 2430 response.
For example when using dual 2216nd woofers.
The down size is that the lower driver impedance can present a lower load impedance to the power amp at high frequencies unless care is taken.
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