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Re: MMG OWNERS ,PREPARE TO BE AMAZED : APOGEE CALIPER CROSSOVER ADAPTED TO MMG

Posted by lne937s (A) on March 12, 2007 at 15:49:41

In Reply to: MMG OWNERS ,PREPARE TO BE AMAZED : APOGEE CALIPER CROSSOVER ADAPTED TO MMG posted by Jacques T on March 9, 2007 at 22:28:52:

On your crossover, a couple of things...

Firstly, the woofer panel is a little over 5 ohms impedance and the Tweeter is ~3.8-4 ohms. These speakers are not the same as Apogees. Your crossover calculations are not accurate. That doesn't mean that everything follows exact calculations, but rather that your justification is incorrect.

Now, I think you are kind of on the right track. After testing different values, I ended up with:

30uF on high pass
2.5mH on lowpass inductor
33uF on lowpass shunt

The lowpass approximates a Bessel filter (using a low DCR inductor like Erse). I found the 30uF to sound better than lower crossover points. Your highpass is lowering and your low pass is rising. This may look better in simulations, but most simulators are based on flat frequency response from the drivers- the dip you see in a simulation wouldsimply attunates a rise in output at the crossover frequency in the tweeter section. I think if you do some measurements, you will see a rise in the midrange output(not flat).

Lowering the crossover point of the second generation has a number of benefits due to broader dispersion in the midrange and the ability of the 8 trace tweeter (essentially the same as the MG 12) to handle it. However, by raising the frequency of the lowpass, you will increase the overlap of the drivers, not only increasing output, but also increasing interactions, cancellations, and resonances on the diaphragm caused by two drivers playing the same frequencies on the same diaphragm that are not in a phase aligned crossover topology.

Please see the frequency response of the 1st gen MMG here:

http://www.enjoythemusic.com/magazine/viewpoint/1199/donibbles.htm

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