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MG1.6 electrically-flat crossover, revision 3


MG1.6 electrically-flat crossover, revision 3

After listening to the revision 1 crossover for two days, and the revision 2 crossover for a week, I concluded that the revision 2 crossover had an emphasis in the midrange. I noted that if I plotted the sum of the magnitudes of the woofer and tweeter sections without considering phase, the sum had a 1dB rise in the midrange.

I designed a new resistor network that flattens both the complex sum of the woofer/tweeter sections, and the sum of the magnitudes of the woofer/tweeter sections. These are likely indicative of on-axis and room response respectively.

As before, I built the resistor network into a pair of DIY speaker cables. It requires no modifications to the stock crossover. I used 5%, 10W resistors.

The resulting electrical response is as follows (green=woofer, red=tweeter, dark blue=complex sum magnitude, yellow=complex sum phase, light blue=sum of magnitudes).

The effects of the new design are:

The speaker's output level is reduced by 3.5dB.

The woofer section's -3dB point is raised from 200Hz to 330Hz.

The tweeter section's -3dB point is lowered from 1.6KHz to 1.1KHz.

Both the complex sum of the woofer/tweeter sections, and the sum of the magnitudes of the woofer/tweeter sections, are flat to within 1dB. This is electrical response, not acoustic response. I left a slight dip in the midrange in order to avoid a dip in the bass.

The crossover frequency remains unchanged.

As for sound, the revision 3 crossover is inbetween the revision 2 crossover and the stock crossover. Vocals, pianos, and acoustic guitars are improved. I would characterize the sound as fairly neutral.

If you're looking for an upgrade, four resistors can make a big difference. Also, if you have a tube amp, you may want to halve the resistor values because your amp's output impedence is already having a similar effect on the MG1.6 crossover.

Mart, would you like a writeup for the tweaks page? (Give me a week to make sure I don't feel a need for revision 4).

Happy listening!

Ed





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Topic - MG1.6 electrically-flat crossover, revision 3 - EdG 19:41:08 03/24/02 (12)


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