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Date: March 27, 2002 at 18:11:36
From: Jason U., [s0.net-lab1.dist.maricopa.edu]
Subject: Re: 3 way speaker system

URL: Electro's Realm


Some of you are a little off on what to pick for full-range loudspeakers. It is good to pick drivers that have good roll-off but the filter will change the effect of the roll-off. Using a higher order filter may give you good roll-off around -24 dB/octave but this depends the driver characteristics. Use compensation or zobel network for the woofer or midrange. The compensation network makes the woofer's impedance graph more flatter and makes it easier to get a more predictable response from the filter.

When picking for the crossover point, try to stay away at least an octave away from the FS. If you can't, try to use a higher order filter. It is hard to stay away for the midrange driver, so use a notch filter.

You can use mix order filters in any 2-way or 3-way design. Remember to measure the loudspeaker at differnt angles because of lobing problems.

Its not always best to use a 3-way in home theater systems because they are too large and more complex than 2-way. A 3-way loudspeaker is best to use when you have the volume at MAX all the time.

If you didn't construct a 2-way loudspeaker than you will have a hard time making a very good 3-way loudspeaker. I suggest you make a 2-way loudspeaker for starters.

Using an 8 inch or 7 inch woofer will work in a 2-way loudspeaker only if the tweeter can go as low as 1500 to 2500 hertz. At these frequencies the distortion will rise at the crossover point. It is best to use a 6.5 inch woofer in a 2-way loudspeaker. This way you can pick 3000 or 3500 hertz for your crossover point and have lower distortion.

Specs to look at when selecting either woofer, midrange, and tweeter are low Lvc (<1mH) , an Fs that is higher or lower than the cut off point, low Qms for less delays, SPL, and frequency response.

Positioning the midrange and the tweeter so they are align with the woofer's voice coil will give more control on the delays. This can be hard for the builder if he or she doesn't have good wood working skills.

Putting an enclosure around the midrange and tweeter makes it so that those speaker drivers doesn't act more like a passive radiator.


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