John Stimson Wrote: > Skunk, full range speakers don't generally have a high-pass filter to > cut off the bass for the woofers. The mechanics of the woofer and the > enclosure do that naturally. It's better to have an electronic or pure > electrical (passive) crossover to do that. It gives you control and > knowledge of the exact frequency, slope, and tuning of the filter so > that you can match up with the high-pass filter on the subwoofer. > > It also eliminates wasted motion of the woofers in your main speakers. > Especially in a sealed enclosure the woofer still moves when excited by > the frequencies below the bass cutoff, but not enough to produce useful > sound. That's a potential source of distortion and/or wasted energy. > > Jon, the slope of the cutoff for a sealed box is 2nd order. The slope > for a ported box is 4th order. John,
You made the mistake of sounding authoritative in your knowledge of electronics, so now, Im afraid I must treat you as such. ;-) Below is my schematic for the active summing circuit. Can you please check it for me? I also have a couple of questions: 1. Is the OPA134 a good choice? Digi-Key has several varieties (OPA134UA-ND, OPA134UA/2K5-ND, OPA134PA-ND) 2. I included the capacitor and resistor in the circuit because I saw no harm in blocking DC voltage, UNLESS it will have an adverse effect on signal quality. Will it? Also, the page I borrowed most of this circuit from specified a cutoff frequency 7.4Hz based on a function that included capacitance and resistance as factors. Is there any advantage to increasing the value of the capacitor and decreasing the value of the resistor (or vice versa) to achieve the same cutoff frequency? 3. Are metal film resistors and polypropylene capacitors the best to use? 4. Will the voltage I apply to the OpAmp make a difference? (I think the specifications said 15V, nominal.) The Outlaw LFM-1 has a fourth-order low-pass filter, and my main speakers are vented, so I should have nicely matched slopes. Thanks again for your help! +-------------------------------------------------------------------+ |Filename: schematic.gif | |Download: http://forums.slimdevices.com/attachment.php?attachmentid=894| +-------------------------------------------------------------------+ -- jonheal Jon Heal says: Have a nice day! http://www.theheals.org/ ------------------------------------------------------------------------ jonheal's Profile: http://forums.slimdevices.com/member.php?userid=2133 View this thread: http://forums.slimdevices.com/showthread.php?t=20907 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/audiophiles
