The sub I've been using for quiet music I got cheap at Goodwill. It had an amp built in, but a proprietary wireless system, and I didn't know how to bypass it and hard wire the input, so I took it out and ended up replacing it with a huge 3rd order filter I calculated online and assembled, before I knew much about doing things the right way, to force a better response curve that extends much lower than the sub was designed for. It doesn't sound great, but it's not bad, it's just quiet, since most of the work it's been doing is below the tuning frequency, but it's sufficient when there's minimal other noise to compete with.
Anyway, this time around I have Vituix, and I was messing around to see if it's even possible to make a passive filter that can modify the curve without being so affected by the wild impedance curve of a ported sub. I arrived at this solution pictured below, which appears to force a steady impedance curve.
My question is: is this just plain stupid, or will it work? I don't yet have enough capacitors to try it. It looks like a big waste of power, so it may not be that good of an option for a portable speaker, but it should allow for much louder spl by compensating the response curve of an compact undersized low tuned sub.
Maybe there are more practical solutions, but with my limited knowledge I can't see why this isn't a reasonable choice among others. It's just a concept now, and I'll probably try it out if you don't think it's not going to work.
I was able to make a variety of curves, but this one looked clean while keeping the impedance form getting too low. Some would go low even when I didn't expect it to, even after putting an 8 ohm resistor after the capacitor (now between the two), which is how I got started on that path.
The original impedance curve came from a simulated enclosure tuned to 28hz
Anyway, this time around I have Vituix, and I was messing around to see if it's even possible to make a passive filter that can modify the curve without being so affected by the wild impedance curve of a ported sub. I arrived at this solution pictured below, which appears to force a steady impedance curve.
My question is: is this just plain stupid, or will it work? I don't yet have enough capacitors to try it. It looks like a big waste of power, so it may not be that good of an option for a portable speaker, but it should allow for much louder spl by compensating the response curve of an compact undersized low tuned sub.
Maybe there are more practical solutions, but with my limited knowledge I can't see why this isn't a reasonable choice among others. It's just a concept now, and I'll probably try it out if you don't think it's not going to work.
I was able to make a variety of curves, but this one looked clean while keeping the impedance form getting too low. Some would go low even when I didn't expect it to, even after putting an 8 ohm resistor after the capacitor (now between the two), which is how I got started on that path.
The original impedance curve came from a simulated enclosure tuned to 28hz
2mF and 5 mF capacitors are in series - they are equivalent of one 1.43 mF capacitor. 1 ohm resistor parallel to driver is mistake - it drops impedance level.
How about line-level low-pass RC filter? Much cheaper, better amplifier load too - just the driver.
How about line-level low-pass RC filter? Much cheaper, better amplifier load too - just the driver.
Thanks, I see that now. The 1 ohm resistor made a significant change in the right direction, but that's a lot more wasted power than I was thinking. I thought the resistor between the 2 capacitors changes how they respond, at least that's how it seemed when experimenting, but yes, removing one and changing the other to 1.43 does the same.
Yes, I've thought about a line level filter. Maybe my reason for shying away from it was how it may respond differently to different sources and amps. Anyway, this was an attempt to find a viable solution after the amp, something to store inside the speaker box.
Yes, I've thought about a line level filter. Maybe my reason for shying away from it was how it may respond differently to different sources and amps. Anyway, this was an attempt to find a viable solution after the amp, something to store inside the speaker box.
The impedance curve now seems of relatively little use with how this circuit seems to force a new impedance curve similar to when using the default flat "curve". but here it is.