Building a LPF/crossover

[bezz]

I don't think that a filter being active or passive accurately reflects the quality of the output signal. If one is designed and suited better to the application than the other, then it will sound better. However, both can be used to perform the same task, and I'd recommend going down the active route using op amps, due to the reasons I mentioned above. A good starting point to get a better overview would be these wiki articles:
Active filter - Wikipedia, the free encyclopedia
Sallen?Key topology - Wikipedia, the free encyclopedia

 

[bezz]

You think?
I figure since this new sub I'm getting is an actual subwoofer, as opposed to full range 12s that I already have it will be able to give a better bottom end kick, and for the $20-30 that it will cost me to set up and get running it can't hurt to give it a shot.
Plans down the track are for 1 or 2 15" powered subs, but as I said before I just can't justify that cost just yet

lol reminds me of the time i used a 10" dse sub with built in 150w rms amp with a couple of mackies at a birthday party. Due to the sheer volume of the mackies you couldnt hear the dse sub distorting so much.. actually didnt sound too bad! Of course it was no substitute for using 1 or 2 of those mackie bass bins instead....

 

[Philthy]

I don't think that a filter being active or passive accurately reflects the quality of the output signal. If one is designed and suited better to the application than the other, then it will sound better. However, both can be used to perform the same task, and I'd recommend going down the active route using op amps, due to the reasons I mentioned above. A good starting point to get a better overview would be these wiki articles:
Active filter - Wikipedia, the free encyclopedia
Sallen?Key topology - Wikipedia, the free encyclopedia

Hmm...so where can I get op amps from? It seems that might be an expensive way to go about getting a free system upgrade.
I assume active filters can be used post-amp as well?

 

[bezz]

Hmm...so where can I get op amps from? It seems that might be an expensive way to go about getting a free system upgrade.
I assume active filters can be used post-amp as well?

you might be right.. not sure on how much an op amp would be that would handle that much power. I know that low power op amps can be as cheap as a dollar or two. I'm guessing increasing the power handling will probably increase the price at the same rate. You might have the same problems with the other components too. I'm not too sure as this isn't really my area of expertise

try Farnell Australia | Australia

 

[Slippy_Trippy]

Didn't realise your current 12's weren't subs, my bad. Yeah should get you a little more low end but if you are outside of in a big room it will leave alot to be desired.

Op-Amps are easily available from Jaycar or online (DSE are cutting down their component range and are therefore useless

Schematics and how to read them for crossover networks are also easily found with a quick good. Could be good to do a quick read on crossovers (not what they do as you clearly know that, but more how the work and the different kinds)

-Slippy

 

[theSeekerr]

ESP Projects Pages - DIY Audio and Electronics - Crossovers and Effects - One of the best resources around on active filters.

No, you can't do active filters post-amp, they simply don't work that way - they ARE amplifiers, just typically unity gain (that is, they don't make things louder).

As to building passive filters - um, don't, if at all possible. Inductors with that kind of power rating are very, very expensive, and decent capacitors that size aren't particularly cheap either.

If you do decide to work your way up to an active filter, the opamp you want from Jaycar is an OPA2134PA - considered "ordinary" by audiophiles, but an excellent opamp to everyone outside the golden-ear brigade. It's certainly the best opamp Jaycar sell, and it will cost you something like $7.

 

[Philthy]

Thanks for that Seeker, I'm finishing up exams today so I'll have time this week to head down to Jaycar and start getting this all sorted out