Active vs. Passive Crossovers...

[Sp00ner]

So, I really need to do something with my subs. My amp is supposed to have a low-pass filter... I think... but if so, it sure seems like it could use more. Is it worth the extra cash to get an active crossover of some sort, or just go with a cheaper passive crossover? I really don't know how far I want to go with the stereo, I don't think I wanna get all crazy with it, maybe just replace the stock speakers and stock amp, and the VERY most...

[Watts-Up]

I like active x-overs better 'cause they are adjustable (usually), and passive actually rob a ltttle bit of power from the amp. The built in x-overs on amps are usually always good enough for subwoofers, you just need a low pass really, but if you are running a ported enclosure it is good to use a subsonic filter (high pass set at the frequency where the ports are tuned to), because any bass lower than the frequency at which the ports are tuned will cause the woofers to unload (loose control and distort).

If you do want a good cross-over, check out Audio control, they are the best! But IMO, a good quality amp like fosgate will usually always have a good enough cross over for built in. :http://www.mobileaudiocontrol.com/

[Pierre]

Originally Posted by Watts-Up

I like active x-overs better 'cause they are adjustable (usually), and passive actually rob a ltttle bit of power from the amp. The built in x-overs on amps are usually always good enough for subwoofers, you just need a low pass really, but if you are running a ported enclosure it is good to use a subsonic filter (high pass set at the frequency where the ports are tuned to), because any bass lower than the frequency at which the ports are tuned will cause the woofers to unload (loose control and distort).

If you do want a good cross-over, check out Audio control, they are the best! But IMO, a good quality amp like fosgate will usually always have a good enough cross over for built in. :http://www.mobileaudiocontrol.com/

+1 on that Watts.

Also the parts for a passive low pass to a woofer below say 300 Hz get large and expensive in a hurry.

Pierre

Pierre

[sidejam]

If you're lucky, your amp might have an adjustable active low pass filter. If you're looking to keep a simple system, I'd recommend a 4-channel amp with built in high/low pass adjustable crossovers. This keeps the number of components and the wiring to a minimum.

Either way, active crossovers are generally better. Most electronic crossovers are usually second order or third order (6 decibels per order). If you just put a coil with a passive system, you'll only get a first order filter. To get a second order passive filter, you'll need a coil and a capacitor. Another disadvantage with passive systems is that with every order, you introduce a 90 degree phase shift. Ummm... I'm starting to babble. Go electronic, it's easier to use and adjust.

[Sp00ner]

http://www.crutchfield.com/S-IICeA8Q...&display=L#Tab

Any good?

[sidejam]

Looks nice to me! But... it does have 3 pairs of outputs. So unless you're going with an amp that uses a pair of channels for the fronts, a pair of channels for the rears, and another set for the sub, it's a bit overkill. How many amps or how many speakers are going to have amplifiers on them? 2 channels for the subs and another 4 channel amp for the main speakers?

If it's just an amp for the subs and you don't need the "bass boost" knob, I'm sure this one would be fine:
http://www.crutchfield.com/S-eEGUDhm...603KX2&g=82600

But an amp like these would keep the wiring down to a minimum and offer plenty of control for the subs and mid/highs:
http://www.crutchfield.com/S-eEGUDhm...0&I=500MRPF250
http://www.crutchfield.com/S-eEGUDhm...0&I=500MRPF450
http://www.crutchfield.com/S-eEGUDhm...20&I=206ZX3504
http://www.crutchfield.com/S-eEGUDhm...0&I=218RSD5004

Personally, I love Phoneix Gold products and by experience, Alpine also has really nice stuff. All those amps have built in adjustable crosovers that would make it easy and quick to tune your subs and main speakers.

[sidejam]

BTW, what kind of amp do you have now?

[Watts-Up]

Do you have passive boxs for the component set? Usually a 3 way if for running a totally active system, which means you will need an amp with 2 additional channels just for the tweeters. If you get an amp for the mids with a nice pass thru x-over, then you can use that low pass out too. If you combine 2 x-overs in series, it doubles the slope/order of the x-overs. So say you have a 12 dB per octave (2nd order) on one x-over, and run it through another 12 dB per octave, then you will end up with a 24 dB per octave (4th order)

[Sp00ner]

I gotta do some more poking around with the current setup... I can't find any adjustment for low pass, and there's a diagram on the bottom that seems to indicate two ways of bridging the outputs, and one way would create a low pass output... but I'm not really sure.

The amp is a Punch 100x2 Transana... the rest of the details are on the bottom of the amp..

[LSJ PUP]

That crossover should be fine for you. I have a kicker crossover very similar to that minus the wired remote control. It has a port for it, but never saw a need for it. It did wonders for me in my truck. The amp will give you all the power you need then just hook that crossover up in series, fine tune that puppy, and enjoy the music. Your going to get a hello of a boost out of your subs with that if you choose. You can also run your speaker amplifiers to that in the future if you want to cut out the bass which is what I did and added more mid-range and amplified the highs. I had it run in series with a Rockford Fosgate Blue Thunder Amplifier which was more then plenty for my 10s.