hihoslva

I am probably going to be replacing my crappy subwoofer amp soon, along with adding a two channel amp for the front speakers.

In researching the amps, I find that most have a high-pass filter @ 120Hz, and a low pass filter @ 80Hz.

The question is: what happens to the frequencies between 80Hz and 120Hz?? If I purchase two identical amps (which I am probably going to do), and set one with the HiPass for the door speakers, and bridge the other one and set it with the LoPass for the sub, what about the "lost" Hz range?

Why would crossovers be set so as to possibly eliminate any frequencies like this? Am I nuts? Could I use the one amp at full-range to eliminate the dropped frequencies, or will I blow up my door speakers (they will most likely be good quality 6x8s when the amps are installed)??

What gives?

hiredgoon

Most crossovers on amps have a 12db/octave crossover slope, so on a 120Hz high pass, at 60Hz the output will be 12db lower than at 120Hz.
Your subs will be 12db lower at 160Hz than 80Hz...etc.

Crossovers just don't cut the frequencies totally out...you might notice your midbass is a bit thin though.

hihoslva

Okay, now I'm getting the "slope" theory - but should I be able to run good quality speakers at full-range power, or will I need to use that HiPass ?

I want to buy a nice set of speakers, and I won't overpower them, but I don't want to blow them up by throwing too much bass at them. I'm talking 6x8" (or maybe keeping the Kenwood 6.5s I have now, which have good power handling).

Will the frequencies below 120Hz blow them up at higher power?

hiredgoon

I'm running Panasonic 5.25's at full range right now, and about 25wrms to each of them. As long as you don't put too much power to your speakers, they should be fine running full range. Keep the bass level in the middle and you should be fine. If you're running a more powerful amp to them you might want to consider using the crossover. Depends on the type of music and the listening level as well. Whenever I'm playing something with a lot of bass, I turn the bass down on the deck and my speakers don't complain.

mazdaspeedwest

the amps crossover should be variable, that way you can dial it in as you like it. If it's fixed, then an offboard variable xover will work. And yes, the xovers do not just "cut" the freqs, they slope them down, the higher the db, the steeper the slope.

you should be able to run decent power from 100hz+ to decent 6.5 or 5x7 or whatever size speakers. let the subs handle the down low and dial the others for mid, mid-bass and highs.

depends on what high power is, if you send 100watts of 60hz, yes it will probably cook them. that same 100watts at say 100-120hz+ will probably be your max limit.

i push 75watts to each, but lower the gain on the rears just slightly and eq'd more up front, crossed over at 86hz, the subs are set to 83hz.

hihoslva

I'm looking at the Rockford Fosgate Punch G120.2 amps - 50W per side RMS at 4 Ohms, and 100W bridged at 4 Ohms (200W max). I'm considering the G250.2 (for the sub, but haven't decided just yet.

Both my door speakers and sub are 4 ohm load, so I'm looking at buying two of these amps, one for each application.

Looking closer, there is a bass level control on the amp, so I could dial down the bass (not the x-over point, but the bass level) to the doors. Looks like a good chioce.

Any thoughts on the RockFos Punch line of amps? I've heard good things....