Ok I have the Alpine 7893R, the European version of the 7894. When your setting your crossover you get a HPF (high pass) and LPF (low pass) settings. I know what a low pass filter does, but what does the high pass do? What type of settings do you normally use?

I think it sounds best when the HPF is flat, but then it allows bass frequencies into your main speakers so when you turn them up they clip.

Give me some advice and be as specific as you can. I'm seriously into home theater / home audio stuff, and know a lot of about how the things work, but the settings on this radio confuse the shit out of me. Plus the manual is so vague.

 

I also have the 7893 (btw the 7894 is a different model, and also available in the Europe - they are different specs)

I havent a clue what all those complicated settings are, at all so I would appreciate some help too. look forward to the answers on this thread

 

this is probably far more information than you are really requesting, but crossovers aren't a simple application issue... give this a read through and post any questions you might have.

repost from an earlier thread, edited for application:

crossovers 1001 & 1002: (go get yourself something to eat and drink - this one is long)
1001:

now, for more advanced installations i use some sort of active low pass crossover to keep only very low (subwoofer) frequencies going to the sub and out of the highs. this reduces the likelyhood of excursion distortion in the mids at high volumes (less lower frequencies, less large movement the mid/bass has to perform), and provides efficiency in not making the amp or speaker produce frequencies that are better reproduced elsewhere (a sub can much more effectively create a 60hz tone compared to a 6" mid/bass driver). so the sub has a low pass crossover, and the signal to the highs amp would have another high pass crossover that allows the mid and highs (anything not going to the sub) to go to the highs amp.
these should work in conjunction w/ each other to try and keep a smooth signal across the entire frequency range. but the crossover separating out the low bass to the sub and everything else to the highs would typically be used pre-amp.
now, that can be filtered at many points today. many headunits have active crossovers built into the deck, active aftermarket crossovers can also be bought for this purpose, and many amplifiers now come with active crossover capabilities. only one of those would need to be used in everything but the most exotic setups. so, depending on the amps, headunit, etc. you would only need to really use one active crossover. amps typically have less flexibility, usually offering only a single pass frequency option - high or low, but at one frequency (some offer more, some offer none). headunits usually have more, but typically offer a selection of 2 or 3 crossover frequency points. while an outboard active crossover will use panametric adjustments (full analog variable frequency adjustment), so that the crossover frequency can be adjusted for each input at almost any frequency.
confusing, no?

crossover points are typically given w/ two figures: the frequency at which they activate and the slope at which they "roll off" the unwanted frequencies. the "roll off' refers to how agressively the crossover 'removes' or mutes the frequencies that aren't allowed to pass. for example Focal K165's have a high pass 3.5khz crossover w/ a 18db/octave roll off. since decibels are based upon a logarithmic base 10 scale and since octave spacings come from halving (lower) or doubling (higher) the frequency - an 18db rolloff / octave says that music information at 1,750hz (1/2 the frequency of the crossover point) will have an audible level of 1/63rd (1 / (10^1.8)) of the original volume. this isn't a step decrease but is typically close to linear in decline. an 18db/octave is a fairly agressive crossover "roll off."

i'll use a figurative car system as an example of this:
i have 3 amp inputs for this system (front, rear, sub). you want to keep the high frequencies in the cabin so your soundstage is correct, and you want the sub to only have low freq.
so, the basic method of using an active crossover - for the average sub, i'd choose a low pass of about 80 hz to 100 hz. (these are normal numbers. bass frequencies 100 hz and below are typically non-directional in nature. ie, the source is difficult to pinpoint.). i would then send a high pass signal to my high's in the cabin starting at about the same point. (high pass around 100 hz) this would allow my highs to do their job w/o worrying about the heavy bass and allows the sub to its job w/o worrying about reproducing high frequencies. now, all of this happens during the pre-amp stage.

also, something to note - even if a speaker is rated from 50 hz to 20k hz, that doesn't mean that the speaker reproduces all sounds at the same level. with me so far? good.

1002:
now, it can get even more complicated... i'll only really brush this issue b/c this is much trickier to deal with. remember that the crossover "roll off" occurs on a linear type decline. that means, for some immediate frequencies right around the crossover point - you have 2 sets of drivers duplicating their efforts. thus, you lose a flat response there, and actually have frequency peaks that can be audible... so, to compensate for this - you have to consider the agression of the "roll off" and the frequency response curve of the speaker and actually set crossover points slightly offset to keep a flat response.
so going back to my example... let's say i know the sub has a fairly flat response curve out to about 120 hz. and i was able to look up that the high's speakers are fairly flat down till about 100hz. and assuming i have a 12db/octave "roll off" on both crossovers, i'd be likely to set my crossover point for the sub at 80hz and the highs at 110 or 120 hz, and use the overlap to blend the sound. if this doesn't make a lot of sense, don't fret over it, as it really is higher level of tweaking than most people ever do... and in fact, most crossovers don't even offer that level of adjustment (especially headunits and amps). the general goal though is to produce the same volume level from 20hz to 20,000hz w/o any dips or rises. that's why many audiophiles want only sealed boxes for subs, as ported boxes are tuned to have a peak response at the port's natural tuned frequency. subs are more efficient when ported, but less accurate.
and as confusing as this can be... it gets even worse when you're dealing w/ multiple crossovers w/ different "roll off" values and with speakers who's response curve is not entirely flat across their response frequency (which is just about every speaker).

bah - now i'm just getting esoteric.