# Question about bi amping and crossovers.



## thebeaushow (Apr 8, 2010)

I'm kind of new to audio and I've heard a lot of confusing things.
Here is my setup currently
Alpine 9887
Alpine PDX 4.100
(2) Alpine 6.5 Type X Ref Component speakers

Right now I have 2 sets of the type x component speakers hooked up to my pdx amp. They are both running through the passive crossover supplied with the speakers. Right now I have the pdx amp set to full range and have my crossover settings on my head unit. This confuses me, as I'm not sure if that's what I want. Since I have the components hooked up through a passive crossover should I have the crossover setting on on the amp or the head unit? 

Now I have two different questions. Should I lose the rear set of components and just have one set for my front stage? I heard this sounds better. Then if I do that should I bi amp those components (the type xs are bi ampable through the passive crossover) Or should I lose the passive crossover and run the speakers straight to the amp and go active through the head unit? Will this blow my tweeter? (the amp is rated at 129w x 4.) 

Any advice would be greatly appreciated.


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## Oliver (Jun 25, 2007)

A crossover is a filter , you are filtering it twice [ active then passive ].

If U go active the speakers will only be controlled by the Alpine 9887, this is preferred by some . . . maybe u will like it too ! 
*
The tweeter won't be damaged unless U cross it over too low* [ work your way down from the highest setting and listen for sounds of distress = popping noises or if it becomes shrill or whiny in it's presentation.

Bi-amping can be searched for and read about , then you will know if U want to try it. 

G'Luck


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## jstoner22 (Jun 30, 2009)

those are a very nice set of components. you could very well get rid of the rears and put your pdx on just the fronts.

in fact i would recommend this for multiple reasons

Bi-Amping will allow you to...

1. bring your soundstage forward.
2. get a little cash from selling the one set.
3. you will gain time alignment between your tweeters and woofers. rather than as a whole.
4. you will have more control over tweeter attenuation
the only thing you would gain over going active is being able to change the crossover point on your tweeters. 

those however are exspensive crossovers that come with those sets. bi-amping allows all the benefits of active except that. because of this, i would just stay passive and keep it simple and SAFE.

and you only want to be using one crossover. if you have the system crossed at the headunit, no need to also on the amp.

using the passives, you just need to cross your sub, and your cutoff for your component woofers.


up until a few months ago, i ran speakers front and back off of my pdx 4.150. my fronts also allow for bi-amping.
i ran it using all four speakers, bridging the power and putting 330watts to my components with no rears, and bi-amping with no rears.
bi-amping with no rear by far has the most benifits. especially if you are able to time delay the tweets separate from the woofers!!

HTH


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## coefamily (Sep 24, 2009)

go active, its easier and can save you money in the long run


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## thebeaushow (Apr 8, 2010)

Thanks for all of the replies.

So I've decided to drop the rear speakers and bi amp the front set. I went and tried to bi amp them through the passive crossover but for some reason I don't think this is working. Whenever I attach the other channel the one set of components becomes quieter and sometimes fuzzy. This happens on both sides. I have no clue why. Should I just lose the passive crossover and go completely active?


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## Oliver (Jun 25, 2007)

Lose the passives be fore you damge something , 'REALLY BAD" !!!

Get a capacitor and wire it inline with your tweeter for protection !
http://diymobileaudio.com/pics/g3cap.jpg


> ... and they require steep crossovers usually 18db (3rd order) or above to protect them from overexcursion. It is also absolutely recommended that you* place a capacitor inline with the tweeter to prevent them from being damaged by turn on/off noises etc...*


.


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## jstoner22 (Jun 30, 2009)

there is a fuse or jumper that you need to switch inside the crossovers to activate the bi-amping mode. otherwise this will happen. takes two seconds to switch over. 

only benefit you would gain from losing them completely is changing the crossover point of the tweeter.
if you don't plan on doing this, just leave them in an bi-amp them.


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## Oliver (Jun 25, 2007)

jstoner22 said:


> there is a fuse or jumper that you need to switch inside the crossovers to activate the bi-amping mode. otherwise this will happen. takes two seconds to switch over.
> 
> only benefit you would gain from losing them completely is changing the crossover point of the tweeter.
> if you don't plan on doing this, just leave them in an bi-amp them.


He *might *gain a cleaner sound and more power to speakers  { as anything added in to a signal chain has the ability to degrade the sound . . . however slightly and passives will use some of the amplifiers power too !


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## thebeaushow (Apr 8, 2010)

I knew it was something simple. Do you know exactly what I have to change on the crossover? I'm not home right now but I'm pretty sure on my crossover there is two fuses in the middle. Do I remove one?


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## jstoner22 (Jun 30, 2009)

the power difference will be negligable by alleviating the tweeters.
personally if the crossover point isn't being changed, i'd like to have the passives in there just as a safety net for expensive tweeters.
but yes, there MIGHT be a very slight gain. 
running active and all it takes is a slip or an idiot messing with your settings and a tweeter can be toasted.

im not sure the layout, but i think you have two fuses in there.
one for adjustment of tweeter attenuation. (you will want this on ZERO). because now you will use your gains etc for attenuation.

also you will have another for bi-amp mode or regular. you will have to switch that over as well.

it will all be pretty well labeled.

just make sure you aren't running power through them while its done.


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## thebeaushow (Apr 8, 2010)

Thanks a ton for all of the input. It makes everything a lot easier. My last question is when I bi amp the components should I have one set of comps on channels one and two and then the other set of channels three and four of the amp? Or should I wire both woofers to channel one and two and both tweeters to channel three and four? Should I turn the gain down in this case since each channel outputs 129 watts and the set of comps as a whole is rated at 75 w rms. (25 tweeter and 50 for woofer). Or will the passive crossover protect them?


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## Oliver (Jun 25, 2007)

A crossover set for 3,000 hz ,{3KHz}, at a steep slope 24 dB will protect the tweeter from playing any frequencies that *are too LOW*.



> Bi-amping is the practice of using two audio amplifiers to power a set of loudspeakers.
> 
> The term derives from the prefix bi-, meaning 'two', and amp, a contraction of 'amplifier'.


YouTube - Amplifier to Speakers, types of connections.Bi-Wire,Bi-Amp,Bridge


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## jstoner22 (Jun 30, 2009)

you are going to want to retune your gains, so drop em right down and start over.

those channels are not putting out 129watts constantly either.

there are only 2 gains on the amp. so you want to pair the tweeters on on (channel 1 and 2) and the woofers on channel 3 and 4.

with the gains down, tune the woofers first, then just tune the tweeters by matching them to the woofers to your liking.
im not sure if your deck offers time alignment, but you can now tune tweets/woofers separately.


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## thebeaushow (Apr 8, 2010)

My head unIt does have time alignment but I don't think I can't do it for both the tweeters and woofers seperatley. Unless I'm missing something?


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## jstoner22 (Jun 30, 2009)

now, you run your tweeters on your front RCAs, then use the RCAs from your rears for the Woofers.

then when doing timealignment, you can time align them individually.
makes a big big difference if you know how to time align properly.

you will only need to cross the RCAs used on the woofers to filter out the low range. (probably anything below 63hz with a 12db slope)

by leaving in the passive crossovers, you can just leave the RCAs used on the tweeters as a pass (no filter applied). since the passive crossover will take care of that.




....don't think of them as two pairs of speakers working with each other. think of them as 4 independant speakers.
they are now High, Mid, and Sub. 
instead of Front, Rear, Sub


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## thebeaushow (Apr 8, 2010)

I have the crossover mode on the 9887 set to 3 way so I can adjust the low, mid l, mid h, and high crossover points. Is this the right mode for what I'm doing? If I do these should I still have a high pass filter on my amp for my woofers?


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## Oliver (Jun 25, 2007)

http://www.diymobileaudio.com/forum/member-product-reviews/22606-review-9887-vs-880-vs-7100-a.html

http://www.diymobileaudio.com/forum/member-product-reviews/17645-alpine-cda-9887-review.html

settings shown in first post ^^^^ for the Alpine CDA 9887 and here is how he used his amp and passives {also from first post in above thread}


> Amp 1: Soundstream Edge 4220 (*4 x 110 @ 4 ohms)* - *2 channels to tweeters* / midrange on passive xovers, 2 channels to midbass


How's this for control >>>


> HIGH 20 Hz~20 kHz (if you tell it to set it to user setting, basically telling the unit you aren't dumb enough to send a 50hz bass note to your tweeter)
> 
> Adjustable slopes: FLAT, 6 dB/oct, 12 dB/oct, 18 dB/oct, 24 dB/oct.
> 
> Each setting has its own volume control (0 through -15db), so speaker level matching can be done.


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## jstoner22 (Jun 30, 2009)

you will use,

low=Sub
mid L = woofers
mid H = nothing since you arent running any
high = tweeters.

do not use a crossover on the amp. set them all to off.
set your crossover only for lows(sub), and your mid L (woofers).

using your deck, like i said before, around 63hz at 12db. hpf on the woofers.
you dont want alot of over lap on the sub and woofers crossover point, and you want it as low as you can generally. this will minimize localization of the sub, and make it appear as if the bass is up front more.
if you are running a ported box and know its tuned frequency. im not sure if the 9887 allows but either run a hpf (subsonic filter) on the sub just above the tuned frequency of the box.
...i don't think it does this. so use this on your subwoofer amp. it is a separate switch from the crossover. you can choose either 15 or 30 i believe.



i'm out of here for a bit though. good luck!!!

1. switch RCAs
2. switch fuses inside to ZERO attentuation and bi-amp mode.
3. re tune!

very simple!


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## Oliver (Jun 25, 2007)

Set at +15 = O level in the real world.

Subwoofer Level:
Can be set from 0 through +15db very easily.


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## jstoner22 (Jun 30, 2009)

a$$hole said:


> Set at +15 = O level in the real world.
> 
> Subwoofer Level:
> Can be set from 0 through +15db very easily.








im confused. what do you mean by this? 

+15 = 0 level in the real world?


i understand his crossover allows for gain adjustment for each preout, (any decent alpine does). but why should he set them at 15?


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## thebeaushow (Apr 8, 2010)

I'm still confused on what to switch on the crossover to change it to bi amp mode. There are two fuses in the middle that are already plugged in. They aren't labeled. I tried to look at the box that the comps came in and it almost looks like when you run it bi amp that you remove both fuses? Could that be right?


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## jstoner22 (Jun 30, 2009)

read the manual.

if you don't have it, you can find one online easy enough.
most manufacturers have them available on their sites.


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## thebeaushow (Apr 8, 2010)

I got it all figured out. It sounds great. Thanks for the help!


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## Oliver (Jun 25, 2007)

thebeaushow,

Glad to hear this !!


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## jstoner22 (Jun 30, 2009)

glad to help!

im sure the system sounds great!!


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## ou812 (Oct 25, 2008)

This has really sparked my interest. I have the same comps running passive off a USacoustics usa-100. I have an Alpha 4050 here that I could try this. Does that sound like enough power? It's a Zed built Alpha so I would assume it's a little underrated.


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## thebeaushow (Apr 8, 2010)

If you aren't already bi amping them I would. Made a huge difference for me.


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## ou812 (Oct 25, 2008)

That's what I'm asking....I have been 100 watts passive and contemplating trying 50 x 4 active through the crossover.


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