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Discussion Starter #1
I know this have been discussed many times before, and i did read the other threads but i still have some questions and i am still unsure about doing a active set up. So my current set up is pretty basic Right now and i was satisfied for awhile but now i want something else. So my system right now i have, an Alpine Cda-117 as my head-unit and 1 audison lrx 4.1k and Hertz Hi energy 6.5 Coaxial and a 12" Image Dynamics IDQ in a sealed box, i have no rear fill so im using the 4.1k to drive the front and my sub. And for my active setup i plan on getting a pair of used Hertz MLk 165's or picking up The hertz hsk 165 xl's and i hope to use my 4.1k for my front stage then use my HD 750/1 for my sub, and i know audison says that the 4.1k can be used in a 2-way active set up, but after reading the other threads it said that to do a active set up my amp would need a band pass setting but i dont see it on my amp, and other threads said that a active setup would need an external crossover, is it absolutely necessary? because i think the 4.1k crossovers are good enough what do you guys think?
 

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The cross over as fine just use the hpf on the alpine with the lowpass on the audison and youve got your mid bandpassed.
Just make sure that slopes and points are correct before turning up the voulme to much.
A cap for your tweet isnt a bad idea eather just incase you get a turn on or off pop.
 

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Discussion Starter #3 (Edited)
But how would that affect my tweets since the tweets are going to be crossed over twice At different points? If I use the crossover on my headunit? Since the amp will be using the same RCA outputs, and I won't be able to use the same points since the tweets are going to be crossed at 1.5khz on the amp and the highest the alpine can go is 100hz
 

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But how would that affect my tweets since the tweets are going to be crossed over twice At different points? If I use the crossover on my headunit? Since the amp will be using the same RCA outputs, and I won't be able to use the same points since the tweets are going to be crossed at 1.5khz on the amp and the highest the alpine can go is 100hz


So you will use one set of RCA outputs (I assume the front ones) to provide the signal for your front woofers and tweeters? I think it would be better if you provided a separate set of outs for driving your tweeters (that is, from head unit point of view, treat your tweeters as "front speakers" applying a high pass crossover to them on the amplifier and no crossover filter on the head unit, and your front woofers as the "rear speakers" on the head unit, applying a high pass filter to them on the head unit). Why do this? This way you can time align tweeters with each other and woofers from each other separately on your head unit. This is one of the reasons to run speakers active. If you drive front front stage with just one set of pre-amp outs, then you don't have the ability to time align tweeters separately from woofers. However, if you insist on your current setup, applying a high pass filter on the head unit will not affect your tweeters at all. They're not meant to play such low frequencies. The high pass filter on your amplifier applied will result in practically no audible information played at 100Hz or lowers, so it doesn't matter if you have another HP filter in those frequencies.

PS: I corrected a mistake in the sentence that now is in bold.
 

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Discussion Starter #5
The thing is I can't choose which I want to apply the high pass to. It will just apply to both front and rear outs, what about the band pass setting? That is the one that I am more confused about, because in the audison manual it said to set the low pass on the mids and use the x10 for the crossover
 

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The thing is I can't choose which I want to apply the high pass to. It will just apply to both front and rear outs, what about the band pass setting? That is the one that I am more confused about, because in the audison manual it said to set the low pass on the mids and use the x10 for the crossover
I made a mistake in the previous post.

This is how you do it:

"Front speaker" channel settings:

Apply no filters on the head unit. On the amplifier select the appropriate high pass crossover frequency that's appropriate for your tweeter. Connect to output to the tweeters. Some recommend to add a capacitor to the tweeter circuit, in order to prevent the tweeter from being damaged by any sort of unpredicted current from amplifier. The capacitor acts as yet another high pass filter with a 6dB slope, so you need to pick a capacitor with such value so that it does not interfere (audibly) with the high pass filter on the amplifier.
(see http://www.apicsllc.com/apics/Misc/filter2.html for capacitor value calculator)

"Rear speakers" channel settings:

On the head unit, select the high pass frequency setting for the woofer, to blend it with the subwoofer (so it will be in the range below 100Hz). On the amplifier, select a low pass filter frequency that's appropriate for your woofer (e.g. 2KHz).

PS: added some stuff about capacitor.
 
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