# highpass filter selection - At Head unit or at Amp



## ak2366 (Dec 27, 2010)

Hi guys i run a pioneer AVH-4300 DVD head source unit and an Alpine PDX-F4 Amplifier at the back

My question is this where is the better place to select where to control the highpass filter is it better at the Source head unit or at the Amplifier

Pioneer headunit - 50hz Upwards 

Alpine PDX-F4 - 30 hz upwards

If i control at source i realized it sort of made my music brighter , just kindly advice the more efficient place to control the highpass . THanks guys


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## robert_wrath (Apr 24, 2011)

Considering the circumstances & configuration of your system layout, controlling HP Filtration from the HU is ideal due to convenience. However, ideal accessibility would be thru an Active Processor.


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## Kh2456 (Jan 15, 2011)

I feel that the amp is more capable of doing so that's why is prefer to use it over the headunit. Not sure if that's bs but that's what I do.


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## ak2366 (Dec 27, 2010)

Kh2456 said:


> I feel that the amp is more capable of doing so that's why is prefer to use it over the headunit. Not sure if that's bs but that's what I do.


So you allow the Head unit to send out a full range signal and when it gets the amp you set crossover frequency at what you want?.... my focal KRX2 component set has a freq response of 70HZ to 20KHZ. Should i set the highpass freq at 70HZ on my alpine pdx-F4's ??


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## adrenalinejunkie (Oct 17, 2010)

As far as setting your HPF, you'll have to play with it a bit. try 100hz and under and see what you like.


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## Kh2456 (Jan 15, 2011)

ak2366 said:


> So you allow the Head unit to send out a full range signal and when it gets the amp you set crossover frequency at what you want?.... my focal KRX2 component set has a freq response of 70HZ to 20KHZ. Should i set the highpass freq at 70HZ on my alpine pdx-F4's ??


Exactly. keep the HPf on your HU off and then you can set it at 70 hz on your amp and then try to experiment with it. I started at 70 changed it to 80 and then settled happily at 75hz. Most use a HPF of 80hz.


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## nick650 (Feb 7, 2011)

You don't need a LPF and a HPF if your running passive. The crossover network will do all that for your, run them full.


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## jcollin76 (Oct 26, 2010)

nick650 said:


> You don't need a LPF and a HPF if your running passive. The crossover network will do all that for your, run them full.


So your suggesting sending a full range signal to the passive components? That's not a good idea.. hp anywhere from 70-100Hz and see what's best for your application. The passive will handle the mid to tweet transition, but won't prevent sub frequencies from getting to your mid/mb, that's why you'll want a hp prior to the passive xover.


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## nick650 (Feb 7, 2011)

jcollin76 said:


> So your suggesting sending a full range signal to the passive components? That's not a good idea.. hp anywhere from 70-100Hz and see what's best for your application. The passive will handle the mid to tweet transition, but won't prevent sub frequencies from getting to your mid/mb, that's why you'll want a hp prior to the passive xover.


Most passive networks have the proper filters and require no need to do anything else. If it does not, then apply a filter.


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## Kh2456 (Jan 15, 2011)

nick650 said:


> You don't need a LPF and a HPF if your running passive. The crossover network will do all that for your, run them full.


Wrong Wrong Wrong Wrong


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## nick650 (Feb 7, 2011)

Kh2456 said:


> Wrong Wrong Wrong Wrong


Think again!


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## kizz (Jun 22, 2009)

I agree... you still need a hp filter. The passive crossover does not have a hp on the mid. 80hz is a good place to start


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## ak2366 (Dec 27, 2010)

adrenalinejunkie said:


> As far as setting your HPF, you'll have to play with it a bit. try 100hz and under and see what you like.


But 100HZ is too HIGH... i love my music to have depth and lows, especially since focals are on the "bright" side


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## kizz (Jun 22, 2009)

ak2366 said:


> But 100HZ is too HIGH... i love my music to have depth and lows, especially since focals are on the "bright" side


well, slowly lower it until you find a point where the midbass can handle the lows without distorting. that could be 100hz or it could be 60hz depending on how much power you are sending them, how your install is, how your eq is, etc...etc... 100hz is just a starting point. start there and slowly lower it until you find the speakers threshold.


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## nick650 (Feb 7, 2011)

Don't forget about the slope of the roll off.


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## adrenalinejunkie (Oct 17, 2010)

ak2366 said:


> But 100HZ is too HIGH... i love my music to have depth and lows, especially since focals are on the "bright" side



"try" 100hz and "under" and see what you like. I didn't suggest set it at 100hz...


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## exoplasm (Mar 5, 2009)

If you have it crossed over into a sub definitly have a hpf on the mids so that you can put more power to them without over excution and distortion. the sub is going to be filling in the lower frequencies anyway. its usualy around 80hz but depends on your setup and cars acoustics. so you might have to play around with it. Higher and amps have more adjustabilty of the crossover frequency and often rolloff at 24db/oct as compared to most head units offer 12db/oct rolloff.


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## ak2366 (Dec 27, 2010)

Thanks guys for all your Inputs. I think putting it at 63 hz or 80HZ from the Head unit pioneer does the trick. Then i allow my Alpine PDX to accept the full range of whatever my Head unit sends , so i set alpine amplifier at 30 HZ. Subwoofer LPF is set to 100HZ on head unit and i noticed that when i adjust the subwoofer LPF on the head unit it instantly affects the tonality of my music , i guess Pioneer didnt make subwoofer and woofer/tweeters function mutually exclusive. I guess there is some sort of algorithm in the HU that makes one affect the other. I found this quite interesting


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## Kh2456 (Jan 15, 2011)

ak2366 said:


> Thanks guys for all your Inputs. I think putting it at 63 hz or 80HZ from the Head unit pioneer does the trick. Then i allow my Alpine PDX to accept the full range of whatever my Head unit sends , so i set alpine amplifier at 30 HZ. Subwoofer LPF is set to 100HZ on head unit and i noticed that when i adjust the subwoofer LPF on the head unit it instantly affects the tonality of my music , i guess Pioneer didnt make subwoofer and woofer/tweeters function mutually exclusive. I guess there is some sort of algorithm in the HU that makes one affect the other. I found this quite interesting


Your post confused me. So youre using your headunit high pass and low pass on the amp? What do you mean you set it to 30 hz on the amp?


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## ak2366 (Dec 27, 2010)

Kh2456 said:


> Your post confused me. So youre using your headunit high pass and low pass on the amp? What do you mean you set it to 30 hz on the amp?


Headunits have both HPF for your normal 4 chanel, and LPF for 2 chanels


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## romanbenoit (Oct 21, 2009)

I'm using that same HU and have been running the HPF @63Hz with the Sub output frequency set to 80Hz...great results. Since the HU and my front-channel amp have the same slope for X-overs, I've found it's just more convenient to use the touchscreen, especially if I want to make adjustments on the go. With your components, you will probably want to bump the HPF to 80HZ and sub to 100Hz and tweak from there.


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## ZAKOH (Nov 26, 2010)

By the way.. a dumb question here. Since the filter implementation is digital, does this mean that there will be no phase shift if the head unit filter is used?


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