using LPF on HU or amp

[pentavolvo 10+ year member]

I have a Pioneer DEH-P6500 which has a low pass filter built into the HU's sub controls, and my Profile California CA400 had a varaible LPF/HPF. Do I want to use the LPF in the HU and turn the filter off on the amp, or turn it off on my HU and control and use the LPF on the amp.

Thanks

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[maniackilla 10+ year member]

i use my HU LPF at 78hz but you amp will override anything less than that depending if you have it set to or not. the HPF in my case was very helpful b/c i dotn have an amp pushing my components or my tweets and its set to 125hz and up ..... atleast its better than hearing below 125hz notes thru tweets //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[stud(k)muffin 10+ year member]

i'd use both cause if the LPF in the HU doesnt work that great the amp wil lblock the highs from your subs anyways just as a precaution so you dont ruin the subs

 

[Matador 10+ year member]

using btoh wont hurt. it might be better to, in case one of them fail (doubt it) or u set the lpf in amp at a higher freq dat u would want by accident.

 

[Lusso5 10+ year member]

The amplifier typically has a higher quality crossover than the head unit, so I tend to use only the amplifier's crossover ...

My experience as well. More specifically: 1st order -6dB/octave, 2nd order -12dB/octave, 3rd order -18dB/octave. The lower order the more frequencies above cut-off pass through.

The HU x-over is likely a lower-order than the amp. Nice thing about using the HU x-over is you have sub bass-boost control right at the deck. If you dont have a control from your amp up front, I would recommend using your HU x-over (so you can have sub bass-boost control) and using your amp x-over, as well, at a slightly higher point than the HU setting.

 

[maylar 10+ year member]

Also, when you put the Pioneer decks in subout mode, the rear speaker outputs are also affected. If you're running rear fill off the deck speaker outputs, that sucks.

It's that way with my 6400, dunno about the 6500.

 

[nswartley 5,000+ posts]

since amp X/o's and filters are terribly unexact, will i really notice a difference between using the HU and amp X/O points?

-nate

 

[Lusso5 10+ year member]

Well, you'd have sub level control at the head unit anyways, so there's no real point in using the HU's crossover since you can always turn the crossover off and leave the sub pre-out on ...QUOTE]
This wasn't the case while I temporarily used a Pioneer DEH-3500. You had to choose a crossver point if the sub pre-out was on. Consequently, you could only control sub bass-level at the crossover point you chose. Granted the 3500 was an entry-level deck - if the Poster's 6500 can control sub bass-level at the pre-out without using the HU x-over, then of course go with the higher order.

 

[99concorde 10+ year member]

why would the sub preout effect the rear speakers. the head unit(i have the same one) has three outputs sub, front, and rear. i dont think you can control the sub output without having the filter on. but i cant remember. i use the lowpass filter on both amp and headunit.