Do you really need high pass filters on HU's??

Systems

I noticed a lot of decks come with high pass and low pass filters built in. My question is.... Do you really need them if A) you are using component speakers that have their own crossovers, and or if you are amping all your speakers of an aftermarket amp (and not using the HU internal amp) that has built in crossovers also? This comes up because I was checking out the Alpine 9807 and 9827, but they dont have the high pass filters built in like the more expensive models such as the 9815 has. I'm thinking I can save some money by getting the 9807 and it will still be ok becuase ill be to use all the other crossovers to really tweak the sound. I guess what im asking is: is it really necessary to have high and low pass filters as well as crossovers on all tje speakers. Thanks for the help.

exalted512

not at all
the 9827 is a good head unit...one of the few alpines i like...
-Cody

MacLeod

Cody is right. Crossovers on the head unit is cool and all and if you can afford them then get them but you dont need em. As you said, components have their own crossover so you wont have to worry about that and virtually all amps have built in crossovers and most have variable crossovers so you can tweak them more.

I have the 9807 and for the most part I really like it. It sounds great and looks awesome. It makes a tiny popping noise when adjusting the volume, however its very light and only does it on certain recordings and 90% of the time you dont hear it so although it bugs the hell out of me when it does it, it is something I can live with for now anyway.

I think Alpine has some quality control issues with their manufactering but for some reason I still really like their gear, espesially their V12 amps. I guess its a nostalgia thang. Back in the late 80's when I first started dabbling in car audio, Alpine was the shiznit. I was never able to afford them so I stuck with the more budget minded Pioneer models but always wanted an Alpine as all the top local systems and all the "cool" guys used em.

Systems

Originally posted by Grand am guy
I noticed a lot of decks come with high pass and low pass filters built in. My question is.... Do you really need them if A) you are using component speakers that have their own crossovers, and or if you are amping all your speakers of an aftermarket amp (and not using the HU internal amp) that has built in crossovers also? This comes up because I was checking out the Alpine 9807 and 9827, but they dont have the high pass filters built in like the more expensive models such as the 9815 has. I'm thinking I can save some money by getting the 9807 and it will still be ok becuase ill be to use all the other crossovers to really tweak the sound. I guess what im asking is: is it really necessary to have high and low pass filters as well as crossovers on all tje speakers. Thanks for the help.

I disagree with the statements that you don't need HPF if you use component speakers.

Filters (High Pass and Low Pass) are *not* crossovers.

As an example - Infinity Kappa Perfect 6.1 components have a frequency response of 75hz-20000hz, they include their own external crossover.

The external crossover takes the wide-band amplified input signal, and divvies the output to the woofer/tweeter depending upon frequency.

Ok - but suppose you have LOTS of bass signal in the 25hz-75hz range - now the lower the frequency, the higher the power level required to reproduce it, correct? - so.... If the Perfect 6.1's are rated at 75hz....exactly what happens to that "extra" power being thrown at the crossover?

Ahhh the frequencies of the amplified signal below 75hz *may* be filtered out by the crossover (or may not - depending upon design) - but if they're filtered out...what happens to that power? Ahhh it's turned into heat at the external x-over (not a good thing!). Or... The signal may just be passed directly to the woofer side - and the woofer may not be capable of reproducing those lowest frequencies accurately - what happens then? You guessed it... either distortion (from out of range low freq's and their harmonics), or MORE HEAT.

Now, suppose you use the HPF on your head unit to filter out anything below 75hz. The h/u filters the signal at line-level - and the amplified output has NONE of the frequencies below 75hz. MUCH less heat (and wasted power) is generated. Less wear/tear on your speakers and external crossovers.

Now, If you're running external amplifiers with HPF and LPF filters, and being fed by line-level signals - you'd do ok without them on your head unit.

exalted512

Originally posted by Grand am guy
My question is.... Do you really need them if if you are amping all your speakers of an aftermarket amp (and not using the HU internal amp) that has built in crossovers also?

-Cody

mbdyer12

Originally posted by HPF



Ahhh the frequencies of the amplified signal below 75hz *may* be filtered out by the crossover (or may not - depending upon design) - but if they're filtered out...what happens to that power? Ahhh it's turned into heat at the external x-over (not a good thing!). Or... The signal may just be passed directly to the woofer side - and the woofer may not be capable of reproducing those lowest frequencies accurately - what happens then? You guessed it... either distortion (from out of range low freq's and their harmonics), or MORE HEAT.

Umm, how many speakers (component or not) have high pass filtering in the crossovers for the woofer? Correct me if i'm wrong but I dont think there is one. Theres no *may* about it as far as I can see

I hope I'm not wrong so I dont look like a 'tard

nadams

Why does Polk say this on their specs for the db570- "Instead of the high-pass filter found in most car speakers, a built-in 2-way crossover network sends the appropriate frequencies to each driver for cleaner sound and better imaging."

exalted512

Originally posted by mbdyer12
Umm, how many speakers (component or not) have high pass filtering in the crossovers for the woofer? Correct me if i'm wrong but I dont think there is one. Theres no *may* about it as far as I can see

I hope I'm not wrong so I dont look like a 'tard

cheaper designs dont filter out everything
-Cody

exalted512

Originally posted by nadams
Why does Polk say this on their specs for the db570- "Instead of the high-pass filter found in most car speakers, a built-in 2-way crossover network sends the appropriate frequencies to each driver for cleaner sound and better imaging."

i think its more of "an addition to the high pass filter" thing
-Cody

geralopez

Here is my Alpine 9815, it is awesome and it is true, Alpines has a very nice parametric x-over and equalizer built in. Also it is true that you'll need more time to adjust your system, considering that you have a lot of filters on the way, your HU then your AMP and finally yours passive x-over for your components, you'll spent more time trying to find your best SQ (well if you are an expertise, you will fix it quickly).

-GLopez

geralopez

Here is the tilting face plate.

Systems

the alpine cda-9815 looks sweet, nice pics! As for high frequencies going to the woofer in a component system and lows going to the tweet....its my understanding that this shouldnt happen. i was under the assumption that the external crossover that came with the components would provide only high to the tweets and only low to the woofers..but people are saying HPF and LPF on HU are different then an external crossover?

Systems

o i see what you are saying....letting the full signal go to the external crossover isnt ideal. Using the decks HPF and LPF plus the external crossovers should provide the best signal for the speakers. With little or no heat, and less work for the crossover. thanks for the help.