Monoblocks And Active Crossovers
06-12-2014, 11:40 AM
#1
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Monoblocks And Active Crossovers Why is it that almost every subwoofer mono block amplifier does not have a defeat / all pass switch to turn off it's built in crossover?
I'm wanting to run an active crossover and time alignment mono, from my Alpine CDA-9887 headunit to my current amp that has a built in 3rd order variable LPF 50-350Hz and a 4th order variable subsonic filter. My Amp Memphis 16-PRD500.1 Monoblock 1 ohm stable has no switch to turn off it's LPF.
If I were to turn the amplifier's LPF to match crossover points at 80 Hz and then run an active crossover and time alignment from the head unit set at 80 Hz with a slope of 24db per octave (4th order), what effect would this have? Will it still be crossed at 80 Hz? Or will it change everything frequency and slope?
Will it screw up the active crossover signals slope and time alignment or will I be ok?
I've very confused with what this will do with the slope and T/A, or if I need a different amp all together. I don't know if it will even work or not thats why I'm asking for some help.
Does any one know of any class d mono amps that are 1 ohm stable and have a defeat able LPF, that doesn't cost $800 for 500-1000 WRMS?
I'm wanting to run an active crossover and time alignment mono, from my Alpine CDA-9887 headunit to my current amp that has a built in 3rd order variable LPF 50-350Hz and a 4th order variable subsonic filter. My Amp Memphis 16-PRD500.1 Monoblock 1 ohm stable has no switch to turn off it's LPF.
If I were to turn the amplifier's LPF to match crossover points at 80 Hz and then run an active crossover and time alignment from the head unit set at 80 Hz with a slope of 24db per octave (4th order), what effect would this have? Will it still be crossed at 80 Hz? Or will it change everything frequency and slope?
Will it screw up the active crossover signals slope and time alignment or will I be ok?
I've very confused with what this will do with the slope and T/A, or if I need a different amp all together. I don't know if it will even work or not thats why I'm asking for some help.
Does any one know of any class d mono amps that are 1 ohm stable and have a defeat able LPF, that doesn't cost $800 for 500-1000 WRMS?
Last edited by TX98Z28; 06-12-2014 at 06:07 PM.
06-12-2014, 06:43 PM
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I can't give you to much info on the rest of your questions as I never run a crossover, I get headunits with GOOD feautures and dedicated Subwoofer outputs that utilize a built-in (to the headunit) LPF, you don't want to send a full range to your subs from your headunit even if you have an amp or crossover with the proper filters, it's just NOT efficient, I've sat in cars where the owner hooked up his subs to the REAR output instead of the SUB output on the radio and was using a crossover and when I switched him over to the SUB output his bass level DOUBLED.
Also keep in mind you just posted this question 7 HOURS AGO, give people a chance before you bump the thread multiple times.
06-12-2014, 06:45 PM
#3
To answer your first question, most Class D subwoofer amplifiers are not full range amps. They are limited in frequency response to under 500hz. This helps simplify the design, keeping production costs down and amplifier efficiency up. Plus, most people are using Class D mono amps to run subs. How many people run subs full range? Why would you?
If you want to avoid cascading your crossover points (combining the amp and deck xovers) simply set the amp xover as high as it will go and use the deck to cross over where you want. That will minimize issues since your amp will only be attenuating frequencies already attenuated by the filters in your deck.
If you want to avoid cascading your crossover points (combining the amp and deck xovers) simply set the amp xover as high as it will go and use the deck to cross over where you want. That will minimize issues since your amp will only be attenuating frequencies already attenuated by the filters in your deck.
06-12-2014, 07:26 PM
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Being that the SOLE purpose of a Monoblock amp is to drive subs I would be absolutely shocked to find one that will do "full range", remember the crossover goes before the amp so if the crossover's LPF is set lower then the amps LPF it won't matter as the amp can only reproduce the sound being sent to it.
I can't give you to much info on the rest of your questions as I never run a crossover, I get headunits with GOOD feautures and dedicated Subwoofer outputs that utilize a built-in (to the headunit) LPF, you don't want to send a full range to your subs from your headunit even if you have an amp or crossover with the proper filters, it's just NOT efficient, I've sat in cars where the owner hooked up his subs to the REAR output instead of the SUB output on the radio and was using a crossover and when I switched him over to the SUB output his bass level DOUBLED.
Also keep in mind you just posted this question 7 HOURS AGO, give people a chance before you bump the thread multiple times.
I can't give you to much info on the rest of your questions as I never run a crossover, I get headunits with GOOD feautures and dedicated Subwoofer outputs that utilize a built-in (to the headunit) LPF, you don't want to send a full range to your subs from your headunit even if you have an amp or crossover with the proper filters, it's just NOT efficient, I've sat in cars where the owner hooked up his subs to the REAR output instead of the SUB output on the radio and was using a crossover and when I switched him over to the SUB output his bass level DOUBLED.
Also keep in mind you just posted this question 7 HOURS AGO, give people a chance before you bump the thread multiple times.
. I never intended to run my sub amp full range, just didn't know how to get around the amps built in internal crossover as I doesn't have a defeat switch.
06-12-2014, 07:35 PM
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Ok makes sense, so if I set my active crossover on the head unit to 80 Hz for my sub, the sub amp will only see 80Hz period. An the amps crossover becomes useless if I set it to some ridiculous frequency like 350 Hz . I never intended to run my sub amp full range, just didn't know how to get around the amps built in internal crossover as I doesn't have a defeat switch.
. I never intended to run my sub amp full range, just didn't know how to get around the amps built in internal crossover as I doesn't have a defeat switch.they put the crossovers on amps for the idiots that buy cheap headunits and use REAR preouts instead of SUB preouts (that get filtered).
06-12-2014, 07:49 PM
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To answer your first question, most Class D subwoofer amplifiers are not full range amps. They are limited in frequency response to under 500hz. This helps simplify the design, keeping production costs down and amplifier efficiency up. Plus, most people are using Class D mono amps to run subs. How many people run subs full range? Why would you?
If you want to avoid cascading your crossover points (combining the amp and deck xovers) simply set the amp xover as high as it will go and use the deck to cross over where you want. That will minimize issues since your amp will only be attenuating frequencies already attenuated by the filters in your deck.
If you want to avoid cascading your crossover points (combining the amp and deck xovers) simply set the amp xover as high as it will go and use the deck to cross over where you want. That will minimize issues since your amp will only be attenuating frequencies already attenuated by the filters in your deck.
So I just set the amps LPF as high as it will go and it will minimize weird stuff
from happening? Will this have any effect on my slope @ 80 Hz active?
06-12-2014, 08:01 PM
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basically, if the HU's LPF is set to 80 (to low if you ask me, I use 125) then only 80 and below get sent to it, it has no way to create sound it doesn't receive so in that scenario setting the amps crossover at 100 (if your HU's set at 80) is the same as setting the amps crossover to 350, because it's only receiving 80 and below so it has nothing to filter above that.
they put the crossovers on amps for the idiots that buy cheap headunits and use REAR preouts instead of SUB preouts (that get filtered).
they put the crossovers on amps for the idiots that buy cheap headunits and use REAR preouts instead of SUB preouts (that get filtered).
. Depending on what my subs enclosure size will be and how low my mids will go will be my x-over point I will probably put it at 100 Hz. If I had the cash I'd buy one of those 4 ways active Pioneer head units and be in heaven, but I don't have a $1000 to spend. 3 way active for me for now. 