[amlebede]

What do you think is a recommended bandpass (maximum) for a subwoofer in the trunk in a E90 with Logic 7?

[kaigoss69]

Will you still be using the underseat subs in conjunction with the trunk subs or not?

The underseat "subs" in an L7 system can adequately handle frequencies down to about 50Hz so if it were me, I would bandpass the underseat subs between 50Hz and the natural cutoff frequency of the oem amp (~150Hz), and low pass the trunk subs at 60Hz.

Thing is, unless you are amping the underseat subs, you cannot remove the lower frequencies, and you will have some issues with cancellation.

[VP Electricity]

Originally Posted by amlebede

What do you think is a recommended bandpass (maximum) for a subwoofer in the trunk in a E90 with Logic 7?

The question is not complete enough to be answered.

Please expand.

[TMR]

A bandpass will be larger than a sealed or ported enclosure and only give you a peak FQ response in the tuned area and sound dead everywhere else. What are you trying to do in your car? What sub are you using? How much power? What is your ultimate goal?

[VP Electricity]

Originally Posted by TMR

A bandpass will be larger than a sealed or ported enclosure and only give you a peak FQ response in the tuned area and sound dead everywhere else. What are you trying to do in your car? What sub are you using? How much power? What is your ultimate goal?

You assume he means enclosure. He might mean bandpass filter frequencies (i.e., a subsonic and a LP for a sub, or bandpass for the underseat woofers.)

Well, Dude, we just don't know.

Philip Seymour Hoffman, The Big Lebowski

[amlebede]

I am using my underseat subs with a trunk 12'' 400 watt Kenwood subwoofer. My goal is sound quality. The trunk sub is in a sealed enclosure.

[VP Electricity]

Thanks, but you haven't clarified your question, so I am still not sure what you are asking. Are you asking about xover points, if so for what?

[amlebede]

I am connecting an aftermarket amp to the BMW amp. I need to decide what point it would be best to set the bandpass on the aftermarket amp if:
1) I am still using the underseat subs
2) Sound quality is priority
3) I am not changing anything on BMW amp

[kaigoss69]

The term "bandpass" is being used incorrectly. When you bandpass frequencies, you are cutting off the bottom and the top of the frequency spectrum and you ar left with a "band" of frequencies. You would not want to do this with a subwoofer as it is designed to play down to the natural roll-off frequency of the enclosure. You will want to low-pass the sub, which means you feed it the bottom portion of the frequency spectrum, normally 80Hz and below. Sometimes, depending on the enclosure, you will need to engage a subsonic filter, which cuts off the very low frequencies in order to prevent the sub from overexcursion due to frequencies you would not hear anyway (20Hz and below, for example), but I would not call this bandpassing.

This brings me to recommending a set-up but I will refrain from doing so since the various options have been discussed to death in this forum so again, SEARCH ..... and you will find.

[VP Electricity]

Originally Posted by kaigoss69

The term "bandpass" is being used incorrectly. When you bandpass frequencies, you are cutting off the bottom and the top of the frequency spectrum and you ar left with a "band" of frequencies. You would not want to do this with a subwoofer as it is designed to play down to the natural roll-off frequency of the enclosure. .

Not neccessarily... the term "subsonic filter" comes to mind. If he is talking about driving the 8" underseat, then he is technically talking about a bandpass even though he is misusing the term.

Move the freaking dials until the speakers sound good and leave them there. I would probably go with 40 on the HP and 150 on the LP to start... but turn them til it sounds good. Then stop.

[kaigoss69]

Originally Posted by VP Electricity

Not neccessarily... the term "subsonic filter" comes to mind.

As mentioned in my post, I would not consider the use of a subsonic filter in combination with a low-pass filter "bandpassing" since the frequencies you are eliminating on the bottom end are pretty much inaudible, in musical terms.

[amlebede]

Originally Posted by kaigoss69

As mentioned in my post, I would not consider the use of a subsonic filter in combination with a low-pass filter "bandpassing" since the frequencies you are eliminating on the bottom end are pretty much inaudible, in musical terms.

I thought the subsonic filter was suggested to not overexhaust the subwoofer rather than to improve sound quality.

[manuelpolaco]

What I understand, he is using the logic 7 oem amp to move all oem speakers except the enclosed subwoofer in the trunk which is using an aftermarket amp. The solution is simple, place the low pass filter of the aftermarket amp at 90-80hz.

I used a 3 way crossover to do a low pass filter for the trunk subwoofer, bandpass filter for the aftermarket sws-8 underseats and high pass filter for the component speakers. It sound great.