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Discussion Starter · #1 ·
Hello all, Just found this site and its got me really thinking about a DIY component setup for my 97 thunderbird. I want to run a 3 way setup with a midbass in the doors and a midrange and tweeters in the kickpanels. It seems like the dayton drivers are pretty popular around here. Would the 7 inch driver work well as a midbass from 90 to 350-400hz?. As far as crossovers, I was thinking about trying to build my own passives, but I also saw that dayton makes a passive that looks like it would fit my needs. http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=260-150
Would I get good results with these. I also saw that alot of people recommend active crossovers here. Is this a better way to go than passives? i would have to buy at least one more amp (maybe 2) as well as the crossover in that case but that stuff can be had cheap off of ebay
 

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First off, welcome to the forum.

Active is a better way to go, but it is more expensive. Using the Dayton passives that you saw won't totally do the trick. Those crossovers just set a crossover point. They don't incorporate Zobel networks or L-Pads. They also don't compensate for any peaks and dips in your frequency response. In other words, passives are much harder to design. An active setup allows much more flexibility.

The Dayton drivers are great and the 7" that you're looking at will indeed go down to 90 hz. In fact with proper door treatments it will go much lower. They are a great start to a killer setup. For the money they're hard to beat (if at all).
 

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Zobels or L-pads are used to "match" the efficiency of your drivers and also to elimate resonances in the Impedance curve of your speaker.

For instance, if you have an 8ohm mid that is 90db sensitive and a 4 ohm tweeter that is 93db sensitive you have to lower the output of the tweeter by 3db to adjust for the sensitivity difference, but also by another 3db to adjust for the resistance difference between the drivers.

The other passive component you will have to add is a way of eliminating the impedance resonance of your drivers. This isn't always a necessity, but will completely alter the response of your sound if not taken into account. This is especially important if you are using a crossover with a slow rolloff (1st and maybe even 2nd order).

NOTE: both of these circuits should be designed before the crossover since they change the overall impedance of your speakers. Being that the impedance value is intrinsic to the calculation of crossover components this needs to be done first and then remeasured. Unless of course you are using an active crossover. With an active crossover the crossover itself does not care about the impedance of the speaker and therefore you can build notch filters, L-pad filters, and impedance correction circuits after the amplifier without worrying about screwing up your crossover points and slopes.
 

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As minivanman stated above active, If you can afford it. Control, Control, Control of the drivers. I have yet to hear two cars to sound totally alike even when they where the same car with the same setup. So passive are set at a point and you are stuck with it. Now don't get me wrong with a lot of Research and testing you car you can come up with passive system that can reach the level of an active system and in many case exceed it. Its all about planning and testing, and planning and testing again.

Mark
 

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Discussion Starter · #6 ·
So would a plain electronic 3 way crossover upstream of the amps be sufficient. I intend on running 3 2 channel amps OR a 2 channel and a 4 channel so that each speaker has its own channel.
 

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King Nothing said:
So would a plain electronic 3 way crossover upstream of the amps be sufficient. I intend on running 3 2 channel amps OR a 2 channel and a 4 channel so that each speaker has its own channel.
No, you will need a 4 way crossover. Highpass for the tweeters, 2 Bandpasses, 1 for the midranges and 1 for the midbasses, and a lowpass for the subs.
 

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King Nothing said:
So would a plain electronic 3 way crossover upstream of the amps be sufficient. I intend on running 3 2 channel amps OR a 2 channel and a 4 channel so that each speaker has its own channel.
If your head unit has its own subwoofer output, that should work just fine
 

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Stumbo said:
If your head unit has its own subwoofer output, that should work just fine
True, but you will still need that bandpass filter on the midbasses. You can use the lowpass on the active crossover, run that into the midbass amp and then use the highpass on the amp the get the bandpass you need for the midbasses. So it is not as simple as just running the sub from the head unit.

There is a couple of other ways you could do it with the same components, but with the stand alone 4 way active crossover it is just easyer and you have a little more control. Also I would look for a quality crossover that acts as a line driver as well (a high voltage output) that will help with the noise floor of the system.

Mark
 

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Discussion Starter · #10 ·
My sub amp is low passed at 90 hz. It also has an output that is high passed at 90 hz. If I use a 3 way crossover downstream of the sub amp the Xover in the sub amp along with the lowpass in the actual crossover will act as a bandpass, correct? Then I can use the bandpass on the crossover for my mids and the high pass for the tweets
 
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