# port and crossover question



## showagon (Apr 30, 2008)

ok, so i want to make a sub box in my room, i'm predicting it to be about 5-6 ft tall, my question is is it ok to have the port (12"X3") facing the same direction as the subs (2 10's facing the listener). its a simple ported box.

and my crossover question, i am picking up an amp for said subs and i have the input impedance of the amp, could i just build a low pass crossover pre-amp with the supplied amp impedance? its like 20kiloohms or something.


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## DasBot (Jun 1, 2008)

First I recommend small to medium sealed boxes. A port only does what a bass boost does. And having a sealed box will allow more punch and power handling to the sub. This will also save you time and space. 

If you've already built the enclosure, it's not a big deal to have the ports on the front. You only need to make sure the back of the port has some breathing room. Usually the same as the diameter of the port. In this case, 3".

Second, Legacy / Pyramid makes a little crossover / bass booster for like $20. All you need is to tap off a PC's +12vdc power or buy a little wall mounted power supply. You only need .5A at 12vdc.

I can give you more info in a PM.


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## Spasticteapot (Mar 5, 2007)

showagon said:


> ok, so i want to make a sub box in my room, i'm predicting it to be about 5-6 ft tall, my question is is it ok to have the port (12"X3") facing the same direction as the subs (2 10's facing the listener). its a simple ported box.


and my crossover question, i am picking up an amp for said subs and i have the input impedance of the amp, could i just build a low pass crossover pre-amp with the supplied amp impedance? its like 20kiloohms or something.[/QUOTE]

If you're handy with a soldering iron, you can make an active filter out of an op-amp and a few capacitors. You can also use the same op-amp to mix both the left and right channels from the PC into one sub channel.


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