SyLvEsTeR20007

Hello all,

Just registered as I could do with some help, I have hit a wall in my understanding and have read a fair bit but I am having a hard time getting my head around the porting of the box.

I started out with a sealed enclosure for the sub and am a bit underwhelmed by the bass. The enclosure is exactly 0.8 as per Pioneers recommendation for a sealed enclosure but I have probably made some pretty n00b mistakes (see attachment "inside sub").



I suspect that the wadding is not good for the internal resonance. The subs instructions does say that inside of the box should have some kind of isolation layer.

In any case, I have decided to rebuild the speaker section of the entire speaker and combine all 3 sections into a single enclose and isolate the mids and tweeters from the sub with airtight dividers in an effort to reduce the weight and improve the bass by porting the sub.

This is why I am here, I am trying figure out a few things and ill list them below to help people answer.

So, in no specific order.

Can I use multiple ports to reach the desired port size for the sub, how do I tune the sub using the port length.

I have no problems getting the right volume for the ported enclosure.

Also, I have found that many people seem to say there is little to no difference running a sub in serial or parallel 2 ohms or 4 ohms and so on. IS this true? I am currently running the mids and highs at 4 ohms as per how they are built, and then the sub is currently in 2 ohms mode (so to speak).

So, I am building a new speaker section (top half of the device as you see it), I am also thinking about building it with a slot port and not using round pipes.

Advise is always welcome and since I am building this thing, I have no issues with changing the design to make this all work out for the best sound.

Thanks in advance.

veeman

iTrader: (3)

Why not use Pioneer's recommendation for the ported sub? They should have the port volume calculated for you. You can use multiple ports, but the dimensions differ dramatically. For example, a 3 cubic foot box tuned to 30hz would only need a minimum 3" port that is only 4.85" long to avoid port noise, but if you had 2 ports, they would need to be smaller and would be shorter as well...great if you have limitations in box dimensions, example: the same box with two 1.5" diameter ports, need to be only 2.42" each to avoid port noise. Basically if you double the number of ports at half the diameter, you quarter the total volume. Anyway, just go to this link and enter your details and how many ports you want and it will tell you how long they have to be:

LinearTeam

A slot port just needs to have the same area for the port, for example if the calculator says 4" diameter round port, that's equal to approx. 12.566 square inches. The slot port would be basically 12" x 1" and the same length.

As far as 2 ohm vs 4 ohm...very little discernible difference in SQ. Generally, higher impedance allows for better damping factor (amplifier's ability to control the woofer), but I have found little difference in most of my systems. This is more of a power issue, if your amp delivers a lot more power into 2 ohms vs 4 ohms, and your speaker can handle it with no issues, then the 2 ohm usually works better because you have more headroom to drive your speaker louder without clipping. More power is nice to have if you want to get louder. Also, the added power usually negates any advantages from the better damping factor at 4 ohms (with less power). If you don't have an amp yet, and cost etc.. is not an issue, go with the 4 ohms (even though I have yet to hear a difference, I always like to set things up as best technically and theoretically as I can.)