[Kevin Haskins]

You have to be a little more specific. It is a 1st/2nd octave device so (20Hz-80Hz) and most people cross them over electronically below 80Hz. Most of what people perceive as bass passes well above this range so none of the subwoofers I design are necessarily what you would call midbass devices. Once you get into midbass frequencies, you get into a lot of location issues. You get into frequencies that will cancel/add in difficult to predict ways with the main speakers. For that reason, subs are designed as subs (1st/2nd octave) and anything that is going to play above 80Hz is designed into a finished loudspeaker.

Kevin Haskins
Exodus Audio

 

[Kevin Haskins]

I doubt if it is your receiver. You should check that subsonic filter and make sure you have the right corner frequency and Q. Room placement makes a big deal but you should be able to tell if it is good/bad/indifferent in any room.

Make sure you modified the subsonic filter properly. It can make a huge difference if it is off.

Kevin Haskins
Exodus Audio

 

[Kevin Haskins]

It might... I don't have a schematic. Why didn't you use the 20k? You can go down to Radio Shack, buy a resistor for less than a buck and change it quick.

Kevin Haskins
Exodus Audio

 

[Kevin Haskins]

Correct the resistor first. If you are troubleshooting something, you work through the easy obvious things first. It is a process of elimination type of activity where you start with the easy things to check that don't take much time or money and progress to the more complicated/expensive things only if you have to.

As said above, you don't need a 20K resistor. You can use two 10K in series and achieve the same thing or any combination that adds to 20K. A 1/8W- 1/4 W resistor is all you need. It is a small signal level signal of a couple volts.

Kevin Haskins
Exodus Audio

 

[Kevin Haskins]

This was posted for me in the avs forums:

Your internal volume is 6.35 cuft, so when you subtract for the displaced volume of the ports,driver and amp, your final volume is about 6cuft. For two 4" ports at 17 inches long, your tune is almost 24hz.....and that's the problem. Plug up one port and you're tune will be 17hz. See if that takes care of the problem. Make sure you plug it completely. Stuff in a rolled up pair of socks and then tape a piece of cardboard over the front. You'll have a lot of port noise from the air speed, but at least the bottoming should stop.

Is this true? Do i have to build another box to the right frequency?

The final volume is about 6 cubic feet. But the documentation calls for 100% fill and the two 17" ports are Precision Sound flared ports, their effective length is 16" each. It should be tuned about 21Hz with the two ports & 100% fill but you will find if you build that enclosure according to the Google Sketchup dimensions, the tune will be ever so slightly lower due to the location of the exit of the ports and it's proximity to the rear of the cabinet, effectively lengthening the port. It comes out more like 20Hz. Either way.... 1 or 2 Hz doesn't make much of a difference in this case.

The 100% fill also gives you a larger effective volume and a lower Qa. The final result of that & the subsonic filter is shown in the documentation.

If you go out on the Internet and ask for help, some of it will be good advice, and some of it will be bad. Start by troubleshooting it via the obvious things first. Get that resistor right, make sure you built everything to spec, make sure you have the coils hooked up right and make sure you are using the 100% polyfill. The couple Hz tuning difference at around 20hz isn't going to do all that much for the subjective sound quality of the upper bass.

I think you have other problems but you may as well start with everything as it should be before getting started trying to troubleshoot something.

Kevin Haskins
Exodus Audio