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Hi All,

I have just built a ported sub woofer & can't seem to get any frequency below 30 hz.

The sub woofer driver is a Mach audio IXL 18.
The cabinet was designed with the help of gperkins_1973 & is tuned to 15hz.

There is a build thread (I tried to insert the link but became to long)

The problem is when I run some test tones from 100 hz to 15hz the sound drops off after 30hz.
The driver is getting a signal as you can still hear something but all the bass disappears & it sounds a lot quieter.

I have just updated my Onkyo amp to a TX-SR577
The amp to drive the sub woofer is a Behringer 2500 & have also had to connect a Samson s convert.
I am only running the one sub woofer from the Behringer amp.

I have spoken to Graham & he has been working with me on this & suggested several adjustments to the pins on the back of the behringer, but can't seem to make any difference.

Even when the sub woofer was run in bridge mode there was no difference.

If anyone can help with this problem would be greatly appreciated.

Thanks.
Jeff.
 

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The problem is usually a HPF switch in the wrong position but it appears Graham covered that aspect. Did you try changing the switch positions as a test tone was playing, so you can distinctly hear the difference?
Hi Mike,

I got him to try that and it make very little difference. I got Jeff to move the switch no: 3 to the left and right.

This one's a real puzzler.

cheers

Graham
 

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Mike,

Yep but he said there was no difference.

One thing he also did say was when he changes the onkyo to stereo the sub isn't working. Ive asked him to send me a pic to show how his speaker settings are set in the onkyo menu.

I don't think there is a problem with the ep2500, its gotta be a switch thing going on somewhere.

cheers

Graham
 

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Mike,

Here's a pic he sent me to show the back. Ignore the switches as he has changed them from that.

From memory:

Onkyo sub out - Samson input - rca to rca (-10 input)

Samson output (+4) - ep2500 input 1 - xlr to xlr.

Samson gain is set to 12 o'clock.

cheers

Graham

Electronics Cable management Technology Electronic device Wire
 

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Mike,

Because off the time difference between me and Oz it takes a bit off time to get the response but he should respond by the time I get home.

He has tried bridged and no difference, still nothing below 30hz.

The S-convert worked and boosted the signal correctly so that is fine.

He has not tried input 2 on its own but I doubt very much it will be any different but its worth a shot.

cheers

Graham
 

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I sent Jeff a track which has alot off 13-19hz tones in it which was a test track made up by a guy I know so it will be interesting to see how he gets on.

Unless the hpf cut off switch is knackered and set to on. I would be surprised if both inputs 1 and 2 hpf switches would be dudd though.

cheers

Graham
 

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Have you checked the driver with sub 30hz tones. Make sure the driver is moving, if its movement starts to reduce once your go below 30hz, then something is filtering out the material. If its movement increase as it should, then that should rule out any filtering issues. I had to help a guy with his IB, and the issue was a setting on is processor. If your Onkyo has a setting to specify the sub is a THX sub, select yes. This setting merely tells the amp you sub will go to 20hz and below. The THX might not help, but its worth trying it just to see, if nothing else it will rule out that as an issue too.
 

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Dan,

The onkyo he has doens't have any form off THX decoding on it. I am wondering if it is a setting on his dvd player as I had the same issue with my blu ray player and the bass was rubbish. War of the worlds was really bass light and when I changed one off the audio settings it now blasts out alot off bass. It was the same for dvd's and blu rays.

I am waiting to find out what make off dvd player he has.

cheers

Graham
 

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DRC shouldnt filter at a specific frequency, it balances the frequencies being reproduced. I think we need to know if the driver is still moving once the sine waves descend below 30hz. To test it properly, you need REW to generate a sine wave at say 50hz and at a decent spl level, just not too high. Reduce frequency and the cone excursion should consistently increase. If it stops doing this below 30 hz then this indicates an active filter, if the driver continues to increase is amount of excursion below 30hz, then its likely not a filtering issue at all and we should look at other possibilities.
 

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He can't use REW at the moment as he doesn't have the correct soundcard and cabling etc..

This is why I gave him sinewaves from 10-100hz to hear how it sounds as he doesn't have a spl meter at present.

The samson doesn't have any form of hpf. It purely a signal booster device that boost or cuts from consumer audio voltage to pro audio voltage and visa versa.

cheers

Graham
 
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