Room modes and subwoofer interconnects

[Brian Walter]

I finished building a subwoofer a week ago (Dayton Quatro 15 in a 5.5 cuft box, tuned to 18 Hz or) and I'm getting some serious room modes. I've tried placing the sub in a couple different locations, but it seems there is a major null at the listening position. I don't have too much choice for basic layout, so I can't really move the listening position. But I can move the sub around quite bit. I have basically two questions:
1) Any tips on how to go about reducing the null at the listening position?
2) How long of an interconnect cable can I use? It might limit how many choices I have for positioning the sub.

Brian Walter

[Kal Rubinson]

The only effective ways to remove the null at the listening position are (1) to move the listening position and (2) to add effective bass trapping to reduce the energy at the problem frequency. AFAIK, no EQ will do it.

You can probably use VERY long interconnects, especially if they are balanced. What lengths are you considering?

Kal

[ThomasW]

Use this for a quick and dirty look at the room modes.

http://www.mcsquared.com/metricmodes.htm

There are stand-alone software based calculators of you want to get a better idea of what's happening.

http://home.comcast.net/~thomasw-2/SubwooferSetupandEQpage12.html

Yes long IC's are fine. I'm running 40' from one of my subs.

Bass traps and EQ can be helpful. EQ can lower the frequencies on either side of the null, evening out the response. And sometimes what appears to be a null is just less room gain in that spot. EQ boost can be used if that's the situation.

[Brian Walter]

Thanks Thomas, the mcsquared website doesn't seem to be responding at the moment, but Iill give the room mode spreadsheet linked on the second link a try.

Brian

[Dennis H]

To make it easier to find a good spot for the sub, put it where your ears normally are in the listening position and walk around with the mic. Wherever you get the smoothest response is where to put the sub. Don't forget to move the mic up and down as well as around the room.

[Brian Walter]

To make it easier to find a good spot for the sub, put it where your ears normally are in the listening position and walk around with the mic. Wherever you get the smoothest response is where to put the sub. Don't forget to move the mic up and down as well as around the room.

This sounds like good idea, but I might have a problem getting my sub up onto my couch, but I'm sure I can find someone to help me, beer is cheap. I also just realized that I have french doors that open into my office that I can try both open and closed to see if that might make a difference in the response.

Thanks for the ideas, I'll give them a try this evening.

Brian Walter

[---k---]

Opening and closing the doors will likely make a huge differance.

I think the others have covered everything. But, rest assured, you are not alone in your trouble. Square Room???

[Brian Walter]

But, rest assured, you are not alone in your trouble. Square Room???

I don't think the room is quite square, I'll have to measure it when I get home and see what I'm dealing with exactly. I think it's about 24' x 20', with twin doors that open up into my 12' x 14' or so office.

Brian

[noah katz]

How about putting the sub close to the listening so its nearfield output is relatively stronger than the room response.

[stidrvr]

How about putting the sub close to the listening so its nearfield output is relatively stronger than the room response.

That's what I had to do. I had to put the sub behind the couch where I sit. I have vaulted ceilings in my house and its rather open. That's why planning stages for a dedicated room in the basement are in effect