Choosing an SVS sub

[Steve42]

I used to think that too, but having 3 subs in this room, all with the same null and then switching to my current beast and having it go away, I'd have to say that it may be a bit more accurate to say that it is how a particular sub interacts and its placement within that room that has a lot to do with it. The former subs were 1 down firing, side ported, and 2 front firing, front ported; the current one is downfiring, top ported (and considerably larger than any of the others).

Very interesting. In my current room over the past 7 or so years, I've had somewhere around 15 different subs of ALL types, sealed, ported, PR based, downfiring, forward firing, etc. etc. And with every single one there is a steep null at 28Hz at the same listening position. It varies maybe 2-3dB depending on the placement and the sub, but as long as the place I measure stays the same (at the listening position) that is all the varience I have. Sure sub design and placement will have some effect, but a null of this nature is pretty much all about the room. Now if I were to place my SPL meter a couple of feet to one side or another or forward, that null goes away. the physics and the dimensions of the room do not change with different subwoofers. Now subs themselves can have FR anomolies, like boosts at certain frequencies and holes in others depending on the design, but these are not true nulls and peaks that are caused by room dimensions and the location of the listening position in relationship to those room dimensions. My guess is maybe the sub you have now has a little boost at the "null" frequency you experienced with your other subs. That and/or your listening/testing position changed a little. Again different subs cannot change the physics that are invloved that will effect the freq. response of a room based on it's dimensions. Things like Bass traps can help, as well as other room treatments.
Just ask someone like Mark Seaton or Ethan Winer of Real Traps.

 

[j_garcia]

I realize that the room is normally responsible for the null. That is based on the wavelengths and the room's dimensions and that will not change significantly with placement etc..., but like you said, it is most likely that this sub just happens to be a good fit for the FR of this room and my listening position. It is phyisically the same location for each sub, because I really only have that one spot available. The LP has not changed, but I do have the same thing as you - if I take a reading 2ft in any direction, the null is significantly diminished, likely because the LP is near the center of a nearly square room.

I did actually have one thing that changed however, and that is a 6' cloth screen around a light in the opposite corner of the room which may inadvertently be acting as a sort of bass trap and helping with the null as well.

 

[Steve42]

I realize that the room is normally responsible for the null. That is based on the wavelengths and the room's dimensions and that will not change significantly with placement etc..., but like you said, it is most likely that this sub just happens to be a good fit for the FR of this room and my listening position.

My point is that a true null (or peak for that matter) is a result of the room. I think our definiton of what a null is might be a little different. When I'm talking about a bad "null", usually, I'm talking about a very narrow and steep dip in the FR that is somewhere around 10-15dB. I realize some subs are going to be a better match FR wise for a given room due to it's own FR. I can see a different sub helping with maybe as much as a 4-5dB "dip" in frequency compared to another sub. But to solve a narrow, steep "null" like 10-15dB, I just don't see that happening. Maybe something like that screen did impact it somehow, or maybe something else. And like I said before perhaps you are not talking about the same kind of "steep" null I am talking about.

 

[Quant]

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What's your price limit? If you can afford $1400 and can stand a 17" cubed sub, I know of one that can fill that room, and you won't be able to bottom out the driver or hear any port noise (it's not an SVS though).

What sub is that you would recommend?

 

[Steve42]

I'm talking about the Earthquake MKV-15. Just do a search on MKV-15 in this forum, and you'll get plently of info.

 

[j_garcia]

Maybe something like that screen did impact it somehow, or maybe something else. And like I said before perhaps you are not talking about the same kind of "steep" null I am talking about.

Nope, we're not talking about the exact same thing. I don't have any -10 to -15dB nulls, just a 5-6dB "dip" at that one point. I understand what you are saying though.