[Mike-48]

You did it right -- as long as you were listening for the null at the main listening position -- not at the sub.

[MONKEYWICKEDMONKEY]

You did it right -- as long as you were listening for the null at the main listening position -- not at the sub.

Damn. Hahaha ok I guess I have to do it again.

[Mike-48]

That's why it's easier to put a mic at the MLP, run the sweeps, and look at the response on a laptop, which you can have near the phase control. Easier, but not the only way. Maybe you have a helper who can turn the knob while you listen?

[MONKEYWICKEDMONKEY]

That's why it's easier to put a mic at the MLP, run the sweeps, and look at the response on a laptop, which you can have near the phase control. Easier, but not the only way. Maybe you have a helper who can turn the knob while you listen?

I’ll see if my kiddo can help.

[DBC]

The bottom graph looks better than the top. Keep in mind we're only really concerned from teh crossover frequency on down, usually around 80Hz or so. What it does above there is less critical.

If you have 2 subs, there are some strategies you can use to use cancellations in your favor to get a flatter response. Details in this article on my blog.

I've not read through this entire thread so my apologies if someone else has already addressed this.

I had twin 15" HSU Sealed Subs for quite a while in my 2-channel music system. I eventually realized that a lot of my room peaks and nulls were caused by the subs exciting the walls and or floor causing all kinds of havoc in the lower frequencies. Once the walls and or floors start vibrating they produce their own low frequency pressure waves.

I found that Auralex SubDude isolation platforms effectively isolate forward firing Subs from the floor. In my case the subs were exciting the floor (vibrating) and those vibrations extended out to and up the walls. The isolation platforms eliminated that problem and I started to get much flatter low frequency room response.

https://www.sweetwater.com/store/detail/SubDudeHT--auralex-subdude-ht-subwoofer-isolation-pad

I also found that downward firing subs are worse yet (get them on isolation platforms). Even once you get them on isolation platforms you have to be careful about how close you place them to walls. Since they fire down & out, then can cause an adjacent wall to begin vibrating and that will travel to the floor and other walls. In my case if I had them 12 or more inches from the wall they would not excite the wall.

[Digi-G]

Someone earlier said that corner placement will maximize bass output of a sub.  That is true.  Even the manufacturer of my SVS sub recommends corner placement.

However, my experience, with 2 different subs in 2 different rooms, corner placement excited room modes and it wasn't pretty.  In both cases I got a massive hump around 40-45 Hz that couldn't be tamed.  I've had better luck placing my single subwoofer midway along a side wall.  But like everyone is saying - experiment.  YMMV.