Subwoofer prodcues WAY more bass when I press on the speaker (unorthodox setup)

[Shlink]

Im using a subwoofer box I made myself years ago for a car, now hooked up to my computer speakers using an old PSU to power the amp. The sub speakers are old JBLs that I found being discarded at a tradeshow. They are maybe 12" (x2).

The speakers sound alright most of the time, if I turn them way up I do get some buzzing. However I noticed that if i gently press on the speaker (hard enough that I'm not just dampening vibrations, but actually building up enough air pressure inside the box so the other speaker pushes out a little bit) the bass sounds get much cleaner and probably about 3x-4x louder.
Does anyone have a clue as to how I could make them sound like this all the time? Is my box supposed to be under air pressure on the inside? (lol I don't think so)
Is it possible adding holes for air ports would do something?
The two speakers are NOT in separate air chambers, they share the same box. While typing this I'm wondering if that could have anything to do with anything.

Any insight would be appreciated, and I could also upload some videos of what I'm talking about if you'd like some clarification.

Thanks in advance!!

 

[j_garcia]

Do you have any polyfill inside the cabinet?

 

[Shlink]

Do you have any polyfill inside the cabinet?

Negative. There is no polyfill. Just air.

 

[funky waves]

Its possible you have them wired out of phase, so when they are playing they are canceling each other, when you stop one cone the cancellation is reduced.

 

[Shlink]

Its possible you have them wired out of phase, so when they are playing they are canceling each other, when you stop one cone the cancellation is reduced.

huh, you're on to something here!
I tried unplugging one of the speakers and it had a similar effect.. not quite as clean as when I put pressure on one, but still much improved.

The amp has two ports for speakers, and I'm realizing now that I'm not really sure what the proper set up is, but having both speakers on the same terminals has resolved my issue.

I've attached an image of the LCH and RCH speaker ports, maybe someone can explain them better to me.
Interestingly enough the speakers worked as well as they do in the pictured orientation, while they were wired to the middle two ports (which appear to both be negative, so I'm not really sure whats supposed to be where anymore)

Anyway, they're working now.. and if anyone wants to explain to me why they didn't work while using both 'channels' that would be cool.

 

[funky waves]

Does the amp have a switch for bridged mode?

 

[Shlink]

Hm, I don't think so, these are the only switches.