Sub position(s) and Decay

[Gordon Palmer]

I have experimented with basic REW functions for a while to set up my subs.
I have had reasonable success using REW and Minidsp to get an acceptable freq response curve.
I am now looking at improving the "attack" of the bass which I see from posts here is related to (among other things) the decay function.
If bass trapping is not an option I was wondering if the proximity of the sub(s) to the MLP has an effect?
Volume reduces with distance from source and decay is "reverberations" so it seems to me the closer the subs to MLP the (relative) less effect from reverb since the direct wave will be relatively stronger than the echo?
So subs within (say) 1.5m of the MLP would be inherently perceived as less "boomy" than those positioned in the front corners (4m away)?
Please excuse my use of terminology I'm not that technical.
Does this have any basis in reality and are there other alternatives to bass trapping?
I've looked at the decay plot for my current sub setup but not sure if it's good,bad or something in between
Any comments appreciated - lines are at 240ms and 480ms

 

[John Mulcahy]

A sub nearby may mean less room influence, but may also mean a reduced bass extension if away from boundaries. Perception of bass is probably more related to the frequency response than the decay behaviour, but slow decays generally go hand in hand with peaks in the response. Probably best attaching the mdat of the measurement to allow people to comment on it.

 

[Gordon Palmer]

Attached

 

[John Mulcahy]

You seem to be measuring at dangerously high levels, about 30 dB louder than needed. Hope you are out of the room or wearing hearing protection when measuring.

The response is fairly even to 80 Hz but then gets pretty erratic. There wasn't any output device or output selection, beyond "L+R", if you were driving both mains as well as the sub probably need to look at the integration between sub and mains.

 

[Gordon Palmer]

Thanks. I think I had the mike setup incorrectly. I wasn't testing at those levels.
I've rerun everything and happy with result.
One quick query...REW gives me option to test all 5 individual speakers but I can't see how I measure the whole system?

 

[John Mulcahy]

There isn't an option to drive all speakers at once, nor any point to that really. L+R is offered though. If you measure individually with a timing reference you can use the trace arithmetic features on the All SPL graph to add up the responses and see how it would look with all playing the same signal at the same time.

 

[Gordon Palmer]

OK thanks I'll have a look