Off axis response of inner-baffle mounting a small woofer

[mattlong8]

Greetings,
I am working on a small stereo 3-way unit (boombox I guess). The mid-woofers are 2" in diameter and I'd like to not use a grill. So, in order to protect them a bit I'd like to mount them inside the 1/2" thick baffle. I plan on using either a simple round over, 45 chafmer, or some combination there in(like smoothing the end of the chafmer). I'm going for a wide dispersion pattern an have chosen the 2" as well as TB 1/2" soft dome for the tweeter to minimize beaming. The 2" will be covering(roughly) 150-4000Hz and the tweeter will be mounted as close as practical.

An externally hosted image should be here but it was not working when we last tested it.

(This was a test box I made to evaluate the design/drivers. please ignore my poor attempt at treating the 2")

Questions: Is it likely that I will lose off axis response in the upper end of the 2"? Will the proximity of the tweeter to the inset in the baffle cause problematic ripple? If so can it be compensated for like baffle step(probably not since it's asymmetric?

My guess is the effects will be hard to predict and pretty subtle. Does anyone have a guess? I know Dave and Earl have done things similar but I haven't heard any of their speakers that do this.

Thanks in advance,

-Matt

 

[weltersys]

The 2" will be covering(roughly) 150-4000Hz and the tweeter will be mounted as close as practical.

Questions: Is it likely that I will lose off axis response in the upper end of the 2"? Will the proximity of the tweeter to the inset in the baffle cause problematic ripple? If so can it be compensated for like baffle step(probably not since it's asymmetric?

Matt,
It is easy to predict that a side by side mounting between the tweeter and midrange will cause large off axis horizontal response dips and peaks around the 4K crossover based on their center to center distance.
Mounting the tweeter vertically over the mid would eliminate that problem from the horizontal plane.

Compared to that, the diffraction from the round overs would be a subtle difference.
I'd suggest a 45 degree chamfer and then smoothing the transition to minimize diffraction.

Art

 

[mattlong8]

Hey Art,
unfortunately there isn't room for vertical orientation so I figured diagonal is a good compromise. Also vertical coverage is about equally important as horizontal.
Heres a rough model:

An externally hosted image should be here but it was not working when we last tested it.

The distance between the centers, not counting the depth offset, is about 1.5". Any closer and it will be in the chafmered part...hmm I might be able to work out something cool looking but I really want the tweeter flush on the front so it spreads out nice and wide.

You still think comb filtering will be a problem? Its not too late for me to adjust, It would be pretty dumb of me to ask if it was.

Thanks for the help, you always come through for me

-Matt

 

[weltersys]

Hey Art,
unfortunately there isn't room for vertical orientation so I figured diagonal is a good compromise.

You still think comb filtering will be a problem?

Matt,

Comb filtering and diffraction are only "problems" when you listen critically .
Judging by the size and shape, it does not appear you are going to be using this box as a studio monitor...