Speakers with a built-in axis tilt

[Buckeye Amps]

I am nearing the completion of my theater build and the last thing up to do is build the false wall (using an AT screen). However a slight wrinkle is that the speakers I am using employ a built-in 10 degree down tilt of the speaker axis. They are JBL Pro Cinema C211's

If I place the speakers as suggested by JBL, the bottom of the speakers would need to sit 7ft off the ground (MLP is 20ft from speaker and ear height is 44" off the floor, so quick right angle calculation says the speaker height has to be 40" higher than the ear height, as the tweeter on these are near the bottom of the speaker).

Since the ceiling is only 9ft tall and the speaker itself is over 30" high, this isn't doable. Plus I wouldn't want the speaker to be right up against the ceiling due to interaction/acoustics.

My first thought was flipping the speaker upside down so it now has a 10 degree up tilt. However JBL (when I ask them) said they can't say if this would work well or not.

The other though was placing the speakers the normal position but using wood shims to give them about a 10 degree up tilt, making the actual axis response flat and then I can place them at a reasonable height so the tweeters are in line with ear height of the MLP.

But I am not sure if I am either over thinking this or misconstruing if the built-in 10 degree axis tilt of the speaker is something I can overcome with simple geometry fixes such as changing speaker orientation or changing the actual physical angle of the speaker cabinet.

Any thoughts/advice?
Thanks!

 

[droid2000]

If it's relatively easy, I'd flip them upside down and give them a listen. You'll probably be able to tell right away if they sound ok.

 

[Buckeye Amps]

If it's relatively easy, I'd flip them upside down and give them a listen. You'll probably be able to tell right away if they sound ok.

Unfortunately not easy, as I am building the speaker stands to use from scratch and need to know ahead of time what height I need to build to

 

[Chesapeake HT]

Can you build your stands with a removable 10deg shim? Then could at least play with that variable.

 

[Buckeye Amps]

Can you build your stands with a removable 10deg shim? Then could at least play with that variable.

Yes but the height would not be correct if the shim doesn’t end up working

 

[alex-z]

Looking at the C211 polar patterns, the 10 degree tilt seems to be a recommendation in order to avoid an on-axis response dip at 1800-2000Hz. I see no reason why you couldn't point them directly on-axis with shims, provided you alter your DSP settings to compensate.

 

[fineMen]

Looking at the C211 polar patterns, the 10 degree tilt seems to be a recommendation in order to avoid an on-axis response dip at 1800-2000Hz. I see no reason why you couldn't point them directly on-axis with shims, provided you alter your DSP settings to compensate.

Most probably you assist yourself with a measurement microphone. If not, then this is the time to get one at hand. You need to scan the vertical radiation in situ with experimental setups, and that will tell eventually. Theoretical deductions won't help, I'm afraid.

 

[nstzya]

Is the “JBL recommended height” really 7 feet? My vote is the variable shim. KISS

BTW, for what it’s worth (in response to the title) my Meridian DSP active speakers have a DSP selectable axis tilt - I hear very little difference when I adjust it.

 

[Buckeye Amps]

Is the “JBL recommended height” really 7 feet? My vote is the variable shim. KISS

BTW, for what it’s worth (in response to the title) my Meridian DSP active speakers have a DSP selectable axis tilt - I hear very little difference when I adjust it.

Based on the math, the bottom of the speaker would need to be 7ft (as the compression driver is on the bottom).

I already put the speakers up and am using shims to tilt. Sounds great so far with some testing.