CD dipole wave-guide - which cut-off to aim for?

[Audiodidakt]

Hi

I am doing some simulation on a dipole wave-guide for a Mundorf AMT. By having a wave-guide, I hope to have constant directivity further up in the frequency-range than the dipole peak will allow the naked AMT to be uniform.

High pass shall be to a nude Scan-speak Illuminator 18WU, which is having its dipole peak around 1700 HZ. This is where the AMT and SS will have cross over.

My question is:
What cut off should I aim for with the wave-guide? Should I aim for 1600 Hz or go to one octave below XO, i.e. 800 Hz? Or maybe somewhere in the middle, say 1200 HZ?

(Due to WAF I would like to have as shallow wave-guide as possible, but not if this means inferior SQ)

I will be usin MiniDSP for crossover

Best regards

Gisle

 

[moep]

Lower would be better and to cross at 1700 you would need a pretty big waveguide anyways, for example Daytons 10" waveguide [0] (just to give an idea of the wg size) operates down to 1.6KHz so you could also use an slightly bigger wg and cross at ~1Khz (the waveguide size will be limit how low you can go).

On the other hand the 18WU will have a hard time reaching low enough to cross to the low end, so after all it would be easier to go 4 and use a smaller wg or other high frequency options?

For the price of the Illuminator and the Mundorf you can by allot of electronics to go 4way.

[0] Dayton Audio H10RW 10" Round Waveguide 1" Threaded
[1] Dayton Audio H12RW 12" Round Waveguide 1" Threaded

 

[dumptruck]

For 1.7kHz constant directivity, you really want control down to around 1kHz.

edit: actually, let me qualify that:
In my experience with several constant directivity waveguides that each work down to about 1kHz, all of them quickly become difficult to work with below ~1.5kHz crossover points. That's the only thing I'm basing my recommendation on.