Help needed in working out how loud I can play

[bvan]

I'm want to use my current 4-way dipole setup to play at some small outdoor parties next summer, maybe only 50 people in a 'chillout' area so don't need to play super loud, but was wanting to have an idea of spl.

After I've build some Lab12 tapped horns the limiting factor is likely to be my mid/bass Beyma Liberty-8 with its small xmax of 2.5mm in OB.

Beyma Liberty 12" Guitar Speakers - Beyma Liberty 12" guitar speaker - Beyma Liberty 300 watt 12" guitar speaker for all high quality guitar applications. Beyma Liberty and other Beyma 12" speakers here.

Its in a 44cm wide open baffle. The highest I can highpass it is 180hz due to the cavity resonance of the Peerless XXLS ripoles that'll be playing +/- 100-180hz (with the tapped horns bellow). The ripole and TPL-150H upper mid should play loud enough I'm hoping….maybe 95-100db at 10m from speakers…or is that wishful thinking?

Luckily I can XO 8th order digital and I'll have more than enough power to give it.

Would someone be kind enough to walk me through calculating excursion at 180hz @300W with dipole Eq taken into account? Hoping I don't have to build boxes for these drivers.

Cheers
Bevan

 

[Dissi]

I can't explain how to calculate maximum SPL in OB. But my simulation program predicts the attached result for the Beyma Liberty in a 44x44 cm baffle at 10 m distance... 🙂

Excursion limit: +/- 2.5 mm
Power limit: 300 W

 

[bvan]

Thanks very much! That does kind of rule out OB. I think dipole loss will be 6db/octave from 770hz, so nearly 12db down. I think I'll have to build sealed boxes, and or get some of the more robust 12p80nds….

Cheers
Bevan

 

[Dissi]

That does kind of rule out OB. I think dipole loss will be 6db/octave from 770hz, so nearly 12db down.

No. I have to clarify, the simulation already includes the full OB baffle step, you don't have to subtract an additional dipole loss! It's WYSIWYG (what you see is what you get). 🙂

Obviously Xmax limits the maximum SPL below 160 Hz, but the Beyma is capable to produce 97 dB at 160 Hz/10 m in the simulated baffle. If the actual baffle is higher than 44 cm, you will even gain 1-2 dB.

Attached: Simulation at 1 m

 

[chris661]

I'd consider adding a pillow or two to the back of each driver. That'll absorb some of the rear-wave, giving you a bit more output.

Simulations would go out of the window, though.

 

[bvan]

That sounds like an idea worth trying Chris.

Thanks both of you.