Crossover point Orphean (Orphean)

by Kevin @, Minneapolis, Monday, December 09, 2013, 21:19 (1498 days ago)

I noticed on the BMS Driver website they listed the Freq. range of the Driver from 300hz. Can you tell me how you arrived at 270 hz. for the crossover point?

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Crossover point Orphean

by Bert @, Tuesday, December 10, 2013, 05:41 (1498 days ago) @ Kevin

I noticed on the BMS Driver website they listed the Freq. range of the Driver from 300hz. Can you tell me how you arrived at 270 hz. for the crossover point?

Under normal conditions this would be the minimum frequency and probably even too low (think 130dB!). In the PA world those drivers need to play a whole lot louder than under domestic situations. This gives for us in combination with a dedicated horn design for proper loading the option to go lower without too much increased distortion due to the extra headroom available.

My rule for the lowest ground frequency possible for a horn with good efficiency:

\frac {fc}{2}
where fc is the resonance frequency of the driver seen as system. For the BMS this would be:

fc=\frac{360}{2}=180
as lowest possible frequency for high efficiency...

Another rule for the lowest possible useable crossover frequency is:

\sqrt{2} \times fc=255
where fc would be the ground frequency of the horn in this example.

I can't go lower than 270Hz with the Orphean as it is. For that I will need a bigger and longer horn. I am have plans to extend the Oris 150 (preparations are already made) and use the BMS on that horn a see what that will bring (if time permits to work on it soon again). I do expect a smooth response down to 210Hz (with some EQ of course) from that combination.

Bert

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BD-Design - Only the Best!

Crossover point Altec 288-16K

by Kevin @, Minneapolis, Tuesday, December 10, 2013, 13:48 (1498 days ago) @ Bert

I was wondering, in your opinion, how low I could safely cross over my Current Drivers on my Midrange horns. I am using the Altec 288-16K drivers with Altec 1005B horns. I am currently running them from 400hz. to 6,000 hz. I am using either 45 tube amp (1.8 watts) or 2A3 tube amp (2.3 watts).

Horn Specs are

[image]


Driver Specs are here: Altec 288-16K Driver

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500Hz...

by Bert @, Tuesday, December 10, 2013, 14:02 (1498 days ago) @ Kevin

I was wondering, in your opinion, how low I could safely cross over my Current Drivers on my Midrange horns. I am using the Altec 288-16K drivers with Altec 1005B horns. I am currently running them from 400hz. to 6,000 hz. I am using either 45 tube amp (1.8 watts) or 2A3 tube amp (2.3 watts).

Below 500Hz the drivers are not loaded at all according to the specifications on the list you provided (no resistance to highly reduce diaphragm movement and increase efficiency) meaning that distortion will get very high. The drivers will not burn out with 2.3Watt at 400Hz but playing below the horn cut-off frequency is never good...

\sqrt{2} \times fc=1.414 \times 500 = 707
where fc would be the 500Hz ground frequency of the 1005B horn ... for highest efficiency and lowest distortion (no matter which driver is used)

Bert

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BD-Design - Only the Best!

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