Otop 8 Power Calculations

[jHands]

Greetings. I am going to be building a pair of Otop 8's in the near future, but I have some questions about delivering power to them before proceeding.

I am aware of how to change the impedance to the amp with parallel vs series wiring the pair of 8's in the enclosure, but does the compression driver after the crossover alter the impedance at the amp?

How much power are people delivering to each of these, safely?

The Beta 8a is rated for 225w continuous power. If I deliver 450 watts to the enclosure, does this then get split into 225 to each of the drivers? I haven't found an amp to do this yet, but I am wondering if my math is correct.

How much power goes to the compression driver?

Noticed someone using a Crown XLS 1502, which delivers 525 watts per channel at 4 ohms. 262.5 is over the max of 225 to the drivers, but some of this has to be going to the compression driver to as well, no?

[Bruce Weldy]

I am aware of how to change the impedance to the amp with parallel vs series wiring the pair of 8's in the enclosure, but does the compression driver after the crossover alter the impedance at the amp?
It doesn't.


The Beta 8a is rated for 225w continuous power. If I deliver 450 watts to the enclosure, does this then get split into 225 to each of the drivers? I haven't found an amp to do this yet, but I am wondering if my math is correct.
Power ratings on speakers are thermal. Your concern should be excursion. That's based on the high pass crossover that you use. You can let 'em run naked or limit them. Unlike a sub, you'll hear 'em start to squawk if you are hitting them too hard. But, with 2 OT8s and 2 subs, the OT8s will outrun the subs with very little power. A crown XLS1500 would be plenty and give you some headroom.

How much power goes to the compression driver?
It gets the same voltage, but as frequencies rise, the impedance does too....meaning the wattage at the driver is much lower than the woofer sees. Don't worry about it.

Noticed someone using a Crown XLS 1502, which delivers 525 watts per channel at 4 ohms. 262.5 is over the max of 225 to the drivers, but some of this has to be going to the compression driver to as well, no?
Regardless of the amp you use, run it wide open and use the speaker processor (driverack) to balance the system by turning down the output of the processor. That way, no one can come up and spin up your amp and blow the speakers.

[jHands]

Regardless of the amp you use, run it wide open and use the speaker processor (driverack) to balance the system by turning down the output of the processor. That way, no one can come up and spin up your amp and blow the speakers.

Forgive my ignorance here, but the Driverack will be between the DJ equipment and the amps, correct?

[Bill Fitzmaurice]

How much power goes to the compression driver?
It gets the same voltage, but as frequencies rise, the impedance does too....meaning the wattage at the driver is much lower than the woofer sees.

Not quite. What happens is that the voltage is the same but power density decreases by 3dB per octave with increasing frequency. That's because the frequency points per octave doubles with each octave increase in frequency. So going from 100 Hz to 1.6kHz the power density drops by 12dB, which is 1/16th power. That's why a HF driver rated for 50 watts has no problem being used with woofers rated at 500 watts.

[Bruce Weldy]

Regardless of the amp you use, run it wide open and use the speaker processor (driverack) to balance the system by turning down the output of the processor. That way, no one can come up and spin up your amp and blow the speakers.

Forgive my ignorance here, but the Driverack will be between the DJ equipment and the amps, correct?

That's correct. It's the last control of the signal before hitting the amps. That's why you can run the amps wide open. The amount of signal reaching the amp will be determined by the Driverack.

[jHands]

Regardless of the amp you use, run it wide open and use the speaker processor (driverack) to balance the system by turning down the output of the processor. That way, no one can come up and spin up your amp and blow the speakers.

Forgive my ignorance here, but the Driverack will be between the DJ equipment and the amps, correct?

That's correct. It's the last control of the signal before hitting the amps. That's why you can run the amps wide open. The amount of signal reaching the amp will be determined by the Driverack.

Ok, so if the amps are wide open, and the driverack is limiting signal to the amp, the wattage is only what the driverack signal allows? I will be running this system off of a 300ah LiFePO4 battery through a 3000 watt renogy inverter. I am trying to run the system the most efficient way possible.

[Bruce Weldy]

Forgive my ignorance here, but the Driverack will be between the DJ equipment and the amps, correct?

That's correct. It's the last control of the signal before hitting the amps. That's why you can run the amps wide open. The amount of signal reaching the amp will be determined by the Driverack.

Ok, so if the amps are wide open, and the driverack is limiting signal to the amp, the wattage is only what the driverack signal allows? I will be running this system off of a 300ah LiFePO4 battery through a 3000 watt renogy inverter. I am trying to run the system the most efficient way possible.

The knob on the amp is an input attenuator, not output. The amp puts out what it puts out based on the input. So, whether you control the input from the driverack or the knob on the amp - it's all the same.

I know pretty much nothing about battery power, but I think you should provide the biggest power supply you can afford. If it's overkill in total power, then at least it will last longer. Right? Win-Win either way.