Crossover build help info

[Lukey123]

Hi everyone, I’m trying to workout what components I need to build a passive crossover, this will be my first attempt at anything like this so any help or info would be helpful and appreciated..I do have a general idea.

I’m trying to build a passive crossover for a modern day version of a Turbosound. TSE 111... 10” mid and 1” compression drivers, @ 8ohm With modern day Neo drivers..

10” mid crossed over to the HF driver at 4khz @ 24db per Octave 8ohm

10” : 200hz - 4khz
1” : 4khz and up

I want to be able to power the cabinet with a single speakon Cable from the power amp, and not have to worry about anything else..

What value components would I need to get a 24db per octave @ 4khz ???

Also how do I stop the amplifiers full power going to both drivers At the same time ??? obviously the HF compression driver isn’t rated at the same RMS power as the Mid bass woffer

Original turbosounds were rated : 10” mid 200w RMS
1” HF 75w RMS

The mid driver I’m considering is a Precision Devices PDN.10MH25 - 10".. or Fane Sovereign Pro 10-300 - 10" I haven’t found a HF driver yet. Any recommendations?

This is all theoretical at the moment and months away from actually being built, but wanted to start getting things ready before I get into the big heavy bits...

Thanks
Luke

 

[AllenB]

how do I stop the amplifiers full power going to both drivers At the same time ??? obviously the HF compression driver isn’t rated at the same RMS power as the Mid bass woffer

It won't, the crossover splits it. Then if the tweeter is more loud than the woofer you can reduce it further using resistors.

 

[Lukey123]

Thanks. What I meant was, how do I stop the HF driver blowing. For example say I have a 500w rms power amp, a 400w rms mid driver and a 100 Rms HF driver with a max peak power rating of 150w.. obviously if the full 500w of the power amp hits the HF it will blow it.. how do I direct the right amount of power to each driver not to overload either. ?

 

[AllenB]

Unless you're planning to play a 5kHz tone at 500W? There isn't much of the total energy at 4kHz and up at 24dB/oct, and it will be very loud way before you reach anything near that.

Is this for domestic use?

 

[Lukey123]

Ah right ok I see, makes sense now....

No it’s for live sound, I’m trying to get my sound company off the ground and building my own is the only way I can afford to get into a Old school fully horn-loaded system, witch is my end goal..

 

[Galu]

What value components would I need to get a 24db per octave @ 4khz ???

You may use this calculator to obtain the circuit and circuit components for the high pass section of your crosover.

ERSE - Crossover Calculator - Fourth Order 2 Way

Use the nearest commercially available component values to the theoretical values displayed by the calculator.

 

[Galu]

Original turbosounds were rated : 10” mid 200w RMS
1” HF 75w RMS

Just to make sure you have understood the power distribution in a two-way loudspeaker system:

Below 4kHz around 80% of the total amplifier power goes to the bass/mid driver.

Above 4kHz around 20% of the total amplifier power goes to the treble driver.

So you see, the treble driver can have a much smaller power handling rating than the bass/mid driver.

 

[AllenB]

So following on if the tweeter is more sensitive than the mid (generic guess 10dB) you might use resistors around the tweeter to reduce its input. Assuming that you do touch on 500W occasionally, the tweeter would be venturing to 10W (normally much less). (Unless you run the amp up into clipping and the distortion harmonics invade the treble region)

 

[Lukey123]

Ah thank you that link is really really helpful. Yeah I completely get get it now, I just assumed there was some kind of wattage / driver protection circuit built into the crossover as a safe guard. Also because a lot of pre made crossovers have wattage ratings .

 

[Lojzek]

Ocassionally you will find in hifi speakers PTC (positive temperature coefficient) element in series with a tweeter to protect it from too large a current.