Query - DIY crossover

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captJackSparrow

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Joined 2015
#1
Hi,

I am building SB12.3, collecting all components and have queries around crossover
Zaph|Audio - SB12.3 3-Way Tower

If you look at above URL requirement is L22 = 4mH and internal resistance R23 = .21 Ohm, whereas the inductor i found locally has internal resistance .83 Ohm

1. So what options do I have, How much component values can vary in a crossover before impacting sound.
2. Can we compensate such requirements and how.
3. Regarding resistor, how do I calculate wattage of any resistor in crossover?
P=V*I
What will be V and I in this case


example
R0 - 2.35 Ohm
R14 - 12 Ohm


I am also looking for a local source of thick copper wire, if I find reasonable and trustable source i'll wind my own.
 
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#2
If you check the FAQs you will see that L22 is a steel laminate core inductor. This uses a smaller length of wire to achieve the required inductance than an air cored coil does and hence has a smaller resistance than an air core coil of the same wire diameter.

Generally, 10W resistors are adequate in the mid and treble sections of a crossover where the power involved is only a fraction of the total system power.
 
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#3
Galu said:
If you check the FAQs you will see that L22 is a steel laminate core inductor. This uses a smaller length of wire to achieve the required inductance than an air cored coil does and hence has a smaller resistance than an air core coil of the same wire diameter.

Generally, 10W resistors are adequate in the mid and treble sections of a crossover where the power involved is only a fraction of the total system power.
Click to expand...
Thanks a lot, didn't notice it was core inductor. Can L18 also be iron core, does it make any difference steel vs Iron core?

What about resistor for woofer.

As for resistor wattage, how do we calculate V and I. Speaker is a load so it will draw only power it needs, right?

Amplifier is 50Watt per channel F5TV2.
 
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#4
captJackSparrow said:
What about resistor for woofer?
Click to expand...
The low frequency voltages are developed across C25/R25 and these deliver the low frequency power to the woofer. Little power is developed in R25 so 10W is adequate..

You are worrying needlessly with a 50W amp - no need to do wattage calculations. The tweeter will pull around 10% of the system power (5W) and the mids probably around 20% (10W). So 10W resistors are adequate for the majority of domestic crossovers.

P.S. I'll have a look at L18.
 
#5
I would use air core coils in the treble and mid sections (including L18). This is because iron cored inductors can introduce distortion which can be noticeable at these frequencies.

However, iron core distortion is less noticeable at bass frequencies so is often used to save copper in bass inductors..

A laminated steel core reduces eddy currents in the core making it superior to a solid iron/steel core.
 
#10
Crossover Cap feedback

Hi All,

For Zaph SB12.3 crossover, C10 = 150 microF(recommended Solen).

-I don't want to spend that much on a Solen 150 mfd capacitor, can you please recommend alternative MKP cap 150 microF at a reasonable price.

-For some other caps recommended in crossover schematic of SB12.3, I am replacing them with easily available caps(Dayton crossover caps and Jantzen-Audio lower end/cost/base model MKP caps). Can you please let me know how these caps are in terms of quality, since I have always used Panasonic and other known cap brands so I am not sure about quality of Dayton and Jantzen-Audio. Are they relabelled caps or they make them themselves?

Thankyou
 
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