Home Brew Al K Universal crossovers.

[laatsch55]

I was thinking a big 50 watt hearsinked 10 ohm Dale...steel cased...

 

[laatsch55]

Ok, got the crossovers fixed, but there was a casualty, the tweet..in the left cab is toast........wanted to get some CT 125's anyway...

 

[laatsch55]

Ok, the 4 --10 ohm seriesed/paralled resistors for the mids/tweets have to go. Is there a resistor that "sounds" better than another one??

 

[NavLinear]

Ok, the 4 --10 ohm seriesed/paralled resistors for the mids/tweets have to go. Is there a resistor that "sounds" better than another one??

I'm no expert but from what I've read if it's in the audio path than metal film or metal foil. What wattage resistor will this circuit require? That could limit your choices.

 

[laatsch55]

It's taken quite a bit f work to toast a 10 watter so I'm thinkin a 20 would last quite awhile....

 

[NavLinear]

It's taken quite a bit f work to toast a 10 watter so I'm thinkin a 20 would last quite awhile....

These are designed for high frequency applications but they have some desirable characteristics. Thinking out loud.

http://www.irctt.com/file.aspx?product_id=285&file_type=datasheet

 

[laatsch55]

I don't see a noise spec....

 

[laatsch55]

This may be as close as I can get...http://www.parts-express.com/mills-10-ohm-12w-non-inductive-resistor--005-10

 

[laatsch55]

Check these out...http://www.soniccraft.com/mills_resistors.htm

 

[NavLinear]

Those look sweet Lee.

 

[NavLinear]

Or two of these in parallel.

http://www.parts-express.com/mills-20-ohm-12w-non-inductive-resistor--005-20

 

[laatsch55]

Yep, I think Joe had mentioned at one time perhaps I should increase the value of said resstor too. I have put a 4.7 uf cap in front of the resistor, as per Joe's recommendation, to filter out a lot of the low frequency energy seen by this part of the crossover and it's helped, I mean at least we are not melting solder anymore...

 

[laatsch55]

Gotta get some sleep. Lat big push on the paperwork before the audit Tuesday...

 

[NavLinear]

Gotta get some sleep. Lat big push on the paperwork before the audit Tuesday...

Good luck with that Lee.

 

[laatsch55]

We also changed the Inductor on Tims Soni's from 1.3 uh to 2.7uh and they are sounding pretty good.

 

[laatsch55]

Joe, how does a roll of wire (inductors) limit frequencies??

 

[Gepetto]

Joe, how does a roll of wire (inductors) limit frequencies??

PFM Lee...

Seriously, good question.

An inductor stores energy in the magnetic field it produces. It gives that energy back when the magnetic field collapses. An inductor resists and instantaneous change in current through it similar to a capacitor resists an instantaneous change in voltage on it. When a change in current through an inductor occurs, the associated increased generation of the magnetic field produces a back EMF effect that opposes the voltage impressed on the inductor and therefore resists the increase in current in the inductor windings.

The fact that higher frequencies driven into any resistive load have a higher di/dt tells you that the change in current is closer to instantaneous at high frequencies than at low frequencies. This higher di/dt associated with higher frequencies is why an inductor blocks high frequencies and passes lower frequencies.

I hope my explanation gets you closer to understanding how an inductor (that roll of wire) works.

 

[laatsch55]

Closer....still a lot of fog out there though....

 

[laatsch55]

So , how they are wound and what they are wound with is a science unto itself ??

 

[laatsch55]

di/dt------change in current/change in time??